Horizontal turbulent channel flow interacted by a single large bubble
Horizontal turbulent channel flow interacted by a single large bubble
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DOI：
10.1016/j.expthermflusci.2014.02.022
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发表时间：
2014-05
影响因子：
3.2
通讯作者：
Yoshihiko Oishi;Y. Murai
中科院分区：
文献类型：
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作者：
Yoshihiko Oishi;Y. Murai
用粒子跟踪测速技术测量了水平壁湍流边界层中单个大气泡对流场的影响。我们着重研究与边界层厚度相当的中间气泡尺寸，以找出改变原始湍流剪应力场的事件。计算结果都是在拉格朗日网格系统上用与单相流动有关的量表示的，而单相流动是随气泡运动的。测量结果显示，气泡产生的二次流围绕自身，这涉及双辊涡，分离的气泡表面上，和强烈的扫流。对于一个小的和近球形的气泡，扫流提供了强大的，以加强湍流动量交换，而检测到一个大的扁平气泡的负交换。该有效长度大致对应于气泡的尺寸。
Flow field modified by a single large bubble in a horizontal wall turbulent boundary layer is measured by particle tracking velocimetry. We focus on intermediate bubble size being comparable to the thickness of boundary layer to find out the events altering the original turbulent shear stress field. The results are all presented by quantities relative to single phase flow on Lagrangian grid system that moves with the bubble. The measurement results reveal bubble-produced secondary flow around itself, which involves twin roll vortices, separation on the bubble surface, and strong sweeping flow. For a small and nearly spherical bubble, the sweeping flow is provided strongly to enhance the turbulent momentum exchange while negative exchange is detected for a large flat bubble. This effective length approximately corresponds to the size of the bubble.