Internal inflow study on a high-pressure centrifugal compressor with shroud and backside cavity in a compressed air energy storage system

The internal flow field and loss distributions are quite complicated in the high-pressure compressor with shroud and backside cavity applied in the compressed air energy storage (CAES) system. It’s necessary to develop physical understandings on the internal flow and losses inside the impeller, shroud cavity and backside cavity by the physical synergy relationship between some key quantities, which is innovatively applied to the internal flow of a high-pressure compressor used in CAES. First, the author successfully built a high-pressure centrifugal compressor test rig for CAES, and carried out the high pressure performance experiment for the first time. The aerodynamic performance of the high-pressure centrifugal compressor is compared by experiment and calculation. Then, the main flow characteristics and loss generation inside the impeller has been studied by analyzing the synergy between velocity and temperature gradient, and some other important quantities. And, the leakage flow characteristics inside the shroud cavity and backside cavity has been discussed by analyzing the synergy between velocity and pressure gradient, and some other key quantities. It is found that the regions where the high energy losses and entropy generation locate correspond to the relatively high synergy angle. At last, the interaction between leakage flow and main flow has been researched through clarifying the loss of temperature and radial velocity. It is found that there exit two boundary lines for leakage flow injecting into main flow.