Prediction of ultraviolet emissions in rarefied hypersonic flow

Predictions of radiative emissions for a reentering satellite are made over the altitude range of 100 km to 160 km. The flow field is determined using the direct simulation Monte Carlo (DSMC) method. An overlay technique is used to simulate the interaction of trace species, necessitated by the extreme variance in species concentration at high altitudes. Ultraviolet radiative emissions of nitric oxide and atomic oxygen are calculated using a noneqnilibrium radiation code. Variation of input parameters include the use of different atmospheric models to determine the free stream conditions and different reaction rates in the relevant exchange reaction. Sensitivity to the input parameters is assessed. Uncertainty in the prediction of emissions is one order of magnitude at the lowest altitude. Effects of input parameters at higher altitudes are found to be reduced due to the extreme rarefied nature of the atmosphere in this region.