Aerodynamic Elasticity Analysis And Optimization Of Composite Wing With Compound Wing

The vertical take-off and landing fixed-wing unmanned aerial vehicle(VTOL UAV)is considered to have broad application prospects and has become a hot research topic due to its advantages such as a wide operating range,long flight time,and low requirements for take-off and landing sites.The thrust/lift combined VTOL fixed-wing UAV achieves vertical take-off and landing by adding a rotor to the wing strut,but the strut changes the wing structure and affects the aerodynamic characteristics and aerodynamic elasticity of the wing.This article focuses on the aerodynamic elasticity analysis and optimization design of a hybrid power composite wing UAV developed by a certain research institute.(1)The feasibility and accuracy of using the S-A one-equation turbulence model to calculate aerodynamic forces are verified by using the standard test data of the NACA4412 wing.The accuracy of calculating static aerodynamic elasticity using the one-way coupling method is verified by using the HIRENASD wind tunnel experimental model.(2)The static aerodynamic elasticity simulation results of the wing are compared and analyzed,and the lift-to-drag characteristics,wing deformation,and longitudinal aerodynamic characteristics of the wing at different angles of attack are studied.The results show that the wing has the best lift-to-drag characteristics when the angle of attack is 2°;the wing with the strut has a higher stall angle,and the strut affects the distribution of negative pressure on the upper surface of the wing;as the angle of attack increases,the vortex at the trailing edge becomes more and more obvious,and the pressure coefficient distribution shows larger fluctuations;the displacement of the wingtip does not change much at the design speed,but the wing with the strut is slightly larger than the clean wing.(3)The modal analysis of the wing is conducted using MSC.NASTRAN to obtain the natural frequencies and modes of the wing.The torsional mode frequencies of the wing are similar,and the modal order of the wing with the strut is greater than that of the clean wing.The dipole mesh method is selected to calculate the aerodynamic forces,and the flow-structure coupling is achieved through infinite spline interpolation.The p-k method is used to analyze the flutter of the wing.The results show that the flutter critical speed of the wing increases with the increase of Mach number and flight altitude,and the flutter speed of the wing with the strut is greater than that of the clean wing.(4)With mass minimization as the optimization objective and wing tip displacement as the constraint,the response surface method is used to optimize the beam and rear wall thickness of the wing.After optimization,the mass of the wing decreases by 25%,and the flutter speed of the wing at 5km altitude decreases by 28.8%.The weight reduction hole of the rib is designed using topology optimization.The reconstructed rib has a mass reduction of 28.6% compared to the original rib,and the maximum deformation is less than 3mm.The research results of this paper can provide reference value for the subsequent optimization of this UAV wing.