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USER'S MANUAL FOR CORHYD: AN INTERNAL DIFFUSER

1. R 180 velocity after bending where D is the pipe diameter and R the radius of the bend Often applied as R 3D Delta is the angle of the bend e g 90 for rectangular bends Code see files CommonFeederPipe m feederpipes m DiffuserLosses m Losses common feeder m Friction due to bend Idelchik 1986 24 E witht o R f UD D 1809D Division of Idelchik 1986 flow Ap a 2 Ap Gest ON 2 K y 4 from Diagram 7 15 geen from Diagram 7 17 Idelchik 1986 or Annex chapter 10 Curves fitted by the following code Determination of zeta in the following zeta double underline c s vRatio q 1 Ar 1 sum q 1 1 q 1 Ad 1 if Dr 1 Dd 1 lt 2 3 zeta c s 0 7956 vRatio 2 0 2732 vRatio 0 956 elseif Dr 1 Dd 1 zeta c 0 3 2 1 else dif 1 Dr 1 Dd 1 1 2 3 zeta c s 0 3 2 1 dif 0 7956 vRatio 2 0 2732 vRatio 0 956 0 3 vRatio 2 1 end Determination of A from Idelchik Paragraph 15 aRatio Ar 1 Ad 1 qRatio q 1iy sum q 1 1 q 1 if aRatio lt 0 35 amp qRatio lt 0 4 Azeta 1 1 0 7 qRatio IH Institut f r Hydromechanik Universitat Karlsruhe 16 An elseif aRatio lt 0 35 amp qRatio gt 0 4 Azeta 0 85 elseif aRatio gt 0 35 amp qRatio lt 0 6 Azeta 0 65 qRatio else aRatio gt 0 35 amp qRatio gt 0 6 Azeta 0 6 end zeta c s A
2. eerta roro pt ertet MIN ee MN EUR 39 4 5 Additional local losses eub menu nennen 40 AG Blocked porns SUD tBle E 4 4 7 X or T diluser SuD HiGIUS E 41 SNE GE LE 43 5 1 JELE Oc sues nestles 43 2 TE RIC A OUI s oeste redii MI UM sects IN EIU 44 6 Design and optmtzatpon 46 6 1 E3rduture le EE 47 062 JBoundar EEGENEN 48 6 3 EEN 50 6 4 CTS EVM Ay ALY SIS ee ierant n EON I adu KCN DU IIa PINE DUNS 50 E E 32 7 1 Ipanema Rio de Janeiro e E WE 22 7 1 1 IR ae 0 100017421 58 7 2 Berazategui Buenos Aires Argentina 68 AME aei S 72 JEMEN 72 10 undo de HI 76 Institut f r Hydromechanik Universitat Karlsruhe 1 10 1 Local loss formulations Division of flow Odelchk 76 10 2 Local loss formulations Orifices Idelchik 79 Institut f r Hydromechanik Universitat Karlsruhe 2 Glossary Table 1 Summary of parameters Parameters are used with the following major indices d diffuser pipeline section p port pipe j jet Parameter Dimension Definition kg m average density of ambient water body De kg m average density of the effluent A n pipe cross sectional area B m equivalent slot w
3. 0 2 4500 5000 5500 6000 6500 7000 7500 2 00 5000 5500 6000 6500 7000 7500 Distance from shoreline x m Distance from shoreline x m Headloss port riser Headloss port riser m I Kass ce e 4500 5000 5500 6000 6500 7000 7500 5000 5500 6000 6500 7000 7500 Distance from shoreline x m Distance from shoreline x m E e 0 05 ae C Port diameter e Port diameter m Velocity per port m s Velocity per port m s I in ce 5000 5500 6000 6500 7000 750b 0 5000 5500 6000 6500 7000 750b Distance from shoreline x m Distance from shoreline x m P a e e ity per jet m s en o Velocity per jet m s en e o gt n 0 gt 4500 5000 5500 6000 6500 7000 7500 4500 5000 5500 6000 6500 7000 7500 Distance from shoreline x m Distance from shoreline x m w E w SS E 3 4E 55 2 5 8 DN E 0 SSS KS 3 3 ritical velocity sedimentation TZ WY m E 5 S 3 E 0 T HA ZEE A 4588 BB BSBA e Distance from shoreline x m Distance from shoreline x m Q 16 75 mVs TH 12 3347 m G 1575 ms TH 14 3405 Gs 20 1 ms IH 1 Or 20 1 miis TH 15 9624 De 23 45 m s TH 15 3969 22145 TH 17 7677 8 mvs TH 17 1841m 26 8 miis TH 19 7851 3 15 TH z 198 Ae 335 TH 21 254m
4. Expansion Sudden expansion Idelchik 1986 Reference velocity 15 V1 Ga see files CommonFeederPipe m feederpipes m DiffuserLosses m Losses common feeder m Gradual expansion Idelchik 1986 2 t 2 8 2 ten 4 tanP 1 A 2 2 with p in rad Av ALN For B gt 50 the formulation for gradual expansion leads to a greater loss coefficient than the one for a sudden expansion Therefore Idelchiks formulas was adopted so that for gt 50 losses are equal the loss for B 50 Code see files CommonFeederPipe m feederpipes m DiffuserLosses m Losses common feeder m Contraction Sudden contraction Idelchik 1986 Reference velocity is esos 4_ Pe V2 Code see files CommonFeederPipe m feederpipes m DiffuserLosses m Losses common feeder m IH Institut f r Hydromechanik Universitat Karlsruhe 15 A Gradual contraction Idelchik 1986 0 0125 Ny 0 0224 ny 0 00723 n 0 0044 n 0 00745 p 2nf 10 with _ 4 219 and in rad 1 For gt 50 the formulation for gradual expansion leads to a greater loss coefficient than the one for a sudden expansion Therefore Idelchiks formulas was adopted so that for gt 50 losses are equal the loss for B 50 Code see files CommonFeederPipe m feederpipes m DiffuserLosses m Losses common feeder m Bending Bend Kalide 1980 reference s velocity Ge 0 131 0 159 2
5. IH Institut f r Hydromechanik Universitat Karlsruhe 18 Vo p V DN a down down 5 NE 2 2 2 down A similar modification is implemented for additional entered local losses If the loss relates to another reference velocity than the one found in the segment described by the given diameter of the Port D the coefficient is multiplied by the ratio of the two velocities Va where V gg is the needed related reference velocity for the given local loss coefficient and V the velocity due to the given port diameter However when entering the loss coefficients the user usually does not know the discharge through the port and therefore does not know the velocity either But the discharge through one port does not change when reaching a different segment of this port Therefore instead of velocities the modification can be done regarding the flow devided by the areas 2 di 2 B __ 6 a dd orig E dd orig 2 orig 2 add orig 2 V A is the original local loss coefficient and A is the related area If there are bom orig where several known additional local losses each is determined separately modified if dd orig necessary and then the sum of all losses is entered into the designated space Using this method very complicated port riser configurations can be calculated with the prog
6. s 018 gt 0 05 5 E i m amp 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Doo 3900 3950 4000 4050 4100 4150 4200 4250 4300 e distance from shoreline x m distance from shoreline x m x 4 225 E Bs 0 15 5 2 0 15 0 1 u 215 D 1 2 ony ae 0 05 E 5 HH Li ilill 13 0 5 ME 5 z o jc 50 I LLTEELEEEFLELLEEEEEELEEEEL OT EFL EET en mr 0 5 D UI II LELTTI TT Sr 0 gt 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x rn distance from shoreline x m 3 2 z gy 25 25 15 2 2 3 1 5 1 5 E S 1 KE gt ua gt oa 51 15 5 15 t 0 5 B B 0 5 0 5 5 Velocity 255 7 7 D 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 d 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 434b distance from shoreline x m distance from shoreline x m Fig 27 Flow characteristics for different flows Left maximum flow 12 m s right design flow 8 m s Top down Individual riser flow distribution along diffuser riser flow deviation from mean losses in port riser configurations line port and jet discharge velocities and diffuser pipe velocities port and diffuser diameter lines Fig 28 shows the flow characteristics for several intermediate flowrates A slight variation of the discharge distribution can be o
7. 0 12 0 30 4 Water pipelines used previously 99 1 4 Used previously corroded 139 1 0 1 5 5 With deposits 127 139 1 0 1 5 7 Appreciable deposits 129 139 2 0 4 0 Cleaned after use for Years 1391 0 3 1 5 9 Heavily corroded Up to 3 0 B Concrete Cement and Q ther Tubes and Conduits I Concrete tubes 1 Good surface plaster finish 139 0 3 0 8 2 Average conditions 1358 2 35 3 Coarse rough surface 139 3 9 Reinforced concrete 84 2 5 tubes Asbestoscement tubes 1 New 34 0 04 0 10 2 Average 84 0 60 IN Cement tubes 1 Smoothed 84 0 3 0 8 7 Nonprocessed 84 129 1 0 4 0 3 Mortar at joints smonthed 122 1 9 6 4 Conduit with a cement 1 Good plaster made of cement with 1 05 0 22 mortar plaster smoothed joints all asperities removed metal casing 122 2 Steel troweled 84 0 5 V Plaster over a metallic 13 10 15 screen Vu Ceramic sult glazed 54 1 4 conduits vili Slag concreta slabs 13 1 5 IX Slag and alabaster Carefully made slabs 13 114 1 0 1 5 filling slabs Wood Plywood and Glass Tu T I Wooden tubes 1 Boards very thoroughly dressed 0 15 2 Boards well dressed 0 30 3 Boards undressed but well fitted 0 70 4 Boards 139 1 0 5 Staved 84 DA Plywood tubes 1 Of good quality birch plywood with trans 0 12 verse grain 1 2 Of good quality birch plywood with longi 0 3 0 05 tudinal grain 1 Glas t bes Pure glass 127
8. 24 ERE gt MNT Se 2 2 n 1 D i q x 9 0 oii pi qi Au 2 gt A Gi D CA j l Di p i j j l rij r i j where the losses along the diffuser are included in the internal pressure pa from equation 18 The first two terms in the numerator denote the difference of the piezometric head hydraulic head 2 0 7 Pai 2 z in zi Aj between the diffuser and the ambient The third term in the numerator is related to the diffuser velocities var The terms in the denominator are related to the jet velocity vi aiqi CcApi and the port and riser losses For outfalls with uniform geometries or for uniform diffuser sections with uniform port riser groups it follows A const a const D const Li L const Assuming a uniform flow distribution among the orifices gives v i v and vpi Vp const Therefore all losses but the riser inlet loss and the port exit loss are constant Aj const Gi 6 Under these assumptions only few parameters change along the diffuser causing the variation of individual flows The other parameters can be joint in constants C Ai Vai EE l Ci Ger 25 For diffuser without risers it 15 fA Institut f r Hydromechanik Universitat Karlsruhe 46 Ai Vai SCH 26 where C and are constants for the whole diffuser or one diffuser section with equal port
9. 4 213 0 1005 25 03 1 e Q 7 988 0 3090 0 038250 13 075 In Q 9 201 1 3485 075535 0 9090 QU 38 828 In Q 27 300 TS PERO 0 6084 38 0 0124 Q 40 466 In Q 6 429 0 2917 07 0 0129 Q 0 4692 QU 0 0067 Q 95 950 In 200 940 0 4529 0 0 0052 0 3091 072 with in 1 5 Code see files duckbill m Inaccuracies n where n is the number of fittings ATV DVWK A110 2001 in pipe siting D mm 200 0 017 300 0 014 400 0 012 500 0 010 600 1000 0 005 gt 1000 0 Inaccuracies n Ge where is the number of fittings ATV DVWK A110 2001 in pipe fittings D mm 2 200 0 009 300 0 006 400 0 004 500 0 003 600 1000 0 0015 gt 1000 0 001 The overall local loss coefficient for one riser port configuration 15 the sum of all applicable coefficients However since not all reference velocities are the same the coefficients have to be modified so all losses can be multiplied with the same velocity For this code the downstream velocity has been chosen to be the reference velocity Vret Therefore CorHyd for example modifies the local loss coefficient due to expansion 2 Ge 7G KN 4 e orig LM with being the original expansion coefficient When multiplying with the square of the downstream velocity Vdown it will cancel out and the coefficient will only be multiplied with the reference velocity it 15 supposed to be multiplied with
10. Q 30 15 ms TH 22 00320 Ur 35 ms TH 22 4214m Fig 44 Flow characteristics for the final design for different discharges Q showing the riser flow deviation port riser headloss port and jet discharge velocities diffuserpipe velocities left without duckbills right with duckbills and total head TH An increasing inflow or increasing ambient water level mainly increase the total head Fig 45 Headwork storage tanks should be capable to manage these changes For slowly increasing future flows an extension of storage tanks can be done only when necessary saving investment costs for the commissioning Discharge vs total head Ambient water level vs total head 22 F head 221 ae 2 Relative head 7 total head water level elevation 20 EM E ud WI me um E 16 a 16 E m E El 14 212 P 5 10 ER E A 8 P a 4 nm ud 4l Total head Relative head total head water level elevation 45 20 25 30 35 7 8 9 10 Discharge nr s Ambient water level m Fig 45 Changes in total head for varying discharges vs constant ambient water level left or maximum discharge vs varying water level right fA Institut f r Hydromechanik Universitat Karlsruhe 71 Especially for this long diffuser a strong influence of the local loss formulations on the discharge profile has been observed Precautiou
11. S W 1996 User s Manual for CORMIX A Hy drodynamic Mixing Zone Model and Decision Support System for Pollutant Discharges into surface Waters U S Environmental Protection Agency Tech Rep Environmental Re search Lab Athens Georgia USA Kalide W Technische Str mungslehre Carl Hanser Verlag M nchen Wien 5th edition 1980 Lee J H W Karandikar J Horton P R Hydraulics of DuckBill Elastomer Check Valves Journal of Hydraulic Engineering April 1998 Miller D S Internal Flow Systems BHRA Cranfield 1990 Mort R B Effects of wave action on long sea outfalls Ph D thesis University of Liverpool September 1989 Muhammetoglu H G nbak A R Operational and Hydraulic Aspects of the Diffuser Sec tio of Antalya Sea Outfall Proc Marine Waste Water Discharges 2000 Philip N A and Pritchard T R 1996 Australias First Deepwater Sewage Outfalls Design Considerations and Environmental Performance Monitoring Marine Pollution Bulletin Vol 33 Nos 7 12 pp 140 146 R V Regler Verfahrenstechnik www regler mannheim com Rawn A M et al Diffusers for Disposal of Sewage in Sea Water Trans Amer Soc Civl Engr 126 Part III 344 1961 Rodrigues M Brito R S do Monte M H M The Submarine Outfall of the Estoril Coast Wastewater System Proc Marine Waste Water Discharges 2000 Shannon NR Mackinnon P A Hamill G A Evaluation of CFD model of sali
12. 1 number of ports at a riser at position 1 angle of gradual expansion or contraction C dimensionless loss coefficient for local losses dimensionless friction coefficient 1 kinematic viscosity Institut fur Hydromechanik Universitat Karlsruhe 3 1 Introduction CorHyd is a computer code for the calculation of flow characteristics in multiport diffuser constructions It includes loss calculations for complex geometries as well as additional flow forcing due to density differences CorHyd 15 a code written within the commercial software MatLab Release 14 from the company Mathworks The code includes a graphical user interface and allows to use all MatLab functions for graphics analysis and also further modifications CorHyd 15 no self executable and needs MatLab to be installed But also open source softwares like Scilab http scilabsoft inria fr or Octave http www octave org allow to import and execute the MatLab based CorHyd files CorHyd is an open source code and allows for easy modifications Downloads of the code and this manual as well as further information are available under http www cormix de corhyd htm An additional version is foreseen to be included into CORMIX Cornell Mixing Zone Expert System from MixZon www cormix info It is based on the same algorithm and includes the same loss formulations but uses the CORMIX interface and allows for easy data transfer between an external hydra
13. 2i ma AE e Ki vw Gi owl 3 Wa Me et 2 e H and 1 0 to wy o mw LO 2 Lan ity is thee height of the cross ctio te d where for z Sp the carves z at different a for A we section of the side mench ft is the height of the moas paragraph 15 scien of the torin straight for Pape fig eem APR am IAM 1 gulli wy Us fe We Hefe e ic Wy eege We 15 an 45 60 Agi e 1 3 hus m 1I il Ba LO 1 1 14 1 0 1 6 iL DEA DEA 0 91 LI L ha 2 65 2 70 0 75 0 84 1 04 1 01 6 38 0 46 0 60 0 76 1 16 1 05 2 20 0 31 0 50 0 65 1 35 1 11 LIN 0 25 USL 0 80 Led 1 19 0 27 5H 1 06 2 060 1 3 LI 0 12 0 36 0 74 1 23 2 44 1 43 14 1 24 0 70 0 98 1 54 2 56 1 59 L 1 30 1 94 1 54 1 77 24 1 10 1 52 116 3 00 2 20 24 2 19 3 23 4 10 5 15 7 15 3n 1 20 1 40 7 80 8 10 9 0 4 0 141 14 2 4 8 15 0 5 33 1 23 5 118 24 0 28 0 6 0 34 7 34 5 15 0 15 4 160 ap 62 0 62 7 63 0 563 0 640 i a8 982 98 6 99 0 Lon ua A Institut fur Hydromechanik Universitat Karlsruhe 76 wye of rhe type F gt Fp and Fe Fei Diagram a 0 90 Passage 10 7 17 m A Wa Fy Feat iy mm ea a 04 sl lest7 art al we M 1 Values of feag 15 90
14. Av jet velocity head m 0 196 3 1 Max jet velocity head m 0 213 3 4 Min jet velocity head m 0 184 2 9 Density head difference m fresh water 0 676 10 7 Sum of averages m 6 368 100 8 Sum of all maximum losses m 6 543 103 6 Sum of all minimum losses m 6 287 99 5 Calc relative total head above sea level m 6 316 Calc absolute total head m 33 316 Losses in port riser configuration at position i Headloss in port riser m 0 879 0 1OvYUL 4S dE FPRRROOO OY lt OUTPUT design recommendations Fischer et al 1979 Sum of Area of ports cross sections downstream Area of diffuser cross sections Sum Ap Ad 059 118 177 236 295 354 END OF RESULTS 5 2 Graphical output Fig 21 shows the graphical output for a given flowrate Qp and the calculated necessary total head H both written in the title of the graph Absolute discharge values at every 1 riser position and the mean discharge are shown in the first bar chart plotted against the x coordinate the distance from shoreline The second bar chart gives the relative discharge deviation which 15 the ratio of individual riser discharge and the mean riser discharge minus one A value of zero than means zero deviation from the mean riser discharge and a value of 0 1 means a 10 deviation which 15 also indicated The allowable range of discharge variation can be modified by the user In the same bar gra
15. Exceptions should avoid near shore impacts by keeping the seaward discharge higher minimized constructional and operational costs using simple manifold geometries with small losses e prevention of off design operational problems in order to avoid particle deposition and salt water intrusion during low flow or no flow periods Institut f r Hydromechanik Universitat Karlsruhe 8 performance tests against unsteady operations in order to reach rapidly steady flow condition after purging during start up optimize intermittent pumping cycles and consider wave induced circulations and water hammer Conflicting design parameters require compromises which are often not sufficiently resolved Bleninger et al 2004 Existing diffuser programs Fischer et al 1979 implemented as code PLUMEHYD and Wood et al 1993 implemented as DIFF have deficiencies for diffuser designs other than pipes with simple ports in the wall They only consider short risers with negligible friction losses and local losses and lack the implementation of long risers like in deep tunneled outfalls with meaningful frictional and local losses Y shaped diffusers complex port riser configurations multiple ports on one riser duckbill valves or other complex port losses Design rules regarding the velocity ratios Fischer et al 1979 or loss ratios Weitbrecht et al 2002 for diffuser sections and downstream ports are only helpful for simple geometries no chang
