نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد مهندسی سازه‌های آبی، دانشگاه کشاورزی و منابع طبیعی رامین خوزستان

2 استادیار گروه مهندسی آب، دانشگاه علوم کشاورزی و منابع طبیعی خوزستان

چکیده

آب­شکن سازه­ای است که در شرایط مختلف بازه­ی رودخانه­ها و با هدف حفاظت از سواحل رودخانه استفاده می­شود. در این مقاله به مطالعه­ی آزمایشگاهی ساختار جریان اطراف آب­شکن­های مستقیم، T و L شکل پرداخته شده است. بدین منظور هیدرودینامیک سه­بعدی جریان اطراف این آبشکن­ها به­صورت آزمایشگاهی و در یک کانال مستقیم با بستر صاف مورد مطالعه قرار گرفت. مؤلفه­های سرعت جریان در سه بعد در اطراف آب­شکن­ها به­وسیله سرعت­سنج سه­بعدی ADV اندازه­گیری شد. نتایج نشان می­دهد نقطه جدایی جریان به فاصله­ی 2 برابر طول آب­شکن­ها و در بالادست آب­شکن­ها می­باشد. حداکثر سرعت متوسط زمانی در امتداد صفحه جدایی جریان و در آبشکن مستقیم ایجاد می­شود. طول صفحه­ی برشی جریان در آب­شکن­های مستقیم، T شکل و L شکل به­ترتیب 10، 9/9 و 5/9 برابر طول جان آبشکن بوده و در نتیجه با افزایش طول بال آب­شکن گستره طولی گردابه پایین دست آبشکن کاهش می­یابد. حداکثر مؤلفه سرعت عمودی جریان در بالادست و دماغه آب­شکن­ها شکل گرفته و شدت آن در آب­شکن مستقیم بیشتر از دو آب­شکن دیگر در این مطالعه می­باشد. همچنین حداکثر انرژی جنبشی آشفتگی (TKE) در تراز 6/0 Z/H=و در امتداد لایه برشی و در آب­شکن مستقیم رخ می­دهد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Three-dimensional Study of Flow Turbulence Extension around Straight, T and L Shaped Groynes in Open Channles using Physical Model

نویسندگان [English]

  • Fatemeh Veisi 1
  • Ahmad Jafari 2

1 M. Sc. Department of Water Engineering, Ramin Agriculture and Natural Resources University of Khuzestan

2 Assistant Professor, Department of Water Engineering, Agricultural Sciences and Natural Resources University of Khuzestan

چکیده [English]

Rivers have long been considered as one of the most important sources of water supply. Flooding during flood events causes irreparable damage. Therefore, some methods such as the protection of river banks against erosion are considered to control the flood. One of the methods for protecting the rivers and controlling their erosion is the use of groynes. Groyne is a structure that uses rock, sand, etc. to   slow down the process of erosion and prevent ice-jamming, which in turn aids navigation . and generates suitable environmental conditions for aquatic organisms in different conditions and in different parts of the river. According to the importance of groynes, a detailed and three- dimensional study of turbulent flow and the intensity  of turbulence extension in these structures is of prime importance . In the present research, three- dimensional turbulent flow was completely studied using ADV advanced velocimeter in straight, L- and T- shaped groynes in a straight canal with a rigid substrate and 20% contraction of the groynes in the canal’s width by collecting numerous data points , and the turbulent extension  was studied in three- dimensions, which is one of the novel charactersistics of this research.

کلیدواژه‌ها [English]

  • Turbulent Flow
  • velocimeter
  • Vortex
  • River
  • Laboratory

1- Abbasi, A.A. and Malek Nejad Yazdi, M. 2014. Experimental investigation on the effect of length, space and shape of Gabion Groynes on local scouring depth. Journal of Water and Soil Conservation. Vol. 21(4). (In Persian).

 

2-    Alizadeh Armaki, H., Vaghafi, M., Ghodsian, M. and Khosravi, M. 2015. Experimental Investigation of Flow and Scour Pattern around Submerged Attracting and Repelling T head Spur Dike. Modares Civil Engineering Journal (MCEJ). Vol. 15. (In Persian).

 3-    Barua, D. K., and K. H. Rahman. 1998. Some aspects of turbulent flow structure in large alluvial rivers. Journal of Hydraulic Research., 36(2), 235-252.

 4-    Dehghani, A.A., Barzzli, M., Fazloula, R. and Zea Tabar Ahmadi, M.KH. 2009. Experimental study of scouring around a series of L-head groynes. Journal of  Water and Soil Conservation. Vol. 16(3). (In Persian).

