流固耦合的水轮机转轮静应力仿真与模态分析

Static Stress Simulation and Modal Analysis for the Runner of Hydro Turbine Based on Fluid-solid Coupling

为研究水轮机转轮在运行中出现的裂纹或断裂问题,避免机组处于不利运行条件下而发生失效,在某电站水轮机转轮设计中,进行了流固耦合的应力计算和模态特性分析。将静应力数值计算结果与材料特性进行比较可知,静应力水平偏小,不会导致转轮产生裂纹。对此,采用全耦合法计算了转轮叶片的5阶模态,并获得了其每阶模态下的固有频率和影响系数。对比锤击法的试验结果可知,该仿真精度较高,在第1、4阶模态下,叶片容易发生共振,在机组运行中应该尽量避免。

For studying the reason of cracking or fracture in the runner of hydro turbine to avoid the failure of unit in adverse operating conditions, the stress calculation and modal analysis of runner are carried out based on fluid-solid coupling in the design of turbine for a hydropower station. The comparison between stress calculation results and material properties shows that the static strength had a low level which can not cause the runner to crack. So the 5 order modes of runner blade are simulated and the natural frequency and influence coefficient under each mode are obtained. Comparing with the results of hammering method, the modal simulation has a higher accuracy, and the results show that the blades will appear resonance under 1stand 4th order mode. The turbine should avoid operating at the condition of 1st and 4th order mode.