16. Froude number Diffuser diameter Dd amp Diffuser Velocities Vd upstream of port m s m s Vp m s Dp m Vj m s Vr m s Fr Vd m s Dd m 1 4 633519 001 4 633519 001 5 1034 0 170 5 1034 1 6388 124 9 0 3010 1 400 2 4 595955e 001 9 229474e 001 5 0621 0 170 5 0621 1 6255 123 9 0 5996 1 400 3 4 579980e 001 1 380945e 000 5 0445 0 170 5 0445 1 6198 123 5 0 8971 1 400 4 4 558982e 001 1 836844e 000 5 0213 0 170 5 0213 1 6124 122 9 1 1932 1 400 5 4 548185e 001 2 291662e 000 5 0095 0 170 5 0095 1 6086 122 6 1 4887 1 400 6 4 550564e 001 2 746719e 000 5 0121 0 170 5 0121 1 6094 122 7 1 7843 1 400 7 4 569866e 001 3 203705e 000 5 0333 0 170 5 0333 1 6163 123 2 2 0812 1 400 8 4 610083e 001 3 664713e 000 5 0776 0 170 5 0776 1 6305 124 3 2 3806 1 400 OUTPUT riser locations intersection with pipe centerline X y Z 1 7500 000 0 000 2 500 2 7450 000 0 000 2 500 3 7400 000 0 000 2 500 4 7350 000 0 000 2 500 5 7300 000 0 000 2 500 6 7250 000 0 000 2 500 7 7200 000 0 000 2 500 8 7150 000 0 000 2 500 9 7100 000 0 000 2 500 Institut fur Hydromechanik Universitat Karlsruhe 43 10 7050 000 0 000 2 500 11 7000 000 0 000 2 500 OUTPUT losses and total head Name of loss Loss m of the relative head Inlet head loss m 0 080 1 3 Feeder head loss m 5 141 81 4 Diffuser head loss m 0 206 3 3 Av port riser headloss m 0 069 1 1 Max port riser headloss m 0 226 3 6 Min port riser headloss m 0 000 0 0
17. Tu et ubi We L a A0 L LU n i 0 26 e 0 20 dE D E 10 t amp Dao n 02 L n No 2 F Ee at ype amp 10 E Le a Sid sei the curvi at UE HEC M oni feet we ge Fit Values of at ur 15 607 at 15580 nS SCH a Fa M fe gt e 004 OJ OI Gelb 1 00 LH LOO 1 00 1 00 201 nal Tal DEI 81 0 64 D i 004 pa 6 50 Mit 0 2 050 D 0 36 0 56 O40 0 98 037 0 36 Ds 0 25 4 25 0 8 0027 025 D 016 0 16 O23 020 018 016 017 LO 000 40 20 Dip 005 00 L2 DO 1 3m 50 2 014 HOT 14 039 0 39 O47 0 39 90 90 140 116 1B 41 78 1 78 344 20 2 20 320 40m E 27 Wirt IH H Institut f r Hydromechanik Universitat Karlsruhe Threaded wyes of the type Fy Fo P Fi Fam Fei Diagram mada of malleable iron 2 7 18 WR Ecce Sade branch O Sot sse the cusves Ee 5 coa ag dilTerent Fy Pei 1 n Af _ Le wi Qu Straight Fes m is the curve E at TO gy Ge aM al EVE Los I I ot Tew Test ossi jm Values af z amd Fest Que Uu KE 43 03 of 805 ae OF o 09 14 Values of fey 0 09 2 80 450 6 00 7 88 Ili 110 15 8 20 0 24 1 0 19 LA 300 2 50 3 2
18. headloss m D 2 0 0 4000 4500 5000 5500 6000 6500 7000 7500 8000 4000 4500 5000 5500 6000 6500 7000 7500 8000 distance from shoreline distance from shoreline x m co e port diameter port diameter m e c port diameter velocity per port and jet m s T velocity per port and jet m s LERLA si ila m a RUPEE PASSA ARS E A E S US D hee 0 5500 6000 6500 7000 7500 4500 5000 5500 6000 6500 8000 distance from shoreline x m distance from shoreline x m I oC ce e 5000 0 an 4000 4500 ho diffuser diameter m MN diffuser velocity m s diffuser velocity m s diffuser diameter m 0 IG 0 S 4000 4500 5000 5500 6000 6500 7000 7500 4000 4500 5000 5500 6000 6500 7000 7500 80 distance from shoreline x m distance from shoreline x m Fig 43 Flow characteristics for final design at maximum flow left column without and right with Duckbill Valves Top down Individual riser flow distribution along diffuser riser flow deviation from mean losses in port riser configurations line port and jet discharge velocities and diffuser pipe velocities port and diffuser diameter lines m Institut f r Hydromechanik Universitat Karlsruhe 70 Flow properties for varying effluent flow Flow properties for varying effluent flow 0 2 Discharge deviation c Discharge deviation
19. number np of losses in a port n in a riser or ng in the diffuser pipe with pipe cross sectional areas Apij Arijand Aq respectively Ap and denote the friction coefficients for related pipe components with length Lait and La diameter Daij equivalent pipe roughness respectively for either port riser or diffuser component j For each port or riser the local and friction loss coefficients are determined iteratively since they depend on the discharge Institut f r Hydromechanik Universitat Karlsruhe 28 Water surface P Fig 13 Definition scheme for the port to port analysis p ambient pressure average ambient water level elevation q discharge through one riser port configuration at elevation z internal diffuser pipe pressure upstream a flow division node with diffuser pipe centerline elevation z4 and horizontal pipe location xq The discharge qi at the position 1 Fig 13 1s calculated as follows 1 The work energy equation applied along a streamline following the diffuser pipe centerline results in eq 18 It equals the diffuser pressure pa directly upstream the port riser branch with the known downstream diffuser pressure plus the known static pressure difference due to the elevation difference plus the dynamic pressure difference plus the known losses occurring in the main diffuser pipe The losses are divided
20. or 20 years Further sensitivity analysis or time series runs chapter 6 2 allow for more detailed analysis of diffuser performance for changing ambient boundary conditions Instead of solving for the total head H of a given design flow CorHyd also allows to solve for the flow rate for a given total head in the headworks Headwork buildings or treatment plant pumps are often limited and the outfall has to be designed for a maximum total head in the headworks Effluent density pe and viscosity v generally do not change significantly Often used values for municipal waste water is 996 998 kg m and v 1 31 10 m s ATV DVWK A110 2001 4 3 Feeder and diffuser The main outfall pipe consist of the feeder pipe which conveys the effluent to the discharge location and the diffuser pipe which disperses the effluent in the ambient The input of both feeder and diffuser pipe sections is done via the start and end point coordinates Xs ys Zs the diameter and the roughness ks To reduce the input parameters the pipeline is schematized with pipe sections The number of used sections is Ng Section limits are locations where either bends or diameter changes or roughness changes occur Fig 15 shows the coordinate system for the parameter input related to the coordinates of section fittings The fittings itself can be characterized by the radius typical 3D4 of a bend if bends between sections occur or an angle p typical 9
21. the receiving water body Diffusers can be single branched or double branched systems T or Y shaped Fig 2 If the the diffuser section is simply laid on the sea bed it 1s composed of port orifices in the wall of the diffuser pipe simple port configuration Fig 3a which may carry additional elements like elastic variable area orifices duckbill valves Fig 3b If diffusers are covered with ballast laid in a trench or even tunneled in the ocean floor vertical risers riser port configuration Fig 3c are connected to the diffuser to convey the effluent to the water body For deep tunneled solutions often rosette like port arrangements similar to a gas burner device Fig 3d are used to save the number of risers and allow for increased dispersion Also risers may carry duckbill valves which change their effective open port area related to the pressure difference between inside and outside the valve They avoid salt water intrusion during low flow periods and allow high discharges during peak flow periods The flow in multiport diffusers 15 controlled by two boundary conditions first the entrance boundary flow rate or head and second the ambient disposal boundary where the effluent physical properties differ from the ambient fluid Both conditions vary in time due to discharge variations diurnal changes storm water events and long term changes due to increased sanitation coverage and pressure variations density variations tides or
22. tidal cycle Vmax 0 3 m s Montevideo S rib Uruguay 50 km Argentina Berazategui i Buenos Aires p Fig 42 Top view of the Rio de la Plata delta showing the location of the Berazategui outfall and the ambient characteristics at its location source Nasa 2005 These very special ambient conditions are not unique and can be found also in other shallow coastal regions of the world e g China Sea or Baltic Sea where also outfalls are planned or already operating But design and control of these outfalls are difficult because existing design guidelines Grace 1978 Williams 1985 Water Research Centre 1990 Wood et al 1993 UNEP 1996 are limited to deep water disposal sites The complex dispersion patterns of the 3 km wide diffuser plume in an unsteady shallow environment and the internal hydraulics of the construction itself are a major challenge for engineering design and predictive mixing and transport models However this paper will focus on the internal hydraulics of the Berazategui outfall installation considering the flow partitioning and related pressure losses in the manifold resulting in a discharge profile along the diffuser The external environmental hydraulics which deal with the effluent mixing with the ambient fluid are not discussed here The calculated internal flow characteristics are summarized in Fig 43 for maximum flow Qmax 33 5 m s and in Fig 44 for several smaller flows all left
23. waste water treatment plant to be constructed for the city of Buenos Aires The sewer system 15 separated from the rainfall canalisation and is designed for an average effluent flowrate of about 25 m s with a maximum peak discharge of 33 5 m s The outfall starts at the pumping basin on the onshore headworks from where a 4500 m long feeder tunnel conveys the effluent to the 3000 m long diffuser in the disposal area Fig 40 The diffuser is composed of vertical risers carrying four ports in a rosette like arrangement Fig 41 aN Dy gt LL LA PS AS AD d TAIT AP T v a T 7 CATT A SE TAAL SIA ALYY Le ap E t zetel E en 4 e dhe U ai I Headworks Se 1 1 So oN PSO NE IS 3 8m 2 8m 1 7m Q 33 5 m3 s Q average 25 5 m3 s 1500 m 1000 m 500 m 7500 m Total number of ports 61 f Institut f r Hydromechanik Universitat Karlsruhe 68 An Fig 41 Side and top view of riser port configuration of diffuser The receiving water body is the Rio de la Plata estuary of the rivers Parana and Uruguay average annual fresh water discharge 23 000 m s The width of the estuary at the outfall location 1s about 50 km with a depth varying from 4 to 7 m Fig 42 Tidal currents including temporal density stratifications dominate the velocity field average local velocity v 0 04 m s maximum velocities during
24. water level elevation 7 in the headworks tank and a constant inflow Qina a steady flow with velocity V and flowrate Q Qin develops in the outfall pipe system Fig 10 Now a higher water level z z Az 1s considered in the headworks tank e g higher inflow Qin from treatment plant or additional pumps are switched on For fast water level rises Az At gt 1 in the headworks pressure waves including water hammer effects may occur in the pipe system These should be prevented by operational means and keeping Az At lt lt 1 After a short time order of seconds the pressure waves are dissipated by pipe elasticity and friction and the new pressure difference between headworks zy and sea water is developed Fig 11 But the flow velocity in the whole pipe system still needs time to accelerate to the velocity according to the new pressure difference This process needs considerable times for outfalls with huge volumes of water in their pipe system After a time t the flowrate Q will increase to the final flowrate Qin During that time the internal pressure in the outfall is generally higher than for both discharges Qin and Qinp This additional pressure is needed to accelerate the whole fluid to the final velocity Fig 12 The energy grade line 15 more inclined than for cases without acceleration headworks H outlet Fig 10 Steady pipe flow with constant boundary conditions Qina outlet Fig
25. which occurs actually once a day 15 7 m s The last 150 m of the diffuser do have too low velocities under this condition Therefore a taper 1s introduced at exactly this position and the diameter reduced from 2 4 m to 1 2 m This reduces the pipe section with velocities lower than 0 5 m s to 25 m 10 ports Under peak discharge 12 m s there are TF Institut f r Hydromechanik Universitat Karlsruhe 58 only 10 m 4 ports where velocities are lower Negative consequences of the taper is higher head 5 increase of the relative head and a more distorted discharge distribution flow properties for Q 8 m s necessary total head H 33 6887m flow properties for Q 8 mie necessary total head H 33 3162m 0 08 0 06 0 04 0 02 discharge per riser 4 m s 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m discharge per riser 9 5 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m 0 1 discharge deviation port riser headloss m discharge deviation port riser headloss m D 1 ES 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 0 1 rem 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m distance from shoreline x m in w E 26 2 0T 3 2 015g s m D 5 18 15 01 3 E Kl ius 2 1 T 2 i L
26. x m T ES E E g m 5 T fegder elo city 2 9538 rhs 4000 4500 5000 5500 6000 6500 rigg 7500 ao distance from shoreline x m Fig 21 Graphical output bar charts showing the discharge per riser the relative discharge deviation and port riser headloss distribution the discharge velocity at ports the velocity in the diffuser pipe as well as port and diffuser diameter The second output Fig 22 describes the hydraulic and energy grade line in fresh water heights of the whole system It indicates locations of major losses and shows the needed total head to drive the system headworks head as well as the total losses Institut f r Hydromechanik Universitat Karlsruhe 45 31 18 e Loss 4 0 91267 m EL phy e VD EE ae ply 12 20 32 e 1 1749 m py z EE py Tz 31 9 31 17 M 3 Total Head fresh water m a a Total Head fresh water m E e Lu 31 13 31 2 31 1 em su DU II E EE 2000 4000 3750 Distance from shoreline x m Distance from shoreline x m Fig 22 Graphical output Energy and Hydraulic grade line of the whole system and the diffuser 6 Design and optimization The governing equation for the individual port discharge is equation 20 Equation 18 in 2 20 devided by qi and squared gives j 2 gt pa B 2elz Zu 1 2 P Aa
27. 0 180 for gradual diameter changes are applied see 2 4 1 for details The user should try to define as less sections as possible but as much as necessary to represent the general position of the pipeline The sections can be chosen independently of the port riser configurations The feeder diameter design is constraint by a maximum diameter to allow scouring of sediments during low flow periods The near future design discharge daily maximum Institut f r Hydromechanik Universitat Karlsruhe 38 should therefore result in feeder velocities gt 0 5 m s DIN EN 1671 ATV DVWK A 110 2001 and ATV DVWK A 116 2005 This corresponds to a maximum feeder pipe diameter of Damax 1 6 The feeder velocity for the far future design flowrate and the same diameter results then in ver Generally flowrates do not more than double or triple during the lifetime of an outfall so far field feeder velocities are from 1 to 2 m s what 15 clearly acceptable in terms of operational viewpoints considering the related energy losses As the feeder also the diffuser pipe is constraint by a maximum scouring diameter Theoretically this would result in a diffuser with different pipe segments as much as risers and under the assumption of a homogeneous discharge distribution each with a maximal diameter of Da maxi 8Q Nn where N denotes the total number of risers and i the observed pipe sectio
28. 0 0015 0 010 Depending on how long these were stored 22 f Institut fur Hydromechanik Universitat Karlsruhe Lula 3 General Features of To allow for an easy input procedure and fast calculations CorHyd consist of different modules Depending on the details of the input CorHyd chooses automatically the applicable modules without user interaction The available modules are 1 One diffuser simple setup 2 Y or T diffuser complex Setup with two diffusers where two diffuser calculations are coupled to be supplied with one feeder pipe only 3 Both modules and 2 are furthermore subdivided into a module for diffusers without risers or ports just holes in the wall and those with risers 4 All calculations can be done either for a given total discharge and solving for the individual discharges and the total head or for a given total head and solving for the individual discharges and the total discharge In each module losses are calculated automatically The user only has to provide simple geometrical specifications out of those geometrical changes along the pipe are calculated and calculations for loss coefficients are done An optional input 1s foreseen to consider special losses for non conventional parts Three methodologies for the analysis of the internal hydraulics i e flowrate distribution along diffuser have been adopted by various authors The first involves a port to port analysis Fischer
29. 0 3 97 4 95 650 aad 10 5 13 3 0 27 1 37 1 81 230 283 3 40 407 4 80 6 00 7 1B 2 54 0 15 1 19 1 54 1 1 35 2 73 3 22 IN 4 32 A Ap 6 53 1 27 L A3 LAT 1 89 1 11 2 38 2 58 RU 4 75 0 55 1 09 Lx 1 80 1 59 165 1 77 1 954 2 27 2 68 3 310 1 00 0 90 1440 1 13 LAN 1 87 1 20 L 1 90 2 56 2 80 Values eT fz gt A1 all FF O30 064 055 asi 049 055 esi 070 rem e fA H Institut fur Hydromechanik Universitat Karlsruhe 78 10 2 Local loss formulations Orifices Idelchik Discharge from a straight tube through an orifice or a perforated plate grid with sharp edged orifices l dp 0 0 015 Diagram Re Wordy v gt 105 14 16 11 18 Ap 1 3 f wi 1 0 707 V1 f see the graph Perforated plate E E E E Orifice 100 ae mil Wor For gt PIV TT 60 22 D UNI or HHA Institut fur Hydromechanik Universitat Karlsruhe 79 Discharge from a straight tube through an orilice or grid with differently shaped orifice edges Re Wordp v gt 10 14 16 11 19 Resistance coefficient Scheme and graph _ 2 pw 2 _ WI ie dn ET dE f where 1 050 f rV1 f for A see Diagrams 2 1 through 2 6 7 f dy t 1 Vt 0 PU 2 where amp 0 4 552 Institut fur Hydromechanik Unive
30. 0 4100 4150 4200 4250 4300 4350 m 0 Distance from shoreline m 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m 53 E 93 ES m E E S 5 2 E 5 E 9 1 5 En 5 o 3850 a Distance from shoreline x m b TH 30 9114 Q 7 2 ms TH 32 3041 m B 4 TH 33 9491 9 6 ms TH 35 6463m 10 6 m s TH 37 9956m 0 12 TH 40 5975 6 m fs TH 30 6547 m 0 2 TH 32 2475m 0 6 4 ms TH 33 8325m 8 5 TH 35 7888m 10 6 m s TH 37 8384m 12 miis TH 40 3412 mj Fig 28 Flow characteristics for different discharges Q left horizontal diffuser right sloped diffuser 3m 449m showing the riser flow deviation port riser headloss port and jet discharge velocities diffuser pipe velocities and total head H Discharge vs total head 45 40 35 Ni e e e Total Head fresh water m Discharge m s Fig 29 Changes in total head for varying discharges vs constant ambient water level Before 1996 the diffuser was operated with lesser ports because 59 of 180 have been closed due to low design discharges Fig 30 shows the flow properties for this modified diffuser Institut fur Hydromechanik Universit
