微型离心泵诱导轮与叶轮轴向距离匹配特性

诱导轮与叶轮匹配不合理,是影响微型离心泵运行稳定性的原因之一。为了研究诱导轮与叶轮之间的轴向距离(简称为轴向距离)的匹配对离心泵性能的影响,该文以一台前置诱导轮离心泵为研究对象,采用数值方法定量分析了不同轴向距离对离心泵能量特性、汽蚀特性和压力脉动特性的影响。选取5种轴向距离,分别为0.1S,0.5S,1.0S、1.5S和2.0S(S为诱导轮轴向长度与叶栅稠密度的比值),对离心泵进行三维流场数值预测。结果表明,轴向距离增加后,扬程和效率均有所增加,汽蚀余量降低,但叶轮内压力脉动幅值升高。其中,在额定工况下,当轴向距离增大至1.0S时,扬程提高了0.61m,效率提高了5.8%,临界汽蚀余量降低了0.4m;轴向距离继续增大后,各项性能变化不大。综合分析认为,轴向距离为1.0S时,诱导轮与叶轮的匹配性能最佳,有利于离心泵稳定运行。研究结果可为微型离心泵诱导轮与叶轮的匹配设计提供参考。

Matching characteristics of axial distance between inducer and impeller of micro-centrifugal pump

The micro-centrifugal pumps are widely used in temperature control fluid circuits of aerospace equipment due to their compact structure and high head. The unreasonable matching between the inducer and the impeller is one of the reasons that affect the operation stability of the micro-centrifugal pump. In order to study the effects of the axial distance between the inducer outlet and the impeller inlet (hereinafter referred to as axial distance) on the performances of the centrifugal pump, this paper took a centrifugal pump with front inducer as the research object, using a numerical method to quantitatively analyze the effects of different distances on the characteristics of energy, cavitation and pressure pulsation in the centrifugal pump. In this research, five axial distances were selected, which wee 0.1S, 0.5S, 1.0S, 1.5S and 2.0S (S is the ratio of the inducer axial length to the chord-spacing ratio), and then numerical predictions of the three-dimensional flow filed of the centrifugal pump were made for the five conditions. The results shown that with the increase of the axial distance, both the head and efficiency increased, and the net positive suction head (noted as NPSH) decreased, while the amplitude of pressure pulsation in the impeller increased. Among them, under the rated operating conditions, when the axial distance was increased to 1.0S, the head of the centrifugal pump was increased by 0.61 m, and the efficiency was increased by 5.8%, the critical NPSH was reduced by 0.4 m, however, as the axial distance continues to increase, the head, the efficiency, the NPSH valve and the pressure pulsation changed little. Comprehensive analysis indicated that when the axial distance was 1.0S, the matching performance of the inducer and the impeller was the best, which was conducive to the stable operation of the centrifugal pump. The research results provide a theoretical reference for the matching design of the inducer and the impeller of the micro centrifugal pump.