导叶对液力透平机组工作稳定性的影响

Effect of guide vane on the stability of a set of hydraulic turbine runs

为了提高液力透平工作时的稳定性,降低机组的振动,在液力透平叶轮进口前添加不同数量的导叶,采用SSTk-ω湍流模型,利用FLUENT软件通过在各过流部件内设置监测点计算在不同导叶数下液力透平内的压力和压力脉动情况,然后通过快速傅里叶变换将压力脉动的计算结果进行处理,分析液力透平各过流部件内压力脉动的时域和频域分布,最后总结导叶数对液力透平机组工作时稳定性的影响规律。研究表明:当导叶数等于9时蜗壳内的压力脉动主频幅值最小;随着导叶数的增加,叶轮内的最大压力脉动幅值逐渐减小,而导叶数对尾水管内压力脉动幅值的影响较小;要提高液力透平机组的稳定性需降低液力透平内的压力脉动幅值,而通过叶轮进口前添加导叶的方法可以很好地降低液力透平内的压力脉动幅值,但导叶数不能太少也不能过多。

In order to enhance the stability of hydraulic turbine ,and reduce the vibration of hydraulic turbine when it is working ,this paper added a set of guide vanes at the impeller import of hydraulic turbine ,set the monitoring points through ANSYS‐CFD software in the each flow passage components , and calculated the changes rule of pressure and pressure fluctuation within hydraulic turbine under the different guide vane numbers by using the turbulence model SST k - ω, transformed the calculation results of pressure fluctuation by FFT ,analyzed the distribution of time domain and frequency domain within each flow passage components , finally , analyzed and summarized the results . The study found that the dominant frequency amplitude of pressure fluctuation is minimum in the volute when the guide vane numbers is equal to nine . With the increase of guide vane numbers ,the greatest amplitude of pressure fluctuation is gradually decreased in the impeller , but the effect of the guide vane numbers on amplitude of pressure fluctuation is smaller in the draft tube .The method that a set of guide vanes are added to the impeller import of hydraulic turbine can good reduce amplitude of pressure fluctuation ,enhance the stability of hydraulic turbine ,but the guide vane numbers neither too much nor too little .