Experimental Study On Long Bend Spillway Of Jing Foshan Reservoir

Spillway is an important part of earth rockfill dam hydropower station,which directly affects the safe operation and flood control and discharge capacity of reservoirs,and is also the research focus of hub hydraulics.The Jin Foshan water control project has the characteristics of high water head,complex geological conditions and the bend of the downstream river,which are influenced by these factors to form the spillway in the form of the bend.The long curved section of spillway is characterized by complex flow conditions,rapid discharge flow and large single width flow.The lateral water level difference is large(convex concave high),which is easy to cause the water flow folding,causing the impact damage of the side wall of the bend and affecting the safe operation of the reservoir.This paper takes the curved spillway of the Jin Foshan of Nanchuan,Chongqing as the research object.Through the three-dimensional numerical simulation and physical model test,the characteristics of the water flow in the long bend section of the spillway are studied.The flow condition of the long bend section is improved by the positive addition of the bottom of the canal,and the flow energy dissipation is carried out with the high and low bucket to solve the practical engineering problems.In the future,the design and optimization of the project provides a reference.The main research results are as follows:(1)By physical model experiments indicates that bend section of Jin Foshan spillway has deflected current phenomenon due to the large length,and the highest water level difference is mainly in the central angle 9° location(up than the top of the bend);By studying adopt the bottom of the superelevation channel method with different height values and non engineering measures,study show that the right side of the bottom raised 1.5 meters,which can effectively improve flow conditions.(2)The research of numerical simulation shows that the effect of scheme of Superelevation channel 1.5m is best in these sides of the flow state,the horizontal water level difference and the flow distance of the bend section are analyzed under different flow rates.(3)The experimental study shows that the energy dissipation effect of the high and low ridge type is better than that of the twisted skew bucket,and the flow pattern and the placement point are better.According to the calculation results of three-dimensional mathematical model,the outlet beam of the low ridge is narrowed to 2.3m,and the inletof the bucket is reduced by 40%.At the same time the interior wall surface is designed to slope.So that will eliminate cavitation,and the effect is better.(4)Through the analysis of the related factors and relevant empirical formulas that affect the water super high value of the bend section,and obtained the relationship between the water level difference and the high value of the bottom of the canal.The formula of the water level difference is optimized,and the formula after the optimization is more accurate.