Effects of Corona Discharge on Free-Convection Heat Transfer Inside a Vertical Hollow Cylinder

Vortex rolls induced inside a vertical hollow cylinder are found to increase the free-convection heat transfer rate from the inside surface. The vortex rolls are induced by the corona wind generated between 0.05-mm-dia wire electrodes placed vertically on the inside surface of the vertical hollow cylinder. The increase in heat transfer rate is determined experimentally and is based on the heat input required to maintain the inside surface of the cylinder at constant temperature. The experimental results without corona discharge are compared with an analytical heat balance. A Mach-Zehnder interferometer is used for boundary layer visualization.