Effect Of Wing Flexibility Research Articles

Numerical simulation of a flapping four-wing micro-aerial vehicle

A three-dimensional numerical simulation of a four-wing (two wings on each side, one on top of another) flapping micro-aerial vehicle (FMAV), known as the Delfly micro, is performed using an immersed boundary method Navier–Stokes finite volume solver at Reynolds numbers of 5500 (forward flight condition). The objective of the present investigation is to gain an insight to the aerodynamics of flapping wing biplane configuration, by making an analysis on a geometry that is simplified, yet captures the major aspects of the wing behavior. The fractional step method is used to solve the Navier–Stokes equations. Results show that in comparison to the Delfly II flapping kinematics (a similar FMAV configuration but smaller flapping stroke angles), the Delfly-Micro flapping kinematics provides more thrust while maintaining the same efficiency. The Delfly-Micro biplane configuration generates more lift than expected when the inclination angle increases, due to the formation of a uniform leading edge vortex. Estimates of the lift produced in the forward flight conditions confirm that in the current design, the MAV is able to sustain forward flight. The potential effect of wing flexibility on the aerodynamic performance in the biplane configuration context is investigated through prescribed flexibility in the simulations. Increasing the wing׳ spanwise flexibility increases thrust but increasing chordwise flexibility causes thrust to first increase and then decrease. Moreover, combining both spanwise and chordwise flexibility outperforms cases with only either spanwise or chordwise flexibility.

Wing flexibility enhances load-lifting capacity in bumblebees

The effect of wing flexibility on aerodynamic force production has emerged as a central question in insect flight research. However, physical and computational models have yielded conflicting results regarding whether wing deformations enhance or diminish flight forces. By experimentally stiffening the wings of live bumblebees, we demonstrate that wing flexibility affects aerodynamic force production in a natural behavioural context. Bumblebee wings were artificially stiffened in vivo by applying a micro-splint to a single flexible vein joint, and the bees were subjected to load-lifting tests. Bees with stiffened wings showed an 8.6 per cent reduction in maximum vertical aerodynamic force production, which cannot be accounted for by changes in gross wing kinematics, as stroke amplitude and flapping frequency were unchanged. Our results reveal that flexible wing design and the resulting passive deformations enhance vertical force production and load-lifting capacity in bumblebees, locomotory traits with important ecological implications.

Force production and asymmetric deformation of a flexible flapping wing in forward flight

Insect wings usually are flexible and deform significantly under the combined inertial and aerodynamic load. To study the effect of wing flexibility on both lift and thrust production in forward flight, a two-dimensional numerical simulation is employed to compute the fluid–structure interaction of an elastic wing section translating in an inclined stroke plane while pitching around its leading ledge. The effects of the wing stiffness, mass ratio, stroke plane angle, and flight speed are considered. The results show that the passive pitching due to wing deformation can significantly increase thrust while either maintaining lift at the same level or increasing it simultaneously. Another important finding is that even though the wing structure and actuation kinematics are symmetric, chordwise deformation of the wing shows a larger magnitude during upstroke than during downstroke. The asymmetry is more pronounced when the wing has a low mass ratio so that the fluid-induced deformation is significant. Such an aerodynamic cause may serve as an additional mechanism for the asymmetric deformation pattern observed in real insects.

Wing Flexibility Effects in Clap-and-Fling

The work explores the use of time-resolved tomographic PIV measurements to study a flapping-wing model, the related vortex generation mechanisms and the effect of wing flexibility on the clap-and-fling movement in particular. An experimental setup is designed and realized in a water tank by use of a single wing model and a mirror plate to simulate the wing interaction that is involved in clap-and-fling motion. The wing model used in the experiments has the same planform with the DelFly II wings and consists of a rigid leading edge and an isotropic polyester film. The thickness of the polyester film was changed in order to investigate the influence of flexibility. A similarity analysis based on the two-dimensional dynamic beam equation was performed to compare aeroelastic characteristics of flapping-wing motion in-air and in-water conditions. Based on the experimental results, the evolution of vortical structures during the clap-and-peel motion is explained. The general effects of flexibility on vortex formations and interactions are discussed. It was observed that the flexibility affects the behavior and orientation of the vortices in relation to the deformation of the wing and interaction with the mirror plate.