31. 11 Pipe flow immediately after a relatively fast change of the water level elevation in the headworks tank Qin gt Qina fA Institut f r Hydromechanik Universitat Karlsruhe 24 outlet O Y de 2 0 Fig 12 Pipe flow after the acceleration of the whole fluid in the outfall took place To calculate the time t during accelerations take place estimates using momentum and mass conservation equations are analyzed for an unsteady incompressible pipe flow along the coordinate s following a streamline The momentum equation 15 lov ST 5 0 10 where denotes energy head The mass conservation equation for an incompressible fluid Op ct 0 in an non deformable pipe OA 0t 0 15 Je Ap Ap 02 F H vi t A v2 t A Q t 11 Further assuming a with constant cross section and length L the first term of 10 15 Ld OE 22 and the second term is Eo AE where 12 gt IC 14991 1 at gd at g and Eo 13 PM the energy heads at the water surfaces at the headworks and at the outlet Eo right after the water level rise in the headworks and before acceleration took place and AE the headloss due to friction ga 2 E 3 2 ze AZ Zp 12 _ Po SC y ie 208 KS 2 d E where r AL D and A the friction coefficient 14 12 13 and 14 in 10 gives Ldv v g dt 20 E 0 15 Additionally for the termi
32. 2835m Ex uu Fig 39 Flow characteristics for different discharges Q left tunneled tapered diffuser with long risers and rosette like port arrangement right same with additional Duckbill valves D 200 mm showing the riser flow deviation port riser headloss port and jet discharge velocities diffuser pipe velocities and total head Hj Table 6 shows the comparison between the different alternatives listed above An optimized diffuser design often results in an increased total head Maximum values are here a 15 9 increase But often cheaper solutions in the order of 5 allow for very good diffuser performance and result in lesser maintenance necessities and better dilution characteristics and therefore cheaper operation Institut fur Hydromechanik Universitat Karlsruhe 67 Table 6 Comparison of constructional alternatives for Ipanema diffuser total head relative difference in total discharge no scouring m head m head to basecase m distribution no of ports L4 449 180 ports 125 50 basecase build 33 32 6 32 0 0 taper 33 69 6 69 0 37 6 20m 8 taper short riser 33 92 6 92 0 60 9 5 20m 8 taper long riser 33 83 6 83 0 50 7 9 20m 8 taper long riser rosettes 33 72 6 42 0 4 6 2 20 m 12 taper DBV 200 34 23 7 23 0 91 14 4 20 m 12 7 2 Berazategui Buenos Aires Argentina The Berazategui outfall 1s planned to discharge the treated effluents of a
33. 60 s D 0 950 3900 3950 TU omg 4250 4300 4350 distance from shoreline x m CO distance from shoreline x m w difusor diameter T E up E 5 s 9 1 5 E E B 5 feeder Velocity 1 7654m s A EET AHHH 0 5 Ka feeder Velocity 1 7684m s iss 55 3900 3950 4000 4050 4100 4150 4200 4250 4300 EC 0 4b ence een D OY UT 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 43 distance from shoreline x m Fig 26 Flow characteristics for design flow Left horizontal diffuser right sloped diffuser 3m 449m Top down Individual riser flow distribution along diffuser riser flow deviation from mean losses in port riser configurations line port and jet discharge velocities and diffuser pipe velocities port and diffuser diameter lines IH Institut f r Hydromechanik Universitat Karlsruhe 55 A flow properties for 12 m s necessary total head H 40 3412 flow properties for 8 5 necessary total head H 33 3162m mean discharge 0 discharge per riser q discharge per riser 4 m s 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance fram shoreline 0 1 0 1 port riser headloss 0 5 port riser headloss 04 2 E 0 05 0 2 ES 039 0 158 2 7 2 E 025 5 DI 0 05 2 Zum
34. 86 for special geometries and some limited ranges of Reynolds numbers although those are not implemented in CorHyd Furthermore additional optional losses can be added manually for risers and ports Examples for non conventional nozzles or flanged orifices are given in the Annex chapter 10 Institut f r Hydromechanik Universitat Karlsruhe 12 Friction smooth transition rough Turning EORUM odio 7 quce Diffusing Ll j Accelerating Combining P ee cu ru Dividing Obstructions c 5 Fig 9 Examples for local losses in pipe flows Miller 1990 fA Institut f r Hydromechanik Universitat Karlsruhe 13 Table 2 Local loss formulations Type of Definition Loss Inlet Sharp edged inlet Idelchik 1986 Reference velocity is 0 5 V Code see files barchart m plotlosses m report m time series m totalHead m The value 0 5 is automatically foreseen in the code if a feeder pipe exists The loss is added only after the whole calculation directly in the result files Although most of the constructions do have sharp edged inlets from the headworks into the feeder pipe other configurations may applied by using the following graphs and changing the code in the mentioned files zeta entry new value Rounded inlets Idelchik 1986 Miller 1978 pid rfd Fl Institut f r Hydromechanik Universit t Karlsruhe 14
35. IH 0 05 5 TIR ln att BH iiid nec pu EE ies DUNT EE umo 0 2 n gt 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 gt 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m distance from shoreline x m diffuser diameter 25 E un e in diffuser velocity m s diffuser velocity m s diffuser diameter m diffuser diameter m feeder Velocity 1 7684m s n LL mmn adn Had EHE HEUTE HH E FUGERE Dee 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 d distance from shoreline x m 0 feeder Velocity 1 7584m s 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 ECH distance from shoreline x m Fig 31 Flow characteristics for tapered diffuser Left reduced diffuser diameter of 1 4 m for end part right basecase both for design flow 8 m s Top down Individual riser flow distribution along diffuser riser flow deviation from mean losses in port riser configurations line port and jet discharge velocities and diffuser pipe velocities port and diffuser diameter lines Constructional alternatives The piling of the diffuser pipe caused problems due to broken piles and therefore leakage at diffuser pipe joints State of the art constructional design alternatives would try to avoid these problems by using a HDPE pipe with concrete weights fixing the diffuser on the ground The
36. Ly 1 L ie CR Paia Pai Zeil 1 7 Z iet gt 3 Nai Ts Lj pt mn AED Aus HA YE Dasa Q0 2 n 2 2 zi gt zi n iP J x 7 D Ais Dij j l For simple diffusers equation 20 reduces to equation 21 if no risers and no port configurations are applied and the diffuser 1s just represented by simple holes in the pipe wall Equation 21 is the one presented in Fischer et al 1979 which has been used for simple diffuser calculations qi Ng i i 2 1 qi C i ml p Sa se hain l j 21 i l aia d i 1 j Fischer et al 1979 defined loss coefficient for sharp edged entrances zi ossia 1 2 0 63 AP dil 2g bs nb and for bell mouthed ports CorHyd furthermore allows to apply Duckbill valves also on simple diffuser systems and therefore uses the previously defined additional local loss formulations which are additionally integrated in the calculations of the coefficient Ce Institut f r Hydromechanik Universitat Karlsruhe 30 3 3 Solving scheme The governing equation can be solved either for a given head or a given total discharge For both a first estimate 15 used as a starting value and further iterations lead to the final value 3 3 1 Solving for total head At the first port riser on the seaward side 1 1 an initial di
37. Seamless steel tubes 1 New unused 22 99 127 0 02 0 107 commercial 2 Cleaned after many years of use 129 Up to 0 04 3 Bituminized 120 Up te 0 04 4 Superheated steam pipes of heating systema 0 10 and water pipes of heating systems with deaeration and chemical treatment of running water 53 3 After year of use in gas pipelines 22 0 12 6 After several years of use as tubing in gas 0 D4 0 20 wells under various conditions 4 T After several years of use as casings in D 06 0 22 wells under different condition 4 H Saturated steam ducts and water pipes of 0 20 heating systems with minor water leakage up to 0 555 and deaeration of water supplied to balance leakage 53 9 Pipelines of water heating systems bide 0 20 pendent of the sourco of supply 13 10 pipelines for intermediate operating 0 20 conditions 53 11 Moderately corroded 139 0 4 12 Small depositions of scale 139 D4 13 Steam pipelines operating periodically and 0 5 condensate pipes with the open system of condensate 53 14 Compressed air pipes fram piston and 0 8 turbocompressors 53 15 After several yeurs of operation under 0 15 1 0 different conditions corroded or with small amount of scale 4 84 129 IH Institut f r Hydromechanik Universitat Karlsruhe 20 A Table 2 3 Equivalent roughness of tubes and channels Continued Group of tubes material State of tube surface and conditio
38. adworks n Ges 0m 3877 m A 4326 m A A Z riser Dol diffuser 24m Fig 33 Side view and cross section of a constructional design alternative for the Ipanema outfall with a diffuser pipe laid in a refilled trench and short risers Institut fur Hydromechanik Universitat Karlsruhe 61 flow properties for 8 ms necessary total head H 33 9202 flow properties for 8 m s necessary total head H 33 6887m 0 1 nean diectarge70 08888877 SPUMA BT 0 08 0 06 0 04 0 02 discharge per riser m s discharge per riser ol m s 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Bo 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m distance from shoreline x m e 0 1 0 6 L E SES Die c 2 005 o amp 0 05 o gt 0 6 5 ES port riser headloss 043 i 0 E i 0 SE E 8 0 05 2 2 005 0 2 9 5 0 235 Oo 2 2 i 0 0 1 B Ep 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 3350 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m distance from shoreline x m uw wo 2 5 2 5 E 9 2 15 9 2 0 15 5 5 15 1 5 a 01 g ME cM th belie bb ll a TEE 005 e Wu III Gs es 000011 e L S
39. anbul To prevent local pollution and to protect ecologically sensitive regions persistent substances have to be reduced directly at the source and the large discharges have to be distributed over a wider area For the latter purpose long outfall pipes with multiport diffuser installations are used to disperse the effluent to non critical levels Jirka and Lee 1994 aided by the natural pollution degradation rates of the receiving water bodies An optimized combination of on land treatment and receiving water capacities especially for nutrient inputs from municipal sources may positively affect the world s severe health problems often directly caused by sanitation problems UNEP 2004 New water quality regulations e g US EPA 1994 Europe EC Water framework directive 2000 Brazil CONAMA 2000 Argentina Uruguay Guarga et al 1992 account for that combined approach and therefore also result in a worldwide increasing utilization of treatment plants with multiport diffuser outfalls e g Australia Philip and Pritchard 1996 USA Signell et al 2000 An outfall is a pipe system between the dry land and the receiving water It consists of three components Fig 1 the onshore headwork e g gravity or pumping basin the feeder pipeline which conveys the effluent to the disposal area and the diffuser section where a set of ports releases and disperses the effluent into the environment to minimize the impacts on the quality of
40. ance from shoreline x m 4 ms H 23 1302 m 4 8 mis 23 8525 m Sb mis H 30 5347 m 6 m s TH 30 8547 m ms TH 32 247 5m Q 0 4 m s TH 33 832bm D e bd ms H 31 5367 m CO 96 m s TH 35 7899 Q 7 2 miis H 32 5585 10 8 m s TH 37 8384m dz 8 ms H 33 7 m 12 TH 40 3412 m Ke e e Fig 30 Flow characteristics for different discharges Q left 59 of 180 ports closed right all ports open showing the riser flow deviation port riser headloss port and jet discharge velocities diffuser pipe velocities and total head Changes in the ambient water level do not have any effect on the flow characteristics but increase the total head To prevent intrusion of ambient water including sediments especially during low flow the port densimetric Froude number should be bigger than unity F Vy Ap gt 1 Wilkinson 1988 where V denotes the port exit velocity the port diameter This gives a critical port velocity Maerz Ap pgD 0 041 m s for Ipanema outfall All port and jet exit velocities third bar chart Fig 28 are considerably higher for all applied flowrates 7 1 1 Diffuser optimization Scouring velocities The present geometry does not allow for scouring velocities in the end part of the diffuser The maximal flow
41. at Karlsruhe 57 under different flow conditions The performance 15 equal the one for higher flows and more ports Flow properties for varying effluent flow Flow properties for varying effluent flow e Discharge deviation e Discharge deviation e 0 1 0 1 RM 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m Distance from shoreline x m EN NEL fy Y 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 ET 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m Distance from shoreline x m e e en e Headloss port riser m Headloss port riser m 2 Velocity port m s Port diameter Velocity per port m s e Port diameter m g e 0 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 3900 3950 4000 4050 4100 4150 4200 4250 4300 435 Distance from shoreline x m Distance from shoreline x m Lm critical vel m s salt water intrusion if Froude 1 Velocity per jet m s Velocity per jet m s 0 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m Distance from shoreline x m Diffuser velocity m s Diffuser velocity m s GA es Diffuser diameter Diffuser diameter m Dist
42. base case The outfall design is herein compared with typical other constructional configurations as they would be applied in actual designs Furthermore a case study of the planned outfall for Buenos Aires Argentina 15 shown to analyse diffuser hydraulics for very long diffusers here 3 km Finally comparisons with conventional diffuser programs indicate the necessity of the implemented extensions of CorHyd 7 1 Ipanema Rio de Janeiro Brazil The Ipanema outfall in Rio de Janeiro Brazil operates since 1975 and discharges actually about 6 1 1012 5 daily variation from 2 1 mio people coarse screened domestic sewage from the southern part of the city into the coastal waters of the Atlantic ocean Fig 23 Carvalho 2003 The outfall was designed for an average discharge of 8 m s equivalent 4 0 mio people with peak discharges up to 12 m s The outfall is made of a 4326 m long Institut f r Hydromechanik Universitat Karlsruhe 52 concrete pipe with a diameter of 2 4 m including a 449 m long diffuser section with 90 ports on each side of the pipe each with a nominal diameter of 0 17 m a spacing of 5 m and pointing downwards with an angle of 45 to the horizontal Carvalho et al 2002 Fig 24 and Fig 25 The diffuser is in a depth of about 27 m The slope of the diffuser line could not be found in literature The Ipanema outfall 15 one of the few outfalls which have been monitored in detail with special emphasi
43. bserved for these flow variations only for the sloped diffuser The changes of the total head for increasing discharges are shown Fig 29 But the most critical point stays the low scouring velocity which affects almost 40 96 of the diffuser 169 m and about 60 ports for the flowrate of 6 m s which is presently the average flow IH Institut f r Hydromechanik Universitat Karlsruhe 56 A Flow properties for varying efuent fow Flow properties for varying efluent flow Discharge deviation e Discharge deviation e o e 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m e 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m E 1 E 5 E a e a 8C g 0 Ka 2 2 Do 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 3 0 5 Distance from shoreline x I 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 a Distance from shoreline x m GA EH E t 5 E port diameter E 5 E E a E D Ka ker t gt o o 1 g 8 5 gt 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 m 1 Distance from shoreline x gt 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m y E z s o x D 9 critical vel m s salt water intrusion if Froude 1 gt 850 3900 3950 4000 405
44. configurations for different and varying discharge and ambient conditions The calculation is based on the application of the steady continuity and work energy equations between ambient fluid at the discharge points and the effluent inside the diffuser pipe Emphasis was given to the implementation of all occurring losses especially if high risers duckbill valves multiple ports and more complex discharge configurations are applied Detailed calculations for the internal manifold hydraulics in the outfall pipes show a strong sensitivity on the representation and formulation of local losses even for relatively simple riser port configurations An optimization methodology yields a homogeneous discharge distribution along the diffuser minimization of the total head and prevention of sedimentation or ambient water intrusion in the diffuser under varying inflow and ambient conditions The final design achieves lower costs for material use and operation as well as the minimization of environmental impacts and operational stability for off design conditions Acknowledgments The authors like to express their gratitude to the student assistants Martina Kurzke and Jan Muller who contributed to the coding of the present program Thanks to Rob Doneker from Mixzon Inc for his friendly and scientific help and the offer to include the program in CORMIX the Cornell Mixing Zone Expert System We furthermore appreciated the data support from TideFlex Technologies fro
45. ctice for multiport risers CorHyd does apply for multiple ports at one diffuser position but not for multiple risers at one location on the diffuser pipe CorHyd considers round pipes For rectangular pipes an equivalent diameter has to be used The angle between riser and diffuser axis is assumed to be nearly 90 Institut f r Hydromechanik Universitat Karlsruhe 27 3 1 4 Automatic implementation of loss formulations additional losses CorHyd automatically applies the necessary local loss formulations for the user given inputs For special configurations which need more detailed specifications of geometries additional input is necessary for the calculations If for example the port is mounted perpendicular onto the riser this local bending loss is not included but can be added as a known loss If a riser has more than one port it 15 assumed that the discharge flowing through the riser with T shape including this additional loss and 15 distributed evenly among all ports 1 for two ports both would have half the discharge The formulations for local losses applied in CorHyd assume reasonable high Reynolds numbers above 10 and reasonable geometrical distance above 3 times the diameter between geometrical changes to avoid interaction of losses Modifications of the listed formulations can be found in Idelchik 1986 for special geometries and some limited ranges of Reynolds numbers but have not been implemented in Co
