Aero optical effects simulation technique for starlight transmission in boundary layer under high speed conditions
Abstract Aero optical effects for starlight transmission in the high speed flow field will reduce the accuracy of the star sensor on an aircraft. Numerical simulations for aero optical effects usually require plenty of calculations, which cause difficulties when designing a celestial navigation system for a high speed aircraft. In this study, an Aero Optical Simulator For Starlight Transmission (AOSST) in the boundary layer is developed. It effectively reduces the computational burden compared to that of the widely used CFD simulation, and it achieves satisfactory accuracy. In this simulator, gas ellipsoids satisfying certain design rules are used to simulate coherent density structures in boundary layers. Design rules for the gas ellipsoids are found from published experimental and high fidelity CFD simulation results. The generated wavefront distortion by AOSST is anchored with the scale law for aero optical distortion in the boundary layer by determining some control parameters, which enables the simulator to output reliable results over a wide range of flight states. Four numerical examples are provided to verify the performance of AOSST. The results demonstrate that AOSST is able to simulate the directional dependence of aero optical distortions in boundary layers, the variation trend of distorted wavefront shapes with Reynolds number, and the grayscale distribution on the disturbed star map.