鼓泡流化床中流动特性的多尺度数值模拟  

MULTI-SCALE SIMULATION ON HYDRODYNAMIC CHARACTERISTICS IN BUBBLING FLUIDIZED BED

作　　者：王帅[1] 于文浩[1] 陈巨辉[2] 张天浴 孙立岩[1] 陆慧林[1] 

机构地区：[1]哈尔滨工业大学能源科学与工程学院,哈尔滨150001 [2]哈尔滨理工大学机械动力工程学院,哈尔滨150080

出　　处：《力学学报》2016年第3期585-592,共8页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金(51390494,51406045);中国博士后基金(2015M581443);黑龙江省博士后基金(LBH-Z15055)资助项目

摘　　要：鼓泡流化床因其较高的传热特性以及较好的相间接触已经被广泛应用于工业生产中,而对鼓泡流态化气固流动特性的充分认知是鼓泡流化床设计的关键.在鼓泡流化床中,气泡相和乳化相的同时存在使得床中呈现非均匀流动结构,而这种非均匀结构给鼓泡流化床的数值模拟造成了很大的误差.基于此,以气泡作为介尺度结构,建立了多尺度曳力消耗能量最小的稳定性条件,构建了适用于鼓泡流化床的多尺度气固相间曳力模型.结合双流体模型,对A类和B类颗粒的鼓泡流化床中气固流动特性进行了模拟研究,分析了气泡速度、气泡直径等参数的变化规律.研究表明,与传统的曳力模型相比,考虑气泡影响的多尺度气固相间曳力模型给出的曳力系数与颗粒浓度的关系是一条分布带,建立了控制体内曳力系数与局部结构参数之间的关系.通过模拟得到的颗粒浓度和速度与实验的比较可以发现,考虑气泡影响的多尺度曳力模型可以更好地再现实验结果.通过A类和B类颗粒的鼓泡床模拟研究发现,A类颗粒的鼓泡床模拟受多尺度曳力模型的影响更为显著.Bubbling fluidized beds have been widely applied to various industrial processes owing to superior inter-phase contact and high heat transfer characteristics. Fundamental knowledge of the hydrodynamic characteristics is essential for the design of such reactors. In bubbling fluidized bed systems,the non-uniform flow structure in the form of bubbleemulsion phases makes the accuracy of numerical model limited. Bubbles are the typical meso-scale structures in bubbling fluidized beds. To describe the effects of such meso-scale structures, a bubble structure-dependent（BSD） drag model is developed with one extremum condition of energy dissipation consumed by the drag force, which is incorporated into the two fluid model. The simulations of gas-solid flow behavior in bubbling fluidized beds with with Geldart A and B particles are performed and some parameters including bubble velocity and bubble diameter are analyzed. The results indicate that the present model with consideration of bubble effects obtains a zonal distribution of the drag coefficient with solid concentration, which establishes a relationship between the drag coefficient and the local structural parameters.Comparisons with experimental data, the BSD drag model can obtain a better prediction than the conventional drag model.Meanwhile, the simulation reveals that the BSD drag model has a more significant impact on the predition of bubbling fluidization with Geldart A particles.

关 键 词：曳力系数 气泡 流化床 多尺度 

分 类 号：TK224[动力工程及工程热物理—动力机械及工程]