Table of Contents
ISRN Mechanical Engineering
Volume 2011, Article ID 162687, 8 pages
http://dx.doi.org/10.5402/2011/162687
Research Article

Aerodynamics of Flapping Wing at Low Reynolds Numbers: Force Measurement and Flow Visualization

Unsteady Aerodynamics Laboratory, Department of Aerospace Engineering, IIT Kanpur 208016, India

Received 31 January 2011; Accepted 8 March 2011

Academic Editors: M. Ali and P. Zhang

Copyright Β© 2011 Abhijit Banerjee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Flow field of a butterfly mimicking flapping model with plan form of various shapes and butterfly-shaped wings is studied. The nature of the unsteady flow and embedded vortical structures are obtained at chord cross-sectional plane of the scaled wings to understand the dynamics of insect flapping flight. Flow visualization and PIV experiments are carried out for the better understanding of the flow field. The model being studied has a single degree of freedom of flapping. The wing flexibility adds another degree to a certain extent introducing feathering effect in the kinematics. The mechanisms that produce high lift and considerable thrust during the flapping motion are identified. The effect of the Reynolds number on the flapping flight is studied by varying the wing size and the flapping frequency. Force measurements are carried out to study the variations of lift forces in the Reynolds number (Re) range of 3000 to 7000. Force experiments are conducted both at zero and finite forward velocity in a wind tunnel. Flow visualization as well as PIV measurement is conducted only at zero forward velocity in a stagnant water tank and in air, respectively. The aim here is to measure the aerodynamic lift force and visualize the flow field and notice the difference with different Reynolds number (Re), and flapping frequency (f), and advance ratios ( 𝐽 = π‘ˆ ∞ / 2 πœ™ 𝑓 𝑅 ).