Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/69909
標題: Characteristics of steady horseshoe vortex system near junction of square cylinder and base plate
作者: Lin, C.
Ho, T.C.
Dey, S.
關鍵字: vortices
boundary layers
cylinders
plates
Reynolds number
wall-mounted cube
convective heat-transfer
turbulent-boundary-layer
mass-transfer
forced-convection
channel flow
laminar
juncture
block
array
期刊/報告no:: Journal of Engineering Mechanics-Asce, Volume 134, Issue 2, Page(s) 184-197.
摘要: This paper presents an experimental investigation on the characteristics of a horseshoe vortex system near the juncture of a square cylinder and a horizontal base plate, using particle image velocimetry and flow visualization technique. Experiments were conducted for Reynolds numbers (based on the free stream velocity and the width of square cylinder) ranging from 2.0 X 10(2) to 6.0 X 10(3). The flow patterns are first classified into four major regimes: Steady horseshoe vortex system, periodic oscillation vortex system with small displacement, periodic breakaway vortex system, and irregular vortex system. The classifications can be demonstrated as a figure of Reynolds number versus the ratio of the height of square cylinder to undisturbed boundary layer thickness. The study then mainly focused on the characteristics of steady horseshoe vortex system (corresponding to Reynolds numbers ranging from 2.0 X 10(2) to 2.5 X 10(3)). The nondimensional characteristics, including the horizontal and vertical distances from the primary vortex core to frontal face of the vertical square cylinder and bottom boundary of the base plate, respectively, the height of stagnation point at frontal face of the square cylinder, and the down-flow discharge as well as circulation of the primary vortex, all increase with increase of the ratio of the height of square cylinder to undisturbed boundary layer thickness. However, they all decrease with the increase of the aspect ratio (i.e., the height-to-width ratio) of the square cylinder. The study provides essential properties of a steady horseshoe vortex system and gives an insight for related engineering applications. It can be served as a basis for more complicated horseshoe vortex systems occurring at high Reynolds numbers.
URI: http://hdl.handle.net/11455/69909
ISSN: 0733-9399
文章連結: http://dx.doi.org/10.1061/(asce)0733-9399(2008)134:2(184)
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