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Thesis Advisor王维 ; 陈延佩
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline化学工程
Keyword气固流态化 颗粒动理学理论 介尺度结构 能量非均分 双峰分布


Other Abstract

Gas-solid fluidized systems are typical nonlinear non-equilibrium systems. Inside such systems, particles aggregate and form meso-scale structures such as non-uniform clusters. The meso-scale structures have significant effects on the momentum transfer of gas and particles. Accurate description of these non-uniform structures is hence very important to successful mathematical modeling of fluidization. However, the two-fluid model based on traditional kinetic theory of granular flow does not take into account the non-uniform structures present in gas-solid fluidized systems. Moreover, based on the clustering behavior of particles, it is reasonable to simplify the non-uniform structure into a dilute-dense two-phase description. By assuming that particles in the dilute and dense phases have different granular temperatures and mean velocities, the solid phase as a whole will exhibit a bimodal velocity distribution which well reflects the non-Maxwllian and energy nonequipartition features of gas-solid fluidization. Based on the bimodal distribution, a new kinetic theory is derived and further employed to build a structure-based multi-fluid model.In Chapter 2, we developed the kinetic theory of binary granular mixture, which can be viewed as a generalization of gas-solid fluidized system with dilute-dense structure if the exchange between the dilute and dense phases can be well considered. Transport terms like the stress-strain relationship are derived for binary granular mixture. The results show that the collision frequency and stress-strain relationship derived from the new kinetic theory are in better accordance with the characteristic of binary granular mixture than previous results.Chapter 3 presents two applications of the kinetic theory of binary granular mixture. The first application is the calculation of granular temperature of mixed particles in a simple shear flow. The result of numerical computing is consistent with the results of molecular dynamics or DEM simulation. The second application is the prediction of the free path of particles in the context of a vibro-fluidized granular system. We divide the particles into two species, one consisting of particles moving towards positive x-direction and the other towards negative x-direction. The results developed in Chapter 2 are used to predict the free path of particles. The results agree well with the DEM simulation of the vibro-fluidization system. In Chapter 4, we propose a psedo-fluid model based on kinetic theory of binary mixture. Particles in the dilute and dense phases are regarded as two different particle species. The kinetic theory of binary mixture with addition of exchange terms is used subsequently to determine the transport coefficients. At last, Chapter 5 summarize the thesis and gives prospects for study of fluidization modeling and kinetic theory in the future. 

Document Type学位论文
Recommended Citation
GB/T 7714
梅一枫. 基于双峰速度分布的动理学理论及其在双颗粒混合物与气固流态化中的应用[D]. 北京. 中国科学院研究生院,2016.
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