Supersonic-inlet boundary-layer bleed flow

Abstract

Boundary-layer bleed in supersonic inlets is typically used to avoid separation from adverse shock-wave-boundary-layer interactions and subsequent total-pressure losses in the subsonic diffuser and to improve normal-shock stability. Methodologies used to determine bleed requirements are reviewed. Empirical sonic flow coefficients are currently used to determine the bleed-hole pattern. These coefficients depend on local Mach number, pressure ratio, hole geometry, etc. A new analytical bleed method is presented to compute sonic flow coefficients for holes and narrow slots, and predictions are compared with published data to illustrate the accuracy of the model. The model can be used by inlet designers and as a bleed boundary condition for computational fluid-dynamic studies.