Experimental investigation of turbulent boundary layer dynamics via active manipulation of large-scale structures

Abstract

The dynamic response of a zero pressure gradient turbulent boundary layer (TBL) to an active flow control actuator was experimentally studied using continous laser particle imaging velocimetry (PIV). In previous experiments using a single hot-wire, it was shown that the synthetic large-scale structure (LSS) introduced by the plasma-based actuator, located in the outer region of TBL, had a strong modulating and reorganizing effect on the near-wall turbulence. In the study reported here, an actuator, optimized for the experimental TBL, was placed at the upper boundary of the log-linear region of the TBL to produce a spanwise uniform, periodic synthetic LSS in order to study the response of the TBL to these large-scale perturbations. Planar PIV over a narrow streamwise region was used to measure the time-resolved, two-dimensional velocity downstream of the actuator at a series of streamwise point locations. Using PIV, the modulating effect of the synthetic LSS on the near-wall turbulence is described in more detail. The results are discussed and compared with previous hot-wire measurements and numerical simulations of the actuated TBL.