混流式水轮机尾水管压力脉动换算初探

针对混流式水轮机尾水管压力脉动换算问题,本文提出了一种基于零环量单位流量的相对流量和基于叶片出口速度头压力脉动相对幅值来预测原型机尾水管进口压力脉动的方法。首先通过速度三角形进行了理论分析,并以某电站尾水管锥管压力脉动为例,分别在模型水轮机和相似原型机上比较了本文推荐方法与标准推荐方法的优缺点。之后采用该方法对12个电站水轮机模型和相似原型机尾水管压力脉动试验结果进行比较,模型和原型表现很好的相似性。最后在原型机上比较了基于本文方法的预测结果和现场测量结果,两者吻合性较好,证明了该方法的可行性。

Exploratory analysis on pressure fluctuation conversion in Francis turbine draft tubes

This paper presents a prediction method of the fluctuation amplitude of pressure in Francis turbine draft tubes, using data conversion into two parameters: relative discharge to a zero-swirl unit discharge, and dimensionless pressure fluctuation amplitude relative to the velocity head at the runner blade outlet. We conducted a qualitative analysis on the velocity triangle at the runner outlet and compared this new method with the norm-recommended method in terms of pressure fluctuation in the draft tube cone of a Francis turbine. Then, the method was applied to the models of 12 power plants and their homologous prototypes, and comparison of the calculations gives a satisfactory similarity between the model and homologous prototype. Further, we compared the predictions with field test results and obtained a good agreement between them. Thus, our conversion method is effective and feasible for analysis of pressure fluctuations.