Effect of Flexural and Torsional Wing Flexibility on Lift Generation in Hoverfly Flight

The effect of wing flexibility in hoverflies was investigated using an at-scale mechanical model. Unlike dynamically-scaled models, an at-scale model can include all phenomena related to motion and deformation of the wing during flapping. For this purpose, an at-scale polymer wing mimicking a hoverfly was fabricated using a custom micromolding process. The wing has venation and corrugation profiles which mimic those of a hoverfly wing and the measured flexural stiffness of the artificial wing is comparable to that of the natural wing. To emulate the torsional flexibility at the wing-body joint, a discrete flexure hinge was created. A range of flexure stiffnesses was chosen to match the torsional stiffness of pronation and supination in a hoverfly wing. The polymer wing was compared with a rigid, flat, carbon-fiber wing using a flapping mechanism driven by a piezoelectric actuator. Both wings exhibited passive rotation around the wing hinge; however, these rotations were reduced in the case of the compliant polymer wing due to chordwise deformations during flapping which caused a reduced effective angle of attack. Maximum lift was achieved when the stiffness of the hinge was similar to that of a hoverfly in both wing cases and the magnitude of measured lift is sufficient for hovering; the maximum lift achieved by the single polymer and carbon-fiber wings was 5.9 × 10(2)( )μN and 6.9 × 10(2)( )μN, respectively. These results suggest that hoverflies could exploit intrinsic compliances to generate desired motions of the wing and that, for the same flapping motions, a rigid wing could be more suitable for producing large lift.

Experimental and Numerical Fluid-Structure Analysis of Rigid and Flexible Flapping Airfoils

A combined experimental and computational study is presented for an airfoil undergoing a combined pitching and plunging motion at Reynolds number 100,000, where transition takes place along laminar separation bubbles. The numerical simulation approach addresses unsteady Reynolds-averaged Navier―Stokes solutions and covers transition prediction for unsteady mean flows. To study the effect of wing flexibility, the aerodynamic computational method is coupled with a structural solver using a Galerkin method. The numerical simulations are validated using high-resolution, phase-locked stereoscopic particle image velocimetry for one flapping case with a reduced frequency of k = 0.2. Hereby both a rigid and a flexible birdlike airfoil are investigated. The flow reveals strong unsteadiness resulting in moving laminar separation bubbles, both well captured by the numerical simulations performed in this study.

Effect of Wing Flexibility on Lift and Thrust Production in Flapping Flight

In bird and insect flight, wing deformation plays an important role in aerodynamic performance. The wing deformation is produced by neuromuscular control and/or by aeroelastic effects. The focus of the current study is to evaluate the effects of wing deformation by coupling a large-eddy simulation solver with a linear elastic membrane model. Different membrane prestresses are investigated to give a desired camber in response to the aerodynamic pressure. All simulations are carried out at Re = 10, 000 for forward flight with an advance ratio of 0.5. The results show that the camber introduced by a flexible wing increases the thrust and lift production considerably. An analysis of flow structure reveals that, for flexible wings, the leading-edge vortex stays attached on the top surface of the wing and glides along the camber and covers a major part of the wing, which results in high force production. On the other hand, for rigid wings, the leading-edge vortex lifts off from the surface resulting in lower force production. Further, introduction of the camber also increases the force component contributing to thrust, leading to a high thrust-to-lift ratio. In comparison to a rigid wing, a 40% increase in thrust is observed for the low-prestress case, which results in a camber of 0.25 chord. Further, the results also show that the wing with high spanwise prestress and low chordwise prestress offers better performance both in terms of force production and uniformity in the force-induced cambering.

Static aeroelastic analysis of a three-dimensional oblique wing

Requirements for the aeroelastic analyses of an oblique-wing aircraft have posed serious problems because available analysis programs cannot be applied to asymmetric configurations in the subsonic through the low supersonic speed range and the effects of the wing leading edge suction forces are completely disregarded. Therefore, a capability to perform static aeroelastic analyses of an oblique wing at arbitrary skew positions was developed based on the framework of the MSC/NASTRAN static aeroelastic analysis. By the means of DMAP alterations, a portion of the subsonic static aeroelastic analysis scheme was modified to insert an aerodynamic influence coefficient matrix created externally by the NASA Ames Research Center aerodynamic panel codes. The modified scheme can cover the subsonic as well as the supersonic range for both symmetric and asymmetric configurations. Static aeroelastic responses of the oblique wing are studied at two skew angles and, in particular, the capability to calculate three-dimensional camber effects on the aerodynamic properties of the wing is investigated. Various aerodynamic coefficients of the rigid oblique wing are computed for two Mach numbers, 0.7 and 1.4, and the angle of attack is varied from −5 through 15°. Also, the wing flexibility effects on the aerodynamic coefficients and the displacement are examined at a Mach number of 0.7 for a 45° swept wing.

