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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/45992

    Title: Effects of velocity fluctuations on heat transfer enhancement
    Authors: Chen, Tseng-Yuan;Du, R. K.
    Contributors: 淡江大學航空太空工程學系
    Keywords: Approximation theory;Boundary layers;Heat convection;Heat transfer coefficients;Kinetic energy;Nusselt number;Temperature measurement;Thermocouples;Three dimensional;Velocity measurement;Vortex flow;Wind tunnels;Heat transfer enhancement;Turbulators;Velocity fluctuations;Heat transfer;heat transfer;mathematical analysis;Nusselt number;velocity;wind tunnel
    Date: 2003-05
    Issue Date: 2013-03-20 16:22:42 (UTC+8)
    Publisher: Heidelberg: Springer
    Abstract: The three-dimensional velocity fluctuation effects on heat transfer enhancement were experimentally investigated using a wind tunnel system and cylinders placed upstream of the test section in the wind tunnel. The cylinders with different diameters were used as turbulators to generate vortical flow motions with three-dimensional velocity fluctuations. A heated plate, part of the tunnel wall, was placed far downstream of the cylinders such that it was subjected mainly to flows with velocity fluctuations but with negligible steady vortical motions. These studies included three-component velocity measurements to characterize the near-wall and cross-section velocity fields and to obtain the turbulent kinetic energy. The temperatures were measured by thermocouples on the heated plate to obtain the convection heat transfer coefficients and the Nusselt numbers. Results indicate that the heat transfer was enhanced by the velocity fluctuations, which is attributed to the modification of boundary layer velocity profiles without the modification of boundary layer thickness. The resulting normalized Nusselt number was approximately a parabolic function of a dimensionless parameter, the product of Reynolds number and normalized turbulent kinetic energy.
    Relation: Experiments in Fluids 34(5), pp.548-555
    DOI: 10.1007/s00348-002-0571-z
    Appears in Collections:[航空太空工程學系暨研究所] 期刊論文

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