流体微团作用与流动结构变化试验分析

为了分析湍流流动中流体微团所受作用与流动结构变化之间的关系,在槽道湍流边界层中通过粒子图像测速(PIV)技术,拍摄流向-展向平面流场,采用本征正交分解方法提取湍流流动中不同尺度的含能结构。采用矢量象限组合分析方法,将流场中流体微团所受作用分为肿胀作用、弯曲作用和旋转作用。结果表明:流动结构变化机理与这3种作用相关;肿胀型条带间流体微团受到的主要作用是弯曲作用,在弯曲作用下直条带会弯曲,弯曲条带在肿胀作用下汇聚成肿胀型条带;随着流动结构尺度减小,旋转作用逐渐增大。

Test Analysis of Fluid Micelle Action and Flow Structure Change

In order to study the relationship between the action of fluid micelle and the change of flow structure in turbulent flow,the flow-to-spread plane flow field was captured by Particle Image Velocimetry(PIV) technique in the turbulent boundary layer of the channel.Energy-bearing structures at different scales in turbulent flow were extracted by means of proper orthogonal decomposition. By means of vector quadrant combined analysis,the actions of fluid micelle in the flow field were divided into swelling,bending and rotation. The results show that the mechanism of flow structure change is related to these three actions. The main action of the fluid micelle between the swelling bands is bending. The straight band bends under the action of bending,and the bending band converges into a swelling band under the action of swelling. As the scale of the flow structure decreases,the rotation gradually increases.