侧向随动力作用下大展弦比柔性机翼的稳定性

 随动力能够诱发弹性结构发生颤振失稳。以侧向随动力和集中质量分别模拟发动机推力和外挂质量,考虑机翼垂直弯曲-扭转刚度比、集中质量大小、侧向随动力和集中质量的位置以及机翼后掠角和上反角的影响,研究了受侧向随动力作用的大展弦比柔性机翼的气动弹性稳定性。数值模拟所采用的大展弦比柔性机翼非线性气动弹性模型耦合了几何精确完全本征运动梁模型和ONERA动失速非定常气动力模型,该模型考虑了几何非线性、动失速和材料各向异性。模拟结果表明,侧向随动力对机翼颤振可以具有稳定作用,其具体表现依赖于若干变参数的影响,如：减小机翼垂直弯曲-扭转刚度比;发动机吊舱靠近翼根布置;使发动机推力作用点在法向上与机翼弹性轴靠近;单纯的集中质量避免布置在柔性机翼中部,且布置在机翼弹性轴之前或下方,这些设计或布置均有利于提高带发动机吊舱/有效载荷外挂的柔性机翼的气动弹性稳定性。

Stability of High-aspect-ratio Flexible Wings Loaded by a Lateral Follower Force

Follower force could induce flutter instability of elastic systems. Parametric studies on the aeroelastic stability of high-aspect-ratio flexible wings subject to a lateral follower force are performed, with the lateral follower force and concentrated mass representing the engine thrust and engine mass or external payload, respectively. The effects of variations of several parameters are investigated, including the ratio of flapwise bending stiffness to torsional stiffness, the concentrated mass, a lateral follower force and the location of a concentrated mass, and the wing sweep and dihedral. The geometrically exact, fully intrinsic theory for dynamics of a moving beam is coupled with unsteady ONERA dynamic stall aerodynamic model, which yields the nonlinear aeroelastic model of high-aspect-ratio flexible wings used in the present numerical studies. The nonlinear aero-elastic model considers geometrical nonlinearity, dynamic stall and material anisotropy. Results obtained indicate that the lateral follower force may stabilize the wing, the performance of which depends specifically on several parameters. The aeroelastic stability of high-aspect-ratio flexible wings with the engine nacelle or external payload can be improved by the following designs or configurations: reducing the ratio of flapwise bending stiffness to torsional stiffness, mounting the engine nacelle close to the wing root, keeping the thrust location in the flapwise direction close to the wing’s elastic axis, avoiding the existence of a concentrated mass in the middle region of the wing span, and moving the concentrated mass forward before or downward below the wing’s elastic axis.