大型混流式模型机组动应力及压力脉动测试研究

最近几年在若干水力工程中，由于设计及机组运行调度的不合理，一些电站的机组，尤其是转轮叶片出现了局部裂纹问题，这引起了业界的高度关注。为此，东方电机在模型机组和真机上开展了叶片表面的动应力及表面压力脉动的测试。呈现模型机组测试的结果，通过这种测试发现最大的压力脉动幅值出现在转轮进口边区域，叶片表面上的压力脉动幅值明显大于转轮与活动导叶动静干涉所在的无叶区诱发的压力脉动幅值以及尾水涡所在的尾水管区域诱发的压力脉动幅值。叶片表面的压力脉动对应的主频和动应力对应的主频一致，主要为叶片数通过频率。动应力表现为类转频、尾水涡频率和动静干涉频率的叠加。

Dynamic Stress and Pressure Fluctuation Test on Model Unit of Huge Francis Turbine

In recent years, due to the unreasonable design and operation on several hydraulic projects, some hydraulic power station unites operate not well, especially the rotor blades have suffered from local cracks. This has caused high concern in the hydraulic electric industry. For understanding the crack reason, the dynamic stress and surface pressure fluctuation of the blade surface are tested by Dongfang electric machinery company in model unit and protype machine. The results of model tests are presented The largest pressure pulsation amplitude is taken place at the trailing edge of the runner blade and of the pressure pulsation amplitude on the blade surface significantly greater than pressure pulsation caused by guide vane and runner rotor and stator interference and draft vortex in draft tube, respectively. The frequency of pressure fluctuation is same with the frequency of dynamic stress and the frequency is consist rotating frequency, draft tube vortex frequency and rotor and stator frequency.