Nonequilibrium recombination after a curved shock wave

The effect of nonequilibrium recombination after a curved two-dimensional shock wave in a hypervelocity dissociating flow of an inviscid Lighthill-Freeman gas is considered. An analytic solution is obtained with the effective shock values derived by Hornung (1976) and the assumption that the flow is 'quasi-frozen' after a thin dissociating layer near the shock. The solution gives the expression of dissociation fraction as a function of temperature on a streamline. It can then provide a rule of thumb to check the validity of binary scaling for the experimental conditions and a tool to determine the limiting streamline which delineates the validity zone of binary scaling. The effects upon the nonequilibrium chemical reaction of the large difference in free stream temperature between free-piston shock tunnel and equivalent flight conditions are discussed. Numerical examples are presented and the results are compared with solutions obtained with two-dimensional Euler equations using Candler's code (1988).