基于计算流体力学-离散单元法耦合的粗糙壁面颗粒趋壁沉积过程的数值模拟

Numerical Simulation on Process of Particle Deposition on a Rib-roughened Surface Using CFD-DEM

细微(直径小于50μm)颗粒物在通风和空调管道内的沉积现象普遍存在,由于工程中实际加工问题不存在绝对光滑的表面,粗糙结构的存在使颗粒沉积过程更为复杂,明确颗粒与颗粒、壁面碰撞、反弹和颗粒团聚规律对于提高室内空气质量和提升设备效率有重要作用。采用计算流体力学(computational fluid dynamics,CFD)-离散单元法(discrete element method,DEM)耦合模型对三维矩形光滑和底部布有横肋的粗糙壁面不同粒径颗粒的沉积过程进行模拟计算。结果表明,颗粒无量纲沉积速率与实验值吻合度较高,颗粒在沉积过程中受二次流的影响使得20、50μm的颗粒绝大部分沉积在壁面两侧附近,并且在两侧壁面附近,50μm颗粒的概率密度将达到5μm的34倍。

The deposition of fine(diameter less than 50μm)particulate matter in ventilation and air conditioning ducts is a common phenomenon,due to there is no absolutely smooth surface in actual engineering,the rough structures make the particle deposition process more complicated.Clearing the regular of particle-particle and particle-wall collision,rebound and particle agglomeration plays an important role in improving indoor air quality and equipment efficiency.The computational fluid dynamics(CFD)-discrete element method(DEM)coupling model was used to simulate the deposition process of different sizes particles on a three-dimensional rectangular smooth and rib-roughened surface.The results showed that the non-dimension particle deposition velocity was in good agreement with the experimental value.The particles were affected by the secondary flow during the deposition process so that most of the 20μm and50μm particles were deposited near the both side of the surface,and near the both side surface,the probability density of 50μm particles reached 34 times that of 5μm particles.