CFD and Energy Loss Model Analysis of High-Speed Centrifugal Pump with Low Specific Speed

Abstract

High-speed centrifugal pumps with low specific speed have the characteristics of a small flowrate, a high head, and being compact and light weight, making them promising candidates for applications in the thermal management of aerospace and electronic devices. The energy loss in the low specific speed pump is critical and complex due to the large impeller diameter, the narrow and long flow channel, and the small outlet width. In this paper, an analysis method based on an energy loss model and computational fluid dynamics simulations (ELM/CFD) is proposed to analyze the performance of the low specific speed pump with a fully sealed structure. Experiments were carried out under variable water flowrates. The results show that the empirical correlation method failed to accurately predict the performance of high-speed centrifugal pumps, because the bearing clearance leakage and motor channel leakage are ignored. Moreover, the volume loss and hydraulic loss are calculated based on the empirical parameters of commonly used pumps that are different from the high-speed pump with the low specific speed in the complex flow channel structure. The ELM/CFD method calculates various loss power based on the simulation results and can predict the head and efficiency with deviations less than 2% and 5%, respectively. ELM/CFD can accurately analyze the optimization direction of the pump. The hydraulic loss and the volume loss of the impeller are the dominant factors that restrict the pump efficiency under the lower flowrates, while the hydraulic loss of subsequent flow channels becomes important under the larger flowrates.