Experimental study of heat transfer enhancement with point-to-ring corona discharge

In this study, we experimentally inquire into the mechanism of the electric field for heat transfer enhancement by a point-to-ring corona gas discharge with either positive or negative applied voltage. We use a self-assembly 2D2C particle imaging velocimetry system to visualize and record the flow field. Results show that in our configuration the onset voltage of positive corona discharge is only slightly higher than that of the negative corona as a relatively large ring electrode is used. The current-voltage relationship follows Townsend's quadratic equation. The electrode distance has a slight effect on the current-voltage relationship. The time-averaged velocity demonstrates that the positive corona produces a faster and thinner jet compared to the negative one, and the region of the ionic wind is limited at low corona voltage. In addition, it is observed that the ionic wind can dramatically enhance heat transfer by ∼ 200%, and the enhancement effect of the positive discharge is more significant than that of the negative one. Furthermore, the proposed ionic wind generator has low power consumption, and therefore it is energy efficient.