Hydrodynamical simulation of the electric wind in a cylindrical vessel with positive point-to-plane device

Electrical corona discharges at atmospheric pressure in a positive point-to-plane configuration create an electric wind from the point to the plane which, in a closed cylindrical vessel, generates in a few seconds axisymmetrical vortices in the vessel. Photography and video recording show that a small ring vortex appears around the discharge axis, close to the plane, enlarges and progressively fills the vessel up to a stationary situation. A simplified stationary model was first used in order to take into account the measured values of the wind velocity along the discharge axis as well as the velocity held lines visualized by smoke particles. Simulation and experimental results are in fairly good agreement, and a few particular adjustments concerning temperature profiles were made to improve the numerical results. Then, a dynamical model, including the effect of the repetitive ionizing fronts (streamers) occurring in the filamentary discharge, allows one to render an account of the transient evolution of the velocity field lines towards the stationary vortices. Although the numerical simulation could not be continued to a steady state, it shows that a small ring vortex is created near the point electrode, moves rapidly from the point to the plane and then begins to enlarge at the right (experimental) place.