基于LBM-DEM的热态颗粒流体系统传热传质高效数值方法研究

Particle-fluid interaction systems are ubiquitous in various industrial processes whereas present complex heat and mass transfer characteristics, because of momentum exchange, heat and mass transfer co-existing with complicated multi-scale structure, the interaction mechanism between them is very complex. In this proposed project, the heat and mass transfer between non-spherical particle(s) and fluid will be studied based on LBM-DEM, and understand the mechanism of heat and mass transfer in deep-seated. The research contents include: 1) Efficient parallel algorithm with good parallel scalability based on multi-core CPU-GPU heterogeneous platform, data storage and access characteristics of CPU and GPU also needs to be fully considered. 2) Based on the fully considering of the stability conditions which should be satisfied for non-uniform structure in two phases, the heat and mass transfer mechanism of non-spherical particle(s)-fluid systems and the effect of particle cluster on the efficiency of heat and mass transfer will be studied. 3) On the basis of a large number of numerical simulation results, the heat transfer rate and mass transfer rate of the particles with different shapes and different solid volume fractions are quantized, and the mechanism of heat and mass transfer between the two phases will be analyzed deeply. The results not only can be helpful for the study of heat and mass transfer between non-spherical particles and fluid in engineering applications, but also enrich the mechanism of heat and mass transfer between particles and fluid.

非球形颗粒-流体两相流问题广泛存在于各种工业过程中，由于相间的动量交换和传热传质并存且伴随着复杂的多尺度结构，其内部作用机理异常复杂。本项目以非球形颗粒-流体间的传热传质为研究对象，采用基于LBM-DEM的数值模拟方法开展研究，探索深层次的非球形颗粒-流体间的传热传质机理。研究内容包括：1)设计基于多核CPU-GPU异构平台的具有良好并行可扩展性的高效数值方法，同时充分考虑CPU和GPU的数据存储和访问特点；2)在充分考虑两相非均匀结构应满足的稳定性条件的基础上，研究非球形颗粒(群)-流体两相间的传热传质机制和颗粒聚团对传热传质效率影响；3)在大量数值模拟结果的基础上，量化不同形状、不同固体体积分数的颗粒-流体间的传热和传质速率，并对两相间的传热传质机理进行深层次的分析。研究成果不仅对工程应用中有关非球形颗粒-流体间传热传质问题的研究有重要的现实意义，也丰富了颗粒-流体传热传质的相关理论。

非球形颗粒-流体两相流问题广泛存在于各种工业过程中，由于相间的动量交换和传热传质并存且伴随着复杂的多尺度结构，其内部作用机理异常复杂。本项目选取多孔介质型椭球颗粒和基于超二次函数的正方体颗粒作为非球形颗粒研究对象，探索了深层次的非球形颗粒-流体间的传热传质机理。主要研究内容包括以下几个方面：1)面向CPU-GPU异构计算机体系，构造了具有良好并行可扩展性的高效数值方法，并将其推广到大规模颗粒群-流体两相间流动和传热问题的研究中；2)以多孔介质型椭球颗粒为研究对象，研究了多孔介质型椭球颗粒-流体的曳力机制与传热特征，量化了雷诺数Re、颗粒形状Ar和孔隙度ε对曳力系数Cd和平均努塞尔数Nu的影响，并对两相间的传热传质机理进行深层次的分析，然后提出了新的曳力系数与平均努塞尔数新关联式，数值模拟结果与关联式计算值的平均误差分别为1.7%和1.9%；3) 基于超二次函数构造正方体颗粒，研究了正方体颗粒-流体间的曳力机制与传热特征，并针对此类非球形颗粒提出了新的曳力系数Cd与平均努塞尔数Nu新关联式，数值模拟结果与关联式计算值的平均误差分别为0.63%和0.52%；4) 以粗糙纳米管道内甲烷纳米流体的输运为研究对象，通过NEMSMD模拟，利用修正的Green-Kubo关系计算不同纳米通道各个方向的扩散系数，通过拟合扩散系数与纳米通道宽度的关系曲线，分析了纳米管道的传质特性。本项目以数值模拟为载体，从非球形颗粒-流体多尺度结构形成机理出发，针对两类非球形颗粒，分别构建了曳力系数与平均努塞尔数新关联式，研究成果不仅对化工过与高炉燃烧程等应用中有关非球形颗粒-流体两相间传热传质问题的研究有重要的现实意义，也丰富了颗粒-流体传热传质的相关理论。