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首页> 外文期刊>WSEAS Transactions on Fluid Mechanics >Metallographic and Numerical Methods Investigations about Failure of a Kaplan Turbine Runner Blade
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Metallographic and Numerical Methods Investigations about Failure of a Kaplan Turbine Runner Blade

机译：Kaplan涡轮转轮叶片失效的金相和数值方法研究

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The paper presents the results of the failure analysis of a Kaplan turbine runner blade from a hydropower station in Romania. In order to determine the causes that led to the cracks, the authors first carried out metallographic investigations on a sample obtained from the cracked blade. The metallographic investigations included macroscopic and microscopic examinations (light microscopy and scanning electron microscopy) and X-ray diffraction analyzes (XRD). They led to the conclusion that the cracking of the blade was caused by fatigue, initiated by the numerous non metallic inclusions, which were discovered in the vicinity of the blade surface. The results obtained were confirmed by calculations on the resistance and service life estimations of the blade. The calculations carried out included the following steps: construction of the solid 3D-model of the blade, determination of the blade loads from hydrodynamic conditions, linear static analysis of the blade and service life estimations, calculated for maximal stress values of the concentrators. They led to the conclusion that the cracking of the blade started and developed from the stress concentrator placed between blade and blade flange on leading edge direction. In order to decrease the maximal stress value, the authors concluded that the hydrodynamic loads on the blade must be obligatory reduced. Therefore, as the operating conditions (discharge, head, speed, power) are not changeable, the stress reduction could be realized only by increasing the number of the runner blades.
机译：本文介绍了罗马尼亚水电站Kaplan涡轮转子叶片的失效分析结果。为了确定导致裂纹的原因，作者首先对从裂纹刀片获得的样品进行了金相研究。金相研究包括宏观和微观检查（光学显微镜和扫描电子显微镜）和X射线衍射分析（XRD）。他们得出的结论是，叶片破裂是由疲劳引起的，疲劳是由叶片表面附近发现的大量非金属夹杂物引起的。通过计算叶片的电阻和使用寿命估算值可以确认所获得的结果。进行的计算包括以下步骤：构建叶片的实体3D模型，从流体动力学条件确定叶片载荷，对叶片进行线性静态分析和使用寿命估算，并针对集中器的最大应力值进行计算。他们得出的结论是，叶片的裂纹是由前缘方向上位于叶片和叶片法兰之间的应力集中器开始并发展的。为了减小最大应力值，作者得出结论，必须强制减小叶片上的流体动力载荷。因此，由于操作条件（排放，扬程，速度，功率）不可改变，因此仅通过增加流道叶片的数量即可实现应力的减小。

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