分形排布式穿流搅拌桨强化流体混沌混合行为研究

doi:10.11949/0438-1157.20240488

摘要/Abstract

摘要：

为减小混合隔离区，增大混沌混合区，强化流体的混沌混合过程。本文基于分形理论的自相似特性，提出了一种具有分形排布式穿流孔的搅拌桨来强化流体的混沌混合行为。采用计算流体力学（CFD）和实验相结合的方法探究了流体混合过程中的功耗特性、速度分布、剪切应变率分布、隔离区结构以及庞加莱截面。研究结果表明，在相同Reynolds数下，与Rushton桨相比，分形排布式穿流搅拌桨（FAPT）能够有效降低搅拌功耗和功率准数，且随着穿流孔分形迭代次数的增加，搅拌功耗和功率准数进一步降低。其中，FAPT-1体系的功率准数降低6.57%~12.50%，FAPT-2体系的功率准数降低10.95%~19.32%，FAPT-3体系的功率准数降低15.25%~24.66%。在相同功耗下，与Rushton桨相比，FAPT桨能够增强对流体的剪切作用，增大剪切应变率，减小混合隔离区，缩短流体的混合时间，提高流体的混合效率，且随着穿流孔分形迭代次数的增加，这一效果更为明显。

关键词: 分形排布式穿流搅拌桨, 搅拌混合, 流场, 计算流体力学

Abