扩散角对文丘里管内湍流影响的试验研究

为研究扩散角对文丘里管内湍流的影响，采用立体粒子图像测速技术分别对扩散角度为10°、12.5°、15°以及20°的文丘里管扩散段区域进行了测量，得到了平均速度分布，并通过瞬时速度场的统计分析得到了扩散段湍动能分布情况。研究表明，不同扩散角度的文丘里管扩散段内平均速度在截面直径方向成轴对称的单峰分布，湍动能在截面直径上成轴对称的双峰分布，在各试验工况下扩散段内均发生流动分离现象。随扩散角度增加，湍动能峰值增加，主流区径向宽度未发生变化，分离流区径向宽度增加，但对分离流区所占比例的影响较小，高湍动能区变宽；随着雷诺数的增加，湍动能峰值增加，主要由轴向雷诺应力引起，分离流区所占比例略有降低，但主流区和分离流区分布变化较小。此研究为高雷诺数不同角度的文丘里管流场研究提供了实验基础。 

Experimental Study on Effect of Diffusion Angle on Turbulence in Venturi Tube

In order to study the effect of the diffusion angle on the turbulence in the venturi tube, in this work, the stereo-particle image velocimetry is used to measure the transient velocity of the diffusion part of venturi tube, which diffusion angle is 10°, 12.5°, 15°and 20°, respectively, and the time-averaged velocity is obtained. Based on the transient velocity of the diffusion part of the venturi tube, the distribution of turbulent kinetic energy in the diffusion section is obtained by statistical analysis of the instantaneous velocity field. It is shown that the average velocity in the diffusion section of the venturi tubes of different structures presented an axisymmetric single peak distribution in the direction of the section diameter, and the turbulent kinetic energy presented an axisymmetric double peak distribution in the section diameter. Flow separation can be observed in all experimental condition. With the increasing of the diffusion angle, the largest turbulent kinetic energy increases, but the radial width of the main flow zone does not change, and the radial width of the separation flow zone increases, but the effect on the proportion of the separation flow zone is small, and the high turbulent kinetic energy zone widens. With the increasing of Reynolds number, the peak value of turbulent kinetic energy increases, which is mainly caused by the axial Reynolds stress, and the proportion of separated flow area decreased slightly, but the distribution of main flow area and separated flow area changes little. This study provides an experimental basis for studying the flow field of the venturi tube with high Reynolds number at different angles.