 5- Duan, J., 2009. Mean flow and turbulence around a laboratory spur dike. Journal of Hydraulic Engineering., 135(10), 803-811.

 6- Duan, J., He, L., Fu, X., and Q. Wang. 2009. Mean flow and turbulence around an experimental spur dike. Adv. Water Resour., 32(12), 1717–1725.

7- Ettema, R., and Muste, M. 2004. Scale effects in flume experiments on flow around a spur dike in flat bed channel. Journal of Hydraulic Engineering, ASCE, 130(7), 635–646.

8-González-Castro, J. A., K. Oberg, and Duncker, J. J. 2000. Effect of temporal resolution on the accuracy of ADCP measurements. In Building Partnerships, 1-9.

9- Hoseinzade Tabrizi, H., Vaghefi, M. and Ghodsian, M. 2014. Effect of Froude Number on flow pattern and scour around T-shaped spur dikes under submerged and unsubmerged conditions. Modares Civil Engineering Journal (M.C.E.J). Vol. 14, No. 2. (In Persian).

 10- Koken, M., and G., Constantinescu, 2009. An investigation of the dynamics of coherent structures in a turbulent channel flow with a vertical sidewall obstruction. Phys. Fluids, 21(8).

 11- Koken, M., G., Constantinescu, 2008. An investigation of the flow and scour mechanisms around isolated spur dikes in a shallow open channel: 1. Conditions corresponding to the initiation of the erosion and deposition process. Water Resources Research, 44(8), W08406.

 12- Kuhnle, R., and C., Alonso, 2013. Flow near a model spur dike with a fixed scoured bed. International Journal of Sediment Research, 28(3), 349-357.‏

 13- Kumar, M., and A., Malik, 2016. 3D Simulation of flow around different types of groyne using aNSYS fluent. Imperial Journal of Interdisciplinary Research, 2(10).

 14- Kwan, T. F. 1988. A study of abutment scour. Rep. No. 451, School of Engineering, Univ. of Auckland, Auckland, New Zealand.

 15- Li, H., Barkdoll, B. D., Kuhnle, R., and C., Alonso, 2006. Parallel walls as an abutment scour countermeasure. Journal of Hydraulic Engineering, 132(5), 510-520.‏

 16- Mehraein, M., Ghodsian, M. and Khodravi M, M. 2016. Experimental study of submergence effect on turbulent parameter around spur dike located in a 90 bed. Modares Civil Engineering Journal (MCEJ). Vol. 16. (In Persian).

 17- Moosavi, B., Saneie, M., Salajeghe, M. and Motamed Vaziri, B. 2010. Iran-Watershed Management Science & Engineering. Vol. 4, No. 12. (In Persian).

18- Noorbakhsh Saleh, S.M., Vaghefi, M. and Ghodsian, M. 2013. Experimental Investigation of Scour Pattern around Submerged T-Shape Spur Dike in Straight Channel. Iran-Water Resources Research. Vol. 9, No. 2. (In Persian).

 19- Paik, J., and F., Sotiropoulos, 2005. Coherent structure dynamics upstream of a long rectangular block at the side of a large aspect ratio channel. Phys. Fluids, 17(11).

 20- Rajaratnam, N. and B., Nwachukwu, 1983. Erosion near groyne-like strutures. Journal of Hydraulic Research., 21(4), 277-287.

 21- Rhoads, B. L., and A. N. Sukhodolov. 2001. Field investigation of three-dimensional flow structure at stream confluences: 1. Thermal mixing and time-averaged velocities. Water Resources Research, 37(9), 2393-2410.

 22- Safarzadeh, Z. and Safarzadeh, A. 2016. Experimental Study of Turbulent Flow Strutures in Two Groynes Field using PIV Method. Modares Civil Engineering Journal (M.C.E.J). Vol. 16, No. 1. (In Persian).

 23- Safarzadeh, A., Salehi Neyshabouri, S. A. A., and A.R., Zarrati, 2016. Experimental investigation on 3D turbulent flow around straight and T-shaped groynes in a flat bed channel. Journal of Hydraulic Engineering, ASCE, 142(8).‏

 24- Vaghefi, M. Ghodsian, M. and Akbari, M. 2016. The Effect of Secondary Flow Strength on Bed Shear Stress around T-Shaped Spur Dike Locating in Various Positions of a 90 Degree Bend with Rigid Bed. J. Sci. & Technol. Agric. & Natur. Resour., Water and Soil Sci., Vol. 20, No. 75. (In Persian).