Characteristics of low-speed streaks and vortex structures in drag-reduced turbulent channel flow investigated by stereoscopic PIV
Characteristics of low-speed streaks and vortex structures in drag-reduced turbulent channel flow investigated by stereoscopic PIV
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立体PIV研究减阻湍流通道流中低速条纹和涡结构的特征
DOI：
10.1115/imece2004-61023
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
K. Hishida
中科院分区：
文献类型：
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作者：
Feng;T. Segawa;Y. Kawaguchi;K. Hishida
在本研究中，我们采用立体粒子图像测速（SPIV）来研究添加表面活性剂的减阻湍流通道流中的湍流结构特征。测试的减阻液是保持在 25°C 的 CTAC（十六烷基三甲基氯化铵）/NaSal/水系统，CTAC 浓度为 30 ppm。分别在流向-展向和壁-法向-展向平面上对水流(Re=1.1×105)和CTAC溶液流(RE=1.5×105，减阻54％)进行SPIV测量。发现一系列壁法线涡核与低速条纹对齐，条纹两侧涡度信号相反，CTAC溶液流的涡度与水流相比平均降低约一个数量级；溶液流中低速条纹之间的展向间距增加了约42%。使用添加剂也降低了出现在壁法线翼展平面中的涡核的流向涡度。版权所有 © 2004 ASME
In the present study, we employed stereoscopic particle image velocimetry (SPIV) to investigate the characteristics of turbulence structures in a drag-reduced turbulent channel flow with addition of surfactant. The tested drag-reducing fluid was a CTAC (cetyltrimethyl ammonium chloride)/NaSal/Water system maintained at 25°C, having a 30-ppm concentration of CTAC. SPIV measurement was performed for a water flow (Re=1.1×105 ) and a CTAC solution flow (RE=1.5×105 with 54% drag reduction) in both the streamwise-spanwise and wall-normal-spanwise planes, respectively. A series of wall-normal vortex cores were found to align with the low-speed streaks with opposite vorticity signals at both sides of the streaks and with the vorticity decreased averagely by about one order in CTAC solution flow compared with water flow; the spanwise spacing between the low-speed streaks in the solution flow is increased by about 42%. The streamwise vorticity of the vortex cores appearing in the wall-normal-spanwise plane was also decreased by the use of additives.Copyright © 2004 by ASME