Numerical Study of Corona Jet Produced From a Circular Tube Fitted With a Nozzle

Numerical study on the flow characteristics of a plasma jet, which is produced from a needle electrode positioned at the centerline of a circular tube with a grounded stainless-steel nozzle attached at one end of the tube, is presented. This article is particularly aimed at providing additional insight to the flow field inside the tube assembly through visualization of the numerical results obtained. Since flow visualization is very challenging to implement in experimental study of electrohydrodynamics, and thus, no result was available from the previous study. As such, the present results become very useful in understanding the flow inside the nozzle. To this end, six nozzles with two diameter ratios and three taper angles are evaluated for their effectiveness in accelerating the jet produced by corona discharge with positive polarity. The numerical results have confirmed the findings from the previous study that a nozzle with a smaller diameter ratio does not always perform the best in accelerating the flow or producing the maximum volume flow rate due to the flow restructuring inside the nozzle. In addition, the results show that taper angle can further amplify the effect produced by the diameter ratio.