Effects of dynamical spanwise retraction and stretch on flapping-wing forward flights  

作　　者：Kang LIU Bifeng SONG Ang CHEN Zhihe WANG Dong XUE Wenqing YANG 

机构地区：[1]School of Aeronautics,Northwestern Polytechnical University,Xi’an 710072,China [2]Intelligent Aircraft Research Center,Chengdu Technological University,Chengdu 610031,China [3]Research&Development Institute of Northwestern Polytechnical University in Shenzhen,Shenzhen 518057,China [4]Harbin Institute of Technology,Shenzhen 518055,China

出　　处：《Chinese Journal of Aeronautics》2024年第4期181-202,共22页中国航空学报（英文版）

基　　金：mainly supported by the National Natural Science Foundation of China (No. 52175277, 52275293);Resources provided by the Basic Research Program of Shenzhen, China (No. JCYJ 20190806142816524);the Guangdong Basic and Applied Basic Research Foundation, China (No. 2023A1515010774)。

摘　　要：Birds and bats retract and stretch their wings dynamically during each flap in level flights, implying intriguing mechanisms for the aerodynamic performance improvement of flapping wings. A numerical investigation into the aerodynamic effects of such bio-inspired concept in forward flights has been performed based on a three-dimensional wing in plunging motion and a twosection wing in flapping motion. The currently considered Reynolds number and Strouhal number are Re=1.5×10^(5) and St=0.3, respectively. During the research, the mean angle of attack is varied in relatively wide ranges to achieve lift-thrust interconversion for the wings. The conclusive results show that dynamical spanwise retraction and stretch has induced three absolutely desirable scenarios for the oscillating wings in forward flights, namely producing more lift and consuming less power for a given thrust generation, producing more thrust and consuming less power for a given lift generation, and producing more lift and more thrust while consuming less power. Furthermore,the morphing wings have alleviated periodical aerodynamic load fluctuations compared with the non-morphing baseline. The mechanism of the aerodynamic effects of the bionic morphing mode is analyzed with the aid of field visualization. The current article is the first to reveal the absolute advantages of the bionic spanwise morphing. Hopefully, it may help comprehend the behaviors of natural fliers and provide inspirations for performance enhancement of micro artificial flappingwing vehicles.

关 键 词：Flapping wing Morphing wing BIONIC AERODYNAMICS VORTEX Flight 

分 类 号：V276[航空宇航科学与技术—飞行器设计]