Vortex detection in flow pattern control of horizontal liquid-liquid flows by PLIF&PIV methods

Horizontal liquid-liquid two-phase flows have universally existed in important industrial production fields such as meteorological, chemical, and aerospace fields. Active flow pattern control is of great significance to reveal the mechanism of flow pattern transitions, so that flow parameters under different flow patterns can be measured more easily and the measurement accuracy can be improved. In this paper, we carried out an experiment of horizontal liquid-liquid two-phase flows. A cylindrical bluff body was inserted into the pipeline to control the flow patterns. Flow images of stratified flow (ST) and stratified wavy flow (SW), and stratified flow with mixing at interface flow (ST&MI) were obtained based on the planer laser-induced fluorescence (PLIF) and particle image velocimetry (PIV) measurement system. Interface height and aqueous phase velocity distribution were extracted and the vortex structure in the aqueous phase was accurately detected based on the third generation of vortex identification method. The morphological evolution characteristics of vortices under different flow conditions were studied, and the interaction regularity among vortices, droplets, and the liquid-liquid interface was investigated.