EXPERIMENTAL STUDY OF THE NATURAL-CONVECTION PLUME FROM A HEATED VERTICAL CYLINDER

Abstract

This article describes an experimental study of the natural convection from a vertical cylinder, and gives new data for the velocity and temperature distributions of a heat source with real structure and high heating capacity. Two different instruments, a laser Doppler anemometer and 3D ultrasonic anemometer, were used for velocity measurements. Thermistors were used for temperature measurements. Velocity data were used to evaluate volume flow rates. Velocity fluctuations were used to describe the turbulent behavior of the convection plume. Verticle mean velocity profiles and volume fluxes were compared with values obtained by using the approximate solution for the round turbulent plume associated with a point source. Three important results were obtained. First, the present study produced significantly wider velocity profiles than found in previous studies with buoyant jets. Second, the round turbulent model produced significantly higher volume flow rates than real velocity distributions, which was explained by the longer “velocity tails.” Third, the high fluctuating velocities indicate that the core region on the plume was extremely turbulent. The present velocity and temperature data can be used as a new source of information about the convection plumes associated with high heating capacity, and can be used to validate existing computational and theoretical models.