Experimental and DEM studies on the transition of axial segregation in a truck mixer
Experimental and DEM studies on the transition of axial segregation in a truck mixer
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搅拌车轴向偏析转变的实验和 DEM 研究
DOI：
10.1016/j.powtec.2016.08.013
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发表时间：
2017-06
影响因子：
5.2
通讯作者：
Shengqiang Jiang
中科院分区：
文献类型：
--
作者：
Rong Deng;Yuanqiang Tan;Hao Zhang;Xiangwu Xiao;Shengqiang Jiang
对两粒径颗粒在汽车搅拌机内的混合和出料过程进行了实验和数值模拟。将排出的颗粒分成10组相同重量的样品。通过对比放电试样的大颗粒含量（BPC）和放电时间，首先验证了所提出的离散元法（DEM）模型。在此基础上，通过DEM模拟，定量研究了10个排放样品中轴向偏析的转变和BPC的分布，这是目前常规物理实验几乎无法实现的。在轴向偏析转变的数值分析中，混合颗粒也根据其x位置分为10组相同重量的样品。数值计算结果表明，混合过程中颗粒的尺寸差异和滚筒的结构是导致轴向偏析发生和转变的主要原因。小颗粒更容易在大颗粒团簇之间或相似大小的空隙中填充，从而使小颗粒将大颗粒从鼓底挤出，最终促进轴向偏析的发生，在鼓底观察到小颗粒带（样品10），并在混合时扩大到样品9。被挤出的大颗粒逐渐向鼓口移动，导致其他样品中BPC升高。在混合过程中，相对运动与轴向偏析呈正相关，相对矩越强，轴向偏析的速度和程度越大；随着混合的进行，总轴向偏析的速度减小，但轴向偏析的程度增大。放电过程在一定程度上抑制和改善了放电试样的轴向偏析。大颗粒的回落和前馈运动使得排放样品1 ~ 5的BPC与相应的混合样品基本一致，而排放样品6 ~ 8的BPC降低，排放样品9和10的BPC增加。混合和出料过程中轴向偏析的转变决定了出料样品中BPC的分布遵循抛物线规律。
Both experiments and numerical simulations of the mixing and discharging processes of two-sized particles in a truck mixer were carried out. The discharged particles were divided into 10 groups of samples with same weight. By comparing the big particle content (BPC) in discharged samples and the discharging time, the presented discrete element method (DEM) model was validated first. Then, DEM simulations were further performed to investigate quantitatively the transition of axial segregation and the distribution of the BPC in the 10 discharged samples which is almost impossible by conventional physical experiments of state-of-art. In the numerical analysis of axial segregation transition, the mixed particles are also divided into 10 groups of samples with same weight according to their x positions. Numerical results reveal that the size difference of particles and the structure of the drum cause the occurrence and transition of axial segregation during the mixing process. Small particles readily fill in among the big particle clusters or the similarly size gap more easily, thus the small particles force the big particles out from the drum bottom, ultimately facilitating the axial segregation occurs and band of small particles is observed at the drum bottom (Sample 10) and widen to Sample 9 as mixing. The big particles being crowed out gradually move toward drum mouth causing the increase of BPC in other samples. During the mixing process, the relative movements are positively associated with the axial segregation: the stronger the relative moments are, the larger the speed and extent of the axial segregation are; the speed of total axial segregation decreases as mixing progresses, but the degree of axial segregation increases. The discharging process can somehow restrain and improve the axial segregation of the discharged samples. The falling back and feeding forward movements of the big particles make the BPC in discharged Samples 1 to 5 almost be consistent with the relevant mixed samples, whereas the BPC in discharged Samples 6 to 8 decreases and discharged Samples 9 and 10 increases. The transition of axial segregation during the mixing and discharging processes determines the BPC distribution in discharged samples following a parabola law.
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DOI：
--
发表时间：
--
期刊：
Crelle's Journal
影响因子：
--
作者：
Hertz
通讯作者：
Hertz
影响因子：
5.2
作者：
Michinori Yamamoto;Shingo Ishihara;J. Kano
通讯作者：
Michinori Yamamoto;Shingo Ishihara;J. Kano
DOI：
10.1016/s0167-3785(01)80061-0
发表时间：
2001
期刊：
--
影响因子：
--
作者：
G. Enstad
通讯作者：
G. Enstad
影响因子：
0.9
作者：
B. Pollard;H. Henein
通讯作者：
B. Pollard;H. Henein
DOI：
--
发表时间：
2009
期刊：
Machinery Design and Manufacture
影响因子：
--
作者：
Xie Jun
通讯作者：
Xie Jun