颗粒绕流问题中几何形体效应的数值模拟

Simulation of geometric effects of particles on flows and drag around abnormal shape particles

运用计算流体力学 (CFD)模拟方法 ,针对球体、正六棱柱、正四面体、圆柱体和环轮体等不同几何形体颗粒 ,在雷诺数为 10～ 4 0 0条件下研究了颗粒绕流问题中的几何形体效应。基于模拟结果 ,考察了传统非球形颗粒几何表征方法的不足 ;据此定义一个新的表征形体效应的参数 ,并在大量模拟计算结果的基础上 ,关联出以上四种非球形颗粒曳力因数计算公式 ,改进后的曳力因数计算精度大大提高。

CFD modeling and simulation of flows and experienced drag over abnormal-shaped particles, such as sphere, hexahedron, trihedron, cylinder and wheel shapes,were investigated over a range of Reynolds number from 10 to 400. Based on simulation results, the conventional method characterizing an abnormal-shaped particle by using the grain volume or surface area-mean diameters was re-evaluated and was found to be improper in terms of their use in particle drag prediction. Accordingly, a new parameter was defined to take account of the geometrical effects involved and put forward a new correlation of drag coefficients for the above four non-spherical particles. The prediction of drag coefficients was greatly improved.