Influence Of Atmospheric Turbulence On Detection And Imaging Of High Speed Aircraft's Disturbed Flow Field

Since the 21 st Century,the military game between big powers has been escalating.Hypersonic vehicles with faster speed and higher maneuverability shine brilliantly in near space flight.It is imperative to detect and intercept this kind of aircraft.Traditional infrared detection is not often effective in face of fast and flexible aircraft,and with the rapid development of all kinds of infrared stealth technology,the error rate of the traditional infrared detection technology is greatly increased by the clutter interference of laser,infrared decoy and other heat sources,and the situation of deviation and loss of target often appears.In the past ten years,the infrared schlieren photography has shown unique advantages in infrared detection,and the unique optical characteristics of atmospheric turbulence have an unnegligible effect on it.In the paper,the optical characteristics of atmospheric boundary layer turbulence have been studied.The imaging characteristics of the disturbance flow field of hypersonic aircraft under different parameters are analyzed.Besides,the influence of atmospheric boundary layer turbulence on imaging is analyzed.The main contents are as follows:Two kinds of external scale models to estimate the atmospheric refractive index structure constant are compared,and the structure constant model in the urban and sea level environment is verified,which provides the basis for obtaining the atmospheric refractive index structure constant profile under various environment.The fluctuating refractive index field and the actual refractive index field of the atmospheric boundary layer under different background conditions are calculated.According to the basic information of the flow field of a certain aircraft,the refractive index and the gradient of the refractive index at any point of the disturbance flow field in different flight conditions are calculated.The Runge-Kutta ray tracing program is written.The variation characteristics of the angle of light migration at different flight heights and different detection wavelengths are analyzed.Considering the influence of atmospheric boundary layer turbulence on light propagation,the influence of atmospheric boundary layer turbulence on the detection and imaging of the disturbed flow field of the target aircraft under the urban and sea level environment are analyzed.The research results of this paper have good reference value for the infrared schlieren photography of hypersonic vehicle,and further improve the target detection system in the complex atmosphere.