Visualization of the local ionic wind profile in a DC corona discharge field by laser-induced phosphorescence emission

Abstract

Experimental visualization for ionic wind motion originated from DC corona discharges in a needle-plate electrode system has been investigated. A vapor-phase biacetyl tracer with laser-induced phosphorescence emission is used for optically characterizing the ionic wind profile. The ionic wind blows the excited biacetyl molecules away in continuing the visible phosphorescence emission for a long radiative lifetime. The captured image with elapsing time from the excitation presents the shifting location of radiative tracer along the ionic wind direction. The experimental results show the ionic wind profile enhanced in the electric field direction corresponding to the corona discharge progress. Especially, the ionic wind near an initiating point of corona discharges is focused as an advantage of this optical technique. The ionic wind velocity along the electrode axis can be obtained at the location close enough to the corona discharge initiation point, and the velocity at 0.5 mm from the discharge point is figured out as 9.3 to 19.2 m/s under the condition of the EHD Reynolds number of 0.95 × 10 3 to 2.1 × 10 3 .

The Influence of Electrohydrodynamic Secondary Flow on the Collection Efficiency and Deposition Pattern in ESP

“…Massive free ions resulting from the corona discharge move along the electric line and collide with neutral molecules in the air, which transfers the momentum from ions to neutral molecules, known as electrohydrodynamic secondary flow (EHD) [5][6][7][8][9]. The significant effect of EHD on the transport of particles, especially fine particles, has been confirmed in previous studies [10][11][12][13].…”

Thermocapillary Monitoring Using Particle Image Velocimetry Associated With Dynamic Laser Speckle

“…Thus, the pumping movement occurs and, with the increase in concentration, it was possible to visualize the rise in this pumping fluid movement. According to Ohyama et al (2007) and Kitahara et al (2007), most of the techniques used to observe this flow have focused on fluorescent molecules.…”