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Characterization of the vortex formation and evolution about a revolving wing using high-fidelity simulation

Garmann, Daniel J

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2013, PhD, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
A numerical study is conducted to examine the vortex structure and aerodynamic loading about a revolving wing in quiescent flow. The high-fidelity, implicit large eddy simulation (ILES) technique is employed to simulate a revolving wing configuration consisting of a rectangular plate extended out half a chord from the rotational axis at a fixed geometric angle relative to this axis. Shortly after the onset of the motion, the rotating wing generates a coherent vortex system along the leading-edge. This vortex system remains attached throughout the motion for the range of Reynolds numbers explored despite the unsteadiness and vortex breakdown observed at higher Reynolds numbers. The average and instantaneous wing loading also increases with Reynolds number. At a fixed Reynolds number, the attachment of the leading-edge vortex (LEV) is shown to be insensitive to geometric orientation of the wing. Additionally, the flow structure and forcing generated by a purely translating wing is investigated and compared with that of the revolving wing. Similar features are present at the inception of the motion; however, the two flows evolve very differently for the remainder of the maneuver. The role of aspect ratio is also examined, and the span-wise evolution of the leading-edge vortex is analyzed. The mean lift and drag both increase with aspect ratio until the chord-wise growth of the leading-edge vortex becomes constrained by the trailing edge causing a saturation of the aerodynamic loads. Additional LEV substructures form with increased aspect ratio from the increase in local span-based Reynolds number. The genesis of these substructures has been traced to the eruption of secondary, wall-induced vorticity under the LEV that penetrates the LEV feeding sheet. The disrupted shear layer then rolls-up under self-induction to form discrete substructures. Vortex breakdown of the vortex core occurs around mid-span despite aspect ratio of the wing indicating that it does not correlate with the local span-based Reynolds number, but instead, is a result of the pressure gradient established between the root and tip of the wing. Very favorable comparisons of the computational solution with experimental measurements are provided through application of a new data-reduction technique used to accurately compare simulations and experiments of differing spatial resolutions.
Paul Orkwis, Ph.D. (Committee Chair)
Miguel Visbal, Ph.D. (Committee Member)
Shaaban Abdallah, Ph.D. (Committee Member)
Mark Turner, Sc.D. (Committee Member)
218 p.

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Citations

  • Garmann, D. J. (2013). Characterization of the vortex formation and evolution about a revolving wing using high-fidelity simulation [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367927773

    APA Style (7th edition)

  • Garmann, Daniel. Characterization of the vortex formation and evolution about a revolving wing using high-fidelity simulation. 2013. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367927773.

    MLA Style (8th edition)

  • Garmann, Daniel. "Characterization of the vortex formation and evolution about a revolving wing using high-fidelity simulation." Doctoral dissertation, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367927773

    Chicago Manual of Style (17th edition)