Unsteady interaction study between cavity leakage flow and mainstream in transonic compressor

The article employs a validated numerical simulation method to conduct an unsteady numerical study of a transonic compressor with cavity leakage flow. By comparing it with a transonic compressor without cavity leakage flow, the unsteady characteristics of the cavity leakage flow within the compressor are investigated. Additionally, a loss prediction model for the compressor with interstage sealing is established, and proper orthogonal decomposition (POD) is utilized to explore the interaction mechanism between cavity leakage flow and the mainstream flow. The results reveal that, at the highest efficiency point operating condition at the design speed of the compressor, the efficiency of the transonic compressor with cavity leakage flow is reduced by 0.45% compared to that without cavity leakage flow, while the pressure ratio increases by 0.01% and the total temperature ratio rises by 1.2%. The interaction between cavity leakage flow and the mainstream flow exhibits unsteady characteristics, and the cavity leakage flow weakens the intensity of the shock wave at the leading edge of the stator blade root. The first and second modes of the POD analysis at the static blade root capture the spatial characteristics of the concentrated shedding vortex (CSV) and the trailing shedding vortex (TSV), both of which play a dominant role in the flow field structure. Notably, the cavity leakage flow shares the same frequency as the CSV and TSV at the blade root within the static blade passage, leading to a weakening of these vortices and an improvement in corner separation. However, the mixing losses resulting from the interaction of the cavity leakage flow with the mainstream flow, along with the dissipation losses within the cavity, are significant factors contributing to the reduction in compressor efficiency.