Convection from surface mounted repeating ribs in a channel flow

Experiments on low-speed forced convective heat transfer in a two-dimensional channel are reported. One wall of the channel was outfitted with repeating ribs whose height and length were significant compared to the wall-to-wall spacing. The flow was in the transition regime. Photographs of streaklines, produced using a smoke wire technique, provided a qualitative measure of effects of the flowrate and wall-to-wall spacing on the level of flow unsteadiness. The results of the flow visualization showed that the level of unsteadiness was well correlated with a Reynolds number based on the rib length. Measurements of local surface temperature and surface heat flux from the surface of one of the ribs were made using a Mach-Zehnder interferometer. Both uniform surface heat flux and uniform surface temperature ribs were studied. Results indicate that the average heat transfer coefficient was well correlated in terms of a Reynolds number based on the rib length. The effect of variations in channel wall-to-wall spacing was comparatively weak.