| Summary: | 碩士 === 國立交通大學 === 機械工程學系 === 100 === This study experimentally investigates the effects of rotation on heat transfer in a two-pass rotating rectangular channel. The experiments are conducted with two surface conditions: smooth walls and 45°angled ribbed walls. The channel aspect ratio is 0.67. Three Reynolds numbers are studied: 15000, 20000 and 25000. The rotational speed is fixed at 360 rpm for all tests. Rib turbulators are placed on the leading and trailing walls of the channel at an angle of 45°to the mainstream flow direction. The ribs height to hydraulic diameter ratio (e/Dh) is 0.125, and the rib pitch-to-height ratio (p/e) is 10 for all tests.
Detailed measurements are presented in the first pass, in the turn region, and further downstream in the second pass. This study presents the transient liquid crystal technique for local heat transfer coefficient measurements in an internal cooling channel. Stroboscope is used as the photography technique. In this study, the author is able to systematically analyze, and conclude the heat transfer comparison with both smooth walls and ribbed walls. The Nusselt number ratio decreases with increasing Reynolds number in both non-rotating and rotating channels with smooth and ribbed walls.
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