The present work investigated how forcing the boundary layer to transition prematurely to a turbulent state on the suction surface of a single-element wing operating in ground effect affected the forces and surface flow structures. The forces produced and the trailing-edge separation position were shown to be dependent on the trip location. Tripping the boundary layer at locations between 0.1c and 0.5c was shown to reduce overall downforce and drag, but delay the onset of the force-reduction region so that the wing generated more downforce at low ground clearances. This was shown through numerical and experimental methods to be a result of the trips bypassing the formation of a laminar separation bubble in the pressure-recovery region. This negated the bubble's force-enhancement mechanism, which is to increase effective camber, and reduced bubble pressure drag; hence the decreases in downforce and drag being observed. Traihng-edge separation, which caused an effective de-cambering at the trailing edge to reduce circulation, was observed in forced-transition tests. The separation point and trip location had a relationship in which an earlier trip caused earlier separation. This resulted in an almost linear reduction in downforce and increase in drag as the trip was moved upstream. The study highlighted the importance of correct placement of boundary-layer trips, due to the large change in both force production and separation point with different trip locations, in order to achieve accurate representation of a racing car in a wind tunnel. Despite roughness-type trips being capable of fixing transition to the earlier location which would occur at full-scale testing, the occurrence of traihng-edge separation and elimination of the separation bubble are not representative of that expected at full scale.


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    Titel :

    Investigation of forcing boundary layer transition on a single-element inverted wing in ground effect


    Beteiligte:
    Roberts, L.S. (Autor:in) / Correia, J. (Autor:in) / Finnis, M.V. (Autor:in) / Knowles, K. (Autor:in)


    Erscheinungsdatum :

    2014


    Format / Umfang :

    13 Seiten, Bilder, 20 Quellen




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    Forcing Boundary-Layer Transition on an Inverted Airfoil in Ground Effect

    Roberts, L. S. / Finnis, M. V. / Knowles, K. et al. | AIAA | 2017



    Forcing Boundary-Layer Transition on an Inverted Airfoil in Ground Effect at Varying Incidence

    Roberts, Luke S. / Finnis, Mark / Knowles, Kevin et al. | AIAA | 2016


    Forcing Boundary-Layer Transition on an Inverted Airfoil in Ground Effect at Varying Incidence (AIAA 2016-3724)

    Roberts, Luke S. / Finnis, Mark / Knowles, Kevin et al. | British Library Conference Proceedings | 2016