Experiments on Streamwise Vortex Mitigation Using Two-Dimensional Shielding Strips

Roughness elements that accumulate on aerodynamic surfaces can result in turbulent wedges that negatively impact aerodynamic performance. One potential approach for mitigating such undesired boundary layer transition is to place a small two-dimensional “shielding” strip downstream of potential discrete roughness element (DRE) accumulation sites. Shielding strips have been shown to be effective in both experiments and direct numerical simulations. However, there is not yet an analytical approach that allows computationally simple predictions of what shielding strip configurations are effective. In support of developing such a method, this experiment documents the evolution of a streamwise-oriented vortex as it interacts with a shielding strip. Streamwise vortices are a key feature of DRE wakes, so improved knowledge of how these flow features interact with shielding strips is expected to aid modeling efforts. A micro vortex generator (MVG) is used in place of a DRE to produce a streamwise vortex with relatively simple flow topology. A conventional and a cross-style hotwire anemometer measures flow velocities in streamwise and spanwise directions. These data are used both as inflow conditions for DNS and as a comparison to DNS and analytical model results.