Cavitation Auto-oscillation in Inducer Pump-pipes System

摘要

Details of measurements on the instability known as auto-oscillation which occurs in the pump-pipes hydraulic system are presented, the inherent mechanism of its production, development and disappearance are analyzed. The cavities dynamic linear equations are based on free streamline cascade theory, including non-backflow equation and backflow equation. The current study focuses on the feed effect of auto-oscillation energy during the process of transfer in the close loop system. Auto-oscillation occurs during the whole process of cavitation. It has been shown that auto-oscillation is a system oscillation caused by the active dynamic characteristics of the cavitating pump. The system condition's influence on the system stability and frequency is analyzed. Based on the dynamic analysis, backflow equation is first adopted to analyze the pulsating flow instability rapidly, which is more suitable for the calculation of LPRE's cavitating pump. These strongly suggest that the pump dynamics are primarily determined by the complicated flow at inlet to the inducer which involves cavities and pre-swirl generated by a strong backflow. The numerical results are consistent with the characteristics observed in some low frequency dynamic tests on rocket engine turbopumps.