Unsteady characteristic research on aerodynamic interaction of slotted wingtip in flapping kinematics

作     者：Dan LIU Bifeng SONG Wenqing YANG Dong XUE Xinyu LANG Dan LIU;Bifeng SONG;Wenqing YANG;Dong XUE;Xinyu LANG

作者机构：School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China Yangtze River Delta Research Institute.Northwestern Polytechnical UniversityTaiccing 215400China Research&Development Institute of Northwestern Polytechnical University in ShenzhenShenzhen 518057China 

出 版 物：《Chinese Journal of Aeronautics》 (中国航空学报（英文版）)

年 卷 期：2022年第35卷第4期

页      面：82-101页

核心收录：

学科分类：080103[工学-流体力学] 08[工学] 080104[工学-工程力学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：the support from the National Natural Science Foundation of China(Nos.11872314 and U1613227) the Key R&D Program in Shaanxi Province of China(No.2020GY-154) 

主　　题：Aerodynamic interaction Aerodynamic mechanism Flapping Unsteady behavior Wingtip slots 

摘      要：The slotted wingtip structure of birds is considered to be the product of improving flight efficiency in the process of evolution. It can change the vortex structure of wingtip and improve aerodynamic efficiency. This paper reports a numerical investigation of slotted wing configuration undergoing bio-inspired flapping kinematics(consisting of plunging and in-line movement)extracted from a free-flying bald eagle wing. The aim is to eluci-date the collective mechanism of the flow generated by slotted tips and the lift contribution of each tip. Specifi-cally, the objective of the study is to determine how changes in the wing spacing affect the resulting aerodynamic interaction between the slotted tips and how that affects the force generation and efficiency. Changes in the phase angle between the flapping motions of slotted tips, as well as the spacings among them,can affect the resulting vortex inter-actions. The rear tips often operates in the wake of the frontal tips and, meanwhile, the vortex generated by the movement of the rear tips promote the frontal *** interaction of vortices in time and space leads to wing-wing interference and the flow around slotted tips becomes complicated and unstable. The innovative study of wingtip slot in unsteady state leads us to find that the aerodynamic interaction among slotted tips makes the overall lift characteristic better than that of the unslotted wings. The slotted wing configuration can efficiently convert more energy into lift. As the flapping frequency increases, the collective feature of slotted wing with constantly changing gaps can be more advantageous to enhance lift-generation performance.