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Journal of Flow Visualization and Image Processing

ISSN for PRINT: 1065-3090

Institutional price:	$586.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2005, Volume12

138 pages

DOI: 10.1615/JFlowVisImageProc.v12.i3

Issue price - $154.00

FORMATION OF RETURN FLOWS IN MIXED CONVECTIVE GAS FLOW OVER A MODEL HEATED SUBSTRATE

Jyh-Long Tuh
Department of Air-Conditioning and Refrigeration Engineering, Chin Min Institute of Technology, Miaoli, Taiwan 35153, R.O.C.

ABSTRACT

An experimental flow visualization has been carried out here to investigate the transient return flow formation in mixed convection of gas over a heated circular plate embedded in the bottom of a horizontal flat duct, simulating that in a horizontal longitudinal flow reactor. The results reveal that shortly after the transition is started the forced flow is first reversed by the buoyancy force to move upstream in the region near the duct sides just above the outer edge of the heated plate and there are two small return-flow zones in the duct. Then, the forced flow over the entire upstream edge of the heated plate is reversed. Because of the circular geometry of the heated plate, a semicircular return-flow zone appears surrounding the whole upstream edge of the heated plate. This upstream return flow later gradually approaches a steady state. Besides, a downstream unsteady return-flow zone that appears slightly later than the upstream one is also observed in the duct. The two return-flow zones do not contact with each other.