A computational study is conducted on thin flat plates to simulate flows of Reynolds numbers at 10 4 to provide understanding and guidance for micro air vehicles and other low-Reynolds-number airfoil designs. A synergistic effort between experiments and validated and computational fluid dynamics (CFD) tools were used as part of this study. The CFD tool used in this study is an established Reynolds-averaged Navier–Stokes (RANS) solver with a Spalart–Allmaras turbulence model and a correlation-based laminar–turbulent boundary-layer transition model. The computational method was validated against experimental data for flat plates under steady and unsteady kinematic conditions. The objective of the study was to understand unsteady characteristics of a thin flat plate undergoing harmonic pitching (no plunging) around the quarter chord under incompressible flow conditions. Pitching amplitudes were limited to 10 deg to ensure there was no effect of dynamic stall. The focus of this study is to characterize unsteady aerodynamics based on reduced frequency, which was varied between 0.005, 0.05, and 0.5. The unsteady condition of 0.05 was compared against experiments, 2-D RANS, and 3-D hybrid RANS/large-eddy simulation formulations. It was observed that the lift characteristics were reasonably well predicted by the CFD tools when compared to experimental observations. At a reduced frequency of 0.05 , the pitching motion causes an apparent stabilization of vortices resulting in higher oscillatory lift amplitude than the static value. The 3-D RANS better predicted the pitching-moment characteristics compared to the 2-D RANS, attributed to the breakdown of the leading-edge vortex. It was observed that, although thinner flat-plate airfoils have a higher maximum lift coefficient compared to the thicker NACA 0012, they also produce higher instantaneous pitching moment.


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    Titel :

    Unsteady Aerodynamic Characteristics of Pitching Flat Plates at Low Reynolds Numbers


    Beteiligte:

    Erschienen in:

    Journal of Aircraft ; 58 , 4 ; 917-934


    Erscheinungsdatum :

    2021-02-08


    Format / Umfang :

    18 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch




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    Hart, A. / Ukeiley, L. / American Institute of Aeronautics and Astronautics | British Library Conference Proceedings | 2010





    UNSTEADY FORCE GENERATION AND VORTEX DYNAMICS OF PITCHING AND PLUNGING FLAT PLATES AT LOW REYNOLDS NUMBER

    Baik, Y. / Bernal, L. / Shyy, W. et al. | British Library Conference Proceedings | 2011