侧壁式压水室离心泵小流量非稳态旋转失速特性

摘要

Numerical simulation method was used to analyze unsteady rotating stall characteristics in a centrifugal pump with slope volute at low flow rates.Fast Fourier transformation (FFT)was applied to transform time domain pressure signals into frequency domain ones.Results showed that a hump phenomenon occurs in the lift distance curve of the model pump,and the pressure distribution at different positions in slope volute is not uniform;flow structures in different impeller blade channels differ,they are influenced by unsteady action generated by rotating impeller;at different operating conditions,pressure pulsation signals are different, they cause variable excitation frequencies existing in pressure spectram;working at 0.4ФN condition,0.5fR and its higher harmonics appear in pressure spectra,and pressure pulsation magnitude reaches the maximum value at frequency 4fR;at flow rate 0.2ФN,excitation frequencies 0.18fR and its harmonics occur;at 0.05ФN,two different excitation frequencies 0.1 fR and 0.28fR appear in pressure spectra induced by unsteady flow structures in impeller blade channels;the pressure pulsation amplitude at blade frequency does not play the predominant role in pressure spectra under rotating stall status.%用数值计算方法研究具有特殊结构的侧壁式压水室离心泵，分析小流量工况时模型泵的非稳态旋转失速特性，用快速傅里叶变换（FFT）获得压力脉动信号的频谱特征。结果表明，小流量工况时模型泵的扬程曲线呈驼峰状，压水室不同位置处压力分布不均；受叶轮旋转产生的非稳态作用影响，叶轮不同叶片流道内流动结构差异较大。不同流量下，叶轮内部分离涡结构诱发的激励频率各异，0．4ФN工况时模型泵压力脉动频谱图出现0．5fR及高次谐波频率，压力脉动最大幅值出现于4fR频率处；0．2ФN流量时非定常流动结构会诱发0．18fR及高次谐波频率；0．05ФN流量时压力脉动频谱图同时出现0．1fR、0．28fR两种激励频率。旋转失速现象出现时，频谱图中叶频处压力脉动幅值不再起主导作用。