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Transient force generation during impulsive rotation of wall-mounted panels

  • Alexis Pierides (a1), Amir Elzawawy (a1) and Yiannis Andreopoulos (a1)

Abstract

Square and triangular shape actuator panels mounted on the wall of a wind tunnel beneath an air flow have been impulsively rotated with an angular velocity between 3 and $26~\mathrm{rad} ~{\mathrm{s} }^{- 1} $ . A custom-designed balance was used to measure the time-dependent lift and drag forces during the deployment of the actuator, the position of which was monitored by a digital encoder. The measured forces have been compensated for inertia effects which are significant. The results indicated that all lift and drag force coefficients during the transient deployment are different than the corresponding coefficients under stationary conditions at the same deployment angle. It was found that these dynamic effects are augmented with increasing velocity ratio $\mathit{Str}$ . The square actuator was found to have better aerodynamic performance than the triangular ones. Additional experiments within different boundary layers reveal that the generated unsteady forces on the moving panels are affected by the characteristics of the incoming boundary layers. The results showed that the thinner the boundary layer is the higher the forces are. Time-resolved flow visualization studies indicated that during the deployment of the panel the upstream turbulent boundary layer structures and the free stream fluid are decelerated and squeezed in the longitudinal direction as they approach the moving plate. A very thin and highly sheared wall layer develops over the moving panel, it generates a substantial amount of vorticity and it subsequently separates from the three edges of the panel to form a large-scale ring-like vortical structure which is responsible for the transient augmentation of the aerodynamic forces. This structure consists of wrapped around separated shear layers which contain pockets of compressed eddies and free stream fluid originated in the upstream incoming boundary layer and free stream. A horseshoe vortex starts to form over the moving plate and during the final stages of deployment it has been moved upstream while the incoming boundary layer turbulent structures are pushed and diverted upwards.

