Flow analysis and performance improvement of a radial inflow turbine with back cavity under variable operation condition of compressed air energy storage

Abstract

In present study, the effect of back cavity in a radial inflow turbine is investigated numerically. The size effect of labyrinth seal clearance is revealed. The performances of radial turbine with back cavity at different total expansion ratio are also investigated. Results illustrate that the clearance variation of original labyrinth seal in back cavity has limited effect on the leakage flow and the isentropic efficiency. The existence of back cavity reduces the isentropic efficiency at every total expansion ratio, and a maximum isentropic efficiency reduction of 1.5% is obtained when total expansion ratio is 2.89. To control the rotor‐back cavity coupling flow loss, a “rotor‐back cavity seal” is also proposed, and the isentropic efficiency of radial turbine is significantly improved at different total expansion ratio.