脉冲鼓泡床内鼓泡和颗粒混合特性的CFD-DEM数值模拟

CFD-DEM simulation of bubbling and particle mixing properties in pulsed jet fluidized bed

基于FLUENT软件信息传递模式的MPI(message passing interface)并行计算平台,通过用户自定义函数(user-defined functions,UDFs)文件发展一种拟三维颗粒的计算流体力学(computational fluid dynamics,CFD)-离散单元法(discrete element method,DEM)耦合并行算法。采用该算法数值模拟了脉冲鼓泡床内气固两相流动,揭示了气相鼓泡特性和颗粒混合机制。数值模拟结果表明:该算法具有随计算节点数增加的良好扩展性能和加速性能;在鼓泡过程中,主流两侧的小尺度气流涡逐渐发展为双主涡;单气泡通过床层后,颗粒混合仅局限于射流触及区域;数值模拟结果与相关试验和数值模拟结果吻合较好,表明该并行算法能够较好的模拟稠密颗粒气固两相流中鼓泡和颗粒混合特性,为其在大规模并行集群上的应用奠定基础。

Based on the MPI （ Message Passing Interface） platform of FLUENT software, the parallel simulation tech- nique for pseudo three-dimension computational fluid dynamics-discrete element method （CFD-DEM） coupling model was developed through the user-defined functions （UDFs）. Numerical simulation of the gas-solid flow in pulsed jet flu- idized bed was conducted by the developed parallel CFD-DEM coupling model, and the bubbling properties for the gas phase and particle mixing properties were revealed. Simulation results showed that the developed parallel CFD-DEM coupling model could have good scalability and speeded-up performance with increase in the number of computing nodes. Small-scale vortices on both sides of the mainstream gradually evolved into two main vortices in the bubbling processes. The particle mixing only occurred in the jet-influenced region after a single bubble had passed through the bed. The simulation results accorded well with file related experimental and simulation results, which showed that this model could well simulate the bubbling and particle mixing properties in dense particulate flows, laying the foundation for the implementation of the model in massively cluster systems.