高速颤振模型设计中颤振主要模态的判断

颤振模型设计时难以实现完全的动力学相似,需要对颤振主要模态进行合理选择。采用数值分析方法,对颤振模型设计时主要模态的选取问题进行研究。通过各阶模态振型下气动刚度系数的比较、指定运动形式下广义非定常气动力的计算和不同模态截断下颤振结果的收敛特性分析,研究了颤振分析时不同模态运动之间的相互影响,对模态运动引起的气动力和颤振特性变化进行评估。以高超翼面模型为研究对象的数值算例结果表明,几种分析方法所判断的颤振主要模态基本一致。其中基于振型的广义气动刚度系数参数,避免了非定常气动力的计算,可作为颤振模型设计或颤振分析时主要模态选取的快速判断方法。

Judgment on main flutter mode in high-speed flutter model design

It is difficult to achieve completely dynamic similarity for flutter model design. Theoretical support would be necessary to define the main flutter modes to guarantee data validity of wind tunnel flutter test. The judgment of the main flutter modes in high-speed flutter model design is studied analytically in the present paper. The effects of mode motion on generalized unsteady aerodynamic force and flutter characteristic are numerically investigated by a set of parameters, including generalized aerodynamic stiffness coefficients, unsteady aerodynamic force and flutter speeds. By comparing the results of those parameters, the interplay between mode motions is revealed. Analytical results of a high-speed sweepback wing show that the main flutter modes obtained by different methods are consistent. The aerodynamic stiffness coefficient in the expression of mode shape need not pay attention to aerodynamic force and could be taken as a quick criterion for main flutter mode selection in flutter model design and analysis.