リブ付き平行平板間流れの共存対流熱伝達〔熱工学, 内燃機関, 動力など〕

概要

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Two dimensional calculation was performed for combined convection heat transfer in a channel with two ribs attached to one wall, following the previous study on forced convection case without buoyancy. The flow is heated from the surfaces of both ribs and the present study dealt with the two cases of buoyancy-assisting flow and buoyancy-opposing flow. The effect of Reynolds number, Re_L, and modified Richardson number, Ri^*, was examined keeping space between ribs, σ, and blockage ratio, τ, constant (σ=3.0,τ=0.5). Increasing the magnitude of buoyancy, unsteady flows predicted by the present calculation are stabilized in both of two cases. Serious deterioration of Nusselt number on the 2nd rib suddenly occurrs in a certain range of Ri^* due to the flow stabilization. This is because flow unsteadiness plays an important roll for heat transfer enhancement as was described in the previous study. However, in buoyancy-assisting flow, similar deterioration of Nusselt number also appears on the 2nd rib even if flow remains steady. This is caused by the disappearance of strong rotating flow which exists in the cavity between the both ribs and keeps fluid in the cavity cooler.
社団法人日本機械学会の論文
1997-10-25