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ISSN Online: 2377-424X

ISBN Print: 0-85295-345-3

International Heat Transfer Conference 10
August, 14-18, 1994, Brighton, UK

UNSUBMERGED JET IMPINGEMENT HEAT TRANSFER AT LOW LIQUID SPEED

Get access (open in a dialog) DOI: 10.1615/IHTC10.1070
pages 59-64

Résumé

The heat transfer between a round unsubmerged water jet normally impinging from above on a flat horizontal heated surface was experimentally studied in a range of low jet velocities, in operating conditions not yet reported in the open literature. A range of Re from 10000 to 50000 was investigated, with pipe-type nozzles of 10, 14 and 17 mm inner diameters at a distance from the plate ranging from 6 to 20 diameters. A free jet at low Froude numbers exhibits a cross-area contraction in the flow direction and a consequent increase in the mean velocity which heavily affects the heat transfer rate on the wall at the stagnation point. After developing a simple one-dimensional model of the jet motion, only accounting for the effect of gravity, a new and successful way of correlating the heat transfer data at low jet velocity is proposed. The need of accounting for the jet parameters (diameter and velocity) close to the surface, instead of those at the nozzle exit, is clearly emphasized.