Flow fluctuation induced by coaxial plasma device at atmospheric pressure

The flow structure and velocity fluctuation generated downstream from coaxial geometry dielectric-barrier-discharges are investigated at atmospheric pressure. The discharges are characterized using in-situ electrical measurements and optical diagnostics. Both streamers and glow-like discharges are detected in each alternating-current cycle. The flow structure is temporally and spatially resolved using tracer particles, and vortices are visualized in planar velocity distribution patterns. The flow upstream of the discharge is laminar; however, we discover that the spectrum of downstream fluctuation velocity exhibits a nearly Kolmogorov −5/3 slope, which is a typical feature for high Reynolds number turbulent flows. Based on the electron density measured through a line-ratio method, the dimensionless electrical body force derived from the Navier-Stokes equation is estimated to illustrate the generation of Reynolds stress. It is found that although less than 0.1% of the discharge power is converted into the fluctuation kinetic energy, the electrical body force rather than Joule heating plays a dominant role in flow fluctuation.