Simulation of Turbulent Mixing Behind a Strut Injector in Supersonic Flow

摘要

The flowfield downstreamof a strut-based injection systemin a supersonic combustion ramjet is investigated usingnlarge-eddy simulation with a new localized dynamic subgrid closure for compressible turbulent mixing. Recir-nculations are formed at the base of the strut in the nonreacting flowand trap some of the injected fluid.The high levelsnof turbulence along the underexpanded hydrogen jets and in the shear layer lead to a high level ofmixing of fuel andnfreestream fluids. Furthermore, the shear layer unsteadiness permits efficient large-scale mixing of freestream andninjected fluids. In the reacting flowfield, the flame anchoring mechanism is, however, found to depend more on anrecirculation region located downstream of the injectors than on their sides. A region of reverse flow is formed thatntraps hot products and radicals. Intermittent convection of hot fluid toward the injector occurs and preheats thenreactants.