The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's performance with undulating leading edge modification

Nikan Rostamzadeh, Kristy Hansen, Richard Kelso, Bassam Dally

    Research output: Contribution to journalArticlepeer-review

    76 Citations (Scopus)

    Abstract

    Wings with tubercles have been shown to display advantageous loading behavior at high attack angles compared to their unmodified counterparts. In an earlier study by the authors, it was shown that an undulating leading-edge configuration, including but not limited to a tubercled model, induces a cyclic variation in circulation along the span that gives rise to the formation of counter-rotating streamwise vortices. While the aerodynamic benefits of full-span tubercled wings have been associated with the presence of such vortices, their formation mechanism and influence on wing performance are still in question. In the present work, experimental and numerical tests were conducted to further investigate the effect of tubercles on the flow structure over full-span modified wings based on the NACA 0021 profile, in the transitional flow regime. It is found that a skew-induced mechanism accounts for the formation of streamwise vortices whose development is accompanied by flow separation in delta-shaped regions near the trailing edge. The presence of vortices is detrimental to the performance of full-span wings pre-stall, however renders benefits post-stall as demonstrated by wind tunnel pressure measurement tests. Finally, primary and secondary vortices are identified post-stall that produce an enhanced momentum transfer effect that reduces flow separation, thus increasing the generated amount of lift.

    Original languageEnglish
    Article number107101
    Pages (from-to)1-22
    Number of pages22
    JournalPhysics of Fluids
    Volume26
    Issue number10
    DOIs
    Publication statusPublished - 6 Oct 2014

    Fingerprint

    Dive into the research topics of 'The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's performance with undulating leading edge modification'. Together they form a unique fingerprint.

    Cite this