Trailing-edge scalloping effect on flat-plate membrane wing performance

Abstract This investigation studies the effect of trailing-edge scalloping on the lift and drag force coefficients of flat, membrane wings that vibrate at low Reynolds numbers ( 61 , 000 ). A series of rigid, flat plate frames with moderate aspect ratio and repeating membrane cell structure were studied and compared to a rigid plate and a rigid scalloped plate. Lift and drag measurements were acquired using an external force-balance; flow fluctuation measurements were captured with a hot-wire. Results showed that the size and aspect ratio of the latex cell had a greater impact on lift than scalloping and that scalloping had a greater effect on drag than the cell aspect ratio. Compared to the solid wings, the membrane wings exhibited higher lift and drag coefficients, likely due to both effective cambering and dynamic interaction with the free shear layer. While trailing-edge scalloping decreased both the lift and drag coefficients relative to no scalloping, the greater effect was on drag, thus, increasing aerodynamic efficiency. The maximum lift-to-drag ratio was attained for a 25% scallop with a repeating cell aspect ratio of one. A unique nondimensional scaling of the membrane vibration peak frequency is also presented.

[1]  Ismet Gursul,et al.  Unsteady fluid–structure interactions of membrane airfoils at low Reynolds numbers , 2009 .

[2]  Anthony D. Lucey,et al.  Progress on the Use of Compliant Walls for Laminar-Flow Control , 2001 .

[3]  Chih-Ming Ho,et al.  Perturbed Free Shear Layers , 1984 .

[4]  J. Hubner,et al.  A Study of the Wake Characteristics for Membrane Flat and Cambered Plates , 2008 .

[5]  E. Laitone.  Wind tunnel tests of wings at Reynolds numbers below 70 000 , 1997 .

[6]  A. Roshko.  On the drag and shedding frequency of two-dimensional bluff bodies , 1954 .

[7]  Paul Seide,et al.  Large deflections of rectangular membranes under uniform pressure , 1977 .

[8]  Hui Hu,et al.  Flexible-Membrane Airfoils at Low Reynolds Numbers , 2008 .

[9]  Mohamed Gad-el-Hak,et al.  The discrete vortices from a delta wing , 1985 .

[10]  Peter J. Attar,et al.  Experimental Characterization of Limit Cycle Oscillations in Membrane Wing Micro Air Vehicles , 2010 .

[11]  Sundeep Vijay Ravande.  Drag Reduction of Natural Laminar Flow Airfoils with a Flexible Surface Deturbulator , 2006 .

[12]  W. Shyy,et al.  Study of Adaptive Shape Airfoils at Low Reynolds Number in Oscillatory Flows , 1997 .

[13]  Peter Ifju,et al.  Wind Tunnel Testing of Load-Alleviating Membrane Wings at Low Reynolds Numbers , 2009 .

[14]  W. Shyy,et al.  Computation of aerodynamic coefficients for a flexible membrane airfoil in turbulent flow: A comparison with classical theory , 1996 .

[15]  David J. Willis,et al.  Wing structure and the aerodynamic basis of flight in bats , 2007 .

[16]  C. Knisely.  STROUHAL NUMBERS OF RECTANGULAR CYLINDERS AT INCIDENCE: A REVIEW AND NEW DATA , 1990 .

[17]  F. H. Abernathy.  Flow Over an Inclined Plate , 1962 .

[18]  Peter Ifju,et al.  Effects of Membrane Vibration on the Flow Field Surrounding Flat-Plate Membrane Airfoils , 2011 .

[19]  Thomas J. Mueller,et al.  Low Reynolds Number Aerodynamics of Low-Aspect-Ratio, Thin/Flat/Cambered-Plate Wings , 2000 .

[20]  W. Shyy,et al.  Aerodynamics of Low Reynolds Number Flyers , 2007 .

[21]  Peter Ifju,et al.  5 Flexible-Wing Micro Air Vehicles , 2006 .

[22]  Barnes W. McCormick,et al.  Aerodynamics, Aeronautics and Flight Mechanics , 1979 .

[23]  Sergey V Shkarayev,et al.  Introduction to the Design of Fixed-Wing Micro Air Vehicles: Including Three Case Studies , 2007 .

[24]  Kenneth S. Breuer,et al.  The Aero-Mechanics of Low Aspect Ratio Compliant Membrane Wings, with Applications to Animal Flight , 2008 .

[25]  Bret Stanford,et al.  Aerodynamic Coefficients and Deformation Measurements on Flexible Micro Air Vehicle Wings , 2007 .