Fluid-structure interaction for aerodynamic performance evaluation of flapping wing with passive pitching motion

The aim of this study is to investigate the impact of locust-like wing flexibility which is modelled with Mylar and carbon fibre pultruded rods on aerodynamic performance. An in-house 3D Navier Stokes solver coupled with a structure solver has been used to evaluate passive pitching motion and aerodynamic performance. The study has focused on two effects which are variations in the diameter of root and spar distribution. All wings have been analysed for a prescribed flapping motion in a horizontal plane, with a peak-to-peak stroke amplitude of 120 degrees, flapping frequency of 25 Hz, and Reynolds number of 13,500. The flow has been assumed to be laminar, viscous, and incompressible. The diameter of the wing root segment attached to the leading edge has been varied to control the extent of the passive pitching motion. The effect of spar distribution on the aerodynamic performance of the flexible flapping wing has also been investigated. The results revealed that careful selection of wing root parameters and spars distribution can achieve a passive pitch angle with an amplitude of 45 degrees and the highest power economy of 1.26. Moreover, a comparison of the flexible wing with its rigid counterpart suggested that flexible wings modelled with a simple passive pitching mechanism can be an efficient solution for bio-inspired flapping-wing micro aerial vehicles.