Numerical simulation study on thermal radiation transmission and suppression in high-temperature sapphire window

When an aircraft equipped with infrared guidance systems flies at high Mach numbers through the atmosphere, the infrared window interacts strongly with the incoming flow, resulting in aerodynamic thermal radiation effects. This paper models the thermal radiation transmission for flat-panel side-window infrared windows, captures dynamic thermal noise images under ballistic conditions, and introduces spectral filtering techniques to mitigate intense radiation bands in sapphire windows, addressing varying radiation intensities across different bands. Simulation results indicate that, within this trajectory, the window temperature peaks at approximately 470K at the 9th second, with the highest image irradiance of 0.69W/m² in the 3-5μm band, and a non-uniformity of 0.0293 in the thermal noise image. After spectral filtering to suppress the 4.6-5μm band, the maximum image irradiance drops to 0.202W/m² , a reduction of 70.7%, with the non-uniformity decreasing to 0.0215, a reduction of 26.6%. The thermal radiation transfer calculation model and the spectral filtering techniques outlined in this paper offer valuable insights for mitigating aerodynamic thermal impacts and enhancing the performance of infrared detection systems by suppressing thermal radiation.