Ultraviolet radiation characteristics of NO in shock layer of hypersonic vehicle

Abstract

The ultraviolet radiation generated by NO transition in the shock layer of hypersonic vehicle provides an important basis for target detection and recognition. In this paper, direct simulation Monte Carlo (DSMC) method is used to simulate the high temperature flow field of the Apollo aircraft. Based on the temperature, pressure, and mass fraction, SPECAIR software is used to calculate the NO(γ) spectral absorption coefficient, and combined with the line of sight (LOS) method, the ultraviolet radiation produced by the NO(γ) transition along the stagnation line at different heights is calculated. Based on the wall heat flux, the wall energy conservation equation is used to calculate the wall temperature, combined with the Planck's law to calculate the wall radiation, and the influence of the wall catalytic effect on the ultraviolet radiation is studied. The results show that with the increase of the height, the gas pressure and temperature decrease obviously, and the ultraviolet radiation from NO(γ) transition decreases. The wall heat flux calculated by the wall catalytic model is very different. The choice of the wall catalytic model is particularly important when studying the influence of the wall radiation on the ultraviolet radiation.