添加筛网对减阻流体湍流空间结构的影响

应用相位多普勒测速仪（PDA）和粒子图像测速仪（PIV）对添加筛网后的十六烷基三甲基氯化铵（CTAC）减阻流体湍流流场进行试验研究，得到了减阻流体的速度脉动分布以及在筛网后不同位置的减阻流体湍流速度分布和平均速度分布．结果表明：添加筛网后，减阻流体的速度脉动明显增强，随着离网格距离的增大，速度脉动逐渐减弱最后趋于稳定；在靠近筛网处，平均速度分布趋向于和水的速度平均分布相一致，而在远离筛网处，其平均速度分布趋向于减阻流体不加筛网时的平均速度分布；随着筛网层数的增多，靠近网格处减阻流体湍流核心区明显增大，同时在近壁面处出现强烈的漩涡波动，瞬间速度空间分布趋近于水的速度空间分布，在远离筛网处，CTAC减阻流体过渡层明显增厚，在湍流核心区和过渡层之间出现小漩涡，表明被金属筛网破坏的胶束重新缔合成棒状胶束，恢复了减阻性能．

The Effect of Mesh-Addition on the Turbulence Spatial Structure of Drag-Reducing Flow

The turbulence characteristics of a surfactant solution in changing from drag-reducing flow to turbulent flow inside two-dimensional smooth channel and in changing from mesh plug were investigated through phase Doppler anemometry (PDA) and particle image velocimetry(PIV) system.It is concluded that the turbulent velocity fluctuation of the drag-reducing flow increases obviously with mesh-addition,and gets more and more weakened along the flow.The mean velocity profiles of the surfactant solution are similar to that of the water near the mesh plug,whereas the mean velocity profile of the surfactant solution far from the mesh is consistent to that of the surfactant solution flow in smooth channel.The size of the core region of the surfactant solution is obviously larger near the mesh plug than away the mesh plug,and there are intense eddies near the wall.The bubble micelle is assembled to the rod-like micelle,with the result of thickening the intergrades region and of suppressing the formation of the large eddies far from the mesh plug.