Inviscid Flow with Nonequilibrium Molecular Dissociation for Pressure Distributions Encountered in Hypersonic Flight

One-dimensional inviscid nonequilibrium flows of a twocomponent model gas are studied for prescribed pressure variations and an average reaction rate based on recent data for oxygen recombination. These flows are interpreted in relation to the flow along streamlines around blunt hypersonic bodies. Assuming equilibrium conditions in the subsonic region, it is estimated that the flow in the initial supersonic expansion region, which is approximately of Prandtl-Meyer character, will be chemically frozen with respect to the molecular dissociation of the primary components under the hypersonic, high-altitude flight conditions considered. The flight conditions consist of flight velocities between 15,000 and 25,000 ft/sec at altitudes between 154,000 and 246,000 ft. Furthermore, on bodies of small surface inclination beyond the nose, the flow will continue to be effectively frozen for at least 20 ft downstream of the nose. These conclusions may lead to the simplification of procedures for theoretical calculation and testing. The problem of distinguishing a dimensionless length-reaction rate parameter, which characterizes the extent of departures from equilibrium or from frozen behavior in the flow fields of interest here, is discussed.