بررسی آزمایشگاهی تأثیر ارتفاع دریچه تخلیه کننده بر غلظت جریان غلیظ خروجی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری/ سازه‌های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز

2 استاد/ گروه سازه‌های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز

3 استادیار/ گروه سازه‌های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز

چکیده

جریان‌های غلیظ یکی از عوامل مؤثر بر رسوب‌گذاری در مخازن سدهاست که یکی از مشکلات مهم در مدیریت منابع آب می‌باشند. گشــودن دریچه‌های تحتانی سد، روش متداول تخلیه این جریان‌ها و حفظ حجم مفید مخزن می‌باشد انتخاب ارتفاع مناسب دریچه تخلیه جریان بر روی دیواره سد دارای کاربردهای مختلفی در مدیریت مخازن سدها دارد که می‌تواند بر کیفیت آب خروجی از سدها تأثیر عمده داشته باشد. بنابراین در این تحقیق سعی شده به بررسی تأثیر ارتفاع دریچه تخلیه کننده بر غلظت جریان غلیظ خروجی پرداخته شود. بدین منظور چهار دریچه در ارتفاعات 5، 15، 25 و 40 درصد نسبت به عمق سیال پیرامون بر روی یک دیواره در انتهای فلوم کار گذاشته شد. جریان غلیظ ورودی با سه غلظت 5، 15 و 30 گرم در لیتر با یک دبی ثابت تزریق گردید. نتایج نشان می‌دهد که در موقعیت که دریچه در ارتفاعی نظیر 5 درصد عمق سیال پیرامون قرار بگیرد مقدار غلظت خروجی به‌طور متوسط 10 درصد بیشتر از غلظت متوسط جریان پشت دریچه می‌باشد و با افزایش مدت زمان باز نگه داشتن دریچه در اعماق مختلف به دلیل خروج جریان بیشتر، غلظت و درنتیجه راندمان تخلیه جریان غلیظ 40 درصد افزایش می‌یابد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental Investigation on the Effects of Selective Withdrawal Gate on Venting of Turbid Density Current

نویسندگان [English]

  • M. Zayeri 1
  • M. Ghomeshi 2
  • M. Shafaei Bajestan 2
  • A. Fathi 3
1 Ph.D Student of Hydraulic Structures, Shahid Chamran University, Ahwaz, Iran.
2 Professor, Faculty of Water Structures Engineering, Shahid Chamran University, Ahwaz, Iran
3 Assistant Professor, Faculty of Water Structures Engineering, Shahid Chamran University, Ahwaz, Iran
چکیده [English]

Turbidity currents are one of factors affecting in sedimentation and reducing the water capacity of reservoirs and useful life of dams. Opening bottom gates is a conventional method of this currents venting and preservation of the useful volume of the reservoir. Choose a suitable height of gate on the dam has variety of applications in the management of reservoirs that can have a major impact on the water quality. So this study have tried to investigate the effect of selective withdrawal gate on venting of turbid density current through reservoir’s outlet. For this purpose Four gates established at height of 5, 15, 25 and 40 percent compared to the depth of the ambient fluid on a wall in the end of flume. The Turbidity current input with concentrations of 5, 15 and 30 g/L were injected with a constant volume flow rate. The results show when the position of the gate is placed at 5 percent of the fluid depth, the amount of output concentration averagely 10 percent higher than of input concentration of turbidity current. with increasing duration of keeping open the outlate gates, venting efficiency will increasing of 40 percent.

کلیدواژه‌ها [English]

  • turbid density current
  • Reservoir managment
  • venting efficiency
  • reservoir outlet
Bohan JP, Grace JL (1973) Selective withdrawal from man-made lakes: Hydraulic laboratory investigation. Tech. Rep. H-73-4. US Army Engineer, Waterways Experiment Station, Vicksburg, US

Fan J, Morris GL (2009) Reservoir sedimentation. II: Reservoir desiltation and long-term storage capacity, ASCE, Journal of Hydraulic Engineering, 118(3):354-369

Fan JH (2008) Stratified flow through outlets. Journal of Hydroenvironment Research, 2(1):3-18

Flix M, Sturton S, Peakall J (2005) Combined measurments of velocity and concentration in experimental tubidity currents. Journal of Sedimentary Geology, 179:31-47

Forel FA (1892) Theorie du ravin souslacustre, Le leman, F. Rouge, Lausanne. Switzerland, 34:381-386

Harleman DRF, Elder RA (1965) Withdrawal from two-layer stratified flow. Journal of Hydraulic Division 91(4):43-58

Hay AE (1987) Turbidity currents and submarine channel formation in rupert inlet. Journal of Geophysical Research 92:2883-2900

Hino M, Onishi S (1980) Axis-symmetric selective withdrawal: Summary. Department of Civil Engineering, Tokyo Institute of Technology 21:107-122 (in Japanese)

ICOLD (1999) World register of dams, Update. International Commission on Large Dams, Paris

Jirka GH (1979) Supercritical withdrawal from two-layered fluid systems. Part 1:Two-dimensional skimmer wall. Journal of Hydraulic Research 17(1):43-51

Lawrence GA, Imberger J (1979) Selective withdrawal through a point sink in a continuously stratified fluid with a pycnocline. Department of Civil Engineering, University of Western Australia, Australia 79:100-112

Lee HY, Yu WS (1997) Experimental study of reservoir turbidity current. Journal Hydraul. Eng 123(6):520–528

Keshkar SH, Ayobzadeh A, Firozabadi B (2010) Laboratory examination the impact of changes of inlet valve opening height on vertical profiles of velocity and concentration of turbidity current, Seventh Conference of Hydraulic Iran

Lee F, Lai J, Tan Y, Sung C (2013) Turbid density current venting through reservoir outlets. KSCE Journal of Civil Engineering 18(2):694-705

Morris, G, Fan J (2009) Reservoir sedimentation handbook: Design and management of dams, reservoirs, and watershed for sustainable use. McGraw-Hill, New York

Ohey CD (2002) Effects of obstacles and jets on reservoir sedimentation due to turbidity currents. Communication 15, A.J. Schleiss, ed., Laboratory of Hydraulic Constructions, Ecole Polytechnique Fe´de´ralede Lausanne, Lausanne, Switzerland

Ramezani Y, Ghomeshi, M (2011) Evaluation of Effect of Turbidiy Currents on Sedimentation Process in Sefidrood Reservoir, Journal water and soil 25(4):874 -880

Sequeiros OE, Cantero MI, Garcia MH (2009) Sediment management by jets and turbidity currents with application to a reservoir for flood and pollution control in Chicago, Illinois, Journal of Hydraulic Research, 47(3):340-348

Spigel RH, Farrant B (1984) Selective withdrawal through a point sink and pycnocline formation in a linearly stratified flow. Journal of Hydraulic Research 22 (1):35-51

Wang ZY, Hu CH, (2009) Strategies for managing reservoir sedimentation. International Journal of Sediment Research, 24 (4):369-384

Water Research Institute (2000) Sedimentation in the reservoir of large dams, Ministry of Energy, Iran

Wood IR (2001) Selective withdrawal from two-layer fluid. Journal of Hydraulic Division, ASCE 104 (12):1647-1659

Yu WS, Hsu SM, Fan K (2004) Experiments on selective withdrawal of a codirectional two-layer flow through a line sink. Journal of Hydraulic Division, ASCE 130(12):1156-1166

Yu WS, Lee HY, Hsu SM (2000) Experiments on deposition behavior of fine sediment in a reservoir. J. Hydraul Eng 126(12):912-920