Study on the effect of inlet/outlet volute on mixed flow compressor performance for compressed air energy storage system

The inlet/outlet volute is an important static component of mixed flow compressor for compressed air energy storage (CAES) systems. The paper explores the impact of the inlet and outlet volute on the mixed flow compressor performance through unsteady numerical simulation. It was found that while both the inlet and outlet volutes affect the compressor performance, the outlet volute has a greater influence compared to the inlet volute. Furthermore, the interaction between the inlet and outlet volutes demonstrates a significant coupling effect on the compressor's overall performance. The presence of an inlet volute can disrupt the uniformity of the impeller inlet attack angle distribution, leading to a degradation in impeller performance. This non-uniformity is then transferred to the outlet volute, causing an uneven distribution of aerodynamic parameters at outlet volute inlet and increasing pressure loss in the outlet volute. The area with large internal loss in the inlet volute is mainly located in the position where the air flow changes direction, and the entropy generation rate near the outlet volute tongue is larger. The inlet volute significantly impacts the distribution of entropy generation rate in the outlet volute, whereas the outlet volute has minimal effect on the entropy generation rate distribution in the inlet volute. The research in this paper can provide guidance for the design and matching of compressor inlet/outlet volute in the subsequent compressed air energy storage system. • Inlet volute and outlet volute coupling effect is simulated firstly. • Outlet volute tongue effect is analyzed. • Entropy generation rate distribution of inlet volute and outlet volute are studied. • The unsteady flow field of inlet volute and outlet volute are researched.