Research On Aerodynamic Simulation And Performance Degradation Analysis Method Of Damaged Aircraft

Survivability has become one of the important indicators of modern aircraft design.Wing damage will result in changes of the aerodynamic characteristics,which in turn will affect the performance of the aircraft.From the two aspects of aerodynamics and control,this thesis completes the following:(1)Establishes flight dynamic models of the damaged aircraft.Wing damage will cause the shift of the center of the mass of the aircraft,which no longer coincides with the origin of the body axis.Based on any point on the aircraft,flight dynamic models of the damaged aircraft are established.The straighten flight is assumed as the baseline state,and the dynamic small linear perturbed equations are obtained.Matlab/Simulink software is used to build aircraft control simulation system.(2)Studies the aerodynamic characteristics of the wing under projectile attack.Assuming that the projectile vertically penetrates the wing and the shape of the perforation is circular.Four examples are set to study the effects of damage location and the perforation numbers.Using CFD method to simulate the wing flow structure and the changed magnitude of the characteristic coefficient to characterize the strength of damage effects,the influence of different damaged forms on the aerodynamic performance of the wing is obtained.By analyzing the streamlines of the wing flow which are got using Tecplot software,the influence of single hole location on wing aerodynamic performance and the details of interference between two holes are also gained.(3)Builds the aircraft three-dimensional model,sets the damage form and performs the aerodynamic calculation.The thesis chooses Bonanza F-33 aircraft as the research target and reconstructs the shape of it.Wing damage detailed in other papers are referred to,and the wing damage patterns are given.Using CFD and other estimation methods,the aerodynamic data,control partial derivatives and derivatives as well as the mesh parameters are obtained.(4)Analyzes of damaged aircraft stability,flight simulation and performance degradation.The eigenvalues of the state matrix in the system of small linear perturbed equations are solved,and the typical model of the aircraft under different damage cases is analyzed.The simulated flying and hovering of the damaged aircraft are simulated,and the trajectories of radius are compared.Based on the criteria of aircraft agility,this paper presents criteria and classifying methods for aircraft performance degradation.It also divides the performance degradation of the damaged cases in this thesis.The results show that: the closer damage location is from wing leading edge,the stronger the wing lift loss will be;damage reduces the lift-drag ratio of the wing and the angle of attack corresponding to the maximum lift-drag ratio;method for measuring aircraft's performance degradation caused by damage is feasible and the degradation level is higher for stronger damage.