Abstract Fluidized beds are of great importance in various industries and presence of bubbles significantly influence their efficiency. In order to gain a more accurate vision on the dynamics of a single bubble in fluidized beds, formation, rising, and eruption of a single bubble in a rectangular fluidized bed were studied by CFD-DEM and validated by experimental data. Single bubble in a 2-D rectangular fluidized bed at different stages, from forming to erupting, was modeled by the CFD-DEM technique. Investigating the pressure fluctuations and bubble dynamics were the main focus of this study. Pressure fluctuations were measured using a pressure transducer and a high-speed digital camera was used to record the whole bubbling process, from bubble formation on the distributor to its eruption at the surface. Validation was performed by comparing experimental and simulated bubble diameter and pressure fluctuations. CFD-DEM results such as particles and gas velocity vectors, bed voidage and pressure contours revealed new information on characteristics of pressure fluctuations which was not possible to gain by experimental studies. In the formation stage, due to the compression wave from injection, particles accelerate and bed reaches to a packed state. This causes a pressure peak in the pressure. At the beginning of bubble formation on the distributor, pressure decreases and when the bubble detaches from the distributor, pressure reaches a minimum. While bubble is rising through the bed, pressure increases again, however, it remains below zero because of the lower voidage behind the bubble in comparison to pre-injection state and the greater velocity of the gas above and below the bubble. By bubble eruption, another small compression wave is seen in the pressure.

中文翻译：

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通过 CFD-DEM 研究流化床中的气泡动力学

摘要 流化床在各行各业中具有重要意义，气泡的存在对其效率有显着影响。为了更准确地观察流化床中单个气泡的动力学，采用CFD-DEM对矩形流化床中单个气泡的形成、上升和喷发进行了研究，并通过实验数据进行了验证。二维矩形流化床中从形成到喷发的不同阶段中的单个气泡通过 CFD-DEM 技术建模。研究压力波动和气泡动力学是本研究的主要重点。使用压力传感器测量压力波动，并使用高速数码相机记录整个起泡过程，从分配器上的气泡形成到其在表面喷发。通过比较实验和模拟气泡直径和压力波动来进行验证。CFD-DEM 结果，如颗粒和气体速度矢量、床空隙率和压力等值线，揭示了有关压力波动特征的新信息，这是实验研究无法获得的。在形成阶段，由于注入产生的压缩波，颗粒加速并达到填充状态。这导致压力中的压力峰值。在分配器上开始形成气泡时，压力降低，当气泡从分配器上分离时，压力达到最小值。当气泡通过床上升时，压力再次增加，但是，它保持在零以下，因为与预注射状态相比，气泡后面的空隙率较低，并且气泡上方和下方的气体速度更大。通过气泡喷发，在压力中可以看到另一个小的压缩波。