Multi-spectral shocklayer radiance from a hypersonic slender body

This paper presents a methodology for the calculation of the IR shocklayer radiance from a slender hypersonic vehicle. An overlay technique that has been successfully employed for chemically reacting hypersonic compressed and expanding flows has been extended to accurately model the vibrational state distributions of NO, CO, water and CO₂, potential shocklayer radiators in the mid-wave infra-red. The spectral predictions show that radiation from shock heated ambient CO₂ will be an important contribution at most altitudes and speeds slower than 3. 5 km/sec. A detailed vibrational state-specific model of CO₂ excitation has been incorporated with the flow modeling using an overlay technique. Comparisons of the spatial distributions of CO₂ vibrational states with a corresponding Boltzmann distribution at the translational temperature show that there are substantial differences in the populations. These predictions are important for the design of an upcoming sounding rocket experiment.