气固流化系统中动态行为的离散模拟
文献类型：学位论文
| 作者 | 欧阳洁 |
| 学位类别 | 博士 |
| 答辩日期 | 1999-04-26 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 李静海 |
| 关键词 | 模拟 颗粒运动分解 轨道模型 鼓泡流化 循环流化 |
| 其他题名 | Discrete Simulations of Dynamic Behavior in Gas-Solid Fluidization Systems |
| 学位专业 | 流态化工程 |
| 中文摘要 | 将颗粒流体系统中颗粒的运动过程分解为冲力支配的瞬时运动及流体作用控制的非瞬时运动，建立了颗粒运动分解轨道模型。该模型中，气体流动用气固相耦合的Navier-Stokes方程描述，颗粒行为直接通过其运动轨道描述。在颗粒与颗粒作用的碰撞过程中，颗粒运动服从碰撞动力学中的支量守恒定律；在流体与颗粒作用的悬浮过程中，颗粒运动服从牛顿动力学中的力平衡方程。颗粒运动分解轨道模型能够模拟鼓泡床中的鼓泡形成、节涌现象、气泡破碎方式、多孔分布板中的气泡行为及颗粒运动的敏感依赖性。并且该模型还可用于循环流化床中局部与整体非均匀流动结构的模拟。与拟流体模型及现有轨道模型相比，颗粒运动分解轨道模型具有模拟真实、适用面宽、方法简单的优点。 |
| 英文摘要 | This paper presents numerical simulations of two-dimensional gas-solid fluidized beds by establishing the so-called particle-motion-resolved trajectory model, in which fluid motion is described by the Navier-Stokes equation while the behavior of each single particle is calculated by analyzing its moving trajectory. Further, the motion process of each particle is decomposed into a collision process to account for inter-particle interaction and a suspension process related to interaction with the fluid. Momentum conservation of collision mechanics controls the interaction between colliding particles, while the state of each suspended particle is fully dominated by equation of force balance over that particle. The particle-motion-resolved trajectory model makes it possible to generate bubble wake, which that can seldom be obtained by previous trajectory model. While the slugging, which can hardly be simulated by the pseudo-fluid models, can be also simulated by the model. breaking-up form of bubbles and bubbling behaviors near the distributor with several orifices are also shown. Tracking of several individual particles suggests that particle motions in bubbling fluidized systems have sensitive dependence on initial conditions. At the same time increasing orifice size of the gas distributor and gas superficial velocity or decreasing particle diameter can intensify particle's mixing degree. Beside the simulation of bubbling fluidization, overall and local heterogeneity of CFB systems have been simulated. Simulations of local property have indicated the existence of dynamic clusters. The simulations of overall heterogeneity in CFB show that the axial and radial heterogeneous distributions of voidage and particle velocity. The curve of axial voidage distribution indicates that the solid volume fraction in the bottom section of CFB is much more than that in the top sections of CFB. The simulations of solid hold-up give a typical core-annulus structure. On the other hand, the simulations of particle velocity suggest that particle velocity increase axially from the bottom to the top and radially from the wall to the core with increasing gas velocity. These results in this paper indicate that particle-motion-resolved trajectory model can be used for simulating both bubbling fluidization and fast fluidization in much wider applicable range than previous models. On the other hand, this model is simple and call for much less computation cost in comparison with previous discrete models. |
| 语种 | 中文 |
| 公开日期 | 2013-09-27 |
| 页码 | 190 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1988]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 欧阳洁. 气固流化系统中动态行为的离散模拟[D]. 中国科学院研究生院. 1999. |
入库方式： OAI收割
来源：过程工程研究所
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