46. ction site of the Ipanema outfall The calculated internal flow characteristics are summarized in Fig 26 for design flow 8 m s and a horizontal left hand side or sloped diffuser line right IH Institut f r Hydromechanik Universitat Karlsruhe 54 A Pipe sections varying from 59 to 164 ft long and weighing as much as 242 tons gt A reasonably good discharge distribution along the diffuser first bar chart Fig 26 with maximum deviations from the mean discharge of not more than 5 of the mean discharge second bar chart Fig 26 is obtained Due to different pressure losses along the diffuser pipe and the port riser configurations line in second bar chart Fig 26 the discharge 15 increasing here to the seaward end Usually diffuser cannot be laid horizontally as assumed here because of the sloping bathymetries Therefore another calculation is shown in Fig 26 on the right side with a sloped diffuser with an assumed elevation difference of 3 m along the diffuser length of 449 m 6 7 900 The discharge deviation in this case 15 almost neglectable which is due to a higher pressure difference between the sewage in the diffuser pipe and the heavier ambient water especially in deeper waters at the seaward diffuser end The flow velocities in the diffuser pipe continuously decrease in seaward direction fourth bar chart Fig 26 For the last 25 port locations velocities below 0 5 m s are predicted which might cause sedim
47. der Velocity 1 7664m s OCI Jf o D 3900 3950 4000 4050 4100 4150 4200 4250 4300 re 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 134 distance from shoreline distance from shoreline x m Fig 38 Flow characteristics for Left tapered tunneled diffuser with long riser and rosette like port arrangements right tapered tunneled diffuser with long risers both for design flow 8 m s Top down Individual riser flow distribution along diffuser riser flow deviation from mean losses in port riser configurations line port and jet discharge velocities and diffuser pipe velocities port and diffuser diameter lines a Duckbill valves variable area orifices Existing diffusers may also be modified by attaching variable area orifices Duckbill valves DBV to avoid intrusion of saltwater debris or sediment as well as to make the discharge distribution more homogeneous during low flows Fig 39 shows a time series run for a system with duckbill valves compared to a system without Improvements of the discharge profile are especially seen for low flows which 1s even more effective for sloped diffusers Beside the additional costs for Duckbill valves also an increased total head has to be considered 11 96 increase compared to same system without duckbills and 14 compared to basecase IH Institut f r Hydromechanik Universitat Karlsruhe 66 A Flow properties for varying effluent flow Flow properties
48. diffuser continues seaward under its own momentum and the dynamic pressure drops rapidly causing the drawing in of seawater from the landward risers When outfall flow is re activated the discharge may be prevented from leaving through the landward risers by the inflowing denser sea water and a stable circulation may be established Furthermore flow accelerations during pump start up could lead to oscillations WRC 1990 p 212 Wave induced oscillations occur if large waves are passing over a diffuser section in shallow water Grace 1978 p 302 Resonance effects and internal density induced circulations are possible Wilkinson 1985 These have to be analyzed in an additional unsteady analysis more detailed numerical calculation and or laboratory experiments 3 1 2 Single phase pressure pipe CorHyd assumes the whole pipeline as flowing full under all conditions and especially at the minimum flow rate and minimum tide It 15 assumed that air entrance at the inlet is avoided by keeping the top pipe invert under the minimum sea level or using backpressure valves or deaeration chambers Stratified flows due to intruded salt water cannot be analyzed in CorHyd 3 1 3 Geometrical assumptions CorHyd assumes that the discharge through one specific riser with multiple ports 15 homogeneously distributed among these ports This 15 valid for ports with similar geometry at this diffuser position which are mounted at the same elevation what is common pra
49. e ambient water level do not have any effect on the flow characteristics but increase the total head To prevent intrusion of ambient water including sediments especially during low flow the port densimetric Froude number should be bigger than unity F V Ap gt 1 Wilkinson 1988 where V denotes port exit velocity D port diameter This gives a critical port velocity Vp crit Ap pgD 0 041 m s for Berazategui All port and jet exit velocities third bar chart Fig 43 Fig 44 are considerably higher for all applied flowrates Duckbill valves cause additionally a homogenization of the jet exit velocities Fig 43 third bar chart Fig 44 fourth bar chart Scouring velocities above 0 5 m s are obtained for almost the whole diffuser section Fig 43 fouth bar chart Fig 44 fifth bar chart flow properties for 33 5 5 necessary total head TH 21 4604m flow properties for 33 5 m s necessary total head TH 24 4214m mean discharge 0 54918 m s mean discharge 0 5492 mis discharge per riser 4 m s discharge per riser m s D D 4000 4500 5000 5500 6000 6500 7000 7500 8000 4000 4500 5000 5500 6000 6500 7000 7500 8000 distance from shoreline x m distance from shoreline x m port riser headloss 0 2 0 2 QJ port riser headloss 0 1 ho port riser headloss m discharge deviation e discharge deviation e port riser
50. e location roughness diameters etc of the different risers and ports here 5 different port riser groups are chosen and Output Text File energy line discharges and the setup of the outfall Since none of the port riser groups 15 located in segment 6 of the main pipe this 15 by definition a feeder It should be noticed that two ports per riser were chosen for riser groups 1 and 2 As output the energy line EL PL WL and the bar chart showing discharges and velocities Discharge Bar chart were selected e A 0 0002 sg ER NEM Wo LSC os 03 Lon BAN Gm Ee Ee LS 025 05 00002 Addhonal Local Loss Fig 16 The graphical user interface of CorHyd The following chapters explain the data input for each parameter and furthermore recommend which design values should be used The design philosophy is based on the idea that the diffuser should operate with maximum flow and highest ambient water level elevation with further performance tests for intermediate operational schemes 4 1 Ambient Data The first calculation should be done using the average water level elevation at discharge location as value for the ambient water level elevation Hg Furthermore the average ambient density po should be specified Performance checks should explicitly done for the case of maximum average water level elevation Hmax gt and maximum average ambient density Institu
51. e more than half of the ports without the need of modifying the operational scheme Mixing model calculations may show that less ports are necessary during near future flowrates to comply with environmental standards It is therefore recommended to close the landward ports during diffuser construction and open these ports after the flowrates increased over the near future value CorHyd allows to analyse the diffuser performance for these scenarios by simply closing the ports Furthermore it is often easier and cheaper to operate the diffuser under these conditions than operating the final diffuser with low flows A flowrate meter at the outfall inlet has to be installed to record when the modification of the diffuser has to be done and more or all ports have to be opened Furthermore accidents like pipe ruptures due to anchor collisions earthquakes or structural failures can be analyzed by adding the accidental holes with their estimated area transformed into an equivalent diameter Vice versa test can be made by knowing the water level elevation in the headworks the flowrate and the basecase geometry and looking for the dimension of the rupture Step 3 Off design calculation near future design conditions Near future mixing calculations are used to figure out the number of necessary ports for low flow discharges run CorHyd with clogged ports and plot results Analyse pipe velocities and the flow distribution if the final diffuser con
52. ea orifices all with implemented additional local losses occurring in the manifold 9 References Abromaitis A T Raftis S G Development and Evaluation of a Combination Check Valve Flow Sensitive Variable Orifice Nozzle for use on Effluent Diffuser Lines Proceedings of the 68th Annual Conference amp Exposition Water Environment Federation Miami Beach USA October 21 25 1995 ATV DVWK 110 Hydraulische Dimensionierung und _ Leistungsnachweis von Abwasserkan len und leitungen September 2001 ISBN 3 935669 22 4 based on DIN EN 1671 www dwa de ATV DVWK A 116 2005 2 Druckentw sserungssysteme ausserhalb von Geb uden Marz 2005 ISBN 3 937758 15 1 www dwa de Bleninger T Avanzini C A and Jirka G H 2004 Hydraulic and technical evaluation of single diameter diffusers with flow rate control through calibrated replaceable port exits Proc Int Conf Marine Waste Water Discharges and Marine Environment Catania Italy Bleninger T Lipari G and Jirka G H 2002 Design and Optimization program for Internal Diffuser Hydraulics Proc Int Conf Marine Waste Water Discharges Istanbul Turkey Bleninger T Beta Version of CorHyd download under http www ifh uni karlsruhe de ith science envflu Research ww discharges CorHY D htm 2004 Institut f r Hydromechanik Universitat Karlsruhe 72 Bleninger T Bazzuro N and Domenichini P AQUA Receiving Informatio
53. echanik Universitat Karlsruhe T4 Wilkinson D L Purging of saline wedges from ocean outfalls Journal of Hydraulic Engineering Vol 110 No 12 December 1984 Wilkinson D L Seawater circulation in sewage outfall tunnels Journal of Hydraulic Engineering Vol 111 No 5 May 1985 Wilkinson D L Wareham David G Optimization Criteria for Design of Coastal City Wastewater Disposal Systems Proc Clean Sea 96 Toyohashi 1996 Wilkinson D L amp Wareham D G Optimization of Coastal City Wastewater Treatment and Disposal Systems to Achieve Sustainable Development Proc of the 1998 IPENZ Conference 12 16 February 1998 p 6 3 6 7 Wilkinson D L Nittim R Model studies of outfall riser hydraulics Journal of Hydraulic Research Vol 30 No 5 1992 Williams B L 1985 Ocean Outfall Handbook National Water and Soil Conservation Authority Water amp Soil Miscellaneous publication number 76 Wellington Wood I R Bell R G Wilkinson D L Ocean Disposal of wastewater World Scientific singapore 1993 WRc Design Guide for Marine Treatment Schemes Water Research Centre plc Swindon 1990 Institut f r Hydromechanik Universitat Karlsruhe 75 10 10 1 Local loss formulations Division of Idelchik Diverging ewe of ee type Fi Fa gt FaFa Digram a Side branching 10 T 15 Wafa L Gaa anda 90 at lys 2 5 PF m a li Fry
54. entation of particles in the diffuser This number reduces for peak flows 12 m s Fig 27 to about 16 but still the last 75 m of the diffuser have velocities much lower than 0 5 m s That means that even for maximum discharges scouring velocities are not obtained for the end part of the diffuser Considering that the present treatment 15 only coarse screening this might cause problems for the diffuser end part flow properties for Q 8 m s api total head H 33 pim flow properties for 9 8 m s RE total head SH 33 ibis 3 m3 s discharge per riser 4 m s discharge per riser 4 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline port riser headloss 0 25 0 1 0 1 headloss headloss discharge deviation e port riser headloss m discharge deviation port riser headloss m 0 1 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 KO distance from shoreline m 3900 3950 4000 4050 4100 4150 4200 45D 4 4300 434b distance from shoreline x m 25 S E E 2 TT 515 5 S 15 E JA 8 amp 5 2 Il ul 5 t DANT s 5 a 0 S HI Il i 5 3000 3950 4000 4050 4100 4150 4200 4250 4300 43
55. er headloss TH D e a o 2 6 0 05 port riser headloss discharge deviation port riser headloss m 0 1 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 0 1 distance from shoreline x m 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m port diameter e e port diameter m port diameter m 3850 3900 3950 4000 E 4100 4150 4200 4250 4300 4350 distance from shoreline 0 50 39 velocity per port and jet m s velocity per port and jet m s mi Wind e 0 50 yog en oo 4 Su EUIS 4250 4300 4350 distance from shoreline x m diffuser diameter Peu Sh diffuser velocity m s diffuser diameter diffuser velocity m s diffuser diameter m D feeder Velocity 1 2684 5 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 E distance from shoreline x m n feeder Velocity 1 7654m s 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 ECH distance from shoreline x m Fig 36 Flow characteristics for Left tapered tunneled diffuser with long risers right tapered diffuser on piles without risers both for design flow 8 m s Top down Individual riser flow distribution along diffuser riser flow deviation from mean losses in port riser configurations line port and jet discharge velocities a
56. er using the x y z input of the nodes calculates the losses in a riser starts the different calculations start after GUI calculates a criteria for start of sedimentation in the diffuser displays the diffuser setup in a graph totalhead m calculates the maximum total discharge for a given starts the iteration maximum total head with given total Institut fur Hydromechanik Universitat Karlsruhe 34 head instead of discharge NO Riser system pressure no riser m main function for calculating the pressures and main function discharges along the diffuser totalhead norisers m calculates the maximum total discharge for a given starts the iteration with maximum total head given total head instead of discharge Complex System two diffuser bendComplex1 m calculates the angles of pipe bends having the node function locations X y z bendComplex2 m calculates the angles of pipe bends having the node function locations X y z calcComplex m program calculation for complex systems input and some preparatory calculations GUI for the complex system complex losses m calculates the loss coefficient at the junction of function two or more diffusers on one feeder still dummy value compsys m M file for GUI of the complex system conversionl m converts variables for the comples system conversion2 m converts variables for the complex system conversion backl m converts variables for the complex sys
57. es along the diffuser For others they are either unnecessarily conservative or not valid at all because velocities and losses are changing drastically in actual diffuser installations Moreover these problems are often not recognized due to poor monitoring conditions in deep sea Consequences are costly systems in terms of construction operation and maintenance as well as bad dilution characteristics Fig 5 Fig 5 Replaced diffuser which was full of sediment and therefore not working properly courtesy of Eng Pedro Campos Chile CorHyd calculates velocities pressures head losses and flow rates inside the diffuser pipe and especially at the diffuser port orifices Planner designer and operator of outfalls may use it to analyze predict and monitor the discharge behavior of planned or installed diffusers under different boundary conditions The combination with CORMIX will provide a direct linkage to subsequent waste plume modeling and mixing zone analysis fA H Institut fur Hydromechanik Universitat Karlsruhe 9 2 4 Manifold processes Pipe hydraulics are characterized by continuous pressure losses due to wall friction and by local pressure losses due to geometrical changes Manifold hydraulics e diffusers are characterized by several flow separations where local losses depend not only on geometrical relations but furthermore on the discharge rates The flow distribution for simple pipe configurations with uniform geometries alon
58. et al 1979 Wood et al 1993 the second discretizes a fictitious porous conduit French 1972 while the third is based on solving the governing equations on an Eulerian grid for every point of the diffuser Shannon 2002 Mort 1989 The latter two have the advantage that unsteady stratified flow 1 e saltwater intrusion calculations are easier to implement than into the port to port analysis But they have the disadvantage in considering complex geometries and in defining appropriate local loss formulations Besides numerical grid based calculations are very time consuming CorHyd focuses on an optimized design for multiport diffusers for predominant boundary conditions Slowly varying boundary conditions like diurnal discharge variations rainfall events or tidal influences are herein considered as quasi steady Therefore a port to port analysis was chosen for CorHyd CorHyd contains a preprocessor with flexible data input where all geometries are defined and necessary details can be specified The postprocessor includes detailed graphical results as well as performance checks for off design conditions 3 1 Major Assumptions 3 1 1 Steady flow CorHyd assumes slowly and uniformly changing boundary parameters The assumption of considering mainly steady flow conditions in diffuser hydraulics is based on the following estimates fA Institut f r Hydromechanik Universitat Karlsruhe 23 For a constant sea water level and a constant
59. f them with the same specific port riser configuration and is mounted along the pipe section number one Details of the parameter definitions are visualized in Fig 15 The next input denotes the spacing L between each group and the spacing S between each riser in one group often both are the same It follows the input of the port elevation L above the diffuser centerline necessary for calculating the external pressure at the outlets If no risers are applied the value should be zero It follows the input for the port and riser diameters D D and the roughness ksr If no risers are applied riser diameter and roughness should be zero If more than one port is located at one position or at one riser the number of ports N has to be given If ports consist of little attached pipes their length L and related roughness should be given A 50 mm minimum port size for secondary or tertiary level treated effluent and storm water inflow to the sewage system was suggested by Wilkinson and Wareham 1996 for avoiding the risk of blockage Furthermore a minimum port size of 70 to 100 mm for primary treatment plants just screening and settling tank The maximum port diameter should generally be smaller than the diffuser pipeline diameter Dg at upstream position to achieve higher discharge velocities and avoid saltwater intrusion during low flows The riser diameter D Institut f r Hydromechanik Universitat Karlsruhe 39 should allow for riser
