Aerodynamic Evaluation of Flapping Wings with Leading-Edge Twisting

Abstract

The purpose of the current study is to emphasize the characteristics and phenomena of leading-edge twisting in flapping wing vehicles. A fused deposition modeling (FDM) 3D printing method is applied to develop the flapping mechanisms with bevel gears to achieve the leading-edge twisting. Three flapping mechanisms were developed, including simple flapping only (type-A1: normal servo mechanism), flapping with continuous leading-edge twisting (type-B: servo-bevel gear mechanism), and flapping with restricted leading-edge twisting via mechanical stoppers (type-B1: servo-bevel gear mechanism with adjustable mechanical stoppers). Utilizing a low-speed wind tunnel, the aerodynamic performances of these mechanisms are examined by extracting their lift and net thrust forces. The wind tunnel testing data showed that the flapping with restricted leading-edge twisting via mechanical stoppers (type-B1) showed better performance than the simple flapping (type-A1) by 32.9%, and also better performance than the flapping with continuous leading-edge twisting (type-B) by 64%. Next, MATLAB software was used to create the 3D wing surfaces from the instantaneous stereophotography Kwon3D trajectories to fully sketch the leading-edge twisting features. The 2D airfoil cut sections at the mean aerodynamic chord at different stroke moments depict the instantaneous angles of attack to justify the aforementioned wind tunnel testing data and it was verified using a theoretical trajectory model. This comprehensive study using the 3D-printed mechanisms is well suited for the quantitative evaluation of the lift contribution from leading-edge twisting.

The Lift Effects of Chordwise Wing Deformation and Body Angle on Low-Speed Flying Butterflies

“…Experiments on PIV in biomimetic studies are often conducted on an object fixed at a particular point, such as a flapping mechanism [ 25 , 35 , 36 ] or an actual wing [ 18 , 33 , 37 ]. For analyses of the flow field of a real hovering insect, a living specimen is often fixed at a point [ 18 , 26 , 33 ].…”

“…The value of the settling velocity was of order 10 −3 -10 −4 , which was much smaller than the flow field velocity; the tracer particle was hence suitable for the experiment. Experiments on PIV in biomimetic studies are often conducted on an object fixed at a particular point, such as a flapping mechanism [25,35,36] or an actual wing [18,33,37]. For analyses of the flow field of a real hovering insect, a living specimen is often fixed at a point [18,26,33].…”

A Bibliometric Analysis of Flapping Wing Instrumentation

“…Alternative sensors utilize the same mounting methods as the ATI Nano 17, although some also opt to allow adjustable angles of attack [53,54]. Other sensors used include the ATI Mini 40 [55], ATI Gamma [56], F6D45 [57], Deltalab sensor [58], M3816BH [59], and other unspecified sensors [60].…”

“…To help track the motion of the wing, markers can be added to the wing to be better detected by the cameras. This can include strips of tape or lines [17,43]; markers on the roots, tips [34] and/or the spars [30,55]; and colored or reflective markers [48,54]. Alternatively, systems use a coating on the entire wing to allow the full motion of the wing to be observed in imagery, such as in [69,70].…”