长短叶片尾缘形状对离心泵性能与动静干涉的影响

Influence of Long and Short Blades Trailing Edge Shape on Performance and Rotor-stator Interaction in Centrifugal Pump

为探究带分流叶片离心泵内长短叶片尾缘形状对其性能与动静干涉的影响,对长短叶片尾缘压力面与吸力面分别进行不同厚度切削,采用SST-SAS湍流模型对各方案进行非定常数值模拟,结合外特性与PIV试验结果验证其计算准确性,并基于压力脉动、涡量分布分析泵内动静干涉变化。研究结果表明:离心泵长短叶片尾缘压力面切削PSF可有效提高离心泵额定流量点效率,且切削厚度越大,效果越显著,长短叶片尾缘压力面切削PSF还可有效改善额定流量下的离心泵动静干涉效应,减小压力脉动能量损耗,提高离心泵性能,并延长叶片使用寿命,而吸力面切削SSF则会大幅加剧离心泵动静干涉效应。压力脉动与涡量频域分布说明,离心泵叶轮流道内动静干涉主要频率成分为轴频及其倍频,蜗壳流道内动静干涉的主频与次主频分别为fB与0.5fB。对比各方案长短叶片尾缘附近主频涡量得出,短叶片尾缘切削效应较长叶片更为显著。短叶片经过隔舌时涡结构演化程度较长叶片更为剧烈,这一现象导致了长短叶片尾缘附近动静干涉的差异性,由此产生次主频0.5fB。

The change of blade trailing edge shape will affect the wake structure of impeller outflow,which has a significant impact on rotor-stator interaction( RSI) in the pump. To study the influence of long and short blades trailing edge shape on performance and rotor-stator interaction in centrifugal pump by CFD,long and short blades trailing edge filing was applied on pressure and suction sides with different thicknesses respectively. The numerical simulation was carried out by using the SST-SAS turbulence model,and the accuracy of the simulation was verified by performance and PIV test. Rotor-stator interaction in pump was analyzed by pressure fluctuation and vorticity distribution. The results showed that pressure side filing( PSF) can effectively improve the efficiency of centrifugal pump at nominal flow rate,and the greater the filing thickness was,the more remarkable the effect was. On the other hand,PSF can also obviously improve RSI in centrifugal pump at nominal flow rate,so as to reduce the energy loss of pressure fluctuation,improve the performance of centrifugal pump and prolong the service life of blades,while the suction side filing( SSF) greatly aggravated the rotor-stator interaction. The distribution of pressure fluctuation and vorticity in frequency domain showed that the main frequency components of RSI in impeller passage were axial frequency and its multiplication,and the main frequency and secondary frequency of RSI in volute passage were fBand 0. 5 fBrespectively. Compared with the main frequency vorticity near the trailing edge of the long and short blades,the effect of the trailing edge filing of short blade was more significant than that of the long blade. Evolution process of the vortices in RSI region demonstrated that the vortices in RSI region during short blade passed through the tongue were more intense compared with long blade,which determined the difference of RSI near the trailing edge of the long and short blades and resulted in a secondary frequency of 0. 5 fB.