Effect of aerodynamic heating on infrared guided missiles

摘要

Many guided weapons, particularly air-to-air missiles, employ infra-red homing devices to locate targets: Infra-red (IR) seekers receive the electromagnetic radiation from hot emitters, such as aircraft, using wavelengths that are typically between 3 mm and 14 mm. For a target to be detected, there must be a significant contrast, either in strength or in wavelength, between the heat emitted by the target and the background, which is usually the sky. While early IR missiles detected the hot exhaust of the engine, modern weapons can detect the radiation from lower temperature parts of the aircraft such as the skin, which enables the weapon to attack an aircraft from in front. There has been great interest in the shock wave community for many years in heat flux to blunt bodies, but this interest has been primarily concerned with either structural heating or the effect of heating on the flow. The effect of radiant heat on blunt bodies at low Mach number has been of less interest, but is important for missile guidance. The temperature and density distribution has been calculated around the nose of a representative missile nose shape modelled on the ASRAAM missile at a range of Mach numbers from M2.0 to M3.0. These results have been used to estimate the thermal irradiance on infrared seekers for these conditions. As the detail design of missile infrared seekers is classified, the parameters of the seekers have had to be estimated.