Journal of Fluid Science and Technology
Online ISSN : 1880-5558
ISSN-L : 1880-5558
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Numerical Prediction of Heat Transfer Coefficient by Karman's Analogy and an Application for Air-Cooled Motorcycle Engines
Yasushi TAKAHASHIYoshitsugu GOKANMakoto INAYOSHITsuneaki ISHIMATomio OBOKATA
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2007 Volume 2 Issue 3 Pages 570-581

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Abstract

Cooling performance is a significant issue for air-cooled motorcycle engines, because its performance depends on the vehicle motion. Commonly, a heat transfer coefficient is calculated by heat flux and temperature difference, which are solved by energy equation under conjugated condition between a solid and a fluid. However, this method is complicated. Therefore, Karman's analogy based on a relation between the fluid friction and the heat transportation was used to obtain a heat transfer coefficient without solving an energy equation. Partial Cells in Cartesian coordinate method was employed as a CFD (Computational Fluid Dynamics) method for an efficient calculation around complex obstacles. Characteristics of heat transfer in a straight pipe were confirmed by a comparison with the Colburn's empirical formula. The results showed good agreement within ±10% differences under Pr=0.7 and 104<Re<1.2×105. Furthermore, a calculation result of local heat transfer coefficients of an air-cooled motorcycle engine was shown. From the above, a new approach of heat analysis by a CFD was proposed.

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© 2007 by The Japan Society of Mechanical Engineers
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