Hairpin Vortex Generation for Physio-Cyber Simulations and Control

Historically, active separation control has used actuation with large energy influxes, momentum, and high blowing coefficients to achieve reattachment of the flow field. However, recent work by our collaborators has shown numerically that separation control is feasible through utilizing the high-momentum coherent vortical structures, or large-scale motions (LSMs), to reenergize the boundary layer. This method is thought to require less energy than traditional separation control methods. The present work explored experimentally this approach where synthetic vortical structures, generated via synthetic jet actuation, resembling LSMs were injected into the laminar boundary layer flow. The structures were targeted with a jet-assisted surface-mounted actuator (JASMA) to entrain them in the near-wall region of the boundary layer. The JASMA consists of a low aspect ratio cantilevered pin with a mounted synthetic jet to apply further downwash to the flow downstream. The resulting flow was quantified via stereoscopic particle image velocimetry. An upstream plane of synthetic jet data was also supplied as a boundary condition to a DNS solver to yield physio-cyber simulations that were compared to the experimental results.