Transverse Injection Through Diamond and Circular Ports into a Mach 5.0 Freestream

TLDR: In this article, the authors compared the Reynolds-averaged Navier-Stokes and detached-eddy simulation models to obtain a detailed comparison of the secondary structures of the diamond-injector flowfield.

Abstract: Sonic transverse gaseous injection into a Mach 5.0 freestream flow was numerically simulated using two-equation and detached-eddy turbulence models. Circular- and diamond-shaped injectors were investigated in this study. The numerical simulations were compared with available experimental results and it was determined that both the Reynolds-averaged Navier-Stokes and detached-eddy simulation models captured the secondary flow structure. A detailed comparison of the secondary structures was performed for both injectors. Two new vortex structures of practical importance were observed in the diamond-injector flowfield. First, a leading-edge mixing mechanism was identified. Second, a trapped lateral counter-rotating vortex pair was produced. These new structures were observed in both Reynolds-averaged Navier-Stokes and detached-eddy simulation simulations. The detached-eddy simulations indicated that the large-scale structures observed in the plume/wake region of the flowfield were more organized in the diamond-injector test case. To better understand the secondary flow advection mechanism, the magnitudes of the terms in the compressible vorticity transport equation were compared. The diamond-injector structured-grid Reynolds-averaged Navier-Stokes solution was used as a baseline for this study. The inviscid compressibility, vortex-stretching, and baroclinic-torque terms were dominant. Downstream of the barrel-shock region, the baroclinic term was found to diminish when compared with the other inviscid terms. Planar-averaged results for the transport quantities confirmed this behavior. Vortex stretching was found to persist the longest.