Analysis of the impact of windward and angle of attack to the flow field around the optical window on high Mach condition

To improve the optical performance of optical window on the condition of high Mach flying, the structures of flight number field, density field, temperature field and pressure field corresponding to three kinds of aircraft on the angle of attack conditions on 0, 5 and 10 were provided and compared in this paper, as well as the influence to the optical properties of optical system. Firstly, three typical kinds of aircraft models were established based on the windward area of the aircraft head; secondly, the flight conditions on the angle of attack of 0 , 5 and 10 as well as the flight initial environment were provided; then, according to the Navier-Stokes equation and the turbulent model, the flow field distributions corresponding to the three kinds of aircraft model on the conditions of 0, 5 and 10 were obtained and analyzed; finally, taking the optical system on the operating condition of the flat -head aircraft as an example, the Modulation Transfer Function(MTF) on the operating conditions of the three kinds of attack angle were compared and analyzed. By the analyzed results, the Mach field and the destiny field, the temperature field and press field have the same distribution respectively; in the same flight velocity and angle of attack, the optical window of the aircraft owning large windward side has larger temperature and press than the optical window of small windward side aircraft; being the same aircraft, the operating condition of larger angle of attack corresponds to large flow field around the optical window. When the angles of attack are 0, 5 and 10, the values of MTF are 0.188, 0.097 and 0.028, respectively. The work of this study may provide a theoretical basis for the optimization of optical window on the operating condition of high Mach.