流化床内气固流动LBM-DEM模型及介尺度结构-传递关系研究

To investigate the hydrodynamic behaviors between fluid and solid particles in gas-solid fluidized beds, a LBM-DEM model for the dense gas-solid flows will be proposed and developed to realize the fast discrete particle simulation of gas-solid fluidized beds at the particle scale. The proposed method describes the flow and transport behaviors by the lattice Boltzmann method (LBM), tracks the motion of particles by the discrete element method (DEM). The relationship between the meso-structure and properties of both transport and reaction in fluidized bed is investigated to establish quantitative structure-property relationship model, which is used to improve the simulation accuracy of the proposed LBM-DEM model. Considering the better inherent parallelism of both LBM and DEM and the higher performance-price ratio of graphics processing unit (GPU), it is achieved to implement the GPU-based parallel program of the proposed method for enhancing the computation speed and simulation scale. The effectiveness of the algorithm is also validated through the virtual process engineering (VPE) experimental platform, and the three-dimensional full-loop discrete simulation of a circulating fluidized bed at the particle scale is realized to explore the virtual process engineering. The launch of this project is helpful to understand the complex spatiotemporal behaviors and control mechanism of dense gas-solid two-phase flow, form a scientific model methodology for it, and have an important guiding significance for a better understanding of fluidized bed reactor as well as its optimization and design.

针对流化床中流体和固体颗粒间的流体力学行为，拟建立一种适合于稠密气固流动的LBM-DEM模型，在颗粒尺度上实现对气固流化床的快速离散颗粒模拟。该模型将采用格子Boltzmann方法(LBM)描述气相流动和传递行为，采用离散单元法(DEM)追踪颗粒相运动。研究流化床中介尺度结构与“三传一反”的相互关系并建立定量构效关系模型，将其与LBM-DEM模型相结合提高模拟精度。基于LBM和DEM各自具有的良好并行性以及图形处理单元（GPU）拥有的高性价比优势，实现该算法的GPU并行程序，提高计算速度和规模。利用“虚拟过程工程”实验平台检验算法的有效性，并在颗粒尺度上开展循环流化床三维全回路离散模拟的研究。本项目的开展，将有助于深入理解稠密气固两相流动的复杂时空行为及其控制机理，形成适合于稠密气固流动体系的模型方法论，对深入认识流化床反应器以及反应器的优化设计具有重要的指导意义。

针对流化床中流体和固体颗粒间的流体力学行为，本项目已建立了一种适合于稠密气固流动的LBM-DEM模型，在颗粒尺度上实现了对气固流化床的快速离散颗粒模拟。本项目采用了格子Boltzmann方法(LBM)描述气相流动和传递行为，采用了离散单元法(DEM)追踪颗粒相运动。基于颗粒解析的LBM-DEM方法开展了气固悬浮系统大规模直接数值模拟研究，从微观上探索了介尺度结构与“三传一反”的相互关系，揭示了非均匀结构的作用机制和颗粒脉动速度偏离Maxwell分布的内在机理，发现了颗粒运动本构关系存在尺度依赖性，并提出了反映结构效应的曳力关联式以对LBM-DEM离散颗粒模型进行修正；基于LBM和DEM各自具有的良好并行性以及图形处理单元（GPU）拥有的高性价比优势，实现了该算法的GPU并行程序，提高了计算速度和规模；开发了通用气固多相流模拟软件，实现了LBM-DEM下的直接数值模拟和离散颗粒模拟，在化工、冶金、能源、航空航天等相关领域具备广泛的应用前景。本项目的开展，深入理解了稠密气固两相流动的复杂时空行为及其控制机理，建立了适合于稠密气固流动体系的计算模型，形成了自主可控的格子多相流模拟软件，为破解我国CAE软件“卡脖子”难题贡献力量 。