后台阶分离再附湍流流动的实验研究

Experimental Investigation on the Turbulent Separated and Reattaching Flow over Backward-Facing Step

采用激光粒子图像速度仪(PIV)对低速水槽中二维后台阶分离再附湍流流动进行了系统的实验研究.通过大量重复高空间分辨率瞬态速度场测量,获得了时均再附点位置和时均速度场.对实验结果进行统计分析得到了流向、法向速度分量的脉动场、雷诺应力场和展向涡量场,并给出了小涡结构配对、合并和大尺度相干旋涡结构形成过程中所出现的流动特征.

Two-dimensional separated and reattaching turbulent flow over a backwark-facing step in a low-speed water channel was extensively investigated using Particle Image Velocimetry (PIV). Time-averaging reattaching position, velocity field and spanwise vorticity field were revealed. Turbulence intensity field and Reynolds stress field were delineated using statistical analysis based on a large number of measured velocity vector fields. Flow characteristics involved in amalgamations of small vertices and formation of large-scale coherent structures were disclosed.