鱼骨柔性翼等效结构建模及其气动弹性特性分析

Equivalent Structure Model of Fish Bone Active Camber Morphing Concept and Analysis of Aeroelastic Characteristics

鱼骨柔性翼(Fish bone active camber,FishBAC)是一种依靠结构变形实现机翼弯度变化的结构形式,相较于传统的离散式控制面和增升装置,可以在实现机翼弯度变化的同时保持气动表面的连续与光滑。然而,其依靠结构弹性变形实现机翼变弯度的基本特征可能引发潜在气动弹性问题。针对柔性翼潜在的气动弹性问题,本文从结构特性和气动弹性特性两方面进行了研究。在结构特性方面,基于欧拉梁理论和逐段刚化法建立等效结构模型,经有限元验证发现简化模型在计算非均质梁结构保持精度的同时提高了计算效率。在气动弹性特性分析方面,基于等效刚柔耦合翼型模型和非定常气动理论完成了气动弹性特性分析。结果表明,FishBAC建模时需考虑结构柔性,忽略结构柔性会对气动弹性特性的预测存在一定偏差。在驱动力矩低于1.5 N·m时,本文简化的等效结构模型可较好地预测考虑静气动弹性特性的机翼结构形变。使用本文提出的翼型模型考虑结构存在刚柔耦合特性,并预测柔性段所发生的弯度颤振,简化模型与MSC Nastran相比在颤振速度预测上保持了一致性。

The fish bone active camber(FishBAC)is a kind of mechanism which depends on structural deformation to realize changes in airfoil camber.Compared with traditional discrete flaps and lifting devices,it can achieve wing curvature changes while maintaining the continuity and smoothness of the aerodynamic surface.However,relying on structural elastic deformation to achieve the basic characteristics of wing curvature may lead to potential aeroelastic problems.This paper investigates the potential aeroelastic issues of flexible wings from two aspects of structural characteristics and aeroelastic characteristics.In the aspect of structure analysis,an equivalent structural model of FishBAC is established based on Euler beam theory,and a segmented stiffening method is employed to enhance computational efficiency while maintaining accuracy for non-uniform beam structures,which is verified by the finite element analysis.In the analysis of aeroelastic characteristics,the aeroelastic behavior is investigated based on an equivalent rigid-flexible coupled model and unsteady aerodynamic theory.The findings indicate that consideration of structural flexibility is essential in FishBAC modeling,as neglecting it may lead to deviations in predicting aeroelastic characteristics.The results show that the static aeroelastic characteristics can be exactly predicted under the driving torque of less than 1.5 N·m.Additionally,using the airfoil model proposed in the paper to consider the rigid-flexible coupling characteristics of the structure and predict the bending flutter that occurs in the flexible section,the simplified model maintains consistency in flutter velocity prediction compared with MSC Nastran.