An Investigation Into the Heat Transfer and Fluid Flow Around a Circular Cylinder in Buoyancy Assisting Cross Flow

There is considerable interest in mixed convection heat transfer in relation to electronic cooling applications but the physics of this flow in certain situations has yet to be understood. In this paper, an investigation of the heat transfer and fluid flow around a two dimensional circular cylinder is made. The experimental configuration comprised a long heated cylinder suspended in a glass walled enclosure. The airflow within the enclosure was controlled using a baffled axial fan to give a range of low Reynolds numbers from 30 to 83. For three Grashof numbers of 2.40E+04, 3.77E+04 and 5.99E+04, the mean Nusselt number around the cylinder was measured for buoyancy assisting cross flow. Optical techniques were employed to extract the full flow and temperature fields about the cylinder. Digital Speckle Pattern Interferometry (DSPI) was employed to measure the temperature field, and Particle Image Velocimetry (PIV) for the velocity field. The presence of the assisting flow was found to stabilise a naturally oscillatory buoyant flow and led to an increase in the heat transfer coefficient over that found in natural flow.