Direct Numerical Simulation of a Sonic Round Jet in a Turbulent Supersonic Cross Flow

A direct numerical simulation of a round under-expanded sonic jet in turbulent supersonic cross flow has been carried out. The objective is to investigate the mixing mechanism which occurs downstream the jet by use of a passive scalar variable. The Navier-Stokes equations in the cylindrical geometry are solved by use of multiblock overlapping meshes. The method has been validated with a laminar flow in pipe and a convergence study has been carried out. The inlet profile of the cross flow is generated with a precursor turbulent channel at same Reynolds number (Reτ = 180) and Mach number (Mcl = 1.6). In order to reproduce physical conditions more similar to a supersonic combustion ramjet (SCRAMJET) chamber, a heat sink Q̇ has been added in the energy equation. The effect is to decrease the bulk temperature to a lower value than the wall temperature. A test case at injection angle θ = 90 and jet to cross flow momentum flux ratio J = 1 has been carried out. Data have been compared with the results obtained from a similar configuration where the jet inlet is obtained without the nozzle geometry. Some difference are observed in the penetration height of the passive scalar, but the flow topology is quite similar for both cases. A parametric study at different angle θ and jet to cross flow momentum ration J is planned as future work.