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In this paper, the interaction between a dielectric barrier discharge and submicron particles is investigated experimentally using Laser Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV) techniques in a wire-to-plane configuration. The induced electrohydrodynamic (EHD) phenomena have been studied by time-averaged and time-resolved measurements for different AC high voltage waveforms. The main results indicate that the particle time-averaged velocity increases with the HV frequency whatever the measurement position due to electric wind effect. The time-resolved velocity increases during both positive and negative discharges inducing a strongly non-stationary EHD flow. After the propagation of streamers, a reduction of the particle number in the gap is observed at low frequency due to particle charging and electrostatic precipitation by the electric field. [ABSTRACT FROM AUTHOR]

In this study, surface Dielectric Barrier Discharge (DBD) actuators powered by a nanosecond pulsed high voltage are investigated. The goal is to experimentally analyze the effect of dielectric aging on the electrical behavior of the discharge and the surface plasma morphology. The used actuator is made of two conducting electrodes separated by a thin dielectric made of polyimide and arranged asymmetrically. The active electrode is connected to a nanosecond pulsed high voltage power supply and the second electrode is grounded and encapsulated inside a dielectric material. The actuator is aged by using the surface DBD supplied continuously during 15 minutes with a voltage pulse of + 10 kV at a frequency of 1 kHz and a pulse width of 250 ns. The experimental results show the existence of two discharges during both rising and falling periods of the voltage for both virgin and aged actuators. After aging, a third discharge current component is observed during the voltage plateau due to the ignition of additional discharges, which enhance the energy per pulse. ICCD camera images indicate that the plasma layer extends further on the dielectric surface in the case of aged actuators. In addition, large and non-localized filaments appear during the voltage plateau after aging due to the non-homogenous positive space charge distribution that intensifies the electric filed locally. [ABSTRACT FROM AUTHOR]

This paper is a study of a plasma actuator in the absence of external flow by means of particle image velocimetry measurements. The properties of the electric wind produced by the actuator are investigated by spatially resolved and phase-locked measurements. The use of a particle image velocimetry apparatus is of great interest to accurately examine the spatio-temporal history of the electric wind formation. The approach consists of evaluating the time required by the induced airflow to reach a stationary state and also in describing the different states of its formation. The electric wind is generated by a single dielectric barrier discharge excited by a sine waveform of 1 kHz, having an amplitude of 20 kV. Turbulent kinetic energy, swirl strength, pure shear flow and mass flow rate are also used to describe the formation process of the airflow. [ABSTRACT FROM AUTHOR]

The aim of the present work has been to quantify the efficiency of Dielectric Barrier Discharges (DBDs) for the collection of submicron particles. The experiments were performed with incense smoke particles having a mean size of about 0.3 μm. An aerosol spectrometer was employed for characterizing the size distribution of these particles at the outlet of Wire-to-Cylinder (WC) and Plate-to-Plate (PP) DBD reactors. The collection efficiency was estimated for various applied voltages (6 - 26 kV, 1 - 2000 Hz), and airflow rates of 1.6 - 24 L/min. The discharge mode was diffuse, in the case of the axisymmetric configuration, and filamentary, in the case of the planar configuration. When flow rate increases, the discharge current and the electric power decrease in both cases. This effect is less pronounced with the planar configuration. Results obtained with the aerosol spectrometer show that the particle collection efficiency of both reactors is higher at high applied voltage and low flow rate; it decreases at high frequency because of particle oscillations, and at low frequency due to the intermittent nature of the discharge. The frequency range for which the collection efficiency is higher than 90% is wider in the case of WC reactor. [ABSTRACT FROM AUTHOR]

Presents a study which measured the oil electrification occurring with the use of pressboard obtained from a damaged power transformer, and of pressboard degraded by artificial electrical discharges. Comparison of the performances to that of unused pressboard; Influence of additive 1,2,3 Benzotriazole in oil; Factors affecting flow electrification; Discussion of the experimental results.

Presents information on a study on the feasibility of using electrokinetic phenomena for contaminant removal from low-permeability porous media applied to soil decontamination. Physico-chemical phenomena in soils under electric field; Theoretical aspect of electrokinetic phenomena; Experimental results; Conclusion of the study.