Investigating the Impact of Electrode Wire Interaction on EHD Flow in Two-Wire-to-Plate Corona Devices: A Computational Analysis

The present study conducts a numerical investigation of the shielding effect between adjacent corona discharge electrodes in two-wire-to-plate corona devices. The primary focus of the study is to analyze the impact of mutual electrostatic interaction or shielding effect between two high-voltage wires on the electrohydrodynamic (EHD) force’s direction and magnitude, as well as the overall structure of the EHD flow. The findings reveal that the attenuation of the electric current, space charge, and magnitude of the EHD force is more dominant when the distance between the wires decreases. Moreover, the shielding effect is closely related to the wire-plate electrode space and wire radius. The results highlight the importance of considering the shielding effect in designing and optimizing electrostatic precipitators and other corona devices that rely on the EHD flow.

I. Introduction

In 1718, Issac Newton coined the term “electric wind” to describe the flow of an ionized gas during an electric discharge [1]. Subsequently, in 1834, Michael Faraday described the electric wind as a process of momentum transfer caused by collisions or friction between charged and neutral particles, creating airflow [2]. However, in corona discharge, the electrical wind is generated in gases between two electrodes, one of them is highly curved, such as a tip or wire, and is subjected to a high voltage (the stressed electrode); and the other electrode, which is less curved or even flat, is grounded [3], [4], [5]. As a result, an inhomogeneous electric field is formed between the two asymmetrical electrodes, with its maximum value located at the stressed electrode. This electric field accelerates the generated charged particles, and during collisions with neutral gas molecules, they transfer a part of their momentum to these neutral particles. A schematic presentation of the mechanism of the electric wind generation by positive corona is shown in Fig. 1. As a result of these phenomena, the gas particles move globally due to the effect of an electrohydrodynamic (EHD) force. This global fluid flow, which represents the electric (or ionic) wind, is called an EHD flow. To compute the EHD force, it is essential to determine the electric field and the space charge first. In addition, it is worth noting that the configuration of the electrodes plays a significant role in determining this EHD force. Fig. 1.

Ionic wind generation in dc positive corona discharge.