Three-dimensional ionic wind and electrohydrodynamics of tuft/point corona electrostatic precipitator

Abstract

The two-dimensional flow interaction between the primary flow and the secondary flow (often called an electric wind or ionic wind) in the wire-duct electrostatic precipitator (ESP) has been investigated theoretically and experimentally in the past. However, the analysis was limited to the two-dimensional, which is acceptable only for the positive polarity and small tuft spacing. The negative corona, commonly used for the industrial ESPs, generates tufts along the corona wire and the point coronas on the discharge wire and requires three-dimensional analysis. Three-dimensional electric field and space-charge density distributions, and the flow interaction between the primary flow and secondary flow, i.e., electrohydrodynamics were investigated. The computational results show that the secondary flow distribution consists of a donut-shaped ring from each tuft or corona point, which was predicted by the first author 16 years ago. When the primary flow exists, a pair of spiral rings, like Goertler vortices, is formed in the direction of the primary flow. The flow interaction was described using dimensionless number N/sub EHD/, which is the ratio of the ionic wind velocity to the primary flow velocity. The effects of particle motion in the electrohydrodynamic field in the tuft/point corona ESPs are discussed.