A Study on the Hub Side Leakage of Centrifugal Compressor in Steady State and Transient Process

In this paper, in view of the leakage of bearing lubricating oil and gas during start-up and acceleration of high pressure ratio centrifugal compressor system, a lumped parameter model including impeller, vaneless diffuser & volute, hub side seal and pipe is established, and 3-D CFD model is used to obtain the aerodynamics performance of the main compressor components and the hub side seal. The critical boundary line of the flow pressure rise curve of the compressor is calculated, and the maximum threshold value of the valve opening at each speed is obtained; in the meantime, the difference of compressor performance and backflow boundary between transient process and steady state is predicted. The research provides a theoretical reference for explaining the leakage of bearing lubricating oil and gas during the start-up and acceleration of high-speed centrifugal compressor, and puts forward a control scheme for the flow rate of compressor in such process.