基于流固耦合的贯流式水轮机应力分析

Stress analysis of tubular turbine based on fluid-structure coupling

结合不同流固耦合的求解特点和应用条件,在ANSYS Workbench中分别运用单向流固耦合和双向流固耦合的方法对国内某电站的贯流式水轮机在最高水头、设计水头和最小水头三种工况下的静应力和动应力进行了计算分析和比较。结果表明:各种工况下,转轮的最大静应力和最大动应力均出现在叶片根部与轮毂连接处,最大位移均出现在叶片外缘,且叶片位移从根部到外缘逐渐变大;导叶的最大静应力和最大动应力位于根部,最大位移位于外缘。与转轮相比,导叶的应力和位移值都较小。转轮和导叶的最大静应力和最大动应力的最高值出现在最高水头工况。静应力最高值远小于材料的屈服极限,而动应力最高值则达到了材料屈服极限的79%,说明使转轮结构产生破坏的原因不是静应力,而可能是动应力的作用。

Static stress and dynamic stress have been calculated by using a code ANSYS Workbench for a tubular turbine under three working conditions of maximum water head, designed water head, and minimum water head, with one-way coupling and two-way fluid-structure coupling methods. The results show that in the three conditions, all the peaks of static and dynamic stresses of the runner appear at the location of blade-hub connection where the stress concentration is obvious while the deformation increases from the root to its peak location at the blades＇ outer edges. For guide vane, the peaks of its static and dynamic stresses are at the root and its peak deformation at the outer edge, and these peak values are lower than those of the runner. In the condition of maximum water head the peak static stress and peak dynamic stress of the runner and guide vane are greater than those in the other two working conditions. In all the working conditions, the peak static stress is far below the material yield limit and the peak dynamic stress is as much as 79% of the limit value. This means that it is the dynamic stress rather than the static one that may become a cause for cracks on blade and guide vane.