The aerodynamics of circumferential casing-groove in a transonic compressor

This paper presents the results from a numerical investigation into the near casing flow development in a transonic axial compressor rotor. The compressor geometry selected is known to undergo a spike type stall when the mass flow through it is reduced below a critical limit. The paper assesses the development of tip leakage flow and its interaction with the flow within a single circumferential casing groove using a steady Reynolds Averaged Navier Stokes solver. Casing grooves are known to improve stall margin in tip critical compressors. The results from the present study show a detailed picture of the above interaction and the nature of the flow within the groove both of which result in an improvement in the stall margin of the compressor. The negative axial momentum associated with the tip leakage flow is shown to be a major factor affecting the performance of the groove and eventually that of the compressor.