Experimental study on flow field around a cylinder sheltered by a porous cylinder

• Main Authors: Tso-HsinWang, 汪作新
• Other Authors: Chin-Kun Huang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/84258866698598227105

碩士 === 國立成功大學 === 水利及海洋工程學系 === 102 === The change in flow characteristics around a cylinder sheltered by a porous cylinder was investigated experimentally. The models of these two cylinders were mounted on a flat-bed of a horizontal flume and velocities around them were measured by using an Acoustic Doppler Velocimeter (ADV). In order to examine the effects of diameter of the upstream porous cylinder on the studied flow, seven different diameters were tested. It was shown that porous cylinder’s diameter has substantial effects on the flow characteristics around the downstream cylinder. Time-average velocities were calculated to study the main flow feature. In addition, turbulence statistics in velocity field and the related power-spectrum analysis were also presented. The result clearly demonstrates that in comparison with bare cylinder, the turbulence intensities, turbulence kinetic energy and flow velocities around cylinder decrease remarkably when the porous cylinder’s diameter is larger than the downstream cylinder. Consequently, the flow structure around the cylinder has become less complex. It is thus suggested from this result that Db/Dp ≥1 would be preferable in flow characteristics.