矩形管内脈動流の熱・物質輸送特性 : 第2報 振幅が管内に設置された平板面の熱伝達に及ぼす影響
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概要
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This study deals with flow behavior and associated heat transfer in pulsating duct flow. Among the several parameters that govern the transport phenomena of pulsating flow, the effect of pulsating amplitude on flow and heat transfer around the flat plate installed in a rectangular duct is mainly discussed in this paper. Researchers in bioengineering field focus on heat and mass transport characteristics of pulsating flow from the view point of life science. Many mechanical researchers and engineers are also interested in the high efficient mass transport characteristics of blood flow and respiration for the various kinds of medical and engineering applications. Then biomechanical engineering has been established. Pulsating flow in a living body such as blood flow and breath is very complicated and its heat and mass transport mechanisms with high efficiency are not cleared yet due to many times branches of their flexible tubes and pipes. Even for fundamental studies of pulsating flow in a simple shape passage reported by a number of researchers, flow structure with periodical flow rate change and its effect on heat transfer are still at question in spite of more than thirty-year history. Researchers showed conflicting results. Some of them showed heat transfer enhancement due to flow pulsation, the others reported heat transfer prevention or no impact of flow pulsation on heat transfer. In order to make clear the complicated unsteady flow structure with periodical velocity fluctuation and its effect on heat transfer, it must be necessary to have macroscopic observation and image processing analysis of both the flow and temperature fields. The objective of this study, therefore, is to make clear the pulsating flow structure and heat transfer characteristics based on the visualizations of flow and temperature fields. PIV and color schlieren visualization were applied for flow and temperature fields, respectively, in order to make clear the complicated unsteady flow structure and the mechanisms of heat transfer enhancement⁄prevention due to flow pulsation. Results showed that heat transfer enhancement is obtained due to increasing of local flow rate around the flat plate induced by the large scale circulation in the duct and pulsating amplitude strongly influences such flow structure.
- 2011-01-01