圆管湍流的近壁涡结构

Near-Wall Structure in a Fully Developed Turbulent Pipe Flow

本文利用流动显示方法研究圆管湍流的近壁涡结构。采用激光诱导荧光技术显示流场。以每秒２５帧的ＣＣＤ摄象机记录近壁流动结构。通过图象时间序列计算纵向涡的平均间距和平均猝发周期。实验结果表明：圆管湍流的近壁结构和平壁湍流结构类似，但是平均间距和猝发周期均大于平壁湍流的相应参数。本文还利用图象处理技术重构近壁涡的空间图象。

This paper investigates the near wall structures of a turbulent pipe flow at Reynolds numbers ranged from 5000 to 10000. The LIF technique is used for the visualization of the flow patterns which are recorded by a CCD camera at the speed of 25 frames per second. The longitudinal vortices and bursting rates are evaluated from the time series of the images. The results show that both average spacing of the longitudinal vortices and mean time interval of the bursts are greater than those at plate wall of turbulent flows. The Fourier Descriptor technique is used for reconstruction of the vortical structures near the wall, it provides a new tool to explore the spatial evolution of the coherent structure.