Laser Flow Visualization and Velocity Fields by Particle Image Velocimetry in an Electrostatic Precipitator Model J. Mizeraczyk* 1 , J. Dekowski* 1 , J. Podliński* 1 , M. Kocik* 1 , T. Ohkubo* 2 , S. Kanazawa* 2 * 1 Center of Plasma and Laser Engineering, Institute of Fluid Flow Machinery, Polish Academy of Sciences, 80–231 Gdańsk, Fiszera 14, Poland, E–mail: jmiz@imp.gda.pl * 2 Department of Electrical and Electronic Engineering, Oita University, 700 Dannoharu, Oita 870–1192, Japan Abstract: Although improving electrostatic precipitator (ESP) collection of fine particles (micron and submicron sizes) remains of interest, it is not yet clear whether the turbulent flow patterns caused by the presence of electric field and charge in ESPs advance or deteriorate fine particle precipitation process. In this paper, results of the laser flow visualization and Particle Image Velocimetry (PIV) measurements of the particle flow velocity fields in a wire–to–plate type ESP model with seven wire electrodes are presented. Both experiments were carried out for negative and positive polarity of the wire electrodes. The laser flow visualization and PIV measurements clearly confirmed formation of the secondary flow (velocity of several tens of cm/s) in the ESP model, which interacts with the primary flow. The particle flow pattern changes caused by the strong interaction between the primary and secondary flows are more pronounced for higher operating voltages (higher electrohydrodynamic number NEHD) and lower primary flow velocities (lower Reynolds number Re). The particle flow patterns for the positive voltage polarity of the wire electrodes are more stable and regular than those for the negative voltage polarity due to the nonuniformity of the negative corona along the wire electrodes (tufts). Keywords: Flow visualization, Electrostatic precipitator, PIV, Corona Discharge, EHD Flow 1. Introduction In recent years a special environmental concern is directed towards controlling the emission of micron and submicron particles in electrostatic precipitators (ESPs), which operating with high overall efficiency, are not effective in the removal of fine particles. Many of the fine particles of 1 µm or less in size contain toxic trace elements. Hence, there has long been interest in improving ESP collection of fine particles. The motion and precipitation of particles in the duct of an ESP depend on the particle properties, electric field, space charge and gas flow field. It was shown (Ohkubo et al., 1986; Atten et al., 1987; Medlin et al., 1998; Chang and Bai, 2000; Mizuno, 2000; Mizeraczyk et al., 2001; Yamamoto et al., 2002) that a significant interaction between these factors exists, resulting in significant turbulent flow patterns in the ESP. However, it is not yet clear whether these turbulent flow patterns advance or deteriorate fine particle precipitation process. To elucidate the influence of the electrically generated flow disturbances on the precipitation of fine particles in ESPs, more experimental investigations are needed. In this paper, results of the laser flow visualization and Particle Image Velocimetry (PIV) measurements of the particle flow velocity fields in a wire–to–plate type ESP model with seven wire electrodes are presented. This investigation is expected to be helpful in elucidating the motion of the fine particles in ESPs.