曲がりチャネル内乱流熱伝達のパッシブ制御に関する研究

概要

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Direct numerical simulation was performed for a spatially advancing turbulent flow and heat transfer in a two-dimensional curved channel. A rib was placed on either an inner- or outer-wall of the straight part nearby curved-channel inlet for controlling the flow and thermal fields. Outer-wall was heated at the constant temperature and inner-wall was cooled similarly. In the simulation, fully developed flow and temperature computed by the straight channel was given to the inlet of curved channel domain. The frictional Reynolds number was assigned at 150, and the Prandtl number was given 0.71. When a rib was attached to the inner-wall, heat transfer in the upstream region of curved channel was enhanced effectively. On the other hand, placing a rib on the outer-wall caused an enhancement of heat transfer in the relatively downstream region of curved part, suggesting active heat transport of the large-scale vortices. Consequently, the inner-rib case affected more greatly on heat transfer than the outer-rib case. Mean velocity vector and power spectrum analysis implied that development of coherent structures near the outer-wall were controlled by a rib. It was found that inner-rib restrained large-scale vortex, while outer-rib promoted growth and power of large-scale vortex.