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Pitch Ramp Maneuvers as a Prototypical Case in Low Reynolds Number Unsteady Aerodynamics

OL Michael, Kenneth Granlund, Luis Bernal


We revisit the classical problem of a flat plate in linear pitch ramp, with and without streamwise deceleration, motivated by the application of perching Micro Air Vehicles. Lift and drag coefficients can reach values 2-4 higher than quasi-steady maxima, depending on pitch rate. Streamwise deceleration causes increase in peak force coefficients, but has little effect at low and moderate angle of attack. Peak lift coefficient is seen to correlate with the
saturation of the leading edge vortex and its subsequent shedding. Comparison between 2D and aspect ratio 2.0 plates comports with quasi-steady theory.

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Carruthers, A.C. Thomas, A.L.R., and Taylor, G.K. “Automatic Aeroelastic Devices in the Wings of a Steppe Eagle Aquila Nipalensis”, Journal of Experimental Biology, Vol. 210, 2007.

Reich, G., and Wojnar, O., and Albertani, R. “Aerodynamic Performance of a Notional Perching MAV Design”. AIAA 2009-0063.

Graham, G.M., and Strickland, J.H. “An Experimental Investigation of an Airfoil Pitching at Moderate to High Rates to Large Angles of Attack”.

AIAA 1986-0008.

Ol, M., Bernal, L., Kang, C.-K., and Shyy, W. "Shallow and Deep Dynamic Stall for Flapping Low Reynolds Number Airfoils". Experiments in Fluids, Vol. 46, Issue 5, pp. 883-901, May 2009.

Eldredge, J.D., Toomey, J., and Medina, A. “On the Roles of Chord-Wise Flexibility in a Flapping Wing with Hovering Kinematics”. Journal of Fluid Mechanics, Vol. 659, pp. 94-115, Sept. 2010.

Koochesfahani, M.M., and Smiljanovski, V. “Initial Acceleration Effects on Flow Evolution around Airfoils Pitching to High Angle of Attack.” AIAA

Journal, Vol. 31, No. 8, pp. 1529-1531, 1993.

Yilmaz, T. and Rockwell, D. 2010 “Threedimensional Flow Structure on a Maneuvering Wing” Experiments in Fluids, vol. 48, pp. 539-544.

Kaplan, S., Altman, A., and Ol, M. “Wake Vorticity Measurements for Low Aspect Ratio Wings at Low Reynolds Number”. AIAA Journal of. Aircraft, Vol. 44, No. 1, pp. 241-251, 2007.

Hoerner, S.F. Fluid-Dynamic Drag. Hoerner Fluid Dynamics, PO Box 342, Brick Town, NJ, 08723, 1965.

Dabiri, J.O. “Optimal Vortex Formation as a Unifying Principle in Biological Propulsion”. Annual Reviews in Fluid Mechanics, Vol. 41, pp. 17-33, 2009.

Smits, A.J., and Lim, T.T. Flow Visualization: Techniques and Examples. Imperial College Press, 2000.

Birch, J.M., Dickson, W.B., and Dickinson, M.H. "Force Production and Flow Structure of the Leading Edge Vortex on Flapping Wings at High and Llow Reynolds Numbers". Journal of Experimental Biology, Vol. 207, pp. 1063-1072, 2004.



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