Analysis of Impact of a Novel Combined Casing Treatment on Flow Characteristics and Performance of a Transonic Compressor

Abstract

To reduce the negative impacts of stall and surge on compressor performance, a novel combined casing treatment (CCT) structure with axial skewed slots and injection groove is proposed in this paper. The aerodynamic performance, as well as the mechanisms of loss generation, of a transonic axial compressor with NASA Rotor 67 are investigated numerically. The simulation results indicate that, compared with individual casing treatment method, the CCT works effectively with regard to operation performance. The stall margin (SM) is increased by 14.7% with 1.12% decrease in the peak efficiency. The interaction of axial skewed slots and injection groove can be explained by the enhancement of exchange flow in slots and axial motion of fluid. As a result, the leakage flow near the blade tip is eliminated and the flow separation is further suppressed. What is more, an analysis of entropy generation is also conducted. The results reveal that the effect of CCT on loss reduction mainly concentrates in the tip part of the blade, with the loss decrease about 14.46% compared with the original rotor. The best control effect can be expected by appropriate match between geometrical parameters of axial skewed slots and mass flow rate of injection from the parameter analysis.

Enhancement of aerodynamic performance of axial compressors utilizing natural aspiration through optimized casing circumferential slot

“…Increased stage loading frequently triggers amplification of flow instabilities in the form of rotating stall or surge 3 . Thus, appropriate stability enhancement methods should be utilized especially when the stall margin is not adequate to ensure trustworthy operation 4 .…”