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First Thermal and Fluids Engineering Summer Conference

ISSN: 2379-1748
ISBN: 978-1-56700-430-4

HEAT TRANSFER OF DEVELOPING FLOW IN THE TRANSITIONAL FLOW REGIME

DOI: 10.1615/TFESC1.fnd.012660
pages 1051-1063

Marilize Everts
University of Pretoria, Department of Mechanical and Aeronautical Engineering, Pretoria, South Africa

Josua Petrus Meyer
Department of Mechanical and Aeronautical Engineering, University of Pretoria, Pretoria, Private Bag X20, Hatfield, 0028, South Africa


KEY WORDS: transitional flow, developing flow, heat transfer, flow regime nomenclature

Abstract

Limited research has been done on tube flow in the transitional flow regime. These studies considered either fully developed flow, or average measurements of developing flow across a tube length. No research has been done with the focus on developing flow in smooth tubes in the transitional flow regime. Therefore, the purpose of this study was to experimentally investigate the heat transfer characteristics of developing flow in the transitional flow regime. The test section was a smooth circular tube with an inner diameter and length of 11.52 mm and 2.03 m, respectively, and was heated with a constant heat flux. Approximately 300 measurements were taken at Reynolds numbers between 500 and 10 000 at heat fluxes of 6.5 kW/m2 and 9.5 kW/m2. Water was used as the test fluid and the Prandtl number ranged between 3 and 7. It was found that both the start and end of transition were delayed along the tube length and the width of the transition region (difference between the critical Reynolds number and start of the low-Reynolds-number-end regime) decreased slightly along the tube length, as the flow developed. Transition was also delayed with increasing heat flux, but secondary flow effects had no significant influence on the width of the transition region.

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