Research On Side Window Design Of Conformal Surface Of High Speed Aircraft Based On Aero-optical Effect

For high-speed aircraft equipped with infrared imaging detection system,when it is flying at high speed in the atmosphere,its optical window is directly in contact with aerodynamic heat flow.The window is heated by complex heat flow.Its temperature rises rapidly,uneven deformation occurs,and internal stress and strain are also generated.According to the thermo-optic effect and the bounce effect,the aerodynamic effect of the optical window will cause the refractive index field of the window to change,thereby changing the wave front of the beam transmitted through the window,affecting the imaging quality of the infrared imaging detection system to the target,and reducing the impact of the aircraft.The aerodynamic thermal effect of the optical window directly affects the window light transmission.From the perspective of thermal regulation,this paper combines the advantages of the conformal dome and the planar side window to create a conformal curved side window to reduce the aerodynamic thermal effect of the optical window.In turn,the aero-optical effect of the window is weakened,and the imaging quality and detection accuracy of the infrared imaging detection system are improved.In this paper,the research on the side window shape design of high-speed aircraft conformal curved surface and the design of high-speed aircraft conformal curved side window splicing material are completed.Research on the design of side window shape of conformal curved surface of highspeed aircraft.Based on the related theories of heat transfer and elastic mechanics,the finite element calculation model of aerodynamic thermal response analysis of high-speed aircraft optical window is established by using finite element method.The variation of the aerodynamic performance of the conformal domes with different aspect ratio and shape is analyzed.Select the sinusoidal dome with the aspect ratio of 1.5 which has the best aerodynamic performance as the basis function to establish the conformal curved side window,avoid the high temperature region of the dome,and establish the side widow at the low temperature and low deformation region of the sinusoidal dome.The research on the side window shape design of the high-speed aircraft conformal curved surface is completed.The ray tracing software is used to calculate the wave aberration of the side window of conformal curved surface with different heat distribution in high-speed aircraft and the dome under complex thermal environment.The comparison and analysis are carried out to verify the feasibility of weakening the influence of the aero-optical effect by designing the side window of conformal curved surface by thermal regulation.Research on the material preferred selection of side window splicing materials for conformal curved surfaces of high-speed aircraft.The heat conduction occurs between the light-transmitting side window and the opaque dome material,and the dome material characteristics affect the temperature and deformation of the side window.Based on the theory of heat transfer and elastic mechanics,the finite element method for the domes with side windows is established by using the finite element method.The effects of specific properties such as heat capacity,density,thermal conductivity,thermal expansion coefficient,Poisson’s ratio and Young’s modulus on the temperature,deformation of the side window of conformal curved surface were compared and analyzed.The influence law of the thermal response of the side window is given,and the opinions of the dome material selection which is beneficial to improve the aerodynamic performance of the high-speed aircraft are given.According to the law,several actual materials were selected for thermal response analysis,and the dome material with the best aerodynamic performance of the side window was determined.The ray tracing software is used to calculate the wave aberration of the side window of the conformal curved surface with different opaque materials in complex thermal environment,and the correctness of the proposed dome material selection law is verified.