用PIV测试涡旋波流场的速度和剪应力分布

采用PIV瞬态流场测试技术,对二维槽道中的涡旋波流场不同相位上的速度分布和应力分布进行了测试和计算,本文定量地描述了槽道中涡旋波的形成过程及发展规律。通过调整振荡流的振幅和活塞行程,分析了Re数和Sr数对涡旋波流动的影响,得出了槽道内剪应力的分布状况以及平均剪切应力的周期性变化规律。深入分析了涡旋波流场强化传递现象的本质。

On The Measurement of Velocities and Stress in Vortex Wave Field with Particle Image Velocimetry

A technology for direct experimental measurement of velocity vectors and stress distributions in vortex wave field formed in a two dimensional channel with the time-reserved particle image velocimetry(PIV) is presented.The technique can gain a time series of spatial velocity maps for several phases.The results,compared with several thousands such maps,illustrate in detail the variations of the velocity and stress in the channel over a range of oscillation amplitudes and piston stokes and provide a deep insight into the mixing,vortex convection and transport mechanism in such a device.The formation,development and the disappearance process of the vortex wave is described quantificationally.Analysis shows that the vortex wave flow can appear in the channel under moderate Sr and Re numbers.The size and number of the vortices in the field depend strongly on Sr number but weekly on Re number.The stress distribution in the channel and the periodical characteristic of the mean stress vs.time is rendered.