The effects of wettability on the flow pattern and rising gas velocity of gas-liquid two-phase flow in vertical pipe

In the steelmaking processes the wall material is chosen to be poorly wetted by molten steel to prevent contamination of the molten steel. Information on gas-liquid two-phase flows in a poorly wetted pipe however is very limited. In this water model study the flow pattern, the rising velocities of slugs and bubbles, and liquid flow near the outlet of the pipe were experimentally investigated. The shape and size of bubbles and slugs were affected by the wettability, but the boundary between the slug flow and bubbly flow regimes was not sensitive to the wettability. The rising velocities of bubbles and slugs became higher in the poorly wetted pipe than in the wetted pipe for a low water flow rate. At the outlet of the poorly wetted pipe, periodic generation of small bubbles was observed. The liquid flow near the outlet was measured with particle image velocimetry (PIV). The poorly wetted pipe promoted the horizontal spread of the liquid flow issuing from it.