基于双向流固耦合的柔性扑翼变形数值研究

Numerical study on the deformation of flexible flapping wing based on bidirectional fluid-solid coupling

通过研究柔性扑翼变形、惯性力及气动力的相互关系和作用机理,为扑翼飞行器的设计提供参考。在考虑扑翼运动特点的情况下,发展了一种求解雷诺平均N-S方程和结构动力学方程的双向流固耦合数值方法。对柔性翼惯性力方程进行改进,使其更方便与气动升力进行数值对比。针对柔性翼变形研究的困难性,提出了一种通过全翼面应变去分析柔性翼变形的方法。研究结果表明:柔性翼的扑动频率对惯性力和气动升力的影响程度较为一致;柔性翼应变主要集中在前缘和翼根周围,随着远离前缘和翼根,其应变值逐渐减小,应变一定程度上可以反映柔性翼的弦向变形;柔性翼变形导致推力在整个周期上的主要方向为正,能够显著提升扑翼飞行能力。

The study of the interaction and mechanism of flexible wing deformation,inertia force and aerodynamic force could provide reference for the design of flapping wing aircraft.Bidirectional fluid-solid coupling numerical method was developed to solve the Reynolds Averaged Navier-Stokes(RANS)equation and structural dynamics equation with flexible flapping wing motion considered.The inertial force equation of the flexible wing was improved to make it more convenient to compare it with the aerodynamic lift.In view of the difficulty in the study of flexible wing deformation,a method was proposed to analyze the deformation of flexible wing through all-wing strain.The research results show that the flapping frequency of the flexible wing has a consistent effect on the inertial force and aerodynamic lift force.The strain of the flexible wing is mainly concentrated around the leading edge and the wing root.With the distance from the leading edge and the wing root,the strain value decreases gradually.To some extent,the strain can reflect the chordwise deformation of the flexible wing.Due to the deformation of the flexible wing,the main thrust direction in the whole cycle is positive,which can significantly improve the flapping wing flight capability.