An analytical model of the ionic wind in a regular ultracorona

The effect of corona geometry variations on the ionic wind in a regular-type multi-wires-to-rods electrode system is studied analytically and experimentally in air. To seek the relation between the electrode number, gap distance, and pump performance, an electrohydrodynamic (EHD) gas pump with 1-29 emitting electrodes in a plane is critically evaluated by analytical estimations and experimental measurements for the gap distances of 14.5-67 mm. A quasi-one-dimensional analytical model of the pump is developed to understand the basic physics associated with the EHD force and to give some quantitative estimations of the ionic wind as a function of the corona current for different geometries. In the model, the pressure drop is related to geometrical parameters of the EHD gas pump cross-sections. The results show that the deviation observed at low ionic wind velocity in the current dependence of the ionic wind velocity from the known square root dependence is associated with the strong pressure drop varying with the Reynolds number. The ionic wind velocity is slightly dependent on the number of the corona wires. The gap distance dependence of the average positive ion mobility in the corona discharge in air is discussed.