Aerodynamic periodicity of transient aerodynamic forces of flexible plunging airfoils

• 作者: ZHOU Chao ZHANG Yanlai WU Jianghao
• 来源期刊: 中国航空学报（英文版）
• 年，卷（期）: 2021,（1）
• 页码范围: 10-21
• 页数: 12页
• 语种: 英文

摘要

For flapping micro-air vehicles, periodical aerodynamics in every plunging period is always desired in the design of aircraft controlling system. During the periodic plunges of rigid air-foil, either periodical or non-periodical aerodynamic forces can be generated. Real airfoils are usu-ally flexible so that the effect of flexibility on unsteady characteristics of aerodynamic periodicity should be considered. In this study, a fluid structure interaction analysis is employed to systemat-ically investigate the aerodynamic periodicity of a periodically plunging flexible airfoil. The influ-ences of several dimensionless kinematic and structural parameters on aerodynamic periodicity are investigated. The results show that the aerodynamic periodicity of plunging flexible airfoil qual-itatively resembles that of rigid airfoil as the mechanisms contributing to aerodynamic periodicity are kept for airfoil with various flexibilities. However, aerodynamic periodicity at small plunging amplitude and high Reynolds number can be improved as airfoil becomes medium flexible but worsened as airfoil is very flexible. The reason is that the deformation of the airfoil changes the strength and structure of the nearby vortices, thereby leading to weak vortex-vortex and vortex-air-foil interactions. The extent of improvement in aerodynamic periodicity is also found significantly influenced by incoming velocity.