60. fall design must consider both the hydraulics occurring outside and inside a diffuser External hydraulics affect the effluent mixing with the ambient fluid internal hydraulics affect the flow partitioning and related pressure losses in the manifold resulting in a discharge profile along the diffuser CorHyd covers the internal diffuser hydraulics 2 2 External hydraulics dilution requirements First design steps for the external hydraulics of diffusers are either the usage of simple dilution equations e g Jirka 2003 or Jirka and Lee 1994 or the direct application of more detailed mixing models e g CORMIX under given dilution requirements and major choices for the riser port spacing to find a minimum diffuser length and a first port diameter estimate All external hydraulic design methodologies and programs mixing calculations are based on properly working diffusers and therefore use homogeneous discharge distributions along the diffuser line as input Effects of a non homogeneous discharge distribution can be estimated by simple conservative dilution equations for multiport diffusers Jirka and Lee 1996 valid for the assumption of a 2 D plume after single jet merging see Fig 4 The plume centerline dilution S for stagnant water can be obtained with 1 3 S E d 1 Institut fur Hydromechanik Universitat Karlsruhe 7 Ape where jo denotes the buoyancy flux per diffuser length jo g qo with gb g and qo ViB the ma
61. figuration with clogged ports allows to discharge near future flows under reasonable conditions modify the number and the location of the clogged ports to optimize near future flow conditions Check external hydraulics with modified diffuser If either the external hydraulics or even the modified internal hydraulics do not fulfill the general requirements as listed above the user should try to do a re design of the main diffuser characteristics Else proceed to the optimization in step 4 6 4 Sensitivity Analysis Numerical calculations are often based on simplified formulations and non accurate input data both containing uncertainties which have to be considered in the results and if possible limited to certain ranges Quantitative results as obtained with CorHyd at first look seem to promise high accuracies but have to be seen as results within a standard deviation which may vary significantly if compared to laboratory data field data or model data from other Institut f r Hydromechanik Universitat Karlsruhe 50 numerical methods The design process therefore has to foresee a sensitivity analysis to avoid huge errors and to be aware of possible variations Influence of formulation inaccuracies Especially if complex geometries are applied the influence of the formulations for loss coefficients has to be checked carefully As shown in 2 4 1 all loss formulations are based on empirical studies mostly calibrated in laborato
62. for varying effluent flow 0 1 2 T 2 San 3 D 2 5 D e ien 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 G 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m Distance from shoreline x m 15 En o D 1 1 c re 5 5 D 5 D I 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m Distance from shoreline x m B ZS z t SS t e o D 2 2 Ec E gt T3 Fen t o gt 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 gt 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m Distance from shoreline x m 6 A D 9 critical vel m s salt water intrusion if Froude 1 0 fso 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 e 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 Distance from shoreline x m Distance from shoreline x m w C m A D o t 2 Se 5 gt EE 2 5 Distance from shoreline x m 3 Q2 B mis H 31 0648 See 0 272 mis H 32 5885 x eee Q 8 4 H 34 3402m 8 4 H 34 8727 Q 88 mtis 35 386 Q 8 H 36 9677m Q 10 8 H 38 7037m up ADAE Q z 12 H 41
63. g the diffuser depends mainly on the ratio of branching losses and manifold losses But most of the actual diffuser geometries have more complex geometries Diffusers often discharge fluids with higher or lower density than the receiving waters which cause an additional buoyant forcing on the fluid flow Implemented losses in CorHyd include continuous losses due to friction in all pipes feeder diffuser riser and port Local losses are considered automatically in all pipe sections the feeder pipe the diffuser manifold and the attached port riser branches Furthermore additional local losses may be added manually if necessary Local Feeder losses Fig 6 e inlet loss at headworks e horizontal and vertical bends e contractions expansions along the feeder pipe flow separation if several diffusers are mounted on one feeder Local water riser spacing Headworks Feeder supply pipe m Outfall pipeline riser diffuser pipeline Fig 6 Local feeder losses Diffuser manifold losses Fig 7 Implemented local losses along a streamline along the diffuser pipe centerline passing the branch pipes are the division of flow loss for the diffuser pipe passing a riser e horizontal or vertical bends e contractions expansions along the diffuser pipe Institut f r Hydromechanik Universitat Karlsruhe 10 Local water riser spacing Headworks Feeder supply pipe Outfall pipeline r
64. geometrical details to check influences of construction imprecision on final result add additional losses on whole pipe system to account for imprecision vary material properties to check influences of deterioration Check external hydraulics with modified diffuser Table 5 summarizes the effects on a reference case for the discharge profile and the total head if the observed parameters are increased It is distinguished between horizontal and sloped diffusers where either the port elevations are at constant depth or varying along the diffuser fA Institut f r Hydromechanik Universitat Karlsruhe 51 Table 5 Sensitivity of involved parameters on head loss total head and homogeneity of the discharge profile leads to of the total head or the Increasing the discharge distribution resp Total Head Homogeneity 0 with slope or 11 with slope l 1 with slope tC a Diffuser length constant total length or Pipe roughness Cd Number of sers Riser height i Ports per deg e l Port diameter Od T ee 0 moderate in decrease strong in decrease neutral or small changes In summary the above procedure that obviously requires some analyst intervention and adjustment seems to be reasonably unambiguous and straightforward 7 Case studies To demonstrate CorHyd capabilities the outfall from Ipanema in Rio de Janeiro Brazil has been chosen as
65. hand side These are compared with results for the same geometry but with attached duckbill valves with the nominal diameter of 150 mm right hand side A reasonably good discharge distribution along the diffuser first bar chart Fig 43 with maximum deviations from the mean discharge of not more than 10 of the mean discharge second bar chart Fig 43 could be obtained to an equal dilution requirement along the diffuser Due to different pressure losses along the diffuser pipe and the port riser configurations line in second bar chart Fig 43 the discharge is decreasing typically to the Institut fur Hydromechanik Universitat Karlsruhe 69 seaward end which can be prevented by modifying the geometries along the diffuser In this case by reducing the main diffuser diameter to the seaward end The use of duckbill valves provides a more homogeneous flow distribution especially for low flows Fig 43 and Fig 44 right Without duckbills the flow distribution is unaffected by changing the total flow due to neglectable density differences between the effluent and the ambient and the almost horizontal installation of the diffuser Fig 44 first chart left But the total head TH necessary to drive the system 15 higher with duckbill valves Fig 44 legend Larger duckbills 200 mm reduce the total head almost to the level without duckbills but decrease also the effects on the discharge distributions to negligible levels Changes in th
66. head at headworks Equation 19 then allows to calculate the first discharge q The further discharges q2 until qw are calculated using equation 20 A final application of equation 18 allows to calculate pani the necessary pressure at the headworks to drive the system The total head H can be calculated by pan i Ve 1f the water level of a gravity driven system has to be defined The N calculated total discharge is Q The difference to the planned total head 15 diff k Htc If necessary e for diff gt Hi 10000 CorHyd performes further iterations with modified estimates To achieve faster convergence the following algorithm has been implemented to calculate Pd 1 c H Heye N pa 1 YelZjeti Za i Pa 1 2 Li Pac 201 1 Pa 1 c 1 eif diff diff for c gt 2 23 Institut fur Hydromechanik Universitat Karlsruhe 31 The iteration stops if the difference between the given total head and the calculated total head is less than 10 H The results are individual port riser discharges and velocities in all pipe sections along the diffuser and a total discharge These can be displayed or printed with further output options fA Institut f r Hydromechanik Universitat Karlsruhe 32 3 4 System processing sequence and structure of simulation elements For easier understanding of the code as well as to reduce the number of repeated lines the prog
67. ictions also under different flow conditions and further design criterias 1s described in the following chapters 6 1 Far future design conditions First design steps are either the usage of simple dilution equations e g Jirka 2003 or Jirka and Lee 1994 or the direct application of more detailed mixing models e g CORMIX under Institut f r Hydromechanik Universitat Karlsruhe 47 given dilution requirements and major choices for the riser port spacing to find minimum diffuser length and a first port diameter estimate For example The ambient standard is 100 times smaller than the effluent standard Compliance has to be assured outside the mixing zone of 10 times the average water depth This demands for discharges at around 15 m depth an effluent dilution of 100 at 150 m downstream the plume Cormix calculations including a sensitivity analysis with the included program CorSens allow to optimize the general diffuser characteristics for that case e g diffuser of 100 m length 10 ports and port diameter of D 0 2 m Step 1 Baseline calculation Far future design conditions The data from the first successful mixing calculations 15 used as first design alternative for the internal hydraulics run CorHyd with very few diffuser and port riser sections and plot results Pipe velocities Diffuser riser and port velocities should be in between reasonable ranges otherwise the diameters have to be increased or decreased ge
68. idth B Cs Jet contraction coefficient D m internal pipe diameter E m energy head g m s reduced gravity g Ap pg H m head above datum additional indices total head at headworks design water level elevation of ambient water 1 numbering of port riser configurations counting from seaward end to shore starting with 1 numbering of local losses in ports risers or the diffuser m s buoyancy flux per diffuser length jo g qo equivalent sand roughness m riser spacing L m length of the considered pipe section n total number of local losses in between one pipe section N total number of port riser locations 1 of diffuser Na total number of diffuser sections includes feeder Ng total number of port riser groups zZ z number of risers per group 5 number of ports per riser Z p pressure additional indices p pressure loss ambient water pressure Q m s total flow through outfall system q m s individual discharge through a riser or port at position 1 qo m s mass flux per diffuser length qo R m radius of bend Re Reynolds number Re VD v Sc plume centerline dilution SecNo diffuser segment number where this group 15 located in t S time V m s mean flow velocity X m horizontal coordinate of pipe segment centerline location y m horizontal coordinate of pipe segment centerline location Z m position or elevation in the vertical 0
69. iffuser itself or by flanges at the riser pipe an attached port pipe if risers are necessary A tap with a hole of an intermediate size can then be fixed on these flanges and easily replaced even as submarine work Attention has to be paid to avoid abrupt diameter changes and sharp edges to reduce the additional losses caused by these constructional details 4 5 Additional local losses sub menu If complex geometries are applied which are not automatically foreseen in the CorHyd loss formulations further loss values may be included for ports or risers Fig 17 shows the pop up window which opens after clicking on additional local losses In this window additional loss coefficients G related to the port velocity can be given as well as jet contraction ratios Cg Furthermore it is possible to define here 1f Duckbill valves are applied and which nominal diameter they have Also further studies can be done by introducing additional losses and analyzing their effects to check the system performance sensitivity on loss formulations and so far the necessity in doing laboratory studies for achieving more accurate loss formulations For risers additional local losses related to the riser velocity as well as additional bends or a total riser length can be given to achieve more accurate results if complex geometries are applied For example flanges with taps fixed on a port pipe cause an additional loss and a contracting Jet Both effects can be conside
70. ifh uni karlsruhe de www ifh uni karlsruhe de Kaiserstr 12 Universitat Karlsruhe E f T Tel 49 0 721 608 2200 2202 Institut f r Hydromechanik Fax 49 0 721 66 16 86 Bericht Nr xxx USER S MANUAL FOR CORHYD AN INTERNAL DIFFUSER HYDRAULICS MODEL Bearbeiter Dipl Ing T Bleninger Karlsruhe June 2005 Version 1 0 June 2005 USER S MANUAL FOR CORHYD AN INTERNAL DIFFUSER HYDRAULICS MODEL by Tobias Bleninger Gerhard H Jirka Institute for Hydromechanics University Karlsruhe Kaiserstr 12 76128 Karlsruhe Germany bleninger ith uka de http www cormix de corhyd htm Abstract Submerged multiport diffusers for waste water outfalls are designed often considering steady flow conditions for far future scenarios Design aims for lower costs for material use and pumping energy and the minimization of environmental impacts Inadequate attention on the internal diffuser hydraulics also for off design conditions thereby often result in hydraulic problems like partial blockage high head losses uneven flow distribution salt water intrusion and poor dilution causing higher energy demands and stronger environmental impacts The CorHyd computer program has been developed for the calculation of velocities pressures head losses and flow rates inside the diffuser pipe and especially at the diffuser port orifices to analyze and optimize diffuser design alternatives as well as existing diffuser
71. ing geometries along the diffuser the previous criteria are not applicable in general This because 1 the diffuser velocities generally decrease along the diffuser or change considerably if tapering is applied 2 the port riser velocities may change if port riser diameters are varied along the diffuser line causing a variation of C and 3 the flow distribution depends also on the losses along the diffuser causing a variation of For example losses along the diffuser are considerably different for systems with same area ratio but different number of openings Design rules regarding general loss ratios Weitbrecht et al 2002 for diffuser sections and downstream ports are also only applicable for simple geometries no changes along the diffuser For others they are either unnecessarily conservative or not applicable because losses are changing drastically along actual diffuser installations and cannot be summarized for the whole diffuser construction Therefore a design rule for non uniform systems or for uniform sections and groups of a non uniform system has to come out of a combination of a loss ratio buoyancy and riser inlet or port outlet and a velocity ratio diffuser velocity and branch velocity port or riser Equations 25 26 Furthermore sections and groups of a non uniform system have to be balanced in between each other to achieve an overall uniform diffuser performance The optimal procedure to organize these modif
72. internal hydraulics would be affected by only by minor differences in roughness a Covered diffuser or in trench short risers If wave forcing sediment transport or navigation and fishing activities are a major problem for the diffuser pipe it also can be covered Fig 32 or laid in a trench Fig 33 In both cases short risers have to be used to connect the buried pipe with the ambient water The riser pipes with the two attached ports are causing additional losses and therefore distort the discharge profile especially due to the previous tapering causing different riser diffuser ratios and therefore non uniform distributions Fig 34 Increasing the riser diameter in the tapered diffuser end part allows to equilibrate these additional changes because the additional separation losses depend on the diameter ratio between diffuser pipe and riser pipe The risers therefore have a diameter of 0 3 m at the end part and of 0 2 at the near shore part of the diffuser In this case the only change 15 a little increase in total head of about 4 9o compared to the tapered diffuser with no risers and 10 compared to the basecase 34 IH Institut f r Hydromechanik Universitat Karlsruhe 59 pipe protection Fig 32 Side view and cross section of a constructional design alternative for the Ipanema outfall with a covered diffuser pipe and short risers IH Institut f r Hydromechanik Universitat Karlsruhe 60 A gt he
