Experiment characterization of the influence of wall wettability and inclination angle on bubble rising process using PIV

摘要

Bubble behavior is an important branch of the research field of gas-liquid two-phase flow, and the wall has a significant impact on the rising process of a bubble. In this paper, a visual bubble observation platform with an adjustable wall was built to observe the effect of the wall with different inclination angles and different wettability on bubble rising behavior. During this experiment, particle image velocimetry (PIV) was used to obtain the velocity vector field of water around the rising bubble, Through experiments, the instantaneous and average rising velocity of the bubble as well as the flow field around the bubble under different conditions was obtained, and the morphological change of the bubble during its rising process was found. The experimental results showed that the rising velocity of the bubble under the influence of the hydrophobic wall was obviously faster than that under the influence of the hydrophilic wall. Even when the bubble rose near the hydrophobic wall, it was 34.53% faster than that in the free case. When the bubble contacted the hydrophobic wall, it deformed and adhered to the wall to slip up, but when the bubble contacted the hydrophilic wall, it was bounced off the wall. In addition, when the wall was vertical, the bubble rising close to the hydrophilic wall formed a larger range of wake flow. However, the wake formed by the bubble rising near the hydrophobic wall had a smaller wake range and a weaker wake strength. That is, the hydrophilic wall combined with the rising of bubble would bring better mixing effect to the flow field.

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