Study on flutter characteristics of NACA0012 flexible straight wing with high-aspect-ratio

大展弦比NACA0012弹性平直机翼颤振特性研究

¹ School of Aerospace Engineering, Tsinghua University, Beijing 100083, China
² School of Science, Harbin University of Science and Technology, Harbin 150080, China

Received: 16 December 2021

Abstract

采用三维雷诺平均N-S方程和S-A湍流模型求解展弦比为16的NACA0012弹性平直机翼的非定常气动力, 结合机翼动力学方程, 建立了机翼颤振时域分析方法。利用该方法对机翼的颤振特性、颤振过程中的变形和振动响应, 以及瞬时流场进行数值模拟和分析, 并研究材料刚度和密度对机翼颤振速度和频率的影响。结果表明, 由于展弦比较大, 且材质轻柔, 机翼会出现一定幅度的静弯曲变形。第二阶(垂向弯曲)和第三阶(扭转)振动模态的耦合作用是机翼发生颤振的原因, 且颤振频率介于这两阶模态固有频率之间。对比不同材料刚度和密度下机翼的颤振速度和频率, 发现材料刚度的增大会提高颤振速度和频率, 材料密度的增大会使颤振速度先降低然后趋于不变, 颤振频率一直降低。

摘要

The three-dimensional Reynolds averaged N-S equations and the S-A turbulence model are adopted to solve the unsteady aerodynamic forces of NACA0012 flexible straight wing with high-aspect-ratio of 16. Combining with the wing dynamic equation, a flutter time-domain analysis method is established. The flutter characteristics of the wing, the deformation and vibration response in the flutter process, and the instantaneous flow field are numerically simulated and analyzed by using this method. The influences of the material stiffness and density on the flutter velocity and frequency of the wing are also studied. The results show that due to the high aspect ratio and soft material, the wing has a certain range of static bending deformation. The coupling effect of the second (flatwise bending) and third (torsion) order vibration modes is the cause of wing flutter, and the flutter frequency is between the natural frequencies of these two modes. Comparing the flutter velocity and frequency under different material stiffness and density, it is found that the enlarged material stiffness leads to higher flutter velocity and frequency, while with the increasing of material density, the flutter velocity decreases firstly and then tends to be unchanged, the flutter frequency always decreases.