大攻角机翼非线性颤振分析方法

 本文提出了一种计算方法分析大攻角、带分离涡机翼的非线性颤振特性。在机翼变形与广义气动力之间建立一种描述函数关系,利用传统v-g法对机翼运动方程进行求解。此外,还发展了一种迭代运算过程,使得输入的振幅幅值比例调整到与求解颤振方程所得到的比例相协调。计算结果表明本文方法与实验是一致的。

A NUMERICAL METHOD FOR ANALYZING THE NONLINEAR FLUTTER OF WINGS AT HIGH ANGLES OF ATTACK

A numerical method is presented for analyzing the nonlinear flutter characteristics of the wings with separation at high angles of attack. The nonlinear aerodynamic forces are linearized by using the describing function method. Then, the conventional v-g method can be used to solve the structural dynamic equations of the wings. To determine the ratios between the amplitudes of different modes, an iterative procedure is intro-duced.Examples of calculation show that the present numerical method behaves very good convergence characteristics. Generally, only three or four steps are needed to obtain a satisfactory results. It is found from the numerical results that the critical flutter speed of the wings decreases when the angles of attack increases, and the results are agree well with those of the Time Integration Method and experimental data. Besides, the present method takes much less computational time than the Time Integration Method, and it can be easily used for different systems with nonlinear property in practical engineering.