The flapping motion has a great impact on the aerodynamic performance of flapping wings.In this paper,a surging motion is added to an airfoil performing pitching-plunging combined motion to figure out how it influences the lift performance and flow pattern of flapping airfoils.Firstly,the numerical methods are validated by a NACA0012 airfoil pitching case and a NACA0012 airfoil plunging case.Then,the E377m airfoil which has typical geometric characteris-tics of the bird-like airfoil is selected as the calculation model to study how phase differences φ1 between surging motion and plunging motion affect the aerodynamic performance of flapping air-foils.The results show that the airfoil with surging motion has comprehensively better lift perfor-mance and thrust performance than the airfoil without surging motion when 15°＜φ1＜90°.It is demonstrated that surging motion has a powerful ability to improve the aerodynamic performance of flapping airfoil by adjusting φ1.Finally,to further explore how flapping airfoil improves lift per-formance by considering surging motion,the flapping motions of E377m airfoil with the highest lift coefficient and lift efficiency are obtained through trajectory optimization.The surging motion is removed in the highest lift case and highest lift efficiency case respectively,and the mechanism that surging motion adjusts the aerodynamic force is analyzed in detail by comparing the vortex struc-ture and kinematic parameters.The results of this paper help reveal the aerodynamic mechanism of bird flight and guide the design of Flapping wing Micro Air Vehicles(FMAV).

Tao WU;Bifeng SONG;Wenping SONG;Wenqing YANG;Dong XUE;Zhonghua HAN

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

中国航空学报（英文版）

[1]Tao WU;Bifeng SONG;Wenping SONG;Wenqing YANG;Dong XUE;Zhonghua HAN-.Lift performance enhancement for flapping airfoils by considering surging motion)[J].中国航空学报（英文版）,2022(09):194-207

airfoils,E377m

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