稠密同轴气固射流的CFD模拟  

Numerical Analysis of Dense Gas-Solid Coaxial Jet Flow

作　　者：周泉 姜从斌 葛志红 丁建平 马冬 郭进军 ZHOU Quan;JIANG Congbin;GE Zhihong;DING Jianping;MA Dong;GUO Jinjun(Changzheng Engineering Limited Company,Beijing 101111,China)

机构地区：[1]航天长征化学工程股份有限公司,北京100010

出　　处：《化学反应工程与工艺》2019年第6期542-551,共10页Chemical Reaction Engineering and Technology

基　　金：国家重点研发计划资助(2017YFB0602700)。

摘　　要：同轴气固射流在能源领域具有广泛地应用,但大多数研究集中在颗粒浓度较低的工况。为了研究稠密同轴气固射流的流动特性,采用了稠密离散相模型(DDPM)耦合离散元模型(DEM)的方法对该体系进行计算流体动力学(CFD)模拟,该方法同时考虑了孔隙率对气固曳力的影响和颗粒间的碰撞作用。由于射流过程中,气体对颗粒的作用占主导,分别考虑了不同环形气体速度和气固曳力模型对气固流动的影响。模拟结果表明,该模型能合理地模拟在不同气速下稠密气固两相射流的颗粒弥散特性,与实验现象定性一致。在较高气速下,引入湍流模型对预测结果有显著影响,模拟得到的颗粒弥散程度较大。不同气固曳力模型对颗粒弥散的预测有明显影响,Wen&Yu曳力模型下颗粒弥散程度较大,Gidaspow模型次之,Syamlal&O’Brien模型给出的颗粒弥散程度较小。Coaxial jet flow is widely used in power generation field,but most of the research focus on the dilute granular flow.In order to investigate the flow characteristics of dense gas-solid coaxial jet,dense discrete phase model(DDPM)coupled with discrete element model(DEM)that considers the effect of voidage and inelastic collision between particles,is used in this work.Due to the overwhelming force from gas imposing upon particle,the effects of annular gas velocity and gas-solid drag model are both taken into account.It is shown that the simulation with the DDPM coupled with DEM can lead to reasonable particle dispersion phenomenon.As increasing gas velocity,the particle dispersion appears in the form of shear dispersion mode,wave dispersion mode and oscillation model successively,which is in agreement with experimental observation.And the peak value of time-averaged particle concentration along axis firstly decreases and then increases as enhancing gas velocity,in which there exist two competing mechanisms affecting particle dispersion.Additionally,for high gas velocity,the introduction of turbulence model leads to significant effect that leads to larger particle dispersion.Moreover,different drag models give noticeable difference on the prediction of local particle distribution,in which Wen&Yu model gives the largest particle dispersion,followed by Gidaspow’s model and Syamlal&O’Brien model.

关 键 词：同轴射流 颗粒弥散 稠密离散相模型 离散元模型 

分 类 号：TQ021.1[化学工程] TQ021.3