Oil-water biphase chaotic mixing enhanced by punched rigid-flexible combination impeller in mixer-settler

doi:10.11949/j.issn.0438-1157.20160750

Abstract

Abstract:

Signal of punched rigid-flexible combination impeller disturbance of oil-water biphase pressure fluctuation in the mixer-settler were collected and processed by LabView, plus Matlab software. The largest Lyapunov exponent (LLE) and multiscale entropy (MSE) reflected the degree of the chaos in the fluid field. At the same time, the fluid field's visualization technology was adopted to observe fluid mixing performance. It indicated that compared with the rigid combination impeller, with utilizing punched rigid-flexible combination impeller, the fluid field's structure, coupled with the way of energy dissipation was controlled by the synergetic effect of punch hole and flexible impeller. Furthermore, the chaos of fluid and mixing performance were superior to the rigid combination impeller. At rotation speed 88 r·min^-1, the chaotic mixing of fluids was at the optimal state, and the LLE was over zero, testifying the fluid mixing system in chaotic state. Punched rigid-flexible combination impeller system of MSE was significantly higher than that of the rigid combination impeller, indicating mixing performance of punched rigid-flexible combination impeller superior to the rigid combination impeller system. The number of punched holes on the flexible and the thickness of flexible blade had obvious influence on the chaotic mixing performance.

Key words: mixer-settler, rigid-flexible combination, Lyapunov exponent, multiscale entropy, punched impeller, chaos

摘要：

运用LabView和Matlab软件分别采集和处理穿流式刚-柔组合搅拌桨扰动澄清槽中油-水两相流体内部的压力脉动信号，得出的最大Lyapunov指数（LLE）和多尺度熵（MSE），反映流体内部的混沌程度；同时采用流场可视化技术观测流体混合状态。结果表明，相比于刚性组合桨，穿流式刚-柔组合搅拌桨通过穿流孔与柔性部分的共同作用改变流场的结构和能量耗散方式，使流体的混沌程度和混合状态都优于刚性组合桨。当转速为88 r·min^-1时，流体的混沌混合都达到最佳状态，各实验条件下的LLE均大于零，表明流场混合体系已进入混沌状态，且穿流式刚-柔组合搅拌桨体系的MSE明显高于刚性组合桨体系，说明穿流式刚-柔组合搅拌桨的混合效果优于刚性组合桨。另外，柔性片上穿流孔的数目和柔性桨叶的厚度对流场的混沌特性也有明显的影响。

关键词: 混合澄清槽, 刚-柔组合, Lyapunov指数, 多尺度熵, 穿流搅拌桨, 混沌

CLC Number:

TQ027.2

LIU Zuohua, XU Chuanlin, HE Muchuan, GU Deyin, XU Huiqin, HE Haixian, TAO Changyuan, WANG Yundong. Oil-water biphase chaotic mixing enhanced by punched rigid-flexible combination impeller in mixer-settler[J]. CIESC Journal, 2017, 68(2): 637-642.

刘作华, 许传林, 何木川, 谷德银, 许恢琴, 何海先, 陶长元, 王运东. 穿流式刚-柔组合搅拌桨强化混合澄清槽内油-水两相混沌混合[J]. 化工学报, 2017, 68(2): 637-642.

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