Studies Of Flow Structures And Parameters Of The Votex Wave Using PIV

The vortex wave is defined as the wave of the vorticies and the assosiatied wavy core flow. Vortex wave can generate very effective mixing under the condition of laminar flow. Compared with traditional mass-transfer method using turbulent flow, its shear rate and power dissipation are rather low. If combined with membrane technique, it becomes a new high efficient method of mass transfer. So it is worth to study in details. In this paper, the vortex wave is measured using PIV technique. The forming, developing and disappearing process, and the characteristics of vortex wave are studied. The following contents are discussed:A set of experimental equipment is established, which can obtain obvious vortex wave flow. The charateristics and influence parameters of vortex wave flow are analyzed at different Reynolds number and Strouhal number. A serial of vortices are formed in channel and they expand as time increases. When flow's direction is changed, the vortices are pushed to the other wall and disappeared quickly, and then the same process was repeated. At a fixed Reynolds number, as Strouhal number is decreased, vortices' quantity, size and wavelength are all increased, while vorticity and shear rate are decreased. Reynolds number has little influence on the vortex's size and moving track. As Reynolds number is increased, the quantity of vortices is increased first and then decreased, while both vorticity and shear rate are increased nearly in line.What's more, channels with different height and expand angle are also studied. Vortex wave flow can be formed more easily in channels with lower height rather than higher height, right-angle rather than 45 Expanding method.The paper also analysis the vortex wave's mixing characteristics and its forming mechanism. The results of experiment and numerical simulation are compared in the paper, which can be relatively consistent.The result of the paper is useful for study the dynamics characteristics of vortex wave. What's more, this paper is also helpful for the study of vortex wave's mass transfer.