管内脈動流の流動および伝熱特性 : 内部流の伝熱に及ぼす脈動流の効果

概要

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Effects of pulsation on flow and heat transfer characteristics are experimentally examined in the pulsating pipe flows having sinusoidal velocity fluctuation around a nonzero mean. By systematically varying three pulsation parameters (the amplitude, frequency, and mean velocity), time-averaged and fluctuating temperature profiles are measured under the heating condition of constant wall temperature using saturated vapor. The mean Nusselt number, Nu_p, is calculated, and compared with that in ordinary turbulent pipe flows without pulsation. The results show that Nu_p decreases initially as the pulsation amplitude increases, then recovers gradually, and finally becomes much greater than the original value. In the pulsating pipe flows with a non-zero mean velocity, therefore, pulsation cannot always promote heat transfer, but sometime suppresses it, depending mainly on the pulsation amplitude and mean velocity. It is also found that these heat transfer characteristics of a pulsating pipe flow are controlled by the transition of flow patterns with pulsation amplitude from a fully turbulent flow to a conditionally turbulent flow via a transitional flow.
一般社団法人日本機械学会の論文
1996-05-25