We have investigated transition characteristics of a boundary layer on a NACA0012 airfoil with upstream wake generated by an airfoil aligned in tandem with zero angle of attack by measuring velocity signal using hot wire anemometer. Reynolds number based on airfoil chord varies from 2.0 x 105 to 6.0 x 105; distance between two airfoils varies from 0.037 to 1.0 of the chord length. To measure skin friction which is used to identify the transition onset and completion, we have devised a modified wall law to accommodate transitional flows with pressure gradient and nonuniform inflows. Variations of the skin friction are quite similar to that of the fiat plate boundary layer with turbulent inflow. It is found that measured velocity profiles are well consistent with ones computed by modified wall laws in the range up to y+ = 40. Turbulence of the upstream wake shifts the onset of transition upstream and the transitional region longer as the airfoils approach and the Reynolds number increases. Mean velocity distribution gradually varies from a laminar to the logarithmic one during the transition. We have found that the maximum rms velocity fluctuation is located over y+ = 15-20. Strong positive skewness of velocity fluctuation is observed at the onset of transition and the overall rms level of velocity fluctuation reaches 3.0-3.5 in the wall unit. The data are expected to develop a turbulence model for the simulation of transitional flow.


    Zugriff

    Zugriff über TIB

    Verfügbarkeit in meiner Bibliothek prüfen


    Exportieren, teilen und zitieren



    Titel :

    Flow characteristics of transitional boundary layer on the NACA0012 airfoil in wakes


    Beteiligte:


    Erscheinungsdatum :

    1998


    Format / Umfang :

    Seiten


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    Numerical Investigation of Transitional Flows over a NACA0012 Airfoil

    Alam, Mohammad / Suzen, Yildirim B. | SAE Technical Papers | 2008



    Optimal Operation of the NACA0012-IK30 Airfoil

    Camacho, Emanuel A. / Silva, Andre R. / Marques, Flavio D. | TIBKAT | 2023


    Experimental Study of Aerodynamic Characteristics of Partially Flexible NACA0012 Airfoil

    Sun, Xiaojing / Zhang, Xinyi / Su, Ziang et al. | AIAA | 2022


    Numerical Study of Camber Morphing in NACA0012 Airfoil

    Dhileep, Karthick / Kumar, D. / Ghosh, Santanu et al. | AIAA | 2020