Numerical-Experimental Study of the Geometry Effect on the Discharge Coefficient in Labyrinth Side Weirs

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Numerical-Experimental Study of the Geometry Effect on the Discharge Coefficient in Labyrinth Side Weirs

ارائه دهنده: Provider: Meysam Ghiasvand Haji Abadi

اساتید راهنما: Supervisors: Jalal Sadeghian (Ph.D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: جناب آقای دکتر مجید فضلی - جناب آقای دکتر بهرام رضایی

زمان و تاریخ ارائه: Time and date of presentation: March, 04, 2021

مکان ارائه: Place of presentation:

چکیده: Abstract: Weirs are common structures that are often used to regulate the water level and increase the flow capacity. Labyrinth Weirs have a longer canopy length than direct canopy weirs and have a higher discharge under equivalent heigHt. These structures have advantages such as more capacity, easy flow aeration and less fluctuations in the level of water passing through them. Such weirs perform better at low hydraulic heads, and finally, as the hydraulic head increases and sediment accumulates behind the weir, its hydraulic efficiency gradually decreases and water transfer capacity decreases. Due to the lack of studies on Labyrinth Side Weirs and its use with better efficiency than conventional side weir, laboratory and numerical studies on these weirs have been predicted. In this research, using three-dimensional numerical modeling and laboratory results, the flow structure on the labyrinth side weirs (triangular, rectangular and trapezoidal) has been studied and the effect of the Congress Shape parameter on the discharge coefficient changes has been investigated. The main results of this research are as follows.. In each weir, the value of QL reaches its maximum value at one point by increasing the Ht/P ratio, and after that point, the value of QL decreases with increasing Ht/P ratio. Also at a constant Ht/P ratio, QL has a higher value in higher weirs. The results showed that with increasing the Froud number, the discharge coefficient decreases. Comparison of weirs efficiency with heigHts of 5, 10, 15 and 20 cm showed that triangular labyrinth weirs are more efficient than other weirs of the same height and in a constant ratio Ht/P has the highest efficiency. At a certain ratio Ht and Ht / P, smaller overflows have the highest discharge coefficient, and the opposite is true for larger overflows Comparison of the results also showed that the results of numerical simulation are in good agreement with the laboratory results of labyrinth side weirs with depths of 5, 10, 15 and 20 cm, and this shows that the numerical model Flow-3D in estimating the depth of flow on the labyrinth side weirs has worked well. The simulation results showed that the average total RMSE error of the water blade height on the overflows in the numerical method is less than 7%, which indicates the high accuracy of this type of numerical simulation of the RNG turbulence method and its adaptation to laboratory modeling. Key Words: Side weir, Labyrinth Side Weirs, three Cycle, Discharge Coefficient, Flow-3D.

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