Nonlinear fluid-structure interaction response analysis of a large flexible wing under strong gusts

The geometric nonlinearity and aerodynamic nonlinearity cannot be ignored as the large flexible wing undergoes significant deformation when subjected to high gusts. In order to study the response of a large flexible wing under strong gusts, a fluid-structure interaction analysis method based on geometric nonlinear beam theory and computational fluid dynamics (CFD) was established. The fluid model and geometrically nonlinear beam model of a big flexible wing with a semi-aspect ratio of 9 were constructed, and the accuracy of the fluid-structure interaction simulation approach was confirmed by comparing wind tunnel tests of inverted flexible plate. The dynamic response characteristics of large flexible airfoils were examined at various gust ratios (R_G=0.1-0.4). In particular, the dynamic stall aerodynamic characteristics of the airfoils caused by gusts at large gust ratios (R_G=0.4) were examined. The gust response analysis was conducted at a Reynolds number of 10⁵. The results show that significant nonlinear bending deformation of the wing occurs with the increase of gust ratios, and the maximum bending deformation of the wing reaches 63% of the half-spread length at R_G=0.4. Meanwhile, the bending deformation of the wing reduces the width of the spreading distribution of the leading-edge vortex (LEV), which affects the distribution of aerodynamic forces and reduces the gust loads.