Smoke Flow Visualizations for the Study of Surface Dielectric Barrier Discharge Induced Flow Field

Abstract

The flow field induced by surface dielectric barrier discharge (SDBD) is visualized using illumination of smoke seeded to the flow. A planar SDBD of 50 mm span is created on a flat surface between thin copper electrodes separated by layers of kepton tapes which act as dielectric; AC voltage of 25 kV (peak to peak) is supplied across the electrodes. The smoke is illuminated by a planar laser sheet, and the time resolved visualizations are captured using a high speed camera operated at a recording rate of 2000 frames per second. The time evolution of the starting vortex and the steady wall jet that eventually gets established on the surface are recorded. The speed of the smoke front at the beginning of actuation and the starting vortex speed are quantified from the visualizations, which are used for parametric study of the SDBD flow actuator. The DBD actuator is found to induce a maximum velocity of 8 m/s close to the electrode at AC frequency of 2000 Hz. It is found that the starting vortex speed increases as the AC frequency is increased, reaching a maximum at 2000 Hz, after which the starting vortex speed decreases. The temporal behaviour of starting vortex with pulsed actuation is also studied and contrasted with the case of quasi steady actuation.