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ISSN Online: 2377-424X

ISBN Print: 0-89116-299-2

International Heat Transfer Conference 7
September, 6-10, 1982, Munich, Germany

TURBULENT BOUNDARY LAYER HEAT TRANSFER IN THE ENTRANCE REGION OF A PIPE

Get access (open in a dialog) DOI: 10.1615/IHTC7.1450
pages 45-49

Résumé

In the technical applications treating the intensive cooling, the short channnels with small values of l/d very often appear. In this contribution we solve the heat transfer in the very short entrance region by l/d = 4 in the circular tube of the inner diameter d = 50 mm in which the air is flowing with Reynolds numbers from 104 to 105. We suggest a simple mathematical model to calculate the temperature T+ and the heat transfer coefficient in the developing thermal turbulent boundary layer. The problem is formulated mathematically by means of the time-averaged partial differential energy equation for turbulent boundary layer. The fully developed velocity profile is described by the 3-layer scheme, the turbulent thermal diffusivity by two models. The results are presented in the form of T+ = f(y+) and that of Nu = f (Re) for various lenghts l/d.