Numerical Simulation Of Hydraulic Characteristics And Shape Optimization Of Spillway Of Dahongnahai Reservoir

Object: Drainage structure is one of the key problems in water conservancy project construction.The spillway is the main structure of water conservancy project in the process of operation,which cannot be accommodated in the storage capacity to ensure the safety of the dam.The structure layout of spillway engineering has a great influence on hydraulic characteristics of discharge flow,which often faces the problem of insufficient discharge capacity and the flow in the downstream silting pool caused by insufficient discharge energy dissipation,and then affects the safety and stability of downstream buildings.Therefore,this thesis takes the spillway of Dahongnahai Reservoir as the research object,obtains the distribution law of the hydraulic characteristic parameters of the flow field during the spillway discharge process,optimizes the type of outlet energy dissipation section to ensure the water flow safely into the downstream,and provides reference for the design of the spillway of Dahongnahai Reservoir.Method: The spillway discharge capacity,pressure distribution and energy dissipation effect of spillway were determined by physical model test on spillway discharge process of Dahongnahai Reservoir,and relevant conclusions and suggestions were drawn.The spillway discharge process and energy dissipation process under typical flow were numerically simulated with fluid calculation software,and the flow field distribution law inside the spillway was obtained,and the shape optimization was carried out to obtain the optimal design scheme.Results: The spillway can discharge the water flow required by the engineering design in time,and the water depth along the spillway,the water velocity and the dynamic water pressure change of the bottom plate are all within the safe range.However,the silting pool cannot meet the requirements of energy dissipation and impact prevention of water flow under the checking working condition,which is easy to cause erosion damage to the downstream.With the increase of T-shaped pier leg length,the energy dissipation efficiency of scour pool increases significantly.The water depth in the scouring pool can be increased by the T-shaped pier with the anti-impact plate,but the energy dissipation rate decreases with the increase of the length of the anti-impact plate.The flow pattern in the tank is stable after the double-row Tshaped pier is arranged,the energy dissipation increases first and then decreases with the increase of the front and back spacing.In a T-shaped pier with anti-impact plate,the length of leg,length of anti-impact plate and height of pier have significant influence in energy dissipation effect of pool,and the influence on energy dissipation as follows: leg length>pier height>length of anti-impact plate.Considering the turbulent of kinetic energy and energy dissipation effect,the length of leg is 11 m,the height of pier is 2.4m and the length of anti-impact plate is 0.2m,which is the optimal structural scheme designed for the test.The test verifies that the discharge water of the optimized spillway scheme has a stable flow state in the silencer and can smoothly enter the drainage channel.The energy dissipation rate is increased by 13.98%compared with the original design scheme,The problems of insufficient energy consumption and shock resistance in the downstream energy dissipation section are solved.Conclusion: Based on the physical model and numerical simulation,the discharge and energy dissipation process of the spillway of Dahongnanhai Reservoir and the hydraulic characteristic parameters of the water flow were simulated,and the shape of the silting pool was optimized to achieve the expected effect.By comparing the obtained test data with the numerical simulation data,they are in good agreement.The mathematical model established in the table can accurately calculate the hydraulic characteristics of the spillway under different boundary conditions.The optimization of the spillway through the numerical simulation meter could save costs.Improve the work efficiency,and provide a reliable theoretical basis and reference for the optimal design of Dahongnahai reservoir spillway.