Bluntness and boundary-layer displacement effects on hypersonic inlet flowfields.

A numerical analysis has been performed to determine the effects of blunting and heat transfer on the performance of an airbreathing engine inlet. Throat Mach number and total pressure profiles are presented for a mixed compression inlet operating in the Mach 8 flight regime. The variables investigated are spike nose radius, cowl leading-edge radius, and wall temperature. The fluid dynamics phenomena considered include equilibrium dissociation effects and viscous-inviscid interactions. The boundary layer and inviscid analyses have been integrated into a computer program that calculates the complete flowfield. The method of characteristics is used for the inviscid flow calculations. A laminar boundary layer is assumed initially and is computed by the local similarity method. Following transition, an integral parameter solution is employed to calculate the turbulent boundary layer. In all cases, the boundary layer occupies a sizeable portion of the internal flow. The leading-edge interactions are dominated by the effects of bluntness, while the cowl lip radius has a substantially greater effect on throat flow profiles than either thecenterbody nose radius or wall temperature.