导叶几何参数对液力透平压力脉动的影响

Influence of Guide Vane Geometry Parameters on Pressure Pulsations in Hydraulic Turbines

为提高导叶式液力透平的运行稳定性,研究导叶几何参数对液力透平压力脉动的影响。在IS80-50-315型低比转速离心泵反转作液力透平叶轮进口前添加径向导叶,对导叶出口角、叶片数和径向高度采用正交试验设计的方法匹配相同叶轮形成新的液力透平模型,利用CFX软件在蜗壳内、导叶与叶轮间隙和叶轮上沿周向设置监测点进行定常和非定常数值计算,对定常计算结果进行极差分析,得出导叶几何参数对液力透平性能影响的主次因素,形成最优方案组合,并对非定常数值计算压力脉动结果进行时域和频域分析。结果表明:径向导叶几何参数组合对水力效率和水头的影响均为叶片数>径向高度>出口角;导叶式液力透平的压力系数在导叶与叶轮间隙上最大,其次在叶轮上,蜗壳内部压力系数最小;当叶轮叶片数相同时,径向导叶出口角和径向高度的值在合理范围内选取较小值时,有利于降低导叶式液力透平的压力脉动幅值和提高运行稳定性。

In order to improve the operation stability of the guide vane hydraulic turbine,this paper studies the influence of geometric parameters of guide vanes on pressure pulsation of hydraulic turbine,and radial guide vanes are added before the IS80-50-315 low specific speed centrifugal pump reverses to make the inlet of hydraulic turbine impeller.For the outlet angle of guide vanes,the number of blades and the radial height,orthogonal experimental design is adopted to match the same impeller shape to form a new hy-draulic turbine model.CFX software is used to the clearance between the guide vane and the impeller and the monitoring points set along the circumference of the impeller are used for steady and unsteady numerical calculation.The range analysis of the steady calculation results of the orthogonal test design is carried out,and the main and secondary factors affecting the hydraulic turbine performance caused by the geometric parameters of the guide vane are analyzed.Finally,the optimal scheme combination is obtained.Then,the time domain and frequency domain analysis of the unsteady numerical calculation pressure pulsation results are carried out.The results show that the influence of the geometric parameters combination of radial guide vanes on hydraulic efficiency and water head is that the number of vanes is greater than the radial height and the outlet angle.The pressure coefficient of the guide vane hydraulic turbine is the largest in the clearance between the guide vane and the impeller,and the smallest in the impeller;When the number of impeller blades is the same,the value of radial guide vane outlet angle and radial height is selected to be smaller within a reasonable range,which is conducive to reducing the amplitude of pressure pulsation of the guide vane hydraulic turbine and improving the stability of operation.