Abstract:

Based on the particle imaging velocimetry（PIV）measurement of single-phase mixing layer flow，the gas-liquid two-phase bubbly mixing layer with the velocity ratio 4∶1 was experimentally investigated with PIV.The Reynolds number based on the velocity difference of two streams and hydraulic diameter of the channel ranged from 4400 to 158400.It was found that the bubbles injection could enhance the instantaneous velocity fluctuation when Reynolds number was small，but it would depress the instantaneous velocity fluctuation when Reynolds number was large.Afterwards the distributions of statistical Reynolds stress were obtained.Reynolds stress existed only in a very narrow region downstream of the mixing layer and increased with increasing Reynolds number.The distribution of Reynolds stress on the downstream cross-section showed that mean Reynolds stress value would decrease with bubble injection and there would be fluctuations on the same cross-section compared with the single-phase case.

Key words:

混合层, 泡状流, 雷诺应力, PIV

摘要：

在单相实验的基础上，使用PIV对不同位置注入气泡的泡状流湍流混合层流动进行实验研究。混合层高低侧流速比为4∶1，基于两股流体速度差和管道水力直径的Reynolds数范围为4400～158400。与单相相比，气液两相混合层流动脉动速度的测量结果表明，在低Reynolds数时气泡的加入会增强混合层的速度脉动，但随着Reynolds数的增大气泡的加入反而会减弱速度脉动。雷诺应力集中在隔板下游一个较窄的区域内，并随Reynolds数的增大而增大。从流动横截面上雷诺应力的分布可以看出，气泡的加入减小了混合层内的平均雷诺应力，并且与单相相比泡状混合层流动在同一横截面上的雷诺应力分布曲线会产生波动。

关键词:

混合层, 泡状流, 雷诺应力, PIV