For the mallard-inspired flapping wing air vehicle,two additional motion modes-spanwise bending and chordwise twisting are introduced based on rigid flapping.Four different equations describing these varied flapping paths were proposed,and their aerodynamic characteristics during low-speed flight were investigated.Firstly,we choose the NACA 6411 airfoil based on the shape of the mallard wing and modify its curvature and length,creating a flapping wing geometry through lofting.Afterwards,flapping wing flow field grid models are constructed using dynamic grid technology,which include three different flapping forms:rigid flapping,spanwise bending,and chordwise twisting.Finally,we use Fluent to conduct transient simulations,employing the pressure-coupled solver and the k-ω turbulence model,to obtain the aerodynamic characteristics at 2 m/s under various flapping patterns.The results demonstrate that during low-speed flight,the effects of asymmetric flapping,spanwise bending,and chordwise twisting all contribute to increased lift and reduced drag.The three flapping models proposed in this paper can increase the lift by 3.89%,14.78%,and 24.44%,respectively,compared to the traditional symmetric rigid flapping model.Among these,the combined bending and twisting flapping mode provides thrust that is sufficient to offset the aerodynamic drag during forward flight.
关键词
扑翼飞行器/微小型飞行器/仿生/动网格/柔性扑动/气动特性
Key words
Flapping Wing Air Vehicle/Micro Aerial Vehicle/Bionic/Dynamic Grid/Flexible Flapping/Aerodynamic Characteristics
维普
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