The flow of stirring process is complex and multiscale. To analyze the effects of baffle on the flow characteristics driven by paddle turbine, particle image velocimetry (PIV) experiments were performed for the unbaffled stirred vessel and the standard baffled stirred vessel stirred by the single paddle turbine. Under the baffle arrangement, the flow discharge was strengthened, and the range of high-velocity region was obviously expanded, and the velocity significantly fluctuated near the blade. The swirling intensity behind the blade decreased significantly, and no significant wake structure was formed, thereby helping reduce the local velocity difference attributed to the wake structure and facilitate the uniform mixing of materials. The instantaneous velocity field was decomposed into four parts at different scales by employing quadruple Proper Orthogonal Decomposition method. The quantitative analysis of different scale flow structures in stirred process was realized. Under the baffle arrangement, the flow process was facilitated in the measurement plane. In addition, the fluctuation velocity increased significantly, and the mass transfer was enhanced by vortex motion of the fluid elements, which was conducive to the uniform mixing of materials.

中文翻译：

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挡板对桨式涡轮驱动的搅拌容器中循环变化的影响使用四重正交分解

搅拌过程流程复杂，多尺度。为了分析挡板对桨式涡轮驱动的流动特性的影响，对无挡板搅拌容器和由单桨式涡轮搅拌的标准挡板搅拌容器进行了粒子图像测速（PIV）实验。在挡板布置下，气流排放得到加强，高速区域的范围明显扩大，叶片附近的速度波动明显。叶片后方的旋流强度显着降低，未形成明显的尾流结构，从而有助于减小尾流结构引起的局部速度差异，有利于物料的均匀混合。采用四重真正交分解方法将瞬时速度场分解为不同尺度的四部分。实现了搅拌过程中不同尺度流动结构的定量分析。在挡板布置下，有利于测量平面内的流动过程。此外，脉动速度显着增加，流体元素的涡旋运动增强了传质，有利于物料的均匀混合。