Fluid mechanics in a radiatively driven hypersonic wind tunnel-prediction and preliminary experiment

The intrinsic limitations of a conventional hypersonic wind tunnel can be overcome, potentially, if heat is added to the supersonic flow downstream of the throat. The fluid mechanical issues which arise if radiant heat is absorbed downstream of the throat are discussed. In particular, predictions based on an axisymmetric model which includes ray-tracing and energy absorption along rays, real gas thermodynamics and the full unsteady Navier Stokes equations with a boundary layer turbulence model are discussed in terms of the underlying physics of the flow. Issues of interest which affect flow quality, throat survivability and heat transfer include the refraction of rays, spatial and temporal departures from idealized one-dimensional behavior, transient and boundary layer phenomena, etc. A comparison between prediction and a preliminary supersonic flow experiment at a Reynolds number of 10¹⁰/meter using air at 3000 atmospheres is being made and its connection with proof-of-principle experiments discussed.