Numerical Calculation Of Fluid Structure Interaction For Turbine Runner Of Yingxiuwan Hydropower Station

The reason of turbine runner blade crack or direct fracture is very complex,and the blade damage caused by many factors is also diverse.In the past,most of the existing crack analysis of turbine blades are caused by elastic vibration caused by off design conditions and start-up and stop,fatigue damage caused by water resonance and fatigue damage caused by high frequency pressure pulsation.In this paper,the steady-state numerical simulation of the turbine of Yingxiuwan Hydropower Station is carried out.Taking the steady-state results as the initial value of iterative calculation,the transient one-way fluid structure coupling calculation is carried out,and the pressure fluctuation,periodic stress variation and modal vibration mode of runner are analyzed.The research results have important reference value for unit operation maintenance and fault diagnosis.The main research work and achievements are as follows:(1)According to the design data of Yingxiuwan Hydropower Station and the data of runner scanning and mapping,a three-dimensional water body model of turbine calculation domain is established,and the flow passage components such as volute,guide mechanism,runner and draft tube are divided into polyhedral grids with hexahedron as the core.(2)SST k-ω turbulence model and simple algorithm are used to simulate the steady state of Francis turbine under different output conditions.The results show that when the output power P = 11.8 MW,there is "vortex" in the channel and the flow pattern is chaotic.With the increase of production,the flow pattern was improved.(3)The static calculation and analysis are carried out by using the platform of ANSYS Workbench.The strength check shows that the equivalent stress of the runner itself is much smaller than the allowable stress of the maximum safety factor.The modal frequency of runner and the theoretical vibration frequency are not easy to induce resonance in the first six order.The results show that the natural frequency of the runner is 43.15% lower than that of the runner.(4)The results show that with the increase of the turbine output,the stress and strain of the runner structure gradually increase,and the maximum equivalent stress area of the turbine is concentrated at the blade outlet near the lower ring joint,which is consistent with the maximum deformation position.