考虑旋转颤振的折叠机翼非线性颤振分析

Nonlinear Flutter Analysis of Folding Wing with Whirl-flutter

固定翼舰载飞机由于其使用环境的限制,通常采用可折叠机翼。对于翼下吊挂安装涡桨发动机的舰载飞机,发动机-螺旋桨系统与柔性支持系统相互耦合会产生旋转颤振不稳定现象。由于折叠机构间隙的存在,折叠机翼的刚度呈非线性关系特性,通常会引起机翼的极限环振荡。对于安装在折叠机翼上的发动机-螺旋桨组合体,旋转模态与折叠机构的非线性特性的相互作用会影响机翼的动力学特性,进而显著地影响机翼的气动弹性特性。通过在非线性气动弹性方程中引入桨叶气动力与陀螺力矩,采用离散时域状态空间法进行直接仿真的方法,对旋转颤振/折叠翼结构非线性颤振的综合分析方法进行了研究,并进行了算例验证。结果表明:旋转颤振与非线性颤振相互影响会提高旋转颤振临界速度,并且使得机翼的极限环现象消失;旋转颤振与非线性颤振相互影响使得结构的响应更为复杂。

As a result of the limitation of its usage environment,fixed- wing carrier- based aircraft usually adopts foldable wing. For the carrier- based aircraft with turboprops engine under the wing,the combination of engine- propeller and the flexible suspension system are coupled with each other,which whirl flutter phenomenon will appear. Due to the freeplay in the folding mechanism,the structural stiffness appears nonlinear characteristics which usually causes LCO. The whirl modes of engine- propeller interact with the structural nonlinearity,which will change the dynamic characteristics of wing and have a significant influence on the aeroelastic characteristic of wing. By introducing the blade aerodynamic and gyroscopic moment equation,the nonlinearity flutter analysis is presented and validated in the discrete time domain state space. Because of mutual influence between whirl flutter and structural nonlinearity,it is shown that flutter speed is increased and it makes the LCO of wing disappear; the response of structure are more complicated.