Research progress on ultraviolet radiation characteristics of hypersonic vehicles

This study first delves into computational methods, radiation characteristics, and underlying mechanisms of ultraviolet radiation emitted by hypersonic vehicles, the study of which holds immense significance for ensuring safe flight. Based on the principles of hypersonic non-equilibrium flows and the transition mechanisms of ultraviolet radiation, a comprehensive analysis is provided on the computational procedures for determining parameters like the spectral absorption coefficient and molecular number density. Furthermore, the study explores the application scenarios of the line-by-line calculation method and the radiative transfer equation. Numerical and experimental investigations using collision-radiation models on the ultraviolet spectral and radiation characteristics of NO and OH molecules are summarized . The current status of ultraviolet radiation transmission modeling is also presented, focusing on the influence of geometry configuration, observation angle, flight altitude, and flight speed on the ultraviolet radiation. The deficiencies of these models are identified by comparing simulation results with those obtained by recent ground and flight experiments. Future research should prioritize the development of an integrated radiation model and advanced ultraviolet testing and non-equilibrium diagnostic techniques to meet practical needs such as target characteristic detection and thermal protection system optimization.