Corona discharge in air was used to generate a secondary flow that significantly improved the convective heat transfer coefficient in the developing and developed regions of a tube. A wire electrode, charged with a high voltage, was coiled around the insulated circular cylinder. The wire was contacted to negative polarity of high voltage supply. The electrode ionized the air and created a corona current, which was measured experimentally. In this study, the effect of electrode geometry, such as different diameters and the gamut lengths of the coiled wire electrode were investigated. The high voltage used in this research was 15.6 kV. At last, the optimum value of mentioned parameters was specified.