A Numerical Study of the Effect of Loading Profiles on Mixing/Segregation of Particles in the Truck Mixer via DEM
Discrete element method (DEM) was employed to study the mixing of two sizes of particles in a truck mixer. The effects of five different loading profiles on the mixing/segregation of particles were discussed. The contact ratio between particles was adopte
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Abstract Discrete element method (DEM) was employed to study the mixing of two sizes of particles in a truck mixer. The effects of five different loading profiles on the mixing/segregation of particles were discussed. The contact ratio between particles was adopted to quantitatively analyze the particle mixing/segregation degree. The simulation results revealed that the motion of particles in the radial direction is more intense than in the axis one, which leads to the radial mixing/segregation faster and more obvious. It was also indicated that different initial states in the radial direction have little influence on the final mixing states, but the influence in the axial one cannot be ignored. The small particles are more likely to get into the big particle clusters, which can lead to the increase of the mixing/segregation in both axial and radial directions.
1 Introduction In the practical engineering, the well mixed granular mixture needs to be transported to the working site from time to time. One common used transport device is the truck mixer, the main function of which is to avoid segregation of mixtures by mixing during the transportation. The ability of avoiding segregation is one of the most important indexes of the truck mixer. However, the target is not easy to
R. Deng X. Xiao S. Jiang C. Hu School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China Y. Tan (&) Institute of Manufacturing Engineering, Huaqiao University, Xiamen 361021, China e-mail: [email protected] H. Zhang School of Energy and Environment, Southeast University, Nanjing 210096, China © Springer Science+Business Media Singapore 2017 X. Li et al. (eds.), Proceedings of the 7th International Conference on Discrete Element Methods, Springer Proceedings in Physics 188, DOI 10.1007/978-981-10-1926-5_101
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achieve because the particles migrate in different zones of truck mixer according to their physical properties. When the quality of mixture becomes bad during the mixing process, it indicates the occurrence of segregation. The radial segregation process is extremely rapid and considered as the first present phenomenon, that the larger (lower density) particles migrate to the blender walls leaving a core of smaller (larger density) particles in the middle. And the segregation is more obvious with the increase of the particle size and density rate [1, 2]. In a long rotating drum and after a much longer mixing period, the axial segregation occurs and some bands are formed perpendicular to the rotation axis. The decrease of friction on non-rotating end plates can lead to an increase of axial segregation [3]. Finally, if the mixing time is long enough, it can be observed two bands of fine particles at the ends of the drum connected with each other by a thin core of segregated small particles [4]. In short, the occurrence of the radial segregation is rapid in any mixing system. However, the axial segregation occurs very slowly and only for long drums. In addition to particle properties, operating condi
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