The aerodynamic properties of a NACA 0012 airfoil, both stationary and unsteady, in ground effect (for nondimensional ground clearance h/c ≤ 60%) were investigated experimentally at Re = 98,000. For the stationary airfoil, the ground proximity led to a reduced (or enhanced) lift and an increased nose-up (or nose-down) pitching moment for α < 6° (or α > 6°). The drag was, however, always increased in ground effect. For the oscillating airfoil, a substantial change in the aerodynamic loadings, especially during downstroke, was observed for h/c ≤ 30%, leading to a greatly reduced Cl-hysteresis compared to the baseline airfoil. As the case of the stationary airfoil, the lift increase was mainly caused by the RAM pressure effect, but to a greater extent. The dynamic-stall vortex was also weakened and broke down earlier with reducing h/c, rendering an enlarged separated flow compared to the baseline airfoil. The results are of importance in understanding the ground effect on an unsteady airfoil.


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    Title :

    Impact of ground proximity on the aerodynamic properties of an unsteady airfoil


    Contributors:
    Lee, T (author) / Majeed, A (author) / Siddiqui, B (author) / Tremblay-Dionne, V (author)


    Publication date :

    2018-08-01


    Size :

    17 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English





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