论文标题
浮力驱动的气泡流：在异质状态下操作的气泡柱中速度的缩放
Buoyancy driven bubbly flows: scaling of velocities in bubble columns operated in the heterogeneous regime
论文作者
论文摘要
重新审视了异质状态中气泡柱的流体动力学。我们从宜人的纵横比以很大的纵横比以大纵横比的高度分析来表明，浮力使惯性平衡，并且速度比例为$（gd \ varepsilon）^{1/2} $，其中$ d $是气泡柱直径，$ \ varepsilon $ \ varepsilon $ void fraction $ the void fraction $ g $ graveritations callitational Accelerations。 从$ {\ cal {o}}（10^3）$ 0.4 $ m直径列的新实验中，$粒子reynolds数字气泡，并且从对已发布的数据的详细分析中，我们确认自组织在异构型中占主导地位，并且液体流量仅由列直径$ d $ d $ d $。此外，直接的液体和气体速度测量表明，相对速度在异质性方面的终端速度$ u_t $以上，并且在非常大的气体表面速度$ v_ {sg} $上倾向于$ \ sim 2.4 u_t $。所提出的速度缩放显示可用于液体和气体平均速度及其标准偏差。此外，发现它在多种条件下有效，对应于弗洛德号$ fr = v_ {sg}/（gd）^{1/2} $从0.02到0.5。然后，讨论了这种比例对合并媒体的相关性。此外，根据在异质制度开始时使用Zuber \＆Findlay方法成功预测了空隙分数，我们展示了空隙分数与$ fr $的相关性。最终提出了进一步的研究，以将相对速度的增加与已知存在于异质状态存在的中尺度结构联系起来。
The hydrodynamics of bubble columns in the heterogeneous regime is revisited. Focusing on air-water systems at large aspect ratio, we show from dimensional analysis that buoyancy equilibrates inertia, and that velocities scale as $(gD\varepsilon)^{1/2}$, where $D$ is the bubble column diameter, $\varepsilon$ the void fraction and $g$ the gravitational acceleration. From new experiments in a $0.4$m diameter column with ${\cal{O}}(10^3)$ particle Reynolds number bubbles and from a detailed analysis of published data, we confirm the self-organization prevailing in the heterogeneous regime, and that the liquid flow rate is only set by the column diameter $D$. Besides, direct liquid and gas velocity measurements demonstrate that the relative velocity increases above the terminal velocity $U_T$ in the heterogeneous regime, and that it tends to $\sim 2.4 U_T$ at very large gas superficial velocities $V_{sg}$. The proposed velocity scaling is shown to hold for liquid and gas mean velocities and for their standard deviations. Furthermore, it is found to be valid over a wide range of conditions, corresponding to Froude numbers $Fr=V_{sg}/(gD)^{1/2}$ from 0.02 to 0.5. Then, the relevance of this scaling for coalescing media is discussed. Moreover, following the successful prediction of the void fraction with a Zuber \& Findlay approach at the beginning of the heterogeneous regime, we show how the void fraction is correlated with $Fr$. Further investigations are finally suggested to connect the increase in relative velocity with meso-scale structures known to exist in the heterogeneous regime.
