Research On Characteristics Of Ellipsoidal Fairing For High-Speed Aircraft

In recent years,the aircraft with infrared guidance system is gradually developing towards a higher and higher speed.Higher speeds will cause the fairing at the front of the aircraft to form a strong relative movement with the complex airflow,and the air at the front of the fairing will be severely compressed.A shock layer is formed,destroying the uniformity of the nearby flow field density and refractive index.In addition,the complex aerodynamic heat flow will also make the fairing temperature rise sharply.At the same time,the homogeneity of deformation and refractive index will be destroyed.These will have a very negative impact on the imaging quality and guidance accuracy of high-speed aircraft.Therefore,it is necessary to study the aerodynamic performance,aerodynamic thermal performance and aerodynamic optical performance of the fairing.In this paper,the aerodynamic characteristics,aerodynamic thermal characteristics and optical characteristics of the ellipsoidal fairing with various configurations are simulated and analyzed.According to the results obtained,the comprehensive performance of the ellipsoidal fairing in different configurations is analyzed.This paper mainly studies from the following two aspects:(1)Comprehensive performance analysis of ellipsoidal fairing in various configurations.Establish the external flow field calculation model,thermal analysis calculation model and light transmission calculation model of the ellipsoidal fairing when the aspect ratio increases from 0.5 to 2.0 with 0.1 as the step length.The aerodynamic characteristics of the outer flow field,the aerodynamic and thermal characteristics of the fairing and the optical transmission characteristics of the fairing are calculated by using the above models.Taking the change of pressure field,temperature field,heat flux field,density field,temperature distribution,deformation distribution,wavefront aberration distribution,point spread function and image distortion of fairing as evaluation indexes.The above simulation results are analyzed,and the influence of configuration on the comprehensive performance of ellipsoidal fairing is studied..(2)Optimized design of ellipsoidal fairing with large aspect ratio.For the purpose of improving the comprehensive performance of the fairing with large aspect ratio,combining the advantages of the pointed arch fairing and the ellipsoidal fairing,from the perspective of materials and surface shapes,a new idea of material splicing and surface splicing is proposed.The material selection and model selection of the fairing are carried out,the design parameters are given and the aerodynamic performance,aero-thermal performance and optical performance of the new configuration of the fairing are simulated and calculated based on the finite element analysis theory,and the simulation results are used as judges The standard compares and analyzes the comprehensive performance of the new configuration fairing and the original configuration fairing to verify the feasibility of the method.