Determination of Areas on the Surface of Optical Fairings of Various Geometric Shapes Subjected to Maximum Thermal Shock Impacts

Mathematical models have been developed to describe the heating of optical fairings of infrared (IR) devices with various geometric shapes (hemispherical, pyramidal, etc.) under the influence of an external supersonic airflow. Areas on the surface of the fairings subjected to maximum thermal shock impacts have been identified for different flow regimes (laminar, turbulent), which lead to their destruction and IR device failures during firing and flight conditions. The advantages and disadvantages of the considered fairing geometries have been established depending on their flight speed. It has been established that, for the specified ranges of flight velocities, as in the case of hemispherical fairings, a turbulent flow regime is realized over most of their surfaces, and hazardous areas emerge. By additionally treating these areas with an electron beam (which increases the resistance of surface layers to thermal and mechanical impacts), their destruction during operation can be prevented. In this case, the intensity of the pressure gradient's impact on the fairing is reduced. Therefore, during the operation of fairings with different geometric shapes at high flight speeds (above 2∙103…3∙103 m/s), the thermal and mechanical impact (due to pressure gradients in the shock wave) is more intense for fairings with sharp leading edges (pyramids, cones, etc.), leading to their faster destruction under flight conditions.