双孔射流流化床内颗粒混合特性的离散单元法数值模拟  

DEM Simulation on Mixing Characteristics of Particles in Double Jets Fluidized Bed

作　　者：张俊强[1,2] 纪律[2] 李斌[1] 陈海生[2] 边禹铭 

机构地区：[1]华北电力大学能源动力与机械工程学院,河北保定071003 [2]中国科学院工程热物理研究所,北京100190

出　　处：《动力工程学报》2017年第2期91-97,104,共8页Journal of Chinese Society of Power Engineering

基　　金：国家国际科技合作专项资助项目(2014DFA60600);国家自然科学优秀青年基金资助项目(51522605)

摘　　要：将计算流体力学与离散单元法相结合,采用Fortran语言编程,根据牛顿第三定律实现气固耦合,从微观角度剖析了颗粒在流化床内的运动机制.利用Lacey混合指数对流化床内不同特性区域的颗粒混合程度进行了定量分析,并研究了颗粒混合特性的影响因素,得到颗粒轴向和径向混合序列图、气体和颗粒速度分布以及整床和三区的颗粒混合指数分布.结果表明:颗粒受到空气射流作用后,随着混合和偏析的不断进行,最后达到随机完全混合状态;相同表观气速下颗粒轴向混合进程快于径向混合进程;表观气速增大,喷泉区尺度增大,使颗粒径向混合能力得到改善,但对轴向混合能力的影响微弱.Combining the discrete element method （DEM） with computational fluid dynamics, and based on Fortran language programming, a gas-solid coupling model was established according to Newton third law to reveal the motion mechanism of particles in the fluidized bed from the micro-level. The mixing degree of particles in different characteristic regions of the bed was quantitatively analyzed using Lacey mixing index, while factors infuencing the mixing characteristics were studied, during which the axial and radial mixing sequence diagram of particles, the gas and particle velocity distribution, as well as the particle mixing in- dex in the entire bed and at different regions of the bed were obtained. Results show that under the action of air jets, the particles get mixed and segregated, and finally achieve dynamic equilibrium. The axial mixing of particles is faster than radial mixing at the same superficial gas velocity. The scale of fountain area increases with rising superficial gas velocity, while the radial diffusion capacity improves, and the axial diffusion capacity lowers.

关 键 词：流化床 轴向混合 径向混合 离散单元法 混合指数 

分 类 号：TK224[动力工程及工程热物理—动力机械及工程]