Sonic Injection into a Mach 5.0 Freestream Through Diamond Orifices

Abstract

An experimental study to characterize the near-field (x/d<8.0) flow for sonic air injection through 15-deg half-angle diamond-shaped orifices at four incidence angles (10, 27.5, 45, and 90 deg) and two total pressures (0.10 and 0.46 MPa) into a high Reynolds number (53 x 10 6 ) Mach 5.0 freestream was performed. A 90-deg circular injector, with the same exit port area and total pressures, was examined for comparative purposes. The experimental methods included surface oil flow visualization, shadowgraph photography, Mie scattering flow visualization, pressure-sensitive paint, and a pitot-cone five-hole pressure probe. Flowfield documentation, jet penetration, and shock-induced total pressure loss were derived from these data. Attachment of the interaction shock wave was found to depend on both incidence angle and injector pressure. Penetration correlations were developed for both the diamond and circular injectors. An approximate analysis indicated that the shock-induced total pressure loss decreased with decreasing incidence angle and injection pressure, and the largest losses were incurred by the 90-deg circular injector.