高浓度颗粒流体两相流动相间非均匀作用及颗粒动理学研究

In order to address the current problems of low heat and mass transfer rate, low dissipation rate etc. resulted from the heterogeneous flow structures in fluid-particle two-phase flow with high particle concentrations, aiming at the deep insight on the regularity of momentum and energy transfer between phases in high concentration particle and fluid flows, this project applies the Lattice-Boltzmann method into the investigation of temporal and spatial evolution of heterogeneous flow structure, statistically obtains information of particle positions, velocities and force endured etc. to determine the stability conditions. With the Kinetic Molecular Theory combining the characteristics of non-Gaussian particle velocity distribution in the heterogeneous flow structures, this project also establishes the kinetic theory of granular flow for the heterogeneous flow structures to study the mechanism of kinetic energy transfer between the particle and fluid phases. It also intends to establish an interphase interaction model by considering the heterogeneous distribution of particle positions and force on the particles to investigate the momentum transfer regularities between phases. Combined with Large Eddy Simulation of fluid phase and experiments, this project studies fluctuating characteristics of particles in fluidized beds, analyzes the effect of particle collision on particle motions, and reveals the momentum and energy transfer regularities on different levels of heterogeneous flow structures in high concentration particle-fluid flows, thus, lays theoretical foundations on the research and application of hydrodynamics, heat and mass transfer as well as chemical reactions of high concentration particle-fluid two-phase flows.

针对高浓度颗粒-流体两相流动过程中产生的非均匀结构导致两相间传热传质和扩散速率降低等问题，本项目以深入认识高浓度颗粒-流体相间动量和能量传递规律为目标，应用格子-Boltzmann方法研究高浓度颗粒-流体两相流动非均匀结构时空演化规律，统计获得非均匀流动结构内颗粒位置、速度和受力分布等信息，确定流动稳定性条件。应用分子运动理论，结合非均匀结构的颗粒速度分布非高斯性特性，建立非均匀结构的颗粒动理学模型，研究流体-颗粒间脉动能传递规律。结合非均匀结构的颗粒空间位置分布和颗粒受力信息，构建流体和颗粒相间作用力计算模型，研究两相间动量传递规律。结合流体大涡模拟方法和实验研究流化床内颗粒脉动特性，分析颗粒碰撞对颗粒运动的影响，揭示高浓度颗粒-流体两相流动过程中形成的非均匀结构不同层次上动量和能量的传递规律，为流体颗粒两相流动、传热传质和化学反应的研究和应用奠定理论基础。

针对高浓度颗粒-流体两相流动过程中产生的聚团和气泡等非均匀结构，本项目以深入认识高浓度颗粒-流体相间动量和能量传递规律为目标，应用格子-Boltzmann方法研究了高浓度颗粒-流体两相流动非均匀结构时空演化规律，统计获得了非均匀流动结构内颗粒位置、速度和受力分布等信息，确定了两相流动的流动稳定性条件。基于分子运动理论，结合非均匀结构影响的颗粒分布特性，建立了以惯性数为参数的非均匀结构内颗粒相应力模型，解决了颗粒动理学理论中由于非均匀流动结构导致的固相应力变化预测难的问题。研究了流体-颗粒间脉动能传递规律，结合非均匀结构的颗粒空间位置分布和颗粒受力信息，构建了流体和颗粒相间作用力计算模型，研究了两相间动量传递规律。通过数值模拟计算分析与文献实验的对比，验证了非均匀流动结构两相流计算模型的准确性，揭示了高浓度颗粒-流体两相流动过程中形成的非均匀结构不同层次上动量和能量的传递规律。