考虑几何非线性效应的大展弦比机翼气动弹性分析

Aeroelastic analysis of the high aspect ratio wing considering the geometric nonlinearity

针对飞机飞行过程中因受气动载荷作用、机翼几何非线性效应影响气动弹性稳定性,提出考虑结构大变形几何非线性效应的大展弦比机翼气动弹性特性分析方法。通过对MSC.Nastran软件二次开发实现该方法的计算流程。考虑大展弦比机翼几何大变形对气动面网格构型影响,在每个迭代步对气动面网格进行更新,求出大展弦比机翼在给定飞行状态下的静气动弹性变形,获得考虑机翼结构几何非线性效应的刚度矩阵,并进行机翼颤振特性分析。对大展弦比机翼模型进行气动弹性特性分析计算表明,与线性气动弹性分析结果相比,考虑机翼结构大变形几何非线性效应,机翼静气动弹性变形会影响机翼动力学特性,使机翼扭转频率明显下降,导致机翼几何非线性颤振速度低于线性颤振速度。

The large deformation of high aspect ratio wing during flight has an important effect on the aeroelastic stability of an air-vehicle. The aerodynamic performance and flying safety of high-altitude,long-endurance uninhabited air vehicles are greatly affected. Therefore,the geometric nonlinearity of high aspect ratio wing can＇t be ignored. Based on the secondary development of MSC. Nastran software,the method to analyze the aeroelastic characteristics considering the geometric nonlinearity was proposed. Considering the effect of large geometric deformation on aerodynamic surface grid,the aerodynamic surface grid was updated at every iterative step,the static aeroelastic deformation at the flight condition was obtained with a convergent iteration,then the flutter characteristic of the large aspect ratio wing was analyzed based on the stiffness matrix considering the geometric nonlinearity. Using the method,the aeroelastic characteristic of the large aspect ratio wing model was analyzed. It is shown that comparing with the linear result,the dynamic aeroelastic characteristic is affected by the static aeroelastic deformation,the torsion frequency of the wing decreases and the coupled bending-torsional flutter velocity drops at the same time.