Visualization and flow regime identification of downward air-water flow through a 12 mm diameter vertical tube using image analysis

Downward co-current air-water flow through a 12 mm diameter tube has been investigated in an indigenously developed test facility having a typical fluid injection and mixing section. The flow has been characterized and the different regimes of the flow have been identified based on extensive analysis of high speed images. Some unique methods have been proposed for processing the images to establish objective ways for identifying the flow regimes considering different scales of the spatial co-ordinates. Several new flow regimes with intermittent behaviour have been observed, while the absence of churn flow is noted. A unique flow regime map pertinent to the present study has also been proposed.