Possible Effects of Wing Flexibility on the Aerodynamics of Pteranodon

Previous articleNext article No AccessPossible Effects of Wing Flexibility on the Aerodynamics of PteranodonA. D. Sneyd, M. S. Bundock, and D. ReidA. D. Sneyd Search for more articles by this author , M. S. Bundock Search for more articles by this author , and D. Reid Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 120, Number 4Oct., 1982 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/284005 Views: 8Total views on this site Citations: 14Citations are reported from Crossref Copyright 1982 The University of ChicagoPDF download Crossref reports the following articles citing this article:Colin Palmer Inferring the properties of the pterosaur wing membrane, Geological Society, London, Special Publications 455, no.11 (Feb 2017): 57–68.https://doi.org/10.1144/SP455.4A. V. Koroljov Pterosaur flight, Biology Bulletin Reviews 7, no.33 (Jun 2017): 179–228.https://doi.org/10.1134/S2079086417030045K.M. Middleton, L.T. English Challenges and advances in the study of pterosaur flight, Canadian Journal of Zoology 93, no.1212 (Dec 2015): 945–959.https://doi.org/10.1139/cjz-2013-0219Colin Palmer, Gareth Dyke Constraints on the wing morphology of pterosaurs, Proceedings of the Royal Society B: Biological Sciences 279, no.17311731 (Sep 2011): 1218–1224.https://doi.org/10.1098/rspb.2011.1529Colin Palmer, Gareth J. Dyke Biomechanics of the unique pterosaur pteroid, Proceedings of the Royal Society B: Biological Sciences 277, no.16841684 (Dec 2009): 1121–1127.https://doi.org/10.1098/rspb.2009.1899MATTHEW T. WILKINSON Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion, Zoological Journal of the Linnean Society 154, no.11 (Sep 2008): 27–69.https://doi.org/10.1111/j.1096-3642.2008.00409.xBret Stanford, Peter Ifju, Roberto Albertani, Wei Shyy Fixed membrane wings for micro air vehicles: Experimental characterization, numerical modeling, and tailoring, Progress in Aerospace Sciences 44, no.44 (May 2008): 258–294.https://doi.org/10.1016/j.paerosci.2008.03.001T. L. Hedrick, J. R. Usherwood, A. A. Biewener Low speed maneuvering flight of the rose-breasted cockatoo ( Eolophus roseicapillus ). II. Inertial and aerodynamic reorientation, Journal of Experimental Biology 210, no.1111 (Jun 2007): 1912–1924.https://doi.org/10.1242/jeb.002063ADRIAN L.R. THOMAS, GRAHAM K. TAYLOR Animal Flight Dynamics I. Stability in Gliding Flight, Journal of Theoretical Biology 212, no.33 (Oct 2001): 399–424.https://doi.org/10.1006/jtbi.2001.2387K Alexander, J Stevenson A test rig for kite performance measurement, Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 215, no.44 (Dec 2005): 595–598.https://doi.org/10.1243/0954405011518412R. McNEILL ALEXANDER Mechanics of fossil vertebrates, Journal of the Geological Society 146, no.11 (Jan 1989): 41–52.https://doi.org/10.1144/gsjgs.146.1.0041P. S. Jackson, G. W. Christie Numerical analysis of three-dimensional elastic membrane wings, AIAA Journal 25, no.55 (May 1987): 676–682.https://doi.org/10.2514/3.9682Barry G. Newman Aerodynamic theory for membranes and sails, Progress in Aerospace Sciences 24, no.11 (Jan 1987): 1–27.https://doi.org/10.1016/0376-0421(87)90005-4A. D. Sneyd Aerodynamic coefficients and longitudinal stability of sail aerofoils, Journal of Fluid Mechanics 149, no.-1-1 (Apr 2006): 127.https://doi.org/10.1017/S0022112084002573

Control Reversal Effects on Swept-Back Wings

SummaryAileron reversal effects on swept-back wings in general and elevon reversal effects on tailless swept-back wings in particular are discussed on a non-mathematical basis, attention being confined to the orthodox flap type of control. The main purpose of the paper is to convey in the simplest terms possible a clear physical picture of the conditions producing loss of control power, emphasis being naturally laid upon the part played by structural wing distortion. Certain qualitative features relating to the two phenomena are also discussed. As a general introduction to the discussion on aileron reversal effects, the definition of “aileron power” in relation to the actual dynamic condition of rolling is described at some length. For elevon reversal effects on tailless aircraft the effect of wing flexibility on both “elevon power” and on trim in steady symmetric flight is considered. With the descriptive treatment adopted the analysis is of necessity broad and general but is designed to appeal to those not too familiar with the subject. The results of certain calculations on a hypothetical wing, which may be of interest, are included. A mathematical analysis for the quantitative estimation of both aileron and elevon reversal effects is given in the Appendix.