鉛直下向き加熱直円管流の流れと伝熱特性の基礎的研究 : 水の低レイノルズ数流れ

概要

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This study aims at the fundamental research to experimentally clarify performances of heat and flow fields using water in a vertical heated straight circular tube in the Reynolds number region below 2000. The experiments were caried out using a brass tube of 22 mm inner diameter and 1500 mm length which was heated by nichrome wires under a constant heat flux condition from the tube outside. The tube was surrounded by heat insulating layers to avoid heat loss. It was reported that under the condition of a smaller wall heat flux a heat-transfer deterioration was observed due to a decrease of the fluid temperature gradient at the inner tube wall caused by the buoyant force. It was also found that, even in the Reynolds number region of 500 through 800, in the case of a larger heat flux, a heat-transfer enhancement was observed due to a velocity fluctuation caused by the appearance of an inflex poiot of the velocity profile owing to the strong buoyancy force effect near the wall.
1988-07-25