Heat Transfer on the Surface of a Flat Plate in the Forced Flow

Abstract

It is an important problem in the field of the heat exchange to make clear the surface heat transfer. Many studies have been performed regarding this problem. However, because heat transfer is influenced by numerous factors, there are many things remaining unknown. This research was carried out to make clear the effects of some of these factors on heat transfer on the surface of a flat plate in the forced flow. Especially, we wish to know the effects of the surface roughness systematically. As the first step, we experimented with the smooth flat plate which was heated or cooled while measurement was carried on. And by comparing the results with theoretical analyses, we found that our experimental method was reliable. As the next step, we experimented with the roughened plate and made clear the effects of surface roughness. The results of this experiment are : in a range of larger numbers than a certain Reynolds' number, there is formed a special turblent boundary layer which is influenced by the surface roughness, and in this range, the local heat transfer coefficient is independent of the po3ition, and its value becomes the largest when the ratio of the height to pitch of the surface roughness is 0.055.