Brown University School of Engineering

Fluids Seminar: The Role of Vortex Lift on Flapping Wings

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Tuesday, May 06, 2014 3:00pm - 4:00pm

Professor Anya Jones University of Maryland College Park, MD The Role of Vortex Lift on Flapping Wings The lift produced by an entomological flapping wing is investigated via simplified models of the wing kinematics, with a focus on near-impulsively started rectilinear and rotational motions. Force and velocity field measurements are examined in parallel with flow visualization to identify the sources of lift, the relative importance of these contributions, and the time-scales over which they persist. Experiments were performed in water tanks over a large parameter space, including variations in incidence angle, acceleration, flexibility and camber, and planform shape. Acceleration was found to affect the formation and trajectory of the leading edge vortex, but had little effect on the force history at long convective times. Classical aerodynamic theories were found to be a good approximation of the unsteady lift force near the start of a rectilinear surging wing motion at high incidence angle. However, after the initial lift transient, recovery to the classical results of thin airfoil theory required ~10+ convective times.