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中文核心期刊

边界层中CTAB表面活性剂减阻水溶液的湍流特性

Turbulent characteristics of ctab surfactant solution flows in turbulent boundary layers

  • 摘要: 为阐明表面活性剂水溶液的减阻作用,使用LDV对零压梯度的二维湍流平板边界层中的CTAB表面活性剂水溶液的湍流特性进行了实验研究. 结果表明:与牛顿流体相比,CTAB水溶液边界层的粘性底层增厚;主流时均速度分布有被层流化的趋势,对数分布域上移;主流方向速度湍动强度峰值减小,且远离壁面,在靠近边界层中部,出现第2峰值;垂直于主流方向的速度湍动强度受到了大幅度抑制,雷诺应力沿着边界层厚度方向几乎为零. 结果说明CTAB水溶液具有减弱湍流湍动各个成分相关度的作用,从而能够使雷诺应力降低、湍流能量生成项减小最终降低流体的输送动力.

     

    Abstract: In order to clarify the drag-reducing mechanismwith a surfactant solution, the turbulent chara-cteristics of CTABsurfactant solution flow for a zero-pressure gradient boundary layer on flatplates is investigated by using a two dimensional LDV system. The resultsobtained are found as follows compared with the corresponding statistics forwater flow. The viscous sublayer for the surfactant solution is thicker thanthat for water flow. The mean streamwise velocity profile falls betweenthose of laminar and turbulent velocity profiles in Newtonian fluid flow.The peak of the streamwise turbulence intensity is smaller than that forwater, the location where it appears is further away from the wall and thesecond peak appears near the center of the boundary layer. The wall-normalturbulence intensity is greatly suppressed and the Reynolds shear stress isalmost zero throughout the boundary layer, which shows that the surfactantsolution can weaken the correlation between the two components of velocityfluctuation, thus, it can reduce the production of turbulent kinetic energyso that the driven power for transporting fluids can be saved.

     

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