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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

EXPERIMENTAL STUDY OF THE DISSIMILARITY BETWEEN HEAT TRANSFER AND DRAG AT DIMPLED SURFACES IN THE FLOW, DISTURBED BY THE CYLINDER ROD

Get access (open in a dialog) DOI: 10.1615/IHTC16.hte.023015
pages 5267-5274

Résumé

In this paper we present the results of an experimental study of the dissimilarity between heat and momentum transfer on smooth and dimpled surfaces in the channel with the flow, disturbed by the cylinder rod. In experiments, an 8-mm-diameter rod was placed in a slotted channel (height is 30 mm). On one of the walls of the channel were installed floating elements, one of which was coated with dimples. The position of the rod along the channel height was varied. The drag coefficients were determined by direct weighing of the models using one-component strain gauge balance. Heat transfer coefficients were determined by means of the unsteady heat transfer method using the IR camera. It is obtained that the maximum local heat-transfer enhancement for a smooth and dimpled surfaces (up to 2.64 and 3.2 times respectively) is achieved near the reattachment point of the flow with the gap between the wall and the rod of 4 mm. The values of the relative drag coefficients (referred to the drag coefficient measured in a channel without a rod) averaged over the area of the floating elements for smooth surfaces and dimpled lied in the range from (-1.7)-(2.0) and (-2.25)-(2.35) respectively (depending on the Reynolds number and the position of the rod). At a distance from the cylinder downstream, parameters of the flow tended to values corresponding to the undisturbed flow. The values of the Reynolds Analogy Factor for the smooth and dimpled surfaces were in the range of 0.9-7.75 and 0.9-7 respectively.