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 (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.