混砂车搅拌罐内混合过程的数值模拟  

Numerical simulation of mixing process in stirred tank of blender truck

作　　者：肖洋轶[1] 石万凯[1] 刘敬[1] 杨思维[1] 马南飞 

机构地区：[1]重庆大学机械传动国家重点实验室,重庆400044

出　　处：《长安大学学报（自然科学版）》2014年第2期120-126,共7页Journal of Chang’an University(Natural Science Edition)

基　　金：国家科技支撑计划项目(2011BAF09B07)

摘　　要：为了在一定程度上弥补混砂车搅拌罐半经验设计方法的缺陷,以及指导搅拌罐的放大设计,基于Fluent对混砂车搅拌罐内混合过程进行非定常固液两相流的数值模拟。选用非结构化网格、标准k-ε湍流模型、Euler多相流模型、滑移网格法和SIMPLE算法,分析了搅拌区的流场、搅拌功率、固相颗粒分布规律以及混合时间。研究结果表明:搅拌流场的流动特性是上、下搅拌桨相互作用的结果;如何减小切向速度、增大轴向和径向速度是提高混合效果的关键;搅拌桨所受力矩、搅拌功率与转速的关系符合搅拌桨的常规特性;在本混砂罐搅拌均匀后,仍然有主体循环不能到达的区域,造成局部固相体积分数较低,可以通过增加搅拌罐挡板长度来优化流场;通过监测3个典型的点,获得各点浓度随时间的变化曲线,从而得到混合时间,这对实际工艺中混合时间的预测具有指导作用;数值模拟分析对混砂车搅拌罐的优化设计奠定了基础。In order to overcome the shortage of semi-empirical design of the stirred tank ot blender truck to certain extension and guide its enlargement design, the mixing process inside the stirred tank of blend- er truck with solid-liquid two-phase flow was numerically simulated in the unsteady state based on Flu- ent. The unstructured grid, standard k-epsilon turbulent model, Eulerian multiphase model, sliding mesh and SIMPLE algorithm were used to study the flow field, the mixing power, the distribution law of the solid volume in the stirred tank and the mixing time. The results show that the flow characteristics in the flow field are influenced by the upper impeller and the lower impeller. The key to increase the mixing efficiency is to reduce tangential velocity, increase axial and radial velocity. The relationships of agitation speed with torque and power correspond to the conventional characteristics of agitator blade. There are still some regions which do not have the main loop after the flow field distributes uniformly. In those regions, the volume fraction of the solid phase is lower, and the flow field can be optimized by in- creasing the length of baffles. By monitoring the concentrations of three typical points, the mixing time can be obtained which can predict the mixing time in the practical technology. The results are of impor- tance to the optimization and design of stirred tank of blender truck.

关 键 词：机械工程 混砂车 FLUENT 固液两相流 流场 混合时间 

分 类 号：U415.5[交通运输工程—道路与铁道工程]