Numerical Simulation Analysis Of Internal Flow Field Of Horizontal Francis Turbine

Hydroelectric power has unique advantages such as cleanliness and renewable energy.In hydropower generation,water turbines are the most important core components.Therefore,it is necessary to discuss the internal flow field of hydraulic turbines.In this paper,a hybrid power station model HL124-WJ-75 is used as a model to simulate the internal flow field of the turbine.The three-dimensional modeling software UG is used to establish the turbine model,and the basin model needs to be discretized during the simulation.Therefore,the model to be built is imported into the grid division software to discretize it.The paper adopts the ICEM meshing software to divide the volute,the water guiding mechanism and the runner into unstructured grids.Because of the comparatively regular appearance of draft hoses,structured grids are used.Realize the three-dimensional numerical simulation of the internal flow field of the turbine using the Realizable model.In the test process,the internal flow conditions of the hydraulic turbine water diversion mechanism,diversion mechanism,runner and draft tube under no-load conditions,low flow conditions,optimum conditions and rated conditions were simulated.The conclusions are drawn by comparing the streamline diagrams,pressure distributions and velocity distributions inside the various flow components under different conditions.In the end,considering that the dynamic and static interference between the guide vane,runner,and draft tube during the working process of the turbine is also one of the factors that affect the efficiency and stability of the unit,the influence of the dynamic and static interference on the unit under rated conditions is analyzed.According to the internal flow field distribution map,under small flow conditions,due to the small guide vane opening,a large angle of attack will be formed,often occurs at the inlet and outlet of the blade and generate larger flow The pressure gradient,which consumes a portion of the energy,can cause severe turbulence,and is also a major factor affecting the stability of the unit and the cavitation resistance to cavitation resistance.With the increase of the guide vane opening,the degassing condition gradually improves,and the pressure gradient and velocity gradient also gradually decrease.Especially under the optimal operating conditions,the unit efficiency,cavitation erosion resistance performance and stability are all at the maximum.Excellent,stable and efficient.According to the time-domain and frequency-domain diagrams of the dynamic and static interference,the dynamic and static interference between the runner and the stationary vane is the main cause of the pressure pulsation,and it spreads upwards and downwards with the runner as the center,and the dynamic and static interference in the diffusion process.The pulsation effects caused by the gradual weakening,so in the actual operation should pay attention to the dynamic interference between the runner and the fixed guide vane on the unit.