73. into friction losses and local losses like bends and diameter changes or the passage of a branch opening Pai Pai t p g z z T Rala Ya Lossesa 4 1 1 d i 1 Ag i 1 Lai Lossesa i Pe S TRES TER Lj 18 k j l A aii j 2 The work energy equation applied along a streamline following the branch pipe and leaving the diffuser through the orifice results in eq 19 It equals the upstream diffuser pressure pa with the ambient pressure pai plus the static pressure difference due to the IrH Institut f r Hydromechanik Universitat Karlsruhe 29 elevation difference between diffuser centerline and jet centerline plus dynamic pressure difference between the diffuser and one single jet plus the losses occurring in all pipe segments between these points pa Duc P g Zi Zi 2A Y a Losses d i 2 C A k l 2 Jn i A 1 E Pqi Q pij pij E D Losses Gaii 5 6 19 2 G T Duas G denotes the jet contraction coefficient either given by the user or calculated iteratively if Duckbill Valves are applied aiqi VppviApi with duckbill jet velocity dependent on discharge If multiple ports are applied a single jet discharge is 0 9 with o 1 number of ports at a riser at position 1 Solving eq 18 19 for an individual discharge qj gives 2
74. iser diffuser pipeline Fig 7 Local diffuser manifold losses Port riser branch losses Implemented local losses along a streamline going from a diffuser centerline into the riser then into the port and the discharging jet are the division of flow from the diffuser pipe into a riser optional bends or additional losses in the riser the transition or division of flow from riser to port s optional additional losses in the port or at the orifice optional contraction of jet optional duckbill valves at the port orifices Optional means that either additional known geometry changes or local loss coefficients can manually be added to the generally foreseen local losses in ports and risers If for example the port is mounted perpendicular onto the riser this local bending loss 15 not included but can be added as a known loss If a riser has more than one port it is assumed that the discharge flowing through the riser 1s distributed evenly among all ports 1 e for two ports both would have half the discharge Institut f r Hydromechanik Universitat Karlsruhe 11 Local water Headworks riser spacing Feeder supply pipe Diffuser We Outfall pipeline riser diffuser pipeline Fig 8 Local port riser branch losses 2 4 1 Local loss formulations Local losses are due to geometrical differences between one cross sectional area of a pipe and the adjacent o
75. ities Flow distribution check whether the flow distribution lies in between reasonable limits Quin O 1qgi N lt qi lt O Iq N qm for at least the majority of port riser configurations modify the riser group diameters locally modify port group diameters locally introduce additional port riser groups if necessary and repeat local modifying Check external hydraulics with modified diffuser If either the external hydraulics or even the modified internal hydraulics do not fulfill the general requirements as listed above the user should try to do a re design of the main diffuser characteristics Else proceed to the optimization in step 3 Institut f r Hydromechanik Universitat Karlsruhe 49 6 3 design conditions It was common practice to design diffusers only for the final design flow which often caused long term malfunctions during low flow periods A common technique to overcome this problem are expanding diffusers Avanzini 2003 that are designed to meet the initial and final requirements by either closing initially a certain number of ports either with fixed closures or backpressure regulations which open autonomous if enough discharge enters the system Avanzini 2003 and or modifying port diameters using replaceable flanged orifices Bleninger et al 2004 Therefore the number of necessary discharging ports for near future flowrates have to be evaluated Generally half discharge allows to clos
76. long risers Nowadays tunneled outfalls are also affordable in some cases Often long risers have to used in these circumstances Fig 35 To achieve a more homogeneous discharge distribution the riser diameters have to be modified 0 35 m in the end part and 0 25 at the near shore part of the diffuser Fig 36 shows the flow characteristics for a tunneled diffuser with long risers The more homogeneous flow distribution causes that the total head compared to the previous case 15 even bit smaller IH Institut f r Hydromechanik Universitat Karlsruhe 62 A A i i s i TN n APR a RATTEN ET NL e Ta tN W F Mh T T SC om 3877 m A 4326 m Se 7 ports 90 17 tunneled diffuser 224m Fig 35 Side view and cross section of a constructional design alternative for the Ipanema outfall with a tunneled diffuser pipe and long risers IH Institut f r Hydromechanik Universitat Karlsruhe 63 A 3 flow properties for 8 mis total head SE 0 flow properties for 8 necessary total head H 33 6887 3 m s discharge per riser q m s 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m discharge riser o 0 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m 0 05 0 1 Sp port riser headloss 01 c 0 05 0 05 E port ris
77. lvigne Delft Neatherlands EC Water Framework Directive 2000 European Community L327 Brussels Fischer H B List E J Koh R C Y Imberger J Brooks N H Mixing in Inland and Coastal Waters Academic Press New York 1979 French J Internal hydraulics of multiport diffusers Journal WPCF Vol 44 No 5 p 782pp May 1972 Grace R A Marine Outfall Systems planning design and construction Department of Civil Engineering University of Hawaii at Manoa Honolulu Prentice Hall New Jersey ISBN 0 13 556951 6 1978 Guarga R Vinzon S Rodriguez H Piedra Cueva L and Kaplan E Corrientes y Sedimentos en el Rio de La Plata C A R P 1992 Gunnerson C G Wastewater Management for Coastal Cities The Ocean Disposal Option World Bank Technical Paper Number 77 February 1988 pdf http www wds worldbank org servlet WDS IBank Servlet pcont details amp eid 000178830 981019041 65665 Idelchik I E Handbook of Hydraulic Resistance Springer Verlag Berlin 1986 Jirka Mixing processes in wastewater discharges jets and plumes effect of currents and stratification Workshop at the IAHR Congress 24 08 03 29 08 03 Thessaloniki Greece 2003 Jirka and Lee J H W 1994 Waste Disposal in the Ocean in Water Quality and its Control M Hino ed Balkema Rotterdam Institut f r Hydromechanik Universitat Karlsruhe 73 Jirka G H Doneker R L and Hinton
78. m RedValve Company and Elasto Valve Rubber Products EVR company for developing loss formulations for duckbill valves fA Institut f r Hydromechanik Universitat Karlsruhe ii Contents PAPO SUA CL E 1 ACKNOW I dome IES 11 1 YE 3 4 1 1 Ee Oc 4 PRA ee 5 2 1 NDO CRS 5 2 2 External hydraulics dilution requirements 7 2 3 Internal hydraulics operational reourements 8 24 ee 10 2 4 1 Local loss formulations 12 242 PLICHOB Scc M MEME EA ME 19 2 e EE 23 3 1 O ene ee nee ette 23 3 1 1 viral 23 312 Single phase pressure pipe 21 3 1 3 Ge ometrical assumptions o eR Te 27 3 1 4 Automatic implementation of loss formulations additional losses 28 3 2 Governing Te 28 3 3 polvo SCDE HG ee 3l 3 3 1 ONY FOR TOCA BOO MEINE 31 e E 31 3 4 System processing sequence and structure of simulation elements 33 MN U 36 4 1 AmE DA eege 37 RE E 38 4 3 Feeder aud EISE 38 2 4 AG Sho
79. n before the 1 th riser starting counting offshore Although best for sediment removal this solution also called tapering generally is too expensive to install about 20 more expansive than single diameter diffuser and maintain i e cleaning Besides the continuous tapering after one or more branches the only alternative is decreasing the diffuser diameter as a whole Thus a simple configuration is achieved although increased friction losses and separation losses in the diffuser pipe will increase the total head Changes of the diffuser diameter cause only moderate changes in the discharge profile If tapering 15 applied the changes in the discharge profile are even smaller than in the case of changing the diameter generally By applying different diameters for CorHyd calculations it has to be considered that pipes are not available in all sizes and only diameters are applied which are given as internal diameters in catalogues of pipe producers 4 4 Port Riser configurations Instead of typing in ports or risers one by one the concept of port riser groups was used Delft Hydraulics 1995 for easy and fast data input The user should try to use as less groups as possible but as much as necessary to achieve optimized design The total number of different groups is Ng For each port riser group the number of used risers Ng and the location on the diffuser pipe section has to be given E g group number consist of 15 risers each o
80. n from Underwater Sensors AQUARIUS project ECO Geowater Euroworkshop GI and Water Use Management Genova Italy 18 22 03 2003 Bleninger T Lipari G Jirka G H Design and optimization program for internal diffuser hydraulics Proceedings of the International Conference Marine Waste Water Discharges 2002 Istanbul Turkey September 16 20 2002 Brooks N H Seawater Intrusion and Purging in Tunnelled Outfalls Schweizer Ingenieur und Architekt pp24 28 2 1988 Burrows R Outfalls I Pipeline and diffuser manifold design and hydraulic performance IAHR Short Course Environmental Fluid Mechanics Theory Experiments and applications held at University Dundee 2001 Carvalho J L B 2003 Modelagem e an lise do lancamento de efluentes atraves de emissaries submarines Ph D thesis Federal University of Rio de Janeiro COPPE UFRJ Brazil Carvalho J L B Roberts P J W and Roldao 2002 Field Observations of Ipanema Beach Outfall Journal of Hydraulic Engineering Vol 128 No 2 151 160 Charlton J A and Neville Jones P Sea outfall hydraulic design for long term performance in Long Sea outfalls from Thomas Telford London 1988 CONAMA 20 Article 23 3 2000 Conselho Nacional do Meio Ambiente Ministerio do Meio Ambiente Brasilia Brazil Delft Hydraulics User Manual v 1 0 Difflow A simulation program for the design of a multiport diffuser 1995 Author G A L De
81. nal velocity vy it 1s 2 Zoa 1 r Ka 16 Institut f r Hydromechanik Universitat Karlsruhe 25 16 solved for r in 15 and assuming a rough regime where A 15 independent of the flow velocity gives E x 0 edt 2 oe eh 2g i L dv E Zoa Zb V g dt ZO a Zb E L dv Goa ca I 0 Loo Ww dt Zoa zo v v tx D at where v x Vp when the velocity ratio of the prevailing g Zo d ta Va velocity vx and the terminal steady velocity vy 15 x esie tx ta tzo Zs arctgh vi arctgh For t 0 t 15 the time needed to reach the velocity v x vy RE a Zos Z arctgh a arctgh v Vp Ps Or using Zoa Zp ltr E it 1S 2L Vx Va tx 1 9 el arctgh Fal 17 For example applying 17 for x 0 99 and 4 km long outfall an acceleration from Va 0 6 m s to v 0 99 1 2 m s takes aprox 2 min until reaching a velocity of 1 smaller than the terminal steady flow velocity 1 2 m s Headwork design therefore has to consider storage volumes of discharges which are causing water level changes increasing decreasing faster than the fluid in the outfall accelerates Decreasing discharges furthermore may lead to a situation where moving fluid in the outfall sucks the effluent from the headworks even beyond the equilibrium level and afterwards swings back and seawater 15 sucked in the outfall Latter has critical effects on valves m
82. nd diffuser pipe velocities port and diffuser diameter lines a Tunneled diffuser long risers and rosette like port arrangements In the case of tunneled outfall it 1s furthermore tried to reduce the number of risers because these drilling operations are quite expansive Instead of many risers a few huge risers with rosette like port arrangements at the top are constructed Fig 41 The flow characteristics for the tapered tunneled diffuser with long riser and a rosette like port arrangement using half of the risers and having four ports discharging at every rosette are shown in Fig 38 The riser diameters have been increased to cope with the increased flowrate to 0 6 m at the tapered diffuser end and 0 35 m at the near shore part of the diffuser Fig 38 shows also that the internal flow characteristics seem to be similar and also the total head 1s even a bit smaller Furthermore it has to be considered that the application of few rosettes compared to many risers does have an non neglectable effect on the external hydraulics A detailed mixing zone calculation should be analyzed to study this drastic change of the diffuser geometry IH Institut f r Hydromechanik Universitat Karlsruhe 64 A A E P 3877 m A 4326 x Om ports 17 Wu Ho oe 2 BUT 29 n m tunneled 33 m fuser mi Fig 37 Side view and cross sec
83. ne 1 e expansions contractions or bends Fig 9 or the inlet or end of a pipe orifice These changes may lead to flow detachment processes reverse currents in deadzones locally increased accelerations or decelerations increased turbulence which all cause energy losses in closed pipe systems compensated by pressure losses Local pressure losses in a pipe system are generally calculated as 2 2 DI or as headloss P 3 pi where denotes the dimensionless loss coefficient the effluent density V the reference velocity either upstream or downstream the geometrical change There are numerous publications defining local loss coefficients for a large number of different geometries under different flow conditions Thus itself may depend on the Reynolds number the actual flow condition e g flowrate ratios in diverging flows the distance to previous local losses and geometrical reltions Comparisons between these publications showed discrepancies even for simple geometries The choice was in regards to the most accurate works from Idelchik 1986 Miller 1990 and Lee et al 1998 Table 2 gives an overview of implemented local loss coefficients They are calculated automatically in CorHyd These assume reasonable high Reynolds numbers above 10 and reasonable geometrical distance between the changes to avoid interaction of losses Modification of the listed formulations can be found in Idelchik 19
84. ne intrusion in marine outfalls Proc Int Conf Marine Waster Water Discharges 2002 Istanbul Turkey 16 20 Sep 2002 Signell R P Jenter H L and Blumberg A F 2000 Predicting the Physical Effects of Relocating Boston s Sewage Outfall U S Geol Survey Woods Hole MA U S A Swamee P K Jain A K Explicit Equations for Pipe Flow Problems Journal of the Hy draulic Division of the ASCE 102 HY5 May 1976 UNEP 2004 Guidelines on Municipal Wastewater Management Version 3 http www gpa unep org documents wastewater Guidelines Municipal Wastewater Mgnt 20version3 pdf UNEP United Nations Environment Program 1996 Guidelines for submarine outfall structures for Mediterranean small and medium sized coastal communities MAP Technical Reports Series No 112 ISBN 92 807 1618 2 Athens USEPA 1994 Water Quality Standards Handbook Second Edition U S Environmental Protection Agency EPA 823 B 94 005a Washington DC USA Weitbrecht V Lehmann D and Richter A Flow distribution in solar collectors with laminar flow conditions Solar Energy Vol 73 No 6 2002 Wilkinson D L and Wareham D G Optimization Criteria for Design of Coastal City Wastewater Disposal Systems Proc Clean Sea 96 Toyohashi 1996 Wilkinson D L Avoidance of seawater intrusion into ports of ocean outfalls Journal of Hydraulic Engineering Vol 114 No 2 February 1988 Institut f r Hydrom
85. nerally for all sections and or groups Va lt V lt V lt Vi modify feeder diffuser diameter to obtain operable velocities 0 5 m s lt lt 5 m s modify riser diameters to obtain operable velocities 0 5 m s V 5 m s modify port diameters to obtain operable velocities 0 5 m s V 12 m s at least at the majority of port riser configurations Total head The necessary total Head or the final flow should be in the desired order of magnitude otherwise velocities and or locations of high losses should be reduced simplify geometries and or increase diameters to reduce the total head Flow distribution check whether the flow distribution lies in between reasonable limits quis O lg N lt qi lt O Iq N qma for at least the majority of port riser configurations modify riser diameters for the whole diffuser to obtain a more homogeneous distribution of the riser inlet losses modify port diameters for the whole diffuser to obtain a more homogeneous distribution of the port losses 1 e 1f Duckbills are applied Check external hydraulics with modified diffuser If either the external hydraulics or even the modified internal hydraulics do not fulfill the general requirements listed above the user should try to do a re design of the main diffuser characteristics Else proceed to the optimization in step 2 6 2 Boundary condition variations CorHyd does include an automatic routine for c
86. nput clearVar m clears all variables function clogged ports m checks and sorts the ports which the user marked to be function clogged These ports have no discharge in the calculation and should not be considered commonData m reads in common data and starts calculations m input commonfeederpipe m calculates velocities and losses in the feeder pipe no function ports or risers attached create boxes diffuser m creates additional input boxes for the complex system input create boxes ports m creates additional input boxes for the complex system input darcy m calculates the friction coefficient function deviation Thead m calculates the deviation of the total head for the system output function diffuserlosses m calculates the loss coefficients G for the diffuser function duckbill m calculates losses G for duckbill valves function feeder pipes m calculates the pressure along the feeder pipe general function firstport m calculates the coordinates of first port of group and starts function riser location m firstuncloggedport m locates the clogged ports and puts zero discharge on them function Froude m calculates the port densimetric Froude number necessary function for further diffuser analysis like purging pressure riser m main function for calculating the pressures and discharges main function along the diffuser reads in the variables creates the text output file riser location m calculates the locations of the ris
87. ns of use A Metal tubes 16 Condensate pipelines operating periodically 1 0 and water heating pipes with no deaeration and chemical treatment of water and with substantial leakage from the system up to 1 5 355 53 17 Water pipelines previously used 99 1 2 1 5 18 With large depositions of scale 129 3 0 19 Poor condition nonuniform overlapping of GER joints 119 Welded steel tubes 1 New or old but in good condition welded 0 04 0 10 riveted joints 124 138 2 New bituminized 128 0 05 3 Used previously corroded bitumen O 10 partially dissolved 139 4 Used previously uniformly corroded 139 0 15 5 Without noticeable unevenness at joints 0 3 0 4 139 lacquered on the inside layer 10 mm thick adequate state of surface 125 6 Gas mains after many years of use 139 0 5 T With simple or double transverse riveted 0 6 0 7 joints lacquered 10 mm thick on the inside With no lacquer but not corroded 122 8 Lacquered the inside but rusted soiled 0 45 1 0 when transporting water but not corroded 122 9 Layered deposita gas maina after 20 years 1 1 of 139 10 With double transverse riveted jomts not 1 2 1 5 corroded sailed during transport of water 194 139 11 Small deposits 139 1 3 12 With double transverse riveted joints heavily 2 0 comodat 121 13 Apprectable deposits 139 2 0 4 0 14 Used for 25 years in munici
