Aerodynamic performance and flow characteristics of a compressed air energy storage axial turbine with nozzle governing

There is pressure difference between the air storage device pressure and turbine inlet pressure of the compressed air energy storage (CAES) system. The throttling loss caused by pressure difference can be reduced by using a reasonable air distribution mode. In this paper, the mass flow rate, specific work and efficiency characteristics of axial turbine with chamber under two nozzle governing modes are studied. Compared with the throttle governing, for the optimal mode under rated mass flow rate, the average specific work of the turbine increases by 6.8 %, and the average total efficiency increases by 7.0 %. The flow field loss is mainly related to the decreased regulated pressure. As the regulated pressure decreases, there are expansion and mixing losses at the corresponding stator outlet, which reaches the maximum after the regulated nozzle is closed. Moreover, with the base pressure decrease, the flow in the passages tends to be uniform and the loss gradually decreases.