Survey of Blunt Body Flows Including Wakes at Hypersonic Low-Density Conditions

A review of recent experimental and computational studies on blunt body forebody and wake flows is presented, with emphasis on rarefied flows. The influence of rarefaction and real gas on the near-wake structure is examined. It is shown that a vortex is established when there is a strong non-Maxwellian distribution function in the wake, and the size of the wake vortex increases with decreasing Knudsen number. Results from the Navier-Stokes solutions suggest that the overall Knudsen number should be of the order of 0.001 or less before good agreement is achieved between experiment or DSMC for the near-wake surface and flow features, and that the Navier-Stokes solutions agree with the DSMC results for quite large overall Knudsen numbers along the forebody. (AIAA)