Characterizing Shrouded Stator Cavity Flow on the Performance of a Single-Stage Axial Transonic Compressor

Abstract

Shrouded stator cavity flow increases the stator total pressure loss, reduces the compressor isentropic efficiency and thus limits the compressor pressure rise capability. This paper proposes a simplified cavity flow model that consists of flow injection at the stator inlet and flow suction at the stator outlet. Based on this model, a full-factorial parametric study on the leakage flow ratio and the leakage swirl angle is performed at different rotational speeds and incidences. In the first place, the effectiveness of the numerical method is validated against the experimental data based on the full-scale cavity geometry; then, the numerical simulations on the simplified cavity geometry are validated against that of the full-scale one. Results show that the leakage flow ratio plays a dominant role in determining the compressor performance penalty. The isentropic efficiency drops almost linearly with the leakage flow ratio due to deteriorated near-hub separations, and the slope becomes steeper at higher operating speeds and incidences. The leakage swirl angle only has a pronounced effect under a high leakage flow ratio. The efficiency penalty reduces with increasing swirl angle due to an alleviated tangential flow mixing and suppressed near-hub separations. The swirl angle effect is more pronounced at lower incidence conditions. These findings advance the fundamental understanding of shrouded stator cavity flow effects and provide useful guidance for cavity seal designs.