| The discharge capacity of the spillway is directly related to the safe operation of the reservoir.An analysis of the causes of dam accidents in the past found that there are many dam accidents caused by insufficient discharge capacity of the spillway or improper design and application.Therefore,it is necessary to study the design scheme of the spillway.Spillway of Pianyan Reservoir is a straight channel spillway on the bank,with a maximum head of 89.08 m.Underflow energy dissipation is adopted,and the side wall of the energy dissipation pool adopts one-sided progressive expansion.The thesis firstly optimized the shape of the spillway by model test,analyzed the hydraulic characteristics such as water level,flow velocity,hourly average pressure,pulsating pressure,etc.Secondly,the numerical simulation was used to analyze the flow field and turbulent energy distribution in the stilling tank.conclusion as below:(1)The original design scheme discharge capacity of the spillway meets the design requirements,the height of the weir crest of the spillway and the size of the orifice are reasonable;there is a small flow phenomenon near the head of the left and right guide walls of the lock chamber,and the water flow at the tail end of the pier in the lock chamber produces larger fins Phenomenon;aeration spurs the water flow beyond the height of the side wall,and the water body splashes out of the side wall;no stable water jump energy dissipation is formed in the stilling pool.(2)In view of the problems in the original design scheme,the experiment modified its body shape to obtain an optimized body shape,that is,a tapered tail pier was added at the end of the middle pier,and the slope of the aerated sill was reduced from 1:8 to 1:10.The second aeration sill is moved down by 3.75 m,the slope sill of the stilling tank is changed to an upright sill,the bottom plate is deepened by 2.50 m,and the pool length is increased by20 m.The body shape test results of the optimization scheme show that:the flow pattern of various parts of the spillway is significantly improved,the angle of the intersection of the water flow at the tail end of the middle pier is slowed,and the agitated fins are weakened;The stable energy dissipation of the water jump is formed in the energy dissipation tank,the energy dissipation effect is ideal,and the height of the side wall meets the requirements.(3)In order to analyze the continuous flow field and turbulent kinetic energy distribution of the water flow in the unilateral diffusion stilling tank,the Flow-3d software was used to numerically simulate the stilling tank,and the water surface line,flow velocity,pressure and model test obtained by the numerical simulation The results are compared to verify the rationality of this simulation,and the distribution of flow field and turbulent kinetic energy in the stilling tank is analyzed.On this basis,the flow field in the pool at different diffusion angles(3°,5.6°,9°,12°)is simulated.The results show that:above the anti-arc section is the hydrocyclone zone,the water body fluctuates violently,Here,the turbulent kinetic energy is the largest;the diffusion angle of the side wall is 5.6°or less,the vortex scale appearing on the diffusion side in the pool is small,and the submerged water jump is in the pool.When the diffusion angle of the side wall in the pool is 9°,the turbulent energy is up to 52 m~2/s~2,and the energy dissipation of the water body is large,but the vortex scale exceeds more than half of the width of the stilling pool.The vertical axis vortex,the diffusion angle is too large.The research results have certain reference significance for similar engineering design. |
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