极小昆虫翅膀拍动模式的气动特性实验研究
A STUDY ON THE AERODYNAMIC CHARACTERISTICS OF VERY SMALL INSECTS WING FLAPPING PATTERN
何皓翔 1付嘉钧 1白宏磊1
作者信息
- 1. 中山大学深圳校区航空航天学院,广东深圳 518107
- 折叠
摘要
不同于较大的昆虫(如熊蜂、果蝇和鹰蛾等,飞行雷诺数Re>100),极小昆虫(如丽蚜小蜂、西花蓟马和瘿蚊等,Re<100)的翅膀采用更复杂的三自由度拍动形式,对应特殊的非定常高升力机制——"划桨"机制;同时,微小型飞行器(MAV)的飞行雷诺数较高(Re=103～105),其任务环境复杂多变,当MAV面对超载荷或高机动任务时,利用极小昆虫翅膀拍动模式飞行或许可以作为一种新的解决方案.为了深入理解MAV雷诺数下极小昆虫翅膀拍动模式的气动特性,基于三自由度拍动翅膀模型实验(包括直接测力和染色液流动显示,Re=3.9×103～1.0×104)对 3 种典型极小昆虫(丽蚜小蜂、西花蓟马和瘿蚊)悬停飞行状态下翅膀拍动模式的气动力特性进行研究.发现在上挥(upstroke)阶段初期,即"划桨(rowing)"阶段,翅膀受到的铅垂升力急剧增大;在所考虑的雷诺数范围内,翅膀在整个上挥阶段的平均铅垂升力系数(大于 3.1,丽蚜小蜂)明显大于较大昆虫翅膀拍动模式下获得的铅垂升力系数(1.5～2.0).同时,观察到在"划桨"阶段初期,翅膀的前缘和后缘产生一对旋转方向相反的旋涡;进入"划桨"阶段中末期,后缘旋涡脱落,但是前缘旋涡始终附着.这表明在MAV雷诺数下,翅膀上挥过程中的高升力产生机制为"延迟失速机制",而不是极低雷诺数下的"划桨机制".此外,发现在翅膀上挥下拍冲程交替即"打开(fling)"阶段,其高升力机制仍然是"打开机制";然而,也注意到雷诺数效应和双翅效应对"打开"阶段的气动力影响很大.
Abstract
Unlike larger insects(such as bumblebees,fruit flies and hawkmoth,Reynolds number Re>100),very-small insects(such as encarsia formosa(EF),frankliniella occidenalis(FO)and anbremia sp.(AS),etc.,Re<100)have much complex patterns of wing flapping,with three degrees-of-freedom(DOF)being involved and corresponding to different under-lying mechanisms of high-lift generation.Meanwhile,micro aerial vehicles(MAV)are associated with relatively high Re,i.e.,Re=103～105,and their mission environment is complex and changing.When MAVs are faced with overload or high maneuverability mission,flying with very small insect wings flapping patterns may be a new method.To better understand the aerodynamic characteristics of wing flapping pattern of very small insects at high Re,flapping wing model-based experiments are conducted at a range of Reynolds number from 3.9×103 to 1.0×104,taking into account wing planforms and flapping kinematics of three typical very-small insects(i.e.,EF,FO and AS).It is found that the vertical lift on the wing increases dramatically at the beginning"rowing"phase of the upstroke.It is further noticed,however,the time-mean vertical lift coefficient((C¯)VUpstroke)on the wing of very small insects is significantly increased during the upstroke in the Rerange considered in this work,e.g.,(C¯)VUpstroke>3.1 for EF,which is noticeably greater than those(1.5～2.0)of their larger counterparts.Moreover,it is observed that a pair of counter-rotating vortices are produced at the leading and trailing edges of the wing at the starting of the"rowing"phase.With the"rowing"advancing,the trailing-edge vortex sheds while the leading-edge vortex keeps attached,indicating that the high-lift generation during the upstroke is attributed to the delayed stall at the MAVRerange,instead of the"rowing"mechanism identified at the very-low Re range.In addition,it is noticed that the"fling"mechanism still plays a key role in generating the high lift during the"fling"phase,although Reeffects and wing-wing interactions may strongly influence the force behavior.
关键词
极小昆虫/高升力机制/微小型飞行器Key words
very-small insect/high-lift generation mechanism/micro aerial vehicle引用本文复制引用
基金项目
深圳市高校稳定支持重点资助项目(GXWD20201231165807008)
深圳市高校稳定支持重点资助项目(20200830220051001)
出版年
2024
NETL
NSTL
万方数据