基于动态双重网格下喷动床滞止区流动特性CFD-DEM数值模拟

CFD-DEM numerical simulation of flow characteristics in stagnation zone of spouted bed based on dynamic dual grid

基于Fortran语言自行开发了基于动态双重网格方法下的喷动床内气固两相流动的CFD-DEM方法,同时开展了喷动床内径向混合实验与模拟研究,又结合单网格方法对喷动床内0~2.0 s内的滞止区特性进行对比分析,验证了动态双网格方法计算结果的准确性。然后利用动态双网格方法对不同进口气速下和不同初始堆积高度下的喷动床进行数值模拟研究,对滞止区颗粒流动过程进行追踪,结果表明:径向混合实验结果与数值模拟结果有很好一致性;在喷动床内存在一定的滞止区,滞止区内的颗粒流动性较差;初始堆积高度不变,随着进口速度的增加,滞止区高度下降速率和向喷口延伸速度无明显变化;进口速度不变,随着初始堆积高度的增加,滞止区颗粒下降速度随之增加,但其向喷口延伸速度逐渐变慢。

A CFD-DEM model of gas-solid two-phase flow in spouted bed was established based on the dynamic double-grid method.At the same time,the radial mixing experiment and simulation study in spouted bed were carried out.The characteristics of stagnation zone in spouted bed within 0—2.0 s were compared and analyzed with the single-grid method,which verified the reliability of the calculation results using the dynamic double-grid method.Then,the spouted bed with different inlet gas velocities and different initial stacking heights is numerically simulated,focusing on tracking the particle flow process in the stagnation area.The results show that:the experimental results of radial mixing are in good agreement with the numerical simulation results.There is a certain stagnation area in the spouted bed,and the particle mobility in the stagnation area is poor.The initial stacking height is constant,and with the increase of inlet velocity,the height decline rate of stagnation zone and the extension speed to nozzle have no obvious change.The inlet velocity remains the same.With the increase of the initial accumulation height,the falling velocity of particles in the stagnation zone also increases,but the extension velocity toward the nozzle gradually slows down.