Numerical Study Of Bubble Behavior In Vertical Rectangular Narrow Channel

In this paper,Fluent is used and the VOF model for the bubbles motion in two-phase flow is established. The PLIC Front Capturing Method is used to track the motion interface and the motion equation of surface tension is taken into account. Then the motion characteristics of two-dimensional bubbles under the effect of gravity and the condition of swing are explored respectively. The results, which contain the deformation of the bubbles and the effect of surface tension on bubbles' shape in free space, obtained and agree well with the experimental and numerical results of other literatures.Then,in order to study the wall's impact on the bubble,the ascending motion of bubbles with different sizes in a narrow channel is simulated. The characteristics of the deformation process and the flow field around the rising bubbles in narrow channel have been analyzed. It is found that in narrow channel,the bubble is much easier to maintain the circular shape,and the direction of the bubble's wake flow is opposite to that in free space. And the impact of the narrow channel on the bubble's rise velocity has been qualitatively analyzed. In the case of multiple bubbles distributing at the same horizontal level within a narrow channel, the interaction between two bubbles have been studied, the two bubbles are distributed as up and down. The distribution of several bubbles also has been studied. The result reveals that the narrow channel will hinder the bubbles' combination and in still water, the bubbles with different relative distances from the wall have different velocities, in a short while, the bubbles distribution presents as "U" shape.Since the swing situation is very common in engineering, the motion characteristics of a bubble in swing situation are simulated. The momentum equation in dynamic grid and the stress of fluid under the condition are analyzed, the applicability of dynamic mesh model in the case of swing is verified. Two cases with different swing center locations are simulated.By analyzing the simulation results, detailing the effects of swing condition on the bubble shape, flow field, the track and the interaction, it is found that swing would make the bubble shape become more flat, and the flow field and track would be shifted due to the additional speed that generated by swing.In the swing condition, the motion of bubbles in narrow channels is simulated. It is found that the narrow channel can weaken the impact of the swing on bubble deformation and bubble trajectory. Two cases are simulated that the wall locates in the positive direction and the negative direction with respect to the bubble. The results show that when the wall is located in the positive direction of the bubble, the wall has a greater impact on the bubble.