Aerodynamic performance modeling of centrifugal compressors and stability analysis of the compression system for fuel cell vehicles

Centrifugal compressors are one of the most commonly used air compressors for fuel cell air auxiliary systems. However, surge in a centrifugal compressor severely limits the stable flow range of the compressor. In this paper, a mathematic model for predicting the compressor aerodynamic performance based on energy transfer methods was established, and the prediction model was validated through experiments. Then, the dynamic model of the compression system was derived based on the performance prediction model and the Moore-Greitzer model. The stability analysis of the compression system was conducted and it was strictly proved that when the compression system is unstable, the limit cycle exists in this nonlinear system, namely the surge cycle. Furthermore, the simulation of the compression system was conducted and the instability condition of the compression system was presented. The results show that at a constant speed, the compression system instability occurs as the opening of the throttle valve decrease to a specific value, and at some opening of the throttle valve, the compression system instability occurs as speed decrease to a specific value. At last, the effects of structural parameters on surge characteristics were analyzed. The results show that the frequency of surge increase as the volume of the plenum decreases and the frequency of surge increase as the length of the pipe decreases. This research can guide working condition matching and the surge control design of the centrifugal compressor system for fuel cell vehicles.