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首页> 外文期刊>International Journal of Multiphase Flow >Wake-induced relative motion of bubbles rising in line
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Wake-induced relative motion of bubbles rising in line

机译：唤醒引起的气泡沿直线上升的相对运动

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摘要

The motion of nearly spherical air bubbles rising in a column in stagnant water is measured at Reynolds numbers ranging from ReD = 0.2 to 35. The relative velocity is found to be dependent on the distance between bubbles and on their diameter. For the larger bubbles, the relative velocities increased with decreasing distance, reaching maximum values just prior to contact. For the smaller bubbles, the relative velocity decreased prior to coalescence. For the entire range of Reynolds number considered, the wake-induced relative motion results in collisions between bubbles. These collisions culminate in coalescence at the present levels of water purity and surface tension. In order to understand the basic features of the measured relative motion, a simple model is developed. It is based on the known flow field and viscous-wake structure around a single bubble, and examines how other bubbles move within this field. Oseen flow for Re 1 and potential flow with a thin wake for Re 1 are assumed. The approximations involved limit the validity of the model to distances larger than a few bubble diameters. The general agreement between the predictions and experimental results suggest that the model contains the most relevant mechanisms that govern the interaction, within its range of validity. Prior analyses for non-deformable bubbles that predicted an equilibrium due to balance between pressure gradients and wake-induced motion, are contradicted by the observed coalescence. A possible cause for the discrepancy is bubble deformation.
机译：在ReD = 0.2到35的雷诺数下，测量了停滞水中在柱中上升的近球形气泡的运动。发现相对速度取决于气泡之间的距离及其直径。对于较大的气泡，相对速度会随着距离的减小而增加，并在接触前达到最大值。对于较小的气泡，相对速度在聚结之前降低。对于所考虑的整个雷诺数范围，尾流引起的相对运动会导致气泡之间发生碰撞。在当前水纯度和表面张力水平下，这些碰撞最终导致聚结。为了了解所测量的相对运动的基本特征，开发了一个简单的模型。它基于已知的流场和围绕单个气泡的粘性尾流结构，并检查其他气泡在该场中如何运动。假设Re 1出现了可见流，而Re 1出现了较弱的尾流。涉及的近似值将模型的有效性限制为大于几个气泡直径的距离。预测结果与实验结果之间的一般共识表明，该模型包含在有效性范围内控制相互作用的最相关机制。先前的不可变形气泡的分析由于压力梯度和尾流引起的运动之间的平衡而预测了平衡，这与观察到的合并相矛盾。差异的可能原因是气泡变形。

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