The tip leakage flow is strongly related to the aerodynamic performance in compressors, such as pressure rise capability, efficiency and stability, and thus it has attracted a great deal of interest. In engineering application, some methods are used to control the tip region flow. The sloped trench casing treatment is a combination of the axially cutting tip and the trench treated casing. This configuration has been applied in some aero-engines, but only a few papers showed the effects of this type of casing treatment on the performance and stability of compressors. The illustrations of its mechanism is still not very clear, as some research conclusions are even contradictory.

In order to provide some support for the engineering design, numerical simulations are carried out to investigate the effect of the sloped trench casing treatment on performance and stability of a compressor cascade, an isolated rotor and a single compressor stage. The research object gradually evolves from simplified flow model to actual compressor working environment. A detailed study of how the sloped trench casing treatment effects the tip leakage flow structure, especially the tip leakage vortex of a compressor cascade is presented. Results show that the strength of the tip leakage vortex is weakened as the sloped trench casing treatment alters the structure of the tip leakage vortex. Then the simulation results of an isolated rotor and a single stage are studied. For both cases, the effect of the sloped trench casing treatment on the tip leakage flow is analogous to that for the cascade case. With the isolated rotor, the improvement on the performance is not obvious, while under the stage environment, the stability of the compressor is advanced as well as its performance since the tip leakage vortex is controlled and the downstream stator is working under a better inflow condition.


Effect of Sloped Trench Casing Treatment on Performance and Stability of Axial Compressors

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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