The effect of mesh-type bubble breaker on two-phase vertical co-flow

The influence of a mesh-type bubble breaker in a two-phase vertical co-flow is experimentally investigated using high-speed imaging. A range of liquid and gas flow rates were considered that correspond to the gas-to-liquid flow rates ratios (GLRs) from 0.05 to 39.6 covering bubbly, slug and churn flow regimes. The mesh-type bubble breaker was found to be effective in reducing the size of nozzle-generated bubbles in two-phase co-current vertical flow. The bubble size reduction by 50%-70% is observed in the presence of the mesh-type bubble breaker compared to that without a bubble breaker. The results also show that at a given GLR, the mesh-type bubble breaker delayed the flow regime transition compared to that without a bubble breaker. A Froude number correlation was proposed to predict the mean bubble size downstream of the bubble breaker for the bubbly flow regime, which accurately predicted the bubble size over a range of bubble breaker parameters. It is observed that the geometry of the bubble breaker influence the two-phase flow regime transition. At low liquid flow rates, small pore size of the breaker was found to be effective. This effect diminishes at higher liquid flow rate due to the elongation of the bubbles by the liquid inertia. The results also show that a longer bubble breaker located closer to the bubble generating nozzle is the most effective in producing bubbly flow over a longer range of gas-liquid flowrates ratios.