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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-517-2

5-6th Thermal and Fluids Engineering Conference (TFEC)
May, 26–28, 2021 , Virtual

DRAGONFLY-INSPIRED CORRUGATED FOIL FLIGHT DYNAMICS IN HEAVING MOTION ACROSS VARIOUS HEAVING FREQUENCIES

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DOI: 10.1615/TFEC2021.bbe.036712

Abstract

The corrugated wing cross-section significantly affects flight dynamics of a dragonfly. Therefore, a heaving corrugated foil inspired from a dragonfly wing, is being numerically studied in this work. The objective is to understand the effect of heaving frequency on the lift and thrust coefficients of the bio-inspired corrugated foil, thereby unravelling the secret of dragonfly flight at various heaving frequencies of its wing. Two-dimensional numerical simulations are performed over a wide range of reduced frequencies, K = 0.09 - 2.63, covering the entire range of actual dragonfly wing's flapping frequency. The chord-based Reynolds number is 10,000 and a nondimensional heaving amplitude (normalized by the chord length) is 0.15. The results are compared against a smooth heaving NACA (National Advisory Committee for Aeronautics) 0012 foil. Over the studied heaving frequency range for the corrugated foil, at K = 0.09 net drag on the corrugated foil is observed which transitions into a net thrust at K = 1.76 and thereafter a monotonic increase in thrust is observed up to the largest studied reduced frequency. The drag to thrust transition is earlier for NACA0012 foil compared to corrugated foil because of lower leading-edge vortex strength and further at any studied K, NACA0012 foil is better in terms of thrust generation. The present study helps understand the influence of varying heaving frequency in the flight dynamics of dragonflies.