Experimental investigation on upstream and downstream discharges in airflows

Dielectric barrier discharge has widely used in airflow control, ignition and combustion, and other applications; the influence of airflow on dielectric barrier discharge is of extensive concern. Previous studies demonstrate that the discharge becomes more uniform and the discharge intensity decreases with increasing of airflow velocity. In this study, we adopt a discharge cell construction with upstream and downstream structure and study the discharge states and intensities. The experimental results demonstrate that within a specific range of airflow speed, the upstream discharge intensity is decreased, and the downstream discharge intensity is enhanced. The physical basis for this phenomenon is proposed as follows: Within a pulse interval time, some particles, such as charged and metastable particles produced by the upstream discharge, could be transported to the downstream region. The concentration of particles in the downstream region is increased, and these particles play a pre-ionization role in the downstream discharge, the intensity of the downstream discharge is enhanced. Further, factors such as the pulse frequency and the distance between electrodes are discussed in detail, along with the conditions for enhancing downstream discharge intensity.