• Login
    View Item 
    •   DSpace@RPI Home
    • Rensselaer Libraries
    • RPI Theses Online (Complete)
    • View Item
    •   DSpace@RPI Home
    • Rensselaer Libraries
    • RPI Theses Online (Complete)
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Dynamic large eddy simulation of surging airfoils with moderate to large streamwise oscillations

    Author
    Kocher, Alexander W.
    View/Open
    178184_Kocher_rpi_0185N_11044.pdf (4.957Mb)
    Other Contributors
    Sahni, Onkar; Gandhi, Farhan; Oberai, Assad;
    Date Issued
    2017-05
    Subject
    Aeronautical engineering
    Degree
    MS;
    Terms of Use
    This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.;
    Metadata
    Show full item record
    URI
    https://hdl.handle.net/20.500.13015/1944
    Abstract
    Lift force is compared between experiments and LES. Overall, a good agreement is obtained for the lift force in all cases. Additionally, for all cases, flowfields from LES are examined at different phases of the surging cycle. For the moderate advance ratio cases, a similar flow pattern is observed between the two advance ratios and no distinct vortex is shed from the airfoil. However, in all three high advance ratio cases a distinct vortex is shed from the suction side near the geometric leading edge. This prominent leading-edge vortex (LEV) is shed as the minimum velocity is reached in the surging cycle and advects downstream in the horizontal direction with about the mean free-stream velocity. The relative shedding position of the LEV, with respect to the airfoil, varies significantly between the three high advance ratio cases. In the case with the highest advance ratio of 1.2, a reversed flow condition is present and the LEV crosses to be ahead of the (geometric) leading edge before sweeping over the airfoil.; A dynamic large eddy simulation (LES) based numerical investigation is carried out for flow over two surging airfoils with moderate to large streamwise oscillations. In each case, the airfoil is set at a fixed angle of attack and is subjected to a sinusoidal surging motion (i.e., in the streamwise direction). The amplitude of oscillation is characterized by the advance ratio of the blade section, which is defined by the ratio of the maximum relative velocity in excess of the mean relative velocity, or the freestream velocity, to the mean relative velocity. The relative airfoil velocity is defined with respect to the ambient fluid. In this study, the amplitude of the sinusoidal oscillations is varied within a moderate and high range. For the moderate range, a NACA 0018 airfoil at a mean Reynolds number of 300,000 and 4° angle of attack is considered. Two advance ratios of 0.34 and 0.51 are considered to match with the experiments of Strangfeld et al.. For the high range, a NACA 0012 airfoil at a mean Reynolds number of 40,000 and 6° angle of attack is considered at three advance ratios of 0.8, 1.0 and 1.2 to compare with the experiments of Granlund et al.. These cases span a range of operating conditions, including a reversed flow condition.;
    Description
    May 2017; School of Engineering
    Department
    Dept. of Mechanical, Aerospace, and Nuclear Engineering;
    Publisher
    Rensselaer Polytechnic Institute, Troy, NY
    Relationships
    Rensselaer Theses and Dissertations Online Collection;
    Access
    Restricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.;
    Collections
    • RPI Theses Online (Complete)

    Browse

    All of DSpace@RPICommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    Login

    DSpace software copyright © 2002-2022  DuraSpace
    Contact Us | Send Feedback
    DSpace Express is a service operated by 
    Atmire NV