Dynamics of EHD Laminar Plumes: scaling analysis and integral model

In this paper electrohydrodynamic (EHD) plumes are examined in the region far from the injecting electrode and the collector plate, for both two-dimensional and axisymmetric geometries. The relative importance of the conduction mechanisms (convection, drift and diffusion of electric charge) is analyzed. Diffusion turns out to be negligible compared to convection and drift for the experimental conditions. But the transverse drift (Coulomb repulsion) is of the same order of magnitude than convection. We find a set of three differential equations giving the evolution of the velocity at the center of the plume and the widths of the plume and the charged core inside.Ministerio de Ciencia y Tecnología PB96-137

Corona discharge characteristics of narrow coaxial wire- pipe discharge tubes with gas flow

An experimental investigation has been conducted to study corona discharge in a narrow tube. Narrow or capillary corona discharge (dis- charge tube diameter d = 1 to 20 mm) is used for many industrial applications such as flue gas cleaning corona induced plasma reactors, ion sources and electrohydrodynamic heat exchangers. In this work, corona discharge characteristics of narrow coaxial wire-pipe discharge tubes with gas flow are experimentally investigated. The results show that, unlike normal corona discharge, a hysteresis in the corona discharge current-voltage characteristics were observed for narrow tube discharges. The on-set of the corona discharge observed to be significantly depends on the gas temperature and gas flow rates 1.588 cm 0.d. copper tube was placed coaxially outside the system. Entrance and exit gas temperature of the wire-pipe corona discharge zone and outer-grounded pipe gas cooling zone were measured by T-type thermocouples. Time-averaged current was measured by the Keithly electrometer, and air flow rate in both flow channels was measured by a rotameter. The air flow flowing through the corona discharge zone was electrically heated at upstream of the system. Experiments are conducted for the gas flow rate from 0 to 20 [/min., the inlet gas temperature from 10 to 60°C, and the applied voltage from 0 to It 10 k