混流式水轮机转轮叶片裂纹问题

空蚀、泥沙磨损和疲劳裂纹是影响水轮机寿命的三大主要因素，过去人们只是更加注意空蚀和泥沙磨损，而没有把裂纹摆在重要位置。近年来，由于水轮机材料和研制水平的提高，空蚀已不再是电站运行维护的主要难题。但随着使用参数的提高，单机容量和机组尺寸的增大，不锈钢转轮的广泛应用，混流式水轮机的稳定运行问题，或者说混流式水轮机转轮叶片裂纹和尾水管里衬钢板撕裂问题（以下简称“裂纹问题”）逐渐突出，并已引起国内外同行的普遍关注。本文列举了国内外一些电站水轮机转轮裂纹的实例，分析了引起裂纹问题的主要原因，提出了防止裂纹的一些建议。

The Crack Problem of the Runner Blade for Francis Turbine

Cavitation damage, sand erosion and fatigue crack are the main problems that effect the turbine life. In the previously, people pay more attention to the cavitation damage and sand erosion rather than the fatigue crack. In the recent year, the cavitation damage is not longer the main problem duo to the improvement of materials, design and manufacture technology. But with the higher specific speed, larger unit capacity and scale dimension used, the fatigue crack at the Francis runner blade or at the inlet of draft tube that caused by unsteady operation condition are paid more and more attention by the domestic and international experts. In this paper, there are some cases about the Francis runner blade fatigue crack in the world are described. Then the main reasons caused the fatigue crack are being discussed. Some proposes to prevented the fatigue crack are recommended.