Three-dimensional vortex flow near the endwall of a short cylinder in crossflow: Stepped-diameter circular cylinder
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Publication Details
Author list: Chen S.B., Sanitjai S., Ghosh K., Goldstein R.J.
Publisher: Elsevier
Publication year: 2012
Journal: Applied Thermal Engineering (1359-4311)
Volume number: 40
Start page: 36
End page: 47
Number of pages: 12
ISSN: 1359-4311
eISSN: 1873-5606
Languages: English-Great Britain (EN-GB)
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Abstract
The effect of geometry on the flow around a cylinder in crossflow is investigated in this study. Three different stepped-diameter circular cylinders (SDCC s) with varying step heights are used. Extensive flow visualization using the oil-lampblack and smoke-wire techniques and near wake velocity measurements using a hotwire anemometer reveal complex secondary flows on and around the SDCC. Six vortices are observed in the horseshoe vortex system near the cylinder-endwall junction and six additional vortices are found in the step-induced vortex system on the step surface. Based on these experimental results, new secondary flow models are proposed. The step-induced vortices separate from the step surface at both sides and move toward the endwall, washing down the sides of the top/bottom larger diameter cylinders and interact with the separated shear layer and horseshoe vortices. In this process, they modify the near wake flow significantly: they produce an increase in velocity near the endwall region (below the step) and a decrease in velocity near the mid-span region, even altering the oscillatory behavior of the wake. ฉ 2012 Elsevier Ltd. All rights reserved.
Keywords
Flow visualization, Horseshoe vortex, Secondary flow, Stepped-diameter circular cylinder, Uniform-diameter circular cylinder
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