NEAR-WAKE STRUCTURE FOR A GENERIC CONFIGURATION OF AEROASSISTED SPACETRANSFER VEHICLES

Results of a numerical study are presented for hypersonic low-density nitrogen gas flow about a 70-deg blunt cone using the direct simulatio n Monte Carlo method. The flow conditions simulated are attainable in existing low-density hypersonic wind tunnels; encompassing freestream Knudsen numbers of 0.03 to 0.001. Particular emphasis is given to the near-wake dow and its sensitivity to rarefaction and other parametric variations. A stable vortex forms in the near wake at and below a free stream Knudsen number of 0.01, and the size of the vortex increases wi th decreasing freestream Knudsen number. The base region of the now re mains in thermal nonequilibrium for all cases. There is no formation o f a lip separation shock or a distinct wake shock at these rarefied co nditions.