Research On Nonlinear Aeroelastic Response Of Airfoil With Control Surfaces

With the advancement of modern technology,the aeroelasticity issues involved in the development of aerospace vehicles are becoming more and more complex.Due to the increase in flight speed,a series of flight safety problems have been raised.The most dangerous problem is the aeroelastic response of the wing,which can cause the aircraft to crash and die if it is not careful.At present,most of the research on the wing flutter problem uses two-dimensional wing sections in the structural model.And the aerodynamic models are mostly linear aerodynamic forces.With the gradual improvement of flight requirements,the existing research cannot solve the complex flutter problem.Therefore,it is particularly important to study the flutter problems of nonlinear aerodynamic models and three-dimensional wing with complex structures.The major research work of this paper is as follows.(1)A structural model of a three-degree-of-freedom two-dimensional airfoil section with control surface deflection is established.The torque equation of the deflection of the control surface is added to the existing two-degree-of-freedom Onera aerodynamic model,which matches the structure equation of the three-degree-of-freedom wing.Then,using Theodorsen unsteady aerodynamic model and the Onera stall aerodynamic model,which are combined with the structural equations,the motion equations of the system are deduced respectively.(2)Using the V-g method to solve the flutter critical velocity and flutter frequency of the wing in the frequency domain,the flutter characteristics were analyzed based on the influencing factors such as the mass of the wing per unit length,atmospheric density,half-chord length and control surface rotation axis position.The calculation results of the two aerodynamic models are compared and analyzed.(3)The differential equations under the two aerodynamic models are solved by the RungeKutta method in the time domain,and the aeroelastic response analysis of the linear and nonlinear systems is carried out.(4)Extend the two-dimensional wing to the three-dimensional straight wing,and establish a three-dimensional wing structure model with a control surface through the idea of "integration".Using the Theodorsen aerodynamic model,the equation of motion of the system is deduced.And then,the influence of three-dimensional wing-specific parameters on flutter characteristics is analyzed.Finally,the response of the system is analyzed and compared with the two-dimensional wing results.Simulation calculation analysis shows that the calculation results of the Onera aerodynamic model after adding the deflection degree of freedom of the control surface can be accurately verified.Factors such as the half-chord length and the position of the axis of the control surface of the two-dimensional airfoil and the aspect ratio of the three-dimensional airfoil,the length and position of the control surface,all have a significant impact on the flutter characteristics.And different initial value conditions will have different degrees of influence on the flutter critical velocity.