Gas-liquid two-phase flow in a downward facing open channel

There are certain industrial applications where gas is evacuated from below a solid surface by using vertical grooves. To study this phenomenon experimentally, a solid body with a horizontal gas-generating bottom surface is immersed into a liquid. A downward facing open channel in the form of a rectangular groove is cut into the solid. Gas enters at the lower part of the groove and is evacuated at the two ends. The flow is induced by the buoyancy effect in the channel. The morphology and flow pattern in the downward facing open channel is analysed as a function of the gas flow rate entering the groove. Different flow regimes were identified as the volume fraction of the gas inside the channel was increased. High-speed videography and image processing were used to analyse the flow structure inside the channel and to extract quantitative information such as the volume fraction of the gas and the bubble size distribution. Particle image velocimetry (PIV) and bubble image velocimetry (BIV) were used to study the velocity distribution inside the liquid phase and the velocity of the bubbles.