88. ol TUT LLL e 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m distance from shoreline x m 2 5 2 5 z e F E 2 2 gt D 1 5 E o 5 nuc 5 o m 0 5 2 2 0 5 0 5 E T feeder Velocity 1 7664m s 5 0 feeder Velocity 1 7664m s iz 0 4 EE EE 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 43 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 5b distance from shoreline x m distance from shoreline x m Fig 34 Flow characteristics for Left tapered diffuser covered or laid in a trench with additional short risers right tapered diffuser on piles without risers both for design flow Q4 8 m s Top down Individual riser flow distribution along diffuser riser flow deviation from mean losses in port riser configurations line port and jet discharge velocities and diffuser pipe velocities port and diffuser diameter lines These differences especially caused by the local losses of the flow entering a riser and further additional loss formulations would not result out of existing diffuser programs e g Fischer et al 1979 implemented as code PLUMEHYD and Wood et al 1993 implemented as DIFF The design and the important optimization of the riser diameters 15 not possible in other programs although influences on design parameters are huge a Tunneled diffuser
89. onsidering a varying effluent flow or varying total head respectively and varying ambient water level elevations The user therefore has to change the time series values from 0 to 1 in the run m file CorHyd than calculates all parameters for every situation and writes the results in report files and gives a summarized graphical output in addition to the output for the design condition Institut f r Hydromechanik Universitat Karlsruhe 48 Varying flowrates All headlosses with the exception of the buoyancy headloss are almost proportional to the squared flow velocity This means that the flow distribution along the diffuser is the same for all values of the the total flow if density differences are neglectable and or the diffuser is not sloped Considerable density differences in combination with sloped diffusers cause different flow distribution for different total flows Due to the constant influence of sloping on the discharge profile the profile asymptotically approaches the non sloped profile for increasing total discharges Under low discharge conditions diffuser are confronted especially with issues of scouring and or intrusion of seawater Seawater intrusion can seldomly be avoided for all discharges Duckbill valves and small diameter pipes prevent those problems but lead to additional pumping costs or higher headwork storage buildings Intrusion can be prevented if the port densimetric Froude number is bigger than 1 F VJ A
90. ounted on discharge ports CorHyd allows to analyze the internal diffuser hydraulics for steady flow conditions before acceleration or deceleration processes started or after they ended All unsteady conditions in between during all times t can be analyzed by applying CorHyd with the actual flowrate Q t in the pipeline This is based on the assumption that the additional pressure in the outfall 15 not available for changing local parameters e g discharge at one specific port because inertia of the whole water mass prevents local accelerations or decelerations which are not directly related to the general flow changes Similar considerations can be done for the other boundary the sea water level for example due to tidal changes These will lead to the same results as for changing the available head at the headworks But high frequent changes like waves which additionally are local events wave crest above one riser and wave trough above other may cause fast pressure changes at the diffuser outlets This can have effects on the flowrate distribution if the fluid volume in the riser port configuration is relatively small i e for holes in the diffuser wall compared to the additional forcing causing decelerations or accelerations Institut f r Hydromechanik Universitat Karlsruhe 26 Nevertheless the optimization of diffuser geometries the internal diffuser design can be made using steady state equations However very short pum
91. p pgD gt Wilkinson 1988 where V denotes the port exit velocity and D the port diameter resulting in a critical port velocity Vp crit Ap For discharges where it is not possible to meet this criterion saltwater enters the system leading to unsteady two layer flow To describe these processes detailed numerical or physical modeling has to be performed Varying ambient conditions Varying the ambient water level elevation or the density does generally not affect the flow distribution along the diffuser but only the necessary total head to drive the system Maximum and minimum values for ambient water level elevation and density should be analysed whether they may cause operational problems or the necessity of higher storage buildings Step 2 Diffuser characteristics diffuser performance calculations Analyse diffuser performance for intermediate flows run CorHyd time series for varying discharges and plot results Pipe velocities time series results allow to denote diffuser sections where scouring velocities are too low for most of the flowrates and or where port Froude numbers are below or near unity create additional diffuser sections at positions where scouring velocities are not obtained for discharges which occur once a day create additional port riser groups for added diffuser sections starting with the same geometry modify diffuser section diameters locally tapering to obtain scouring veloc
92. pal gas mains 4 4 nonuniform deposits af resin and naphtha lene 139 18 Poor condition nonuniform overlapping of 25 0 joints 133 IV Riveted steel tu bes 1 Lateral and longitudinal riveting with one 0 3 0 4 line of rivets 10 thick lacquered on the inside adequate state of the surface 122 2 With double longitudinal riveting and simple 0 6 0 7 lateral riveting 10 mm thick lacquered on the inside or without lacquer but not corroded 122 With simple latera and double longitudinal 1 2 1 3 riveting from 10 to 20 mm thick lacquered or tored on the inside 1221 4 With four to six longitudinal rows of rivets 2 0 long petiod of use 122 With four lateral and six longitudinal rows of 4 rivets joints overlapped the inside 122 6 Very poor condition uneven overlapping of 23 0 joints 1 22 3 Ld um Roofing steel sheets 1 Oiled 10 0 15 2 Not niled 0 02 0 04 Institut fur Hydromechanik Universitat Karlsruhe 21 Table 2 3 Equivalent roughness of tubes and channels Cunrimied Group Type of tubes material State of tube surface and conditions of uga A rim A Metal tubes Cons e VI Galvanized stae tubes 1 Bright galvanization new 139 0 07 0 10 2 Ordinary galvanization 139 0 1 0 15 VII Galvanized sheet steel 1 New 127 0 15 2 Used previously 139 0 1 0 15 Cast iron tubes 1 New 114 0 25 1 0 2 New bituminized 139 0 10 0 15 3 Asphalt coatad 127
93. ph also the port riser headloss are printed on the second axis because these are generally indicating the reason for strong discharge deviations The third bar chart indicates the port and jet velocities which are interesting for further environmental impact analysis The second axis in this graph shows the variation of port diameters along the diffuser An additional information is given for a critical velocity which is the one where the densimetric port Froude number equals unity The fourth bar chart indicates the velocities in the main diffuser pipe and a critical velocity when sedimentation might occur default value of 0 5 m s As an additional information also the fA Institut f r Hydromechanik Universitat Karlsruhe 44 feeder velocity is mentioned if a feeder is applied the second axis of this graph the diffuser diameter variation along the diffuser 1s shown flow properties for Qr 33 5 mie necessary total head 21 9559 mean discharge 0 54910 mis discharge per riser ER m s 4000 4500 5000 5500 DUU 500 ragg 7500 agag distance from shoreline x m port riser headloss discharge deviation part riser headlass m 0 0 4000 4500 5000 5500 DUU 500 ragg 7500 DUU distance from shoreline x m un B 0 15 E 5 ae D a J 0 05 a 0 mon BM TIL D gy eh 0 4000 4500 5000 5500 BD 500 ragg 7500 Bn distance from shoreline
94. ping cycles order of minutes full shutdown purging of a saline wedge during start up or water hammer issues cannot be analyzed with this steady state analysis Unsteady operation purging during start up shutdown of flow or short intermittent pumping cycles water hammers and the related processes like the presence of a saline wedge or the reduction of operating ports will increase pumping costs and effect the flowrate distribution and so far the dilution Additionally energy costs for purging an intruded outfall are significant Any unsteady operation should be avoided by using duckbill valves slowly closing valves or pumps huge headwork reservoirs allowing long pumping cycles and flushing periods further storage provision may be necessary when tidal cycles do not allow continuous discharge or gravitational discharge only possible during ebb phase or retention of storm flows necessary to avoid overspill But if saline intrusion is occurring a saline wedge purging can be guaranteed for example by using some velocity criterion Wilkinson 1984 or a plug flow system where one half of the outfall volume is accumulated in the headwork storage and then pumped at high velocities 1 5m s Wood et al 1993 pp 122 pp 326 The time required to reach steady state once purging was initiated must also be determined see Wilkinson und Nittim 1992 Burrows 2001 discovered that if flow at the headworks 1s interrupted abruptly the effluent flow in the
95. rHyd 3 2 Governing Equations The governing equations are continuity equations at each flow division and the work energy equation along pipe segments with constant or known flowrate Fig 13 Required input data are the geometry of the discharge structure with sets of diffuser pipe segment locations x y Z riser port segment geometries 1 e cross sections A riser port number and allocation and roughness k Pipe lengths L and pipe joint configurations are calculated automatically out of these parameters Used indices are d for diffuser pipe sections r for riser sections p for port sections and J for jet properties at the vena contracta of the discharging jet The ambient is described by its density p and the average water level elevation H resulting in different external hydrostatic pressures at the vertical location of the jet centreline at the vena contracta at each 1 position along the diffuser pipe where risers or ports are attached The effluent is described by its fluid density and either the total flow rate Q or the total available water level at the headworks total head Hi Additional input fields allow to specify more detailed information on local losses T or Y shaped diffuser configurations or the denomination of clogged or temporary closed ports Implemented local losses are those from chapter 2 4 Herefore Gai denote the local loss coefficients for each j component of the total
96. ram 2 4 2 Friction losses Continuous pressure losses due to friction along the walls or boundary layers in a pipeline are calculated as Lp Vo or as headloss LN 7 D 2 D 2g where is the friction coefficient L the length of the considered pipe section D the diameter V the velocity in the pipe section and the density of the effluent For the calculation of the friction coefficient A the explicit form described by Swamee and Jain 1976 is used 0 25 8 A _ 574 370 It is valid for 19 5 2 219 2 and 4 10 lt Re lt 10 where stands for the equivalent sand D pi A roughness and the Reynolds number Re VD v where v stands for the kinematic viscosity of the effluent Values of k for different pipe materials and surface conditions of use are listed in Table 3 which is an excerpt of Idelchik 1986 If only Mannings n values are known a conversion to k can be done by using the formula lt n 5 87 2g 9 fA Institut f r Hydromechanik Universitat Karlsruhe 19 Table 3 Equivalent sand roughness for tubes of different materials Idelchik 1986 Table 2 3 Equivalent roughness of tubes and channels Group Type of tubes material State of tube surface and conditions of use A mm A Metal tubes 1 Senm ess tubes made Commercially smooth 122 129 139 0 001 5 0 0100 from brass copper lead Aluminum tubes The same 0 015 0 06 i
97. ram consists of several short subprograms The main program that reads in the data and calls the subprograms for calculations 15 called Internal Diffuser Hydraulics For easy input and clarity purposes the program has a graphical user interface GUI Fig 14 shows the processing sequence and structure of the code elements which are furthermore explained in detail in Table 4 There 1s a first division in single and multiple diffusers than a second division in diffuser with and without riser and a third division depending on the parameter to solve for total head or total discharge and individual discharges Loc losses mat C array mat Loc losses mat C array mat plot losses Fig 14 CorHyd organigram for the algorithm IH H Institut f r Hydromechanik Universitat Karlsruhe 33 Table 4 CorHyd subroutines and their purpose 1 Simple Setup one diffuser only add local losses m GUI for additional local losses if the user likes to put input more losses on a port or riser than the ones applied in the code prints the results into a bar chart bend m calculates the angles of pipe bends having the node function locations X y z calculations m calculates diameters and areas length and slope of the input and some diffuser feeder Section the static external heads outside preparatory of the ports from input data calculations check length m checks if the input is possible input check choose system GUI i
98. red and evaluated by entering the loss coefficient e g from chapter 10 2 1n the annex and the contraction coefficient The data given in sub window 15 not saved with the overall result and has to be put again after the calculation Institut f r Hydromechanik Universitat Karlsruhe 40 Additional Local Losses fmi Fig 17 Pop up window for further input of local losses at ports or risers 4 6 Blocked ports sub menu If the user knows blocked ports for already operating diffusers these can be considered in the calculation to analyze this modified diffuser system This may also be done for analyzing diffusers with temporarily closed ports in early design periods Fig 18 shows the input window for clogged ports where only the number of the ports has to be put Clogged Ports X Enter number s af clogged parta e g 1 2 5 8 Cancel Fig 18 Pop up window for clogged ports input 4 7 Y or T diffuser sub menus If two diffuser are connected to one riser the program allows to calculate each diffuser separately and iterate to meet the joined boundary condition equal pressure at the end of the feeder pipe The input for each diffuser 1s analogue to the input for single diffuser outfalls Fig 19 shows the input window for the first and Fig 20 the input window of the second diffuser of the two diffusers Each diffuser can be saved separately in a file Institut fur Hydromechanik Universitat Karls
99. rigin is user defined It 15 recommended to use a fixed datum for vertical coordinates and to locate the x coordinate close to parallel to the diffuser line for better visualization of the results port riser elevation H L Aa Ass A A Aq pipe section 1 4 port discharge niser discharge a d D x 2D ri ports liiser diffuser pipeline Fig 15 Coordinate system used in CorHyd Five pipe sections and two port riser groups are shown in this example Before hitting the Run button the user can choose the format of the output by checking the appropriate radio buttons in the upper right hand corner Possible outputs include a diagram showing the selected configuration a text file a graph showing the energy and pressure grade lines and a bar chart showing the riser discharges diffuser velocities just upstream of every riser and the port velocities When the Run button 15 hit the data 1s read into variables and passed on to subprograms responsible for computation of discharges and pressures fA Institut f r Hydromechanik Universitat Karlsruhe 36 Fig 16 shows the GUI with an example input The graphical user interface consists of 5 tabs Ambient Data i e parameters describing the ambient water body Effluent Data Diffuser Feeder Pipe Configurations 1 e location roughness diameter etc of the main pipe here 6 different sections are chosen Port Riser Configurations i
100. riser configuration The coefficients and depend on the flow ratio of diffuser pipe flow and riser flow at each riser port location which 1s furthermore influenced by the pressure difference caused by A A design rule that is often mentioned in literature Grace 1978 recommends to keep the ratio between the cumulative port areas 2a downstream a diffuser pipe cross section area Aan Smaller than one with the explication that it is impossible to make a diffuser flow full if the aggregate jet area exceeds the pipe cross section area since that would mean that the average velocity of discharge would have to be less than the velocity of flow in the pipe Fischer et al 1979 p 419 A further suggestion taken from Fischer et al 1979 p 419 resumes that the best ratio is usually between 1 3 and 2 3 1 3 lt Xi Apx Aai lt 2 3 These criteria work fine for simple and uniform geometries without risers and for horizontal laid diffusers or for first estimates But they can be unnecessarily conservative if no further optimization is done For example sloped diffusers following the sloped bathymetry may equalize the distortion of the discharge profile resulting from a area ratio bigger than one First estimates for non uniform riser systems can be done by replacing the port cross sectional area in the mentioned criteria with the riser cross sectional area and applying these criteria for each section separately Nevertheless for chang
101. rsitat Karlsruhe 80 Continued ae Pr ip en gt SSS i rt i Discharge from a straight tube through an orifice or a perforated plate Diagram grid with differently shaped orifice edges Re Wor d v gt 10 14 16 11 19 al Resistance coefficient Scheme and graph Ap where f G a f 0 0 01 0 02 0 03 0 04 0 05 dh o oan 044 0 37 031 026 0 22 0 06 0 08 0 12 0 16 0 20 0 19 0 15 0 09 0 06 0 03 204 005 072 0 r dg Discharge from a tube through an orifice or a perforated Diaeram plate grid with differently shaped orifice edges in transition que and laminar regions Re wot Dy v lt 10 105 tentatively 14 16 1 25 lt Re lt 10 10 Wo fo For _ 1 fep Perforated plate Orifice 2 10 lt Re lt 25 33 1 Wo Fo For Re Re qu 3 lt 10 4 33 1 Re f f For where oge Re and fo f Re F see Diagram 4 19 it F is assumed that f corresponds to F F qu is determined as at Re gt 10 10 from Diagrams 11 18 and 11 19 Institut fur Hydromechanik Universitat Karlsruhe
