Investigation of cavitation characteristics in an aircraft centrifugal fuel pump

Abstract

Cavitation is a classic gas–liquid two-phase flow phenomenon that needs to be restricted for the hydraulic performance enhancement of centrifugal pumps. However, due to the particularity of fuel mediums and rigorous aviation conditions, the characteristics of cavitation occurring in aircraft centrifugal fuel pumps have not been elaborated. In this research, cavitation characteristics in an aircraft centrifugal fuel pump with a high rotational speed of 14,000 rpm were investigated by considering the influence of the flow rate ranging from 0.2Qd to 1.2Qd and the fuel temperature ranging from 20 °C to 100 °C. An experiment for testing the hydraulic performance of an aircraft centrifugal fuel pump was built, and a corresponding numerical simulation of gas–liquid two-phase flow was employed. The distributions of the pressure, streamlines, and turbulence kinetic energy in the centrifugal pump for different flow rates and fuel temperatures were comparatively analyzed. The net positive suction head available (NPSHa) was defined to represent the cavitation degree, and the net positive suction head required (NPSHr) was introduced to characterize the critical cavitation occurrence. It was also found that a large area of cavitation bubbles was generated in the inducer and that this area grew to block the flow channel of the impeller when the NPSHa was close to or lower than the NPSHr, which was the cavitation mechanism of hydraulic performance degradation. Additionally, the developments of the NPSHr with the flow rate and fuel temperature were determined adequately using natural exponential curve fitting. It was deduced that the occurrence of cavitation was more sensitive to higher flow rates, especially when the flow rate was higher than the designed flow rate. The effect of fuel temperature variations should also be considered for the long-time high-speed operation of centrifugal fuel pumps in the aerospace industry.