Experimental and numerical studies on the effect of inlet pressure on cavitating flows in rotor pumps

Abstract

This paper aims to investigate the effect of the inlet pressure on the cavitating turbulent flows in rotor pumps through experimental and numerical studies. The cavitation experiment of rotor pumps was carried out and both the flow rates and the inlet/outlet instantaneous pressures under different inlet pressures were monitored during the experiment. Furthermore, a simplified 2D numerical model for analyzing the cavitation flows in rotor pumps was established and the influences of the inlet pressure on the volumetric efficiency, the distribution of bubble volume fraction and the pressure fluctuation were included. The results show that numerical results agree well with experimental data and the inlet pressure indicates a strong influence on the cavitation characteristics. For instantaneous pressures of the inlet/outlet, they pulsate periodically and its dominated frequency changes with the inlet pressure. For the volumetric ratio of the pump, it decreases significantly for the inlet but slightly for the outlet when the inlet pressure drops. For the volume fraction of the vapor phase, it increases with the dropping inlet pressure and the peak of the vapor fraction generally offsets backward as the inlet pressure decreases. For the pressure fluctuations, the pressures of the suction side and the discharge side present a sudden increase at some moment. Moreover, the time for pressure mutations delays with the decreasing inlet pressures.