混砂车搅拌罐内混合过程的数值模拟

发布时间：2019-01-04 18:34

【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。
[Abstract]:In order to make up for the defect of semi-empirical design method of mixing tank and to guide the design of mixing tank, the unsteady solid-liquid two-phase flow in mixing tank was simulated based on Fluent. Unstructured grids, standard k- 蔚 turbulence model, Euler multiphase flow model, slip grid method and SIMPLE algorithm are used to analyze the flow field, mixing power, solid particle distribution and mixing time in the mixing region. The results show that the flow characteristics of the stirred flow field are the result of the interaction between the upper and lower impellers, and how to reduce the tangential velocity and increase the axial and radial velocity are the key to improve the mixing effect. The relationship between the torque, the power and the speed of the impeller accords with the conventional characteristics of the impeller. When the mixing tank is even, there are still some areas which can not be reached by the main circulation, resulting in a lower volume fraction of the local solid phase, so the flow field can be optimized by increasing the length of the mixing tank baffle. By monitoring three typical points, the variation curves of the concentration of each point with time are obtained, thus the mixing time can be obtained, which can guide the prediction of mixing time in practical process. The numerical simulation analysis lays a foundation for the optimum design of mixing tank.
【作者单位】：重庆大学机械传动国家重点实验室;
【基金】：国家科技支撑计划项目(2011BAF09B07)
【分类号】：TU642

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