暖季强降雨对多年冻土南界斜坡路基稳定性影响分析

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.

TURBULENT CHARACTERISTICS OF CTAB SURFACTANT SOLUTION FLOWS IN TURBULENT BOUNDARY LAYERS

In order to clarify the drag-reducing mechanism with a surfactant solution, the turbulent characteristics of CTAB surfactant solution flow for a zero-pressure gradient boundary layer on flat plates is investi- gated by using a two dimensional LDV system. The results obtained are found as follows compared with the corresponding statistics for water flow. The viscous sublayer for the surfactant solution is thicker than that for water flow. The mean streamwise velocity profile falls between those of laminar and turbulent velocity profiles in Newtonian fluid flow. The peak of the streamwise turbulence intensity is smaller than that for water, the location where it appears is further away from the wall and the second peak appears near the center of the boundary layer. The wall-normal turbulence intensity is greatly suppressed and the Reynolds shear stress is almost zero throughout the boundary layer, which shows that the surfactant solution can weaken the correlation between the two components of velocity fluctuation, thus, it can reduce the production of turbulent kinetic energy so that the driven power for transporting fluids can be saved.