基于FLUENT搅拌釜底部回流区的数值模拟研究∗

摘要

To address the low fluid flow rate in the recirculation zone in the glass⁃lined agitated tank bottom that is likely to cause accumulation of materials and hamper the mixing, the flow field of the recirculation zone in the glass⁃lined agitated tank bottom was simulated based on FLUENT. The interior flow field and structure were studied with steady simulation, according to which an induced cone was designed. Then the mixing effect and flow field in the tank with and without the induced cone were comparatively analyzed using unsteady simulation. Results showed that, much more solid material would accumulate in the recirculation zone during the mixing until the vol⁃ume fraction there comes to a certain steady level that is obviously higher than the theoretical level of calcium car⁃bonate volume fraction in uniform mixing, making it hard to disperse equably for solid material. However, the in⁃duced cone can advance the mixing process and shorten the mixing time. At the same time, the induced cone can reduce the recirculation zone, enlarge the bulk flow area and locally increase the axial velocity and turbulent inten⁃sity in the tank, thereby strengthen the mixing effect.%针对搅拌釜底部的回流区内液体流速较低，容易造成物料堆积，不宜进行物料混合的问题，采用稳态数值模拟方法研究了该回流区的内部流场与形状结构，据此设计1个诱导锥，对比分析了在搅拌釜底部回流区安装诱导锥前、后的混合效果与流场。模拟结果表明：随着搅拌的进行，搅拌釜底部物料聚集越来越多直至达到一稳定值，该稳定值明显高于混合均匀时碳酸钙颗粒体积分数的理论值，使物料在釜内难以均匀分布；在搅拌釜底部加入诱导锥能够明显加快釜内物料的混合，缩短混合时间；诱导锥能减小回流区，增大釜内主流循环区域与主流循环液体的轴向流速和湍流强度，从而增强混合效果。