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 inter-action 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 tips.The 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 char-acteristic better than that of the unslotted wings.The slotted wing configuration can efficiently con-vert 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.

Dan LIU;Bifeng SONG;Wenqing YANG;Dong XUE;Xinyu LANG

School of Aeronautics,Northwestern Polytechnical University,Xian 710072,China;Yangtze River Delta Research Institute,Northwestern Polytechnical University,Taicang 215400,China;Research&Development Institute of Northwestern Polytechnical University in Shenzhen,Shenzhen 518057,China

中国航空学报（英文版）

[1]Dan LIU;Bifeng SONG;Wenqing YANG;Dong XUE;Xinyu LANG-.Unsteady characteristic research on aerodynamic interaction of slotted wingtip in flapping kinematics)[J].中国航空学报（英文版）,2022(04):82-101

wingtip,Specifi,unslotted

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