THE EFFECT OF AMBIENT DISSOCIATION ON NONEQUILIBRIUM SHOCK LAYERS.
Interim technical rept. no. 2
CORNELL AERONAUTICAL LAB INC BUFFALO N Y
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The effects of ambient dissociation in a hypersonic free stream were examined for inviscid, nonequilibrium shock layers. The profiles of atom concentrations behind the bow shock were compared with those obtained for an undissociated free stream. Two types of correlations were developed, for fixed enthalpy and for fixed flight speed. For fixed enthalpy, the effect of ambient dissociation was shown to decay rapidly behind the shock. For fixed flight speed, the correlation was expressed by a simple subtraction of the ambient dissociation fraction. The subtraction rule preserves the gas temperature and its validity does not depend on a particular choice of the rate coefficient. The correlations were established for the simplified chemical model of a Lighthill gas. They were also extended to airflows with coupled chemical reactions. In this latter case, the application of the subtraction rule requires that the total oxygen content of the dissociated free stream be properly adjusted. It was found that the mixture must be richer in oxygen than the atmospheric proportion. The predicted correlations were verified on the basis of available numerical solutions for coupled air chemistry. The implications of the results were noted concerning simulation of real-gas effects. Author