Investigation of heat transfer characteristics and flow reversal phenomena in naturally convecting parallel/converging vertical channel flow

Abstract

The natural convective heat transfer characteristics in parallel/converging vertical channel flows and the flow reversal phenomena in a vertical parallel channel were studied. A sophisticated nonintrusive measurement technique called "speckle photography" was employed to measure both the local and average heat transfer rates along vertical heated plates. A Schlieren flow visualization system was used to investigate the thermal boundary layer merging processes with respect to the vertical channel openings. Another experimental setup was carefully devised for smoke flow visualization of the parallel vertical channel flows. This system enabled visualization of the flow penetration in the channel exit region. In the numerical study, the full elliptic equations were solved for the two-dimensional, steady state, laminar, incompressible flow regime. The body fitted coordinate system (BFCS) was utilized for the irregular computational domain. The unknown flowrates were determined by the behavior of the channel centerline velocities in the single plate limit region. This numerical investigation substantiated the experimental results for both the heat transfer characteristics and flow reversal phenomena of vertical channels.