WITHDRAWN: Effects of angle of attack on IR radiation for a hypersonic boost-glide vehicle

Abstract

Hypersonic vehicles emit strong infrared 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 (AOA). 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. Gas absorption coefficients are evaluated through Line-by-Line (LBL) method and the radiative transfer equation is solved with line of sight (LOS) algorithm. Each part of the numerical modules is validated separately. The computational results for a Hypersonic Technology Vehicle 2 (HTV-2) type vehicle show that radiances emitted from gas are at least three orders of magnitude lower than that from the surface. The presence of AOA results in different distributions in surface temperature and therefore changes infrared radiation characteristics in intensity and spectral band. Two group simulations are performed in the steady and transient states, these results indicate that the variation of AOA does have a great effect on the infrared radiance and closely relates to observation angle, spectral band, angle size, angular velocity and time history. A low AOA rate of change is beneficial to reduce the radiance in the side view, but increase the radiance in the upward view. AOA rate of change has little effect on radiation intensity-time variations in the top view.