Nonlinear Aeroelastic Response And Flutter Analysis Of High-Aspect-Ratio Wings

The high-altitude long-endurance uninhabited air vehicles (UAV) have a widely application and are being investigated actively. The aeroelastic problems of the UAV are significant due to its high-aspect-ratio wings. Considering the effect of structural geometric nonlinearity on the wing dynamic characteristics and the wing surface distribution of aerodynamics, it is necessary to use the theory of nonlinear beam with the nonlinear stall aerodynamics for analysis of the nonlineary aeroelasticity of the wing. The major research work of the thesis is as follows: 1. Develop an analytical model of the nonlinear aeroelasticity of the high-aspect-ratio wings and give the nonlinear partial equations of wing structure motion based on the Hamilton principle. 2. The angle of attack of the high-aspect-ratio wings varies largely as the airflow rounds the airfoil. Even in some conditions, the airflow may separate at the tip of wings. The compressive effects of airflow are great on the aerodynamics at high speed's flight. Based on the nonlinear geometric properties of the high-aspect-ratio wings and the nonlinear relationship of the aerodynamic coefficients with the angle of attack and the Mach number, a nonlinear stall aerodynamic model is presented. 3. Formularize the nonlinear aeroelastic equations of the high-aspect-ratio wings by combining the nonlinear beam theory with the stall aerodynamic model. The numerical simulation gives the change relationship of the wing natural frequencies and stead deformation with the angle of attack, the wing aeroelastic response characteristics, the wing nonlinear flutter boundary and the change relationship of the nonlinear flutter velocity and flutter frequency with the angle of attack.