Structure of Flow over a Hypersonic Inlet with Side Compression Wedges

Abstract

The e ow over a hypersonic three-dimensional inlet with ramp and side-swept compression wedges was experimentally studied. Two identical inlet models were tested in the blowdown wind tunnel T-313 at Mach numbers M1 =4 and 6 and in the hotshot wind tunnel IT-302M at M1 =6 and 8. Optical visualization of the e ow, near the inlet entrance and in the inlet duct, as well as oil-e lm visualization of the streamlines on compression surfaces were performed. Distributions of static pressure and heat e uxes on these surfaces in typical cross and longitudinal sections, and pitot-pressure distributions at the inlet duct exit, were obtained. Patterns of the supersonic e ow over the compression wedges and in the inlet duct were identie ed. A characteristic feature of these e ows, in particular, is what the compression wedges form shock waves glancing relative to the wedge surfaces. These shocks induce oblique separations of the boundary layer with intense helical vortices propagating far downstream. As a whole, a complex system of multiple shock and expansion waves and vortex structures occurs over the inlet section of external compression, so that the e owe eld at the inlet-duct entrance, in the duct, and at the exit is signie cantly nonuniform. Tests with a natural development of the boundary layer on compression surfaces and with tripping were carried out. “ Grater-type” trips were used, which demonstrated the high efe ciency at high Mach numbers M1 =6‐8. The unit Reynolds numbers in wind tunnels at the same test Mach number M1 o6 were different, Re11 o20£10 6 1/m in T-313 and Re11 =(2‐2.5)£10 6 1/m in IT-302M, respectively, but the boundary-layer tripping ensured identical e ow regimes determined by thestateof the boundary layer. Experimental data obtained in wind tunnels of different operation principles are in good qualitative agreement even with taking into account some quantitative difference mainly attributed to the unit-Reynolds-number difference.