Influence of channel aspect ratio on heat transfer in rotating rectangular ducts with skewed ribs at high rotation numbers |
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| Authors: | T.-M. Liou S.W. Chang J.S. Chen T.L. Yang Yi-An Lan |
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| Affiliation: | 1. Department of Power Mechanical Engineering, National Tsing Hua University, 30013 Hsinchu, Taiwan, ROC;2. Department of Marine Engineering, National Kaohsiung Marine University, 811 Kaohsiung, Taiwan, ROC;1. Tupolev Kazan National Research Technical University – Kazan Aviation Institute, Kazan, Tatarstan, Russia;2. Bauman Moscow State Technical University, Moscow, Russia;3. Saint-Petersburg State University of Civil Aviation, Saint-Petersburg, Russia;1. National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics and Collaborative Innovation Center of Advanced Aero-Engine, Beijing University of Aeronautics and Astronautics, Beijing 100191, China;2. Department of Air Material Management, Air Force Logistics College, Xuzhou 221000, China;1. National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics, Collaborative Innovation Center of Advanced Aero-Engine, Beijing University of Aeronautics and Astronautics, Beijing 100191, China;2. R&D Center Dept of Discipline Engineering, AVIC Commercial Aircraft Engine Co., Ltd., Shanghai 201108, China |
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| Abstract: | Centerline heat transfer measurements along two opposite ribbed walls in three rotating rectangular ducts roughened by 45° staggered ribs with channel aspect ratios (AR) of 1:1, 2:1 and 4:1 are performed at Reynolds (Re), rotation (Ro) and buoyancy (Bu) numbers in the ranges of 5000–30,000, 0–2, and 0.005–8.879, respectively. These channel geometries are in common use as the internal cooling passages of a gas turbine rotor blade and the tested Ro and Bu ranges are considerably extended from the previous experiences. This study focuses on the heat transfer characteristics in response to the change of AR under the parameter ranges examined. With zero-rotation (Ro = 0), the local Nusselt numbers (Nu0) along the centerlines of two opposite ribbed walls increase as AR increases due to the increased rib-height to channel-height ratio. The Bu impact on heat transfer appears to be AR dependent, i.e. the increase of Bu elevates Nusselt number ratios Nu/Nu0 in the square channel but impairs heat transfer in the rectangular channels of AR = 2 and 4. Acting by the Coriolis effect alone, all the leading edge Nu values in the present Ro range are lower than the zero-rotation references but started to recover as Ro increases from 0.1 in the channels of AR = 1, 2 and from 0.3 in the channel of AR = 4. The trailing edge Nu/Nu0 ratios increase consistently from unity as Ro increases but their responses toward the increase of AR are less systematic than those found along the leading edge. The above findings, with the aids of extended Ro and Bu ranges achieved by this study, serve as the original contributions for this technical community. The Nu/Nu0 ratios in the rotating channels of AR = 1, 2, and 4 fall in the ranges of 0.6–2.2, 0.5–2.7, and 0.5–2.1, respectively. A set of heat transfer correlations is derived to represent all the heat transfer data in the periodically developed flow regions of three rotating ducts. |
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