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1、分类号 单位代码 密 级 学 号 学生毕业设计题 目桨叶层数不同 对搅拌槽内流动场的影响作 者院 (系)专 业指导教师答辩日期年 月 日摘摘 要要搅拌设备广泛应用于工业生产中，如石油、化工、制药、食品、采矿、冶金、废水处理等领域。搅拌操作是工业反应过程中的重要环节，在促进槽内物料流动，使得搅拌槽内物料均匀分布的同时，能够增大传热和传质系数，加速反应的进行。因此，研究搅拌槽的流动性能在工业生产中具有重要意义。本文采用计算流体力学（CFD）对搅拌槽内的三维流动场进行了数值模拟，考察了六直叶圆盘桨（6DT） 、六叶上斜叶桨（6PDTU） 、六叶下斜叶桨（6PDTD）在桨叶层数不同时，搅拌槽内的流动场
2、及搅拌功率。结果表明：相同类型的桨叶，在桨叶层数不同时，槽内的流场不同，双层桨时流体的速度分布比单层桨时更加均匀，功率消耗更大。 （1）6DT 桨在单层时，在整个搅拌槽内形成四个对称的漩涡，功率消耗比较大；6DT+6DT 桨由于上下桨间的干涉作用，两层桨之间漩涡不明显，功率消耗更大。 （2）6PDTU 在单层时，其上扬作用使搅拌槽内形成四个大小不等的漩涡，功率消耗最小；6PDTU+6PDTU 桨由于两层桨的相互作用，槽内流体混合均匀。 （3）6PDTD 桨在单层时，由于其下压作用使槽内流体在搅拌槽内仍然形成四个漩涡，且下部漩涡较小，上部漩涡较大；6PDTD+6PDTD 桨由于两层桨相互干涉，在
3、整个搅拌槽出现六个循环流动。研究结果对搅拌反应器的优化设计具有一定的参考价值。关关 键键 词词：搅拌槽，桨叶层数，计算流体动力学（CFD） ，数值模拟桨叶层数不同对搅拌槽内流动场的影响Numerical Analysis of the Flow Field of Stirred Tank with Different Impeller LayersABSTRACTMixing equipments are widely used in industrial production, such as petroleum, chemical industry, pharmaceutical indu
4、stry, foodstuff, mining, metallurgy, waste-water treatment, etc. Stirring operation is an important part of the industry reaction process, it can promote the flowing of materials and make materials distributing evenly in the stirred tank. At the same time, it can increase the coefficient of heat and
5、 mass transfer and accelerate the reaction.Therefore, it has an important significance in industrial production to study the flow characteristics of stirred tank.Three-dimensional flow fields in stirred tank has been simulated numerically by utlizing Computational Fluid Dynamics (CFD), when the impe
6、ller layers are different, the flow characteristics and the mixing power demand of 6DT, 6PDTU and 6PDTD is researched. The results indicate that: With the same type of impeller, the flow field can be changed due to the different impeller layers. The liquid with dual impellers is mixed evenly than si
7、ngle impeller and it costs maximum power demand. (1) As for the 6DT with single impeller, four symmetrical vortexes are formed in the stirred tank and the power demand is larger. When the impeller is 6DT+6DT, because of the interference function,the vortexes between the upper and the lower impeller
8、is not obvious, it costs maximum power demand.(2)As for the 6PDTU with single impeller, its upward function results in four vortexes with different size in the stirred tank; When the impeller is 6PDTU+6PDTU, because of the mutual interference function between the upper and the lower impeller, The li
9、quid is mixed evenly and the power demand is the least in the stirred tank. (3)As for the 6PDTD with single impeller, its downward function also result in four vortexes in the stirred tank, and the range of the upper vortexes is smaller, while the range of the lower vortexes is larger; When the impe
10、ller is 6PDTD+6PDTD,there are six vortexes in the stirred tank because of the interference function between the upper and the lower impeller. The results are of importance to the design and optimization of the stirred reactor.Key words: Stirred tank, Impeller layers, Computational fluid dynamics(CFD
11、), Numerical simulation桨叶层数不同对搅拌槽内流动场的影响目目 录录1 绪论.11.1 搅拌槽简介.11.2 搅拌槽内流动特性研究现状.11.2.1 宏观流动场.11.2.2 微观特性研究.21.2.3 搅拌槽内流动特性的发展.22 计算流体动力学.42.1 CFD 技术原理介绍 .42.1.1 CFD 简介 .42.2 CFD 技术在搅拌槽中应用 .43 研究目的、研究内容及研究方法.73.1 研究目的.73.2 研究的主要内容.73.3 研究方法.83.3.1 湍流模型.83.3.2 运动部件和静止部件之间相互作用的解决方法.84 搅拌槽内流场的数值模拟.94.1 建立几何模型.94.2 网格划分.
