稠密气固两相流相间作用机理与颗粒动理学的研究

In present proposed project, the hydrodynamic mechanics of interphase interactions of dense gas-solid two-phase flow and kinetic theory of granular flow with impact velocity dependent coefficient of restitution of particles are investigated. Based on kinetic theory of dense gases, the collisional interaction model of variable restitution coefficient of particles is established. The effects of collisional forces on the momentum and energy transfer and dissipation are discussed. The mechanism of particle interaction is revealed due to collisiosns. The kinetic theory of variable coefficient of restitution is derived using the Chapman-Enskog iteration method. The laws on transfer and dissipation of collisional properties for variable coefficient of restitution of particles are explored. The solid phase model is closed through particle collisional pressure and viscosity equations. The Euler-Euler two-fluid model for dense gas-solid two-phase flow, coupled with large eddy simulation (LES) for gas, is proposed to study the synergistic interaction mechanisms of gas-solid interphase and solid-solid collisions under the gas turbulence. The experimental system of the gas-solid fluidized bed with measurements is constructed with biomass, coal and FCC particles as bed materials. The collisional properties of particles, velocities and fluctuation velocities and volume fraction of particles are measured using a CCD camera technique and an optical fiber probe technique in the gas-solid fluidized bed. Combined with numerical simulation and experimental results, the gas-solid two-phase interaction mechanism and synergistic properties are analyzed. The project will provide a foundation for prediction of macroscopic hydrodynamics of dense gas-solid fluidized beds.

本项目将以流化床内稠密气固两相流动为研究对象，基于稠密气体分子运动论，建立颗粒碰撞弹性恢复系数依赖于碰撞速度的变颗粒弹性恢复系数的颗粒碰撞动力学，揭示颗粒之间碰撞作用下动量和能量传递规律，研究颗粒之间相互作用机理。采用Chapman-Enskog迭代法，研究变颗粒弹性恢复系数的颗粒碰撞属性传递和耗散规律，确定固相输运参数计算模型，实现固相模型封闭，构建变颗粒弹性恢复系数的颗粒动理学。结合气相大涡模拟，建立高颗粒浓度气固欧拉—欧拉双流体模型，研究流化床内气固两相相互作用规律。以生物质、煤和FCC颗粒为流化床床料，构建流化床实验平台。采用高速摄像测量技术和光导纤维探针颗粒浓度测量仪测量颗粒碰撞参数以及颗粒速度和浓度分布，获取颗粒脉动速度和浓度的动态特性。结合数值模拟与实验结果，揭示流化床内气固两相相间作用和颗粒碰撞作用对气固动量和能量传递和耗散的控制机制，预测流化床内气固两相宏观流动特性。

稠密气固两相流动广泛存在于化工、能源和冶金以及环保等各种工业过程中，其气体和颗粒两相流动的共同特征是：高浓度颗粒在气体湍流作用下形成颗粒之间相互碰撞作用和气体与颗粒之间的相互作用。颗粒间碰撞作用不仅改变颗粒动力学，导致颗粒动量和能量的损失，同时影响气体与颗粒相互作用以及流体湍流与颗粒脉动之间能量的传递特性。本项目以流化床内稠密气固两相流动为研究对象，基于稠密气体分子运动论，建立颗粒碰撞弹性恢复系数依赖于碰撞速度的变颗粒弹性恢复系数的颗粒碰撞动力学，揭示颗粒之间碰撞作用下动量和能量传递规律，研究颗粒之间相互作用机理。采用Chapman-Enskog迭代法，研究变颗粒弹性恢复系数的颗粒碰撞属性传递和耗散规律，确定固相输运参数计算模型，实现固相模型封闭，构建变颗粒弹性恢复系数的颗粒动理学。建立高颗粒浓度气固欧拉—欧拉双流体模型，研究流化床内气固两相相互作用规律，以及气体湍流作用和颗粒碰撞作用下的气固相间作用和颗粒相互作用机理。所建立的变颗粒弹性恢复系数的颗粒碰撞动力学，揭示颗粒碰撞中颗粒动量和能量传递和耗散与颗粒碰撞速度和颗粒温度之间的内在关系，弥补了恒颗粒弹性恢复系数的颗粒动力学中颗粒碰撞与颗粒脉动速度无相关的局限性，揭示了颗粒之间的相互作用机制。构建的以颗粒碰撞弹性恢复系数依赖于碰撞速度的变颗粒弹性恢复系数为函数的颗粒碰撞应力、碰撞脉动能量通量和能量耗散的本构关系，将恒颗粒弹性恢复系数的颗粒动理学拓展到变颗粒弹性恢复系数的颗粒动理学，拓宽了颗粒动理学的应用范围。.本项目取得主要成果：发表SCI收录论文11篇，EI收录论文3篇，出版学术专著1部，申请发明专利2项，授权发明专利1项，获得2020年度中国石油科学十佳论文，培养硕士研究生9人，博士研究生4人。