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ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

HEAT TRANSFER FROM SPHERES UP TO Re = 6 × 106

Get access (open in a dialog) DOI: 10.1615/IHTC6.1480
pages 341-346

摘要

Heat and mass transfer from a single sphere in forced convective flow has been studied in the range of Reynolds number 1oo < Re < 6 × 106. Up to Re = 1.5 × 105 open wind tunnels were employed. For Re> 1.5 × 105 the tests were carried out in a high pressure wind tunnel which could be pressurized up to 4o bars. The mass transfer experiments are realized with the 10 mm sphere varying the Reynolds number from 100 to 5 × 104. The method of naphthalene sublimation in air (Sc = 2.53) was applied. For the heat transfer tests electrically heated spheres, 16 and 6o mm of diameter, were used. The local skin friction and pressure distribution was measured by means of a 175 mm sphere, while the drag was determined by a strain gauge balance incorporated in a 2oo mm - sphere. The mass transfer results are in very good agreement with the heat transfer results. Beyond the critical Re-number where the length of the turbulent boundary layer is observed to increase due to the upstream shift of the transition point, also the heat transfer increases continuously. Particularly, the experimental results of the total Nusselt number, of the drag coefficient, and of the local pressure and skin friction distribution are reported.