A shock loss model for supersonic compressor cascades

Loss models used in compression system performance prediction codes are oft en developed from the study of two-dimensional cascades. In this paper comp ressible fluid mechanics has been applied to the changes in shock geometry that are known to occur with back pressure for unstarted operation of super sonic compressor cascades. This physics-based engineering shock loss model is applicable to cascades with arbitrary airfoil shapes. Predictions from t he present method have been compared to measurements and Navier-Stokes anal yses of the L030-4 and L030-6 cascades, and very good agreement was demonst rated for unstarted operation. A clear improvement has been demonstrated ov er preciously published shock loss models for unstarted operation, both in the accuracy of the predictions and in the range of applicability. The dram atic increase in overall loss with increasing inlet flow angle is shown to be primarily the result of increased shock loss, and much of this increase is caused by the detached bow shock. For a given Mach number, the viscous p rofile loss is nearly constant over the entire unstarted operating range of the cascade, unless a shock-induced boundary layer separation occurs near stall. Shock loss is much more sensitive to inlet Mach number than is visco us profile loss.