考虑几何非线性的气动弹性模型缩比方法

Scaling method of aeroelastic model considering geometric nonlinearity

随着飞机性能和需求的提高,大展弦比高柔性机翼逐渐成为新型飞机的主要结构形式。这类机翼具有高升阻比、大变形和重量轻等特性,几何非线性效应明显。然而机翼的大展弦比高柔性会带来更大的机翼变形,而机翼大变形则会引起相关的非线性气动弹性行为。为了评估这些非线性气动弹性行为并同时降低设计风险和成本,一般要使用缩比模型进行风洞试验以研究和确认真实飞机的气动弹性特性。基于此,首先使用了传统线性缩比方法来进行缩比,通过刚度质量耦合匹配模态响应法与刚度质量解耦匹配模态响应法这2种线性缩比方法,不断优化缩比结构的设计参数来满足目标缩比值。同时,提出一种动力学有限元模型的非线性静响应-模态协同优化方法,该方法是基于等效静态载荷法的几何非线性气动弹性模型缩比方法,通过2个不同的优化子程序分别匹配全尺寸飞机的非线性静响应和模态振型。结果表明,相比于传统线性缩比模型,考虑几何非线性的缩比模型能够更好地再现全尺寸飞机的非线性气动弹性行为。

The high-aspect-ratio flexible wing has become the main structural type of emerging aircraft with the increasing demand and performance improvement of aircraft.The wing type holds the inherent characteristics of high lift-to-drag ratio,large deformation and low weight,and the geometric nonlinear effect is obvious.However,the high aspect ratio will lead to larger wing deformation,resulting in nonlinear aeroelastic behavior.To evaluate the nonlinear aeroelastic behavior and reduce the risk and cost of the design,it is necessary to design a scaling model and conduct wind tunnel test with a scaling model to represent the aeroelastic characteristics of real aircraft.Based on this purpose,traditional linear scaling approaches are applied first.Two linear scaling methods,stiffness-mass coupled matched modal response and stiffness-mass decoupled matched modal response,and continually optimizes the design parameters of scaled model structure to meet the target values.Then,a new method named the nonlinear static deformation and mode collaborative optimization of the dynamic finite element model is proposed,which employs two different optimization subroutines to match the nonlinear static response and the mode shapes according to the full model equivalent static loads.The results show that,compared with the traditional linear scaling model,the nonlinear aeroelastic behavior of the full-size aircraft can be reproduced better by using the geometric nonlinear scaling method.