Two-phase flow pattern identification in minichannels using image correlation analysis

In the field of two-phase flow image analysis many methods require a complex experimental setup, its demanding calibration and an advanced image analysis process. Thus, in the paper a noncomplex approach to two-phase flow pattern identification involving high speed recording and simple, unfiltered images analysis was proposed. The coefficient which is the percentage measure of rate of gas distribution changes in time inside the minichannel was defined. Such coefficient was used to identify the two-phase flow patterns in water-glycerol and air flow in 3 mm circular, horizontal minichannel. It was shown that the value of a coefficient is suitable for a flow pattern map reconstruction. The correlation analysis of the flow pattern dynamics provided sufficient information of two-phase flow patterns. The following two-phase flow patterns were identified: minibubbles, bubbles, cap bubbles with slugs and slugs. The maximum fluctuation of the proposed Vv coeffcient value was equal to 36% for minibubbles flow and minimum to 3% for slugs flow and cap bubbles with slugs flow. Additionally, the method was tested for different two – phase flows (water – air) including boiling flow. Finally, it can be concluded that the proposed algorithm has the potential to be applied for two-phase flows inside minichannels.