Experimental study on effects of air injection on cavitation pressure pulsation and vibration in a centrifugal pump with inducer

Cavitation commonly induces performance deterioration and system vibration in many engineering applications. This paper aims to investigate the effects of air injection on cavitation evolution, pressure pulsation and vibration in a centrifugal pump with inducer. In this paper, the high-speed camera is used to capture the gas flow pattern and cavitation evolution process in the inducer. The impacts of air injection on the inlet pressure pulsation and vibration are also investigated. The results show that the cavitation development in the inducer undergoes four patterns: incipient cavitation, sheet cavitation, cloud cavitation and super cavitation. During the development of cavitation, the main frequency of the pressure pulsation shifts to lower frequencies, and the amplitude of the vibration increases. In addition, air injection promotes the incipient cavitation but delays the cavitation development. A small amount of air can effectively decrease amplitudes of pressure pulsation and vibration. But as the air content increases, the fluctuations and amplitudes of pressure pulsation and vibration increase.