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Time Dependent Navier-Stokes Solution of a Turbulent Gas Jet Ejected from a Rectangular Orifice into a High-Subsonic Crossflow
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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High temperature exhaust gases from an airborne chemical laser ejected at a jet to freestream dynamic pressure ratio Q of 0.15 from an aspect ratio 1.75 rectangular diffuser exit aligned parallel to the ambient crossflow was numerically simulated. The time dependent, three-dimensional Navier-Stokes equations and a species conservation equation were solved. Diffusive flux effects caused by concentration gradients as well as variable transport and thermodynamic properties were incorporated into the numerical model. Turbulence closure was achieved by a locally varying velocity defect eddy viscosity model. Chemical reactions betwen the exhaust gases and the crossflow were proscribed. The trajectory of the jet plume, the extent of recirculation zones, and regions with high rates of heat transfer were defined. Simplified analyses demonstrated that essential flow phenomena were replicated. Convective processes dominated the low Q jet-crossflow interaction. Thermal diffusion had significantly greater effect than molecular diffusion for the jet-crossflow gases simulated. Jet penetration was dependent upon the molecular weight of the injectant for the constant Q constraint. A molecular weight correction factor was empirically used to synthesize the trajectory of one gas from that of another gas and to correct empirical trajectory formulae for molecular weight variances. Sensitivity analyses relating heat transfer to the injection surface from the jet plume with the magnitude of the turbulence diffusivities were conducted.
APPROVED FOR PUBLIC RELEASE