102. ruhe 41 Complex Setup ge Go umber of dil iererd pal Zrter grows ha 1 Group Number counting trom tee ered 1 Humber od risers per group Is Located in Section Seer Dearie fart risers Irom verban LE mif v bahren bars Epica ug Im E Kee ep Lr mm os Drarce ier o1 Dr oi Roughness of ricer roi Humber of cr er porke per ipa 7 1 Lengi of port CL pug m d port opening diameter Ong Roughness of port Red m Ion Lorn asses Clagged Ports op Gre Number of different port friger groupe ha 1 Crnu Murer counting reen tree eni 1 Number of risers per group Map 1 11 Located in Section Sacha 1 1 ol fart riers Irom verbe LT Imi 0 apace risers Caas Gi es rer pee ati Lr ot m os of Dr oi Roughreess of riser m noms Humber of operis ports Cer eech o L 1 Lengi ot port mil d pret opening diameter Dg gt Roughness of pari Had Ion asses Prats Fig 20 Second input sub window for second diffuser part of Y or T diffuser IrH H Institut f r Hydromechanik Universitat Karlsruhe 42 5 Data Output Before hitting the Run button
103. ry investigations Therefore it 1s recommended to do calculations with additional loss coefficients especially for the port riser configurations and check whether the influence on diffuser performance are important or not If the influence is big it is recommended to do laboratory studies to find better formulations for this special configuration Influence of construction imprecision Submarine construction techniques do not allow for precise pipe allocation and precise pipe fittings Therefore loss coefficients calculated out of loss formulations may have uncertainties due to non precise siting and fitting of the pipes Additional losses are resulting out of these uncertainties Consequences are higher losses These can be estimated using the formula from 2 4 1 for inaccurate sitings and fittings Sensitivity studies on these uncertainties allow for analysis of maximum total head level Varying material properties Additionally changes of materials over time can be considered in further sensitivity calculations where pipe roughness values can be increased and diffuser performance be analysed Wood et al 1993 p 133 If deposition of solids is expected decreased diameters allow to analyse diffuser performance under these condition Step 4 Sensitivity analysis prediction accuracy Final diffuser design under maximum discharge conditions run CorHyd with additional port losses to check influences of loss formulations on final result vary
104. s analysis and further sensitivity analysis allowed to evaluate whether parameter changes are in acceptable orders which has been the case for Berazategui outfall 8 Conclusions Calculations for the internal manifold hydraulics show a strong sensitivity on the representation and formulation of local losses even for relatively simple riser port configurations Special attention is necessary to account for all these losses in multiport diffuser design a fact that 15 often neglected in common programs causing malfunction resulting in different total heads bad discharge distributions and sediment accumulation CorHyd design procedure including CorHyd calculations consider flowrate variations either for short term or long term changes and allow to optimize the diffuser geometry to comply with scouring of sediments under minimal headloss conditions and a homogeneous discharge distribution required from the environmental impact criterias Proper diffuser performance 15 therefore assured for most of the boundary conditions often with cheaper maintenance and operation costs Latter can be achieved by reducing the sedimentation of particles in the diffuser and therefore the cleaning intervals and also a time dependend diffuser extension where fewer pumps are needed at the commission The presented applications here release some assumptions of previous diffuser programs by considering flexible geometry specifications with high risers and variable ar
105. scharge q is estimated for example q Q N with Q total discharge and N total number of risers Equation 19 then allows to calculate the first internal pressure of the diffuser The further discharges until qn are calculated using equation 20 A final application of equation 18 allows to calculate pan 1 the necessary pressure at the headworks to drive the system The total head Hi can be calculated by Hi pan i Yetauent 1f the water level elevation of a gravity driven system N has to be defined The calculated total discharge 15 d The difference to the planned total discharge is diff Q If necessary 1 for diff gt 10000 CorHyd performes further iterations with modified estimates To achieve faster convergence the following algorithm eq 22 has been implemented to calculate qii Q N qi 7 qu T Qe 1 201 91 1 __ for c gt 2 22 Q diff The iteration stops if the difference between the given total discharge and the calculated total discharge is less than 10 Q The results are individual port riser discharges and velocities in all pipe sections along the diffuser and a total head These can be displayed or printed with further output options 3 3 2 Solving for total flow At the first port riser on the seaward side 1 1 an initial internal pressure is estimated for example pai ye N pai Ye Zjeti Zai With total
106. ss flux per diffuser length with the port exit velocity V and the equivalent slot width B Ay A is the port cross section and the riser spacing see Fig 4 z is the observed position in the vertical above the discharging port n 2 D Merging level 2 D Zone dll j N 3 D NN NENNEN Fig 4 Definition diagram for plume centerline dilution equation for multiport diffusers A simple estimate of effects from a distorted discharge profile is a comparison of the centerline dilution for two different mass fluxes a SSC eg Sa a 2 Ont Jo 2 2 10 discharge variation 2 40 0 9 along a diffuser would therefore result in dilution difference of 7 5 1 8 0 93 along the diffuser line These differences are often not considered in further mixing calculations and so far could harm the environment or could lead to critical concentrations with respect to the discharge permit The combination of CorHyd with CORMIX allows to find an optimized internal hydraulics design cost effective resulting in environmental sound solutions 2 3 Internal hydraulics operational requirements CorHyd covers the internal diffuser hydraulics with the following design objectives e uniform discharge distribution along the diffuser in order to meet dilution requirements and to prevent operational problems e g intrusion of ambient water through ports with low flow
107. t fur Hydromechanik Universitat Karlsruhe 37 gt po Further sensitivity analysis or time series runs chapter 6 2 allow for more detailed analysis of diffuser performance for changing ambient boundary conditions like tidal water level changes or seasonal density variations Typical values for sea water density are po 1021 1026 kg m 4 2 Effluent Data The design flow rate shall be the maximum foreseen at the end of design life Generally there 1s a headwork basin or the treatment plant itself with sufficient capacity to accept daily peaks and storm waters or an additional storm water outfall resulting in an average flow rate for the outfall In this case the design can be made on the average daily maximum flow at life end If there is no or a too small basin the ratio of the peak rate of flow to the average rate of flow might range from 6 for small areas down to 1 5 for larger areas and just a storm water overflow the design flowrate 15 the daily peak flow excluding storm waters If there 15 nothing foreseen for daily peaks and storm waters the design discharge has to be the maximum daily flowrate including stormwater discharges The latter design discharge does not occur on a daily basis therefore optimization procedures for non design discharges are even more important than for the other cases Performance checks should explicitly done for the foreseen near future scenarios often considering increasing flows in 5 10
108. tem conversion back2 m converts variables for the complex system create boxes complex m creates additional input boxes for the complex input system create boxes complex port m creates additional input boxes for the complex system display complex m plots the results bar charts display energy complex m plots the energy grade line and the hydraulic grade line display setup complex m plots the geometry of the complex system feeder pipes complex m calculates the pressure along the feeder pipe starts riser locationcomplex1 m es ume eR starts riser locationcomplex2 m pressure riser m main function for calculating the pressures and main function discharges along the diffuser report complex m creates the text output file input of the nodes input of the nodes runcomplex m starts the different calculations start after GUI NO Riser complex system pressure no risercomplex m main function for calculating the pressures and main function discharges along the diffuser f Institut f r Hydromechanik Universitat Karlsruhe 3 5 4 Data Input Input can either be done by typing the data directly into the designated spaces or by importing an existing text file Menu File Load File Input can be saved into a ASCII file Menu File Save File Additional inputs e g Y diffuser or further losses may be defined in sub windows by typing in the data Fig 15 illustrates the used Cartesian coordinate system which o
109. the user can choose the format of the output by checking the appropriate radio buttons in the upper right hand corner Possible outputs include a diagram showing the selected configuration a text file a graph showing the energy and pressure grade lines and a bar chart showing the riser discharges diffuser velocities just upstream of every riser and the port velocities When the Run button 15 hit the data 15 read into variables and passed on to subprograms responsible for computation of discharges and pressures 5 1 Report If the report radio button has been activated for the output an ASCII file 15 written to the program directory and consists of the following parts The header with the date Summary of the results 27 Apr 2005 Input data INPUT ambient data Water level Hd m above datum z 0 m Hd 4 00 Ambient density rho 0 in kg m 1000 00 INPUT effluent data Density rho e of effluent in kg m 999 00 Flowrate of effluent in m s 33 62 INPUT outfall sections Length slope x y and z coordinates for different sections Length Slope x y 2 7500 00 0 00 2 50 1 450 00 0 00 7050 00 0 00 2 50 2 500 00 0 00 6550 00 0 00 2 50 3 2050 00 0 00 4500 00 0 00 2 50 4 4480 00 0 00 20 00 0 00 2 50 5 21 03 0 31 0 00 0 00 4 00 Output data OUTPUT flowrates and velocities Riser Discharges q Total discharge Q Port Velocities Vp and diameter Dp Jet Velocities Vj Riser Velocities Vr Densimetric
110. tion of a constructional design alternative for the Ipanema outfall with a tunneled diffuser pipe long risers and rosette like port arrangements Institut fur Hydromechanik Universitat Karlsruhe 65 flow properties for Q 8 m s necessary total head H 33 7189 D 2 02 SE C i 0 17776 my T d 045 T a 01 0 05 8 2 0 5 fso 3900 3850 4000 4050 4100 4150 4200 4250 4300 4350 3850 3900 3950 4000 4050 4100 l 4150 4200 4250 4300 4350 distance from shoreline m distance from shoreline x m 0 1 _ DR port iserheadloss pg E port riser headloss S 8 005 S 005 E 06 2 e E gt Ka 5 0 NN EM 3 0 ou 2 m 0 05 O22 5 0 05 EE E s 8 5 D 1 deo 3900 3950 4000 4050 4100 4150 4200 4250 4300 PECH 3850 3900 3950 4000 4050 4100 i 4150 4200 4250 4300 4350 distance from shoreline x m distance from shoreline x m g 225 eS i g 2 2 g 2 015E 5 815 5 Ge 1 5 ct gums 01 9 S E ET m erre o TEE i Wil i gos Eo 2 gL o gt 3960 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 gt 3850 3900 3950 4000 4050 4100 4150 4200 4250 4300 4350 distance from shoreline x m distance from shoreline x m N in diffuser velocity m s diffuser diameter diffuser velocity m s diffuser diameter rn fee
111. ulics calculation with CORMIX and the internal hydraulics calculation with CorHyd Publications from Bleninger et al 2002 and Bleninger et al 2005 describe scientific basis and demonstrate comparisons and validation The objectives of this manual are a to provide comprehensive description of CorHyd b give guidance for assembly and preparation of required input data c delineate ranges of applicability d guidance for interpretation of results and e to illustrate practical application 1 1 Installation and start Unzip the matlab files into one folder on your computer Run Matlab and change to the folder where the files have been saved as your working directory Type IDH and the graphical user interface opens up Open an existing test file and press run to do the first calculation fA Institut f r Hydromechanik Universitat Karlsruhe 4 2 Background 2 1 Multiport diffusers Waste water treatment plants commonly discharge treated effluents through outfalls into rivers or coastal waters These plants are designed to minimize environmental impacts by reducing the pollutant concentrations of the effluent Nevertheless even discharges of state of the art treatment plants may cause local pollution of the receiving waters if the effluent contains persistent substances and especially if discharge flowrates are high which is the case for most large metropolitan areas like Buenos Aires New York Rio de Janeiro HongKong Boston Ist
112. velocities which are bigger than the diffuser velocities but smaller than the port velocities to allow for a constant flow acceleration For design discharges a homogeneous distribution should be achieved and often only gravity discharge should allow to drive the system This can be done by either changing port diameters along the diffuser or applying variable area orifices In comparison with fixed constant or invariable port diameters the effective open area of variable area orifices duckbill valves changes with different discharges Therefore they are good for non or low discharge scenarios where intrusion has to be prevented Decreasing fixed port diameter leads to a more homogeneous discharge distribution but to increased losses and total head due to higher velocities Attached duckbill valves give almost homogeneous discharge profiles due to the discharge dependent open area By applying different diameters for CorHyd calculations it has to be considered that pipes are not available in all sizes and only diameters are applied which are given as internal diameters in catalogues of pipe producers Nevertheless often a few centimeters difference in the port orifice diameter makes considerable differences if applied all along the diffuser or in designated pipe sections Furthermore changes of port diameters might be necessary during lifetime of the diffuser to adopt for changing boundary conditions Both can easily realized by flanges at the d
113. waves Institut f r Hydromechanik Universitat Karlsruhe 5 Local water riser spacing Headworks Feeder supply pipe bid Outfall pipeline riser diffuser pipeline Fig 1 Outfall configuration showing feeder pipe and diffuser from side view and top view defining the pipelines and port riser configurations predominant currents ee e mtd a See M c ee oe Be e m 2 e gf 7 shore Une Fig 2 Left standard diffuser Right Y or T shape diffuser configuration IH Institut f r Hydromechanik Universitat Karlsruhe 6 A Fig 3 a simple port source Carlo Avanzini b Variable area orifices duckbill valves Image RedValve Company c riser port configuration Guaraja outfall Sao Paulo State Brazil d rosette like port arrangement Boston Outfall Image Massachusetts Water Resources Authority Boston USA Typical outfalls are several kilometers long and discharge up to 1 112 5 treated effluent through a few ten up to a hundred m long diffuser section with 10 50 ports in 10 to 40 meters depth These constructions may cost a few million Euro Gunnerson 1988 and are difficult to construct and maintain due to deep sea diving limits the strong dependency on weather conditions and the need for uninterrupted discharge for operating systems Therefore savings in construction and operation are of major importance An out
114. ze on mixing characteristics Carvalho et al 2002 These monitoring studies showed in general good mixing characteristics At commissioning 59 of the 180 ports have been closed on purpose to achieve reasonable flow conditions until design flow 15 reached Since 1996 all ports are discharging The constructional design itself 15 unusual with a concrete diffuser line fixed on piles above the seabed The piles proofed to be the weak point of the construction where pile breaks lead to a major rupture in year 2000 Today simpler and cheaper laying methods are available e g HDPE pipes with weights or laid in a trench which promise to be more resistant to dynamic wave forcing and currents En 54 42 E h I E bo k n MN i d di d P a e lhos Cagarnas XI Fig 23 Locoation map of the Ipanema outfall of the city Rio de Janeiro in Brazil Carvalho 2003 Institut f r Hydromechanik Universitat Karlsruhe 53 headworks om 3877 m A 4326 diffuser 74m e ki i lt aw d z x Se i T Wt i lt Ki m e dE E E A gt T Bed be K D db P s M ge a x AC E e d il E 5 4 REF a i D i si e Gm em Fig 25 Image from the constru
115. zeta zeta Zeta s zeta s vRatio 2 AL M db 4 L Code see files CommonFeederPipe m feederpipes m DiffuserLosses m Losses common feeder m T division Idelchik 1986 G 1 1 5 aA A 2 Code see files CommonFeederPipe m feederpipes m DiffuserLosses m Losses common feeder m Straight Gel orifice i Uniform Side Fischer et al 1979 for sharp edged orifices branching y orifice K 0 63 EN 7 depending on the diffuser centerline velocity V4 and the excess energy head E see chapter Fehler Verweisquelle konnte nicht gefunden werden Flexible Lee et al 1998 Red Valve Company Abromaitis 1995 Elasto Valve Rubber Products EVR orifices duckbills 2 D Pu V tuck a e 774 etn Rb bow y ae T ter pg Ee peni reg pe w IH Institut f r Hydromechanik Universitat Karlsruhe 17 Where denotes the headloss the discharge velocity which depends on the effective open area Aguck Which depends on the flow through the valve these parameters are dependend also on the used stiffness of the rubber material The following formulas are taken out of Lee et al 1998 but should be modified related to the used material from the providing company If other materials are used the following formulations have to be modified in the code Vas m s TF 100 F 4 103 1 e Q

USER'S MANUAL FOR CORHYD: AN INTERNAL DIFFUSER

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