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Corresponding author

Email address for correspondence: amir.elzawawy@vaughn.edu

References

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Agui, J. H. & Andreopoulos, J. 1992 Experimental investigation of a three-dimensional boundary layer flow in the vicinity of an upright wall mounted cylinder. Trans. ASME J. Fluids Engng 114 (4), 566576.
Akaydin, D. H., Elvin, N. & Andreopoulos, Y. 2010 Wake of a cylinder: a paradigm for energy harvesting with piezoelectric materials. Exp. Fluids 49 (1), 291304.
Anderson, J. M., Streitlien, K., Barrett, D. S. & Triantafyllou, M. S. 1998 Oscillating foils of high propulsive efficiency. J. Fluid Mech. 360, 4172.
Andreopoulos, J. & Agui, J. 1996 Wall vorticity flux dynamics in a two-dimensional turbulent boundary layer. J. Fluid Mech. 309, 4584.
Birch, J. M. & Dickinson, M. H. 2001 Spanwise flow and the attachment of the leading-edge vortex on insect wings. Nature 412 (6848), 729733.
Borazjani, I. & Sotiropoulos, F. 2010 On the role of form and kinematics on the hydrodynamics of body/caudal fin swimming. J. Expl Biol. 213, 89107.
Buckholtz, J. H. J. & Smits, A. J. 2006 On the evolution of the wake structure produced by a low-aspect-ratio pitching panel. J. Fluid Mech. 546, 433443.
Buckholtz, J. H. J. & Smits, A. J. 2008 The wake structure and thrust performance of a rigid low-aspect-ratio pitching panel. J. Fluid Mech. 603, 331365.
Dickinson, M. H., Lehmann, F. O. & Sane, S. P. 1999 Wing rotation and the aerodynamic basics of insect flight. Science 284, 19541960.
Dong, S., Karniadakis, G. E., Ekmekci, A. & Rockwell, D. 2006 A combined DNS-PIV study of the turbulent near wake. J. Fluid Mech. 569, 185207.
von Ellenrieder, K. D., Parker, K. & Soria, J. 2003 Flow structures behind a heaving and pitching finite-span wing. J. Fluid Mech. 490, 129138.
Ellington, C. P. 1984 The aerodynamics of hovering insect flight. II. Morphological parameters. Phil. Trans. R. Soc. Lond. 305, 1740.
Ellington, C. P., van den Berg, C., Willmott, A. P. & Thomas, A. L. R. 1996 Leading-edge vortices in insect flight. Nature 384 (6610), 626630.
Elzawawy, A. 2012 Time resolved particle image velocimetry techniques with continuous wave laser and their application to transient flows. PhD thesis, The City University of New York.
Freymuth, P. 1988 Propulsive vortical signature of plunging and pitching aerofoils. AIAA J. 23, 881883.
Green, M. A. & Smits, A. J. 2008 Effects of three-dimensionality on thrust production by a pitching panel. J. Fluid Mech. 615, 211220.
Ho, C. H. & Tai, Y.-C. 1998 Micro-electro-mechanical systems (MEMS) and fluid flows. Annu. Rev. Fluid. Mech. 30, 579612.
Ho, S., Nassefa, H., Pornsin-Sirirak, N., Tai, Y.-C. & Ho, C.-M. 2003 Unsteady aerodynamics and flow control for flapping wing flyers. Prog. Aeronaut. Sci. 39, 635681.
Kim, D. & Gharib, M. 2010 Experimental study of three-dimensional vortex structures in translating and rotating plates. Exp. Fluids 49 (1), 329339.
Koumoutsakos, P. & Shiels, D. 1996 Simulations of the viscous flow normal to an impulsively started and uniformly accelerated flat plate. J. Fluid Mech. 328, 177227.
Maxworthy, T. 1981 The fluid-dynamics of insect flight. Annu. Rev. Fluid Mech. (13), 329350.
Paik, J., Escauriaza, C. & Sotiropoulos, F. 2007 On the bimodal dynamics of the turbulent horseshoe vortex system in a wing-body junction. Phys. Fluids 19, 045107.
Pierides, A. 2011 An experimental study on the characteristics of transient deployment of hinged wing actuators within a boundary layer. PhD thesis, The City University of New York.
Ringuette, M. J., Milano, M. & Gharib, M. 2007 Role of tip vortex in the force generation of low-aspect-ratio normal flat plates. J. Fluid Mech. 581, 453468.
Sarpkaya, T & Kline, H. K. 1982 Impulsively-started flow about four types of bluff body. Trans. ASME I: J. Fluids Engng 104, 207213.
Suryadi, A., Ishil, T. & Obl, S. 2010 Stereo PIV measurement of infinite, flapping rigid plate in hovering condition. Exp. Fluids 49 (2), 447460.
Taira, K., Dickson, W. B, Colonious, T., Dickinson, M. H. & Rowley, C. W. 2007 Unsteadiness in a flow over a flat plate at angle-of-attack at low Reynolds numbers, AIAA-65342 conference paper.
Triantafyllou, M. S., Techet, A. H., Zhu, Q., Beal, D. N., Hover, F. S. & Yue, D. K. P. 2003 Vorticity control in fish-like propulsion and control. J. Integ. Comp. Biol 42, 10261031.
Triantafyllou, M. S., Triantafyllou, G. S. & Gopalkrishnan, R. 1991 Wake mechanics for thrust generation in oscillating foils. Phys. Fluids A 3 (12), 28352837.
Vikestad, K., Vandiver, J. K. & Larsen, C. M. 2000 Added mass and oscillation frequency for a circular cylinder subjected to vortex-induced vibrations and external disturbance. J. Fluids Struct. 14, 10711088.
Wang, Z. J. 2005 Dissecting insect flight. Annu. Rev. Fluid Mech. 37, 183198.
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Transient force generation during impulsive rotation of wall-mounted panels

  • Alexis Pierides (a1), Amir Elzawawy (a1) and Yiannis Andreopoulos (a1)

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