Effect of pre-strain and excess length on unsteady fluid–structure interactions of membrane airfoils

Abstract Aerodynamic characteristics of two-dimensional membrane airfoils were experimentally investigated in a wind tunnel. The effects of the membrane pre-strain and excess length on the unsteady aspects of the fluid–structure interaction were studied. The deformation of the membrane as a function of angle of attack and free-stream velocity was measured using a high-speed camera. These measurements were complemented by the measurements of unsteady velocity field with a high frame-rate Particle Image Velocimetry (PIV) system as well as smoke visualization. Membrane airfoils with excess length exhibit higher vibration modes, earlier roll-up of vortices, and smaller separated flow regions, whereas the membranes with pre-strain generally behave more similarly to a rigid airfoil. Measured frequencies of the membrane vibrations suggest a possible coupling with the wake instabilities at high incidences for all airfoils.

[1]  Raphael T. Haftka,et al.  Shape Optimization of a Membrane Wing for Micro Air Vehicles , 2003 .

[2]  Peter Ifju,et al.  Flexible-wing-based Micro Air Vehicles , 2002 .

[3]  P. Jackson,et al.  NUMERICAL ANALYSIS OF THREE-DIMENSIONAL ELASTIC MEMBRANE WINGS , 1987 .

[4]  Kenneth Breuer,et al.  Aeromechanics of Membrane Wings with Implications for Animal Flight ArnoldSong, ∗ XiaodongTian, † EmilyIsraeli, ‡ RicardoGalvao, § KristinBishop, ¶ SharonSwartz, ∗∗ , 2008 .

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

[6]  Miguel R. Visbal,et al.  Unsteady aerodynamics of nonslender delta wings , 2005 .

[7]  P. Vlachos,et al.  Flow Control of a Sharp-Edged Airfoil , 2001 .

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

[9]  B. G. Newman,et al.  Aerodynamic theory for membranes and sails , 1987 .

[10]  F. C. Johansen,et al.  On the Flow of Air behind an Inclined Flat Plate of Infinite Span , 1927 .

[11]  Kenneth S. Breuer,et al.  Dynamics of a Compliant Membrane as Related to Mammalian Flight , 2007 .

[12]  Wei Shyy,et al.  Flapping and flexible wings for biological and micro air vehicles , 1999 .

[13]  Jiezhi Wu,et al.  Post-stall flow control on an airfoil by local unsteady forcing , 1998, Journal of Fluid Mechanics.

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

[15]  Peter J. Attar,et al.  Implicit LES Simulations of a Low Reynolds Number Flexible Membrane Wing Airfoil , 2009 .

[16]  Ismet Gursul,et al.  Unsteady Aerodynamics of Membrane Airfoils , 2008 .

[17]  Yongsheng Lian,et al.  Three-Dimensional Fluid-Structure Interactions of a Membrane Wing for Micro Air Vehicle Applications , 2003 .

[18]  R. Gordnier.  High Fidelity Computational Simulation of a Membrane Wing Airfoil , 2008 .

[19]  K. Breuer,et al.  The Aerodynamics of Compliant Membrane Wings Modeled on Mammalian Flight Mechanics , 2006 .

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

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

[22]  Chris J. K. Williams,et al.  Numerical simulation of viscous flow interaction with an elastic membrane , 2008 .

[23]  H. C. Curtiss,et al.  Aerodynamic properties of a two-dimensional inextensible flexible airfoil , 1984 .

[24]  Ismet Gursul,et al.  Lift enhancement over flexible nonslender delta wings , 2007 .

[25]  B. G. Newman,et al.  Two-dimensional impervious sails: experimental results compared with theory , 1984, Journal of Fluid Mechanics.

[26]  M. P. Païdoussis,et al.  The stability of two-dimensional membranes in streaming flow , 1991 .

[27]  Wei Shyy,et al.  Computational model of flexible membrane wings in steady laminar flow , 1995 .

[28]  J. Rayner,et al.  Ecological Morphology and Flight in Bats (Mammalia; Chiroptera): Wing Adaptations, Flight Performance, Foraging Strategy and Echolocation , 1987 .