Research On Hydraulic Characteristics Of Stilling Basin With Drop Sill And Sudden Expansion

In recent years,with the development of society and economy,People's understanding and attention to hydropower construction is no longer just stay in the economic benefits,but the comprehensive consideration of the impact of the project construction on the ecological environment.On the basis of this,a new type of energy dissipator,a sudden expansion type stilling basin which is applied to high head and large single width flow engineering has been developed.The utility model can be used for energy dissipation with high head and large flow,and has great application prospect in hydropower projects.In this paper,the method of theoretical analysis,model test and numerical simulation was used to study the flow velocity,time averaged dynamic water pressure,fluctuating pressure and energy dissipation efficiency.The main research results and conclusions are as follows:(1)Through the model experiment and numerical simulation,the distribution characteristics of the bottom flow velocity distribution of the sudden and non-abrupt flood-free canal are analyzed and compared,There is a significant difference between the presence and absence of a sudden increase in the presence of the maximum downstream flow rate where the longitudinal section is the center line and the side wall distance of 1/2.The effects of the sudden expansion ratio,the energy of the pool,the height of the tail hole and the length of the pond on the maximum velocity of the sudden flow of the deflagration basin was studied.The empirical formula of the maximum subsurface flow rate and the energy entering the pool was obtained.(2)Based on the experimental data of the model experiment,the distribution of the time-averaged dynamic pressure and the distribution of the maximum dynamic water pressure are analyzed and compared.The distribution of the dynamic pressure on the bottom of the stilling basin is significantly different from that of the non-sudden expansion and expansion furnace,and there is a maximum time when the sudden expansion exists.1/2.The influence of the sudden expansion ratio,the energy of the pool,the height of the tail hole and the length of the pool on the maximum dynamic water pressure on the bottom plate and theside wall of the sudden expansion and fall canopy are studied.Summarize its variation with the influencing factors.(3)Analysis and comparison of the distribution of the pulsating pressure distribution and the maximum pulsating pressure distribution of the downhill stilling basin and the sudden drop-type stilling basin,and obtain the characteristics of the sudden fluctuation pressure.And the pulsating pressure of the deflagration basin was significantly decreased.The influence of the sudden expansion ratio,the energy of the tank,the height of the tail hole and the length of the pool on the maximum pulsating pressure on the bottom plate and the side wall of the sudden expansion and decay were studied,and the variation law of the influencing factors was obtained.The pulsating pressure waveform,probability density and spectral characteristics was analyzed.(4)The energy dissipation effect of sudden expansion type plunge pool were analyzed.The influence of the sudden expansion ratio,the energy of the tank,the height of the tail hole and the length of the pool on the energy dissipation effect of the sudden expansion and decay were studied,and the variation law of the influencing factors was obtained.