Infrared radiation characteristics of a hypersonic vehicle under time-varying angles of attack

Hypersonic vehicles emit strong infrared (IR) radiation signatures that can be treated as a detecting source for object identification and routine diagnosis. This paper is aimed at examining the intrinsic radiation characteristics of a Boost-Glide Vehicle (BGV) under the condition of various Angles of Attack (AOAs). A two-temperature model considering the thermal and chemical non-equilibrium effects is coupled with Navier-Stokes equations solved by the finite volume technique. A gas–solid conjunction heat transfer model is also added into the fluid solver to simulate the surface temperature of the vehicle. The radiative transfer equation is solved with Line of Sight (LOS) algorithm. The computational results for a Hypersonic Technology Vehicle-2 (HTV-2) type vehicle show that radiances of the vehicle are strongly dependent on the surface temperature. The presence of AOA results in the significant difference of the surface temperature. Infrared radiation characteristics are also changed in intensity and spectral band due to the AOA. Simulations are performed with two time-varying AOAs. Transient results indicate that the variation of AOA does have a great effect on the infrared radiance and is closely related to observation angle, spectral band, angle size, angular velocity and time history.