Numerical Modelling of Ionic Wind Generation By Negative Corona Discharge in Ambient Air With Experimental Validation

Abstract

Ionic wind can be potentially applied to active cooling of portable electronics and LED lighting systems 1. Ionic wind is produced by a corona discharge when gaseous ions are accelerated in the electric field and transfer momentum to neutral molecules by collisions 2. This technique is promising because a gas flow can be generated without the need for moving parts and with low power consumption. The basic theory of ionic wind sounds simple but the details are far from clear. In our experiment, a negative DC voltage is applied to a needle-cylinder electrode geometry. Hot wire anemometry is used to measure the flow velocity at the downstream exit of the cylinder. The flow velocity fluctuates but the average velocity increases nearly linearly with the voltage. The current consists of a regular train of pulses with short rise time which are the well-known Trichel pulses. To reveal the ionic wind mechanism by Trichel pulses, a threespecies corona model coupled with gas dynamics is built. The drift-diffusion equation of plasma together with the Navier-stokes momentum equation are solved in Comsol Multiphysics. Multiple time scales are employed: tens of microseconds for the plasma characteristics and longer time scales $( \sim 1\,\mathrm {s})$for the flow behavior. The calculated current and flow velocity are compared to the experimental results. Furthermore, seed particles are included to simulate and visualize the gas flow. Finally, the mushroom-like minijets 3are also reproduced.