後ろ向きステップ鉛直上昇共存対流の熱流動数値解析〔熱工学, 内燃機関, 動力など〕

概要

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Two-and three-dimensional numerical simulations have been performed for mixed convective upward flows over a backward-facing step in a duct. The Reynolds number, expansion ratio and aspect ratio (in 3D sim.) were kept constant at Re=125,ER=2 and AR=16,respectively. The heat flux at the wall downstream of the step was uniform, while the straight wall, the step and the side walls (in 3D sim.) were assumed to be adiabatic. The effect of the buoyancy level, Ri^*, was the major interest in this study. It was found that the reattachment point and the peak Nusselt number point moved upstream as Ri^* was increased, while the secondary recirculation region, which developed at the corner of the step, became larger. It was also found that there existed a secondary flow in a cross section immediately downstream of the step. Flow directed toward the center of the duct becomes more intensive as Ri^* increases, which possibly results in an increase in the level of three-dimensionality of the flow and thermal fields.
社団法人日本機械学会の論文
1997-08-25