Character of Hypersonic Shock Tunnels with Real Gas Effects

Numerical computation is made for obtaining the flow quantities of a diatomic gas behind incident shock waves as well as reflected shock waves in a shock tube. The gas state behind the reflected shock wave provides the reservoir condition for a reflected-type shock tunnel. The vibrational mode of molecules always is assumed to be in equilibrim with the translational temperature, while the degree of dissociation is supposed to be unchanged or attains its equilibrium state instantaneously behind the shock waves. Particularly, the isentropic index, which, for a perfect gas, is identical with the specific heat ratio, is considered as a function of the temperature and dissociation degree. By assuming the temperature and dissociation degree behind the shock wave, the iterative procedure is applied and calculation is performed for the incident shock Mach numbers from 3 to 12. The results show that the degree of dissociation becomes appreciable at high shock Mach numbers and has the remarkable effects on the temperature and density as well as on the value of the isentropic index behind shock waves.