Shape optimization of energy dissipation structure in flood discharge bottom orifice of hydropower station
In view of the problem that the energy dissipation area of a hydropower station was narrow and the tailrace canal of the left bank power station was easily affected,according to the idea of guiding the water tongue to the center of the stilling basin,the shape of the flip-flow guidance scheme and the surface flow diffusion scheme was modified.Finally,the recommended shape was the surface flow dif-fusion energy dissipater.The flow pattern,time-averaged pressure,pulsating pressure,velocity distri-bution,scour characteristics and energy dissipation rate of the original design shape and the recommen-ded shape were compared and studied by means of model test and numerical simulation.The results show that the energy dissipation effect of the original narrow slit scheme is good,but the mainstream of the water tongue is concentrated on both sides of the left and right banks,resulting in local scour on both sides.The surface flow diffusion scheme allows the discharge of water to form a free surface flow pattern,and rapidly diffuses to the whole river channel.The energy dissipation area is expanded,which effectively reduces the time-averaged pressure,pulsating pressure and bottom velocity of the bot-tom plate,with the velocity and pressure distribution becoming more uniform.The scour pit depth of the downstream river channel is reduced by 34%,and the scour range is reduced by 35%,which en-sures the safe operation of the left bank power station.The recommended scheme can provide reference for similar projects.
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