Refinement of breakup models for compact powder agglomerates exposed to turbulent flows considering relevant time scales
Refinement of breakup models for compact powder agglomerates exposed to turbulent flows considering relevant time scales
复制标题
考虑相关时间尺度，对暴露于湍流的致密粉末团聚体的破碎模型进行细化
DOI：
10.1016/j.compfluid.2019.104315
复制
发表时间：
2019
影响因子：
2.8
通讯作者：
Khalifa
中科院分区：
文献类型：
--
作者：
Breuer;Khalifa
基于大涡模拟技术和硬球方法，采用欧拉-拉格朗日方法研究了湍流作用下干粉团聚体的破碎过程。为此，最近开发的湍流、阻力和旋转应力的破碎模型[1]在考虑物理过程的相关时间尺度的情况下进行了改进。取决于有效的破碎机制，确定破碎时间，其定义同一团聚体的两个后续破碎过程之间的时滞。这种物理上的措施确保了该方法不受所采用的时间步长的影响，并避免了碎片的非物理碰撞及其重新团聚。为了研究在更广泛的应用中的建模方法，六种不同的情况下，在一个通用的干粉分散器中的颗粒负载流进行了研究：三种不同的粉末，由于不同尺寸的初级颗粒形成的紧凑的团聚体和两个不同的雷诺数不同的一个因素的八个不同的强度。因此，非常温和的分散速率和团聚体的完全崩解之间的整个范围由该操作条件矩阵覆盖。在分析了最关键的流动区域，其中破碎过程是预先预期的，并最终发现在模拟中，详细的统计数据有关的不同的破碎机制生成和评估。这包括它们占破裂事件总数的百分比和由释放的附聚物的数量标准化的事件数量。此外，在分散器的出口处实现的分散速率被分析并与实验测量结果进行比较[2]。结果表明，建议的增强破碎模型，考虑到物理相关的时间尺度显着提高了预测结果，特别是在高Re的情况下，总体上实现了良好的协议与测量。
Breakup processes of dry powder agglomerates exposed to turbulent flows are investigated based on Euler–Lagrange predictions relying on the large-eddy simulation technique and the hard-sphere method. For this purpose, recently developed breakup models for turbulent, drag and rotary stresses [1] are refined taking relevant time scales of the physical processes into account. Depending on the effective breakup mechanism a breakup time is determined defining a time lag between two subsequent breakup processes of the same agglomerate. This physically motivated measure ensures that the methodology is independent of the applied time-step size and avoids unphysical collisions of the fragments and their re-agglomeration. To study the modeling approach in a wider range of applications, six different cases of the particle-laden flow in a generic dry powder disperser are investigated: Three different powders with varying strength due to different sizes of the primary particles forming the compact agglomerates and two different Reynolds numbers differing by a factor of eight. Thus, the entire range between a very mild dispersion rate and a complete disintegration of the agglomerates is covered by this matrix of operating conditions. After analyzing the most critical flow regions where breakup processes are expected beforehand and finally found in the simulations, detailed statistics concerning the different breakup mechanisms are generated and evaluated. That includes their percentages of the total number of breakup events and the number of events normalized by the number of released agglomerates. Furthermore, the dispersion rates achieved at the outlet of the disperser are analyzed and compared with experimental measurements [2]. It is shown that the suggested enhancement of the breakup models by taking physically relevant time scales into account significantly improves the predicted results especially in the high-Re case and that overall a good agreement with the measurements is achieved.
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DOI：
10.1007/s10494-012-9398-8
发表时间：
2012-05
期刊：
Flow, Turbulence and Combustion
影响因子：
--
作者：
Y. Ammar;A. Dehbi;M. Reeks
通讯作者：
Y. Ammar;A. Dehbi;M. Reeks
使用同步高速视频和热膜测量来表征湍流明渠流中的近床相干结构
DOI：
--
发表时间：
1995
期刊：
影响因子：
--
作者：
M. Garcia;F. López;Y. Niño
通讯作者：
Y. Niño
韧性骨料的湍流破碎。
DOI：
--
发表时间：
2015
期刊：
Physical review. E, Statistical, nonlinear, and soft matter physics
影响因子：
--
作者：
C. Marchioli;A. Soldati
通讯作者：
A. Soldati
DOI：
10.1145/1874391.187410
发表时间：
1987-02
期刊：
ACM SIGSOFT Softw. Eng. Notes
影响因子：
--
作者：
Will Tribbey
通讯作者：
Will Tribbey
DOI：
--
发表时间：
2007
期刊：
影响因子：
--
作者：
S. Harada;R. Tanaka;H. Nogami;M. Sawada;K. Asakura
通讯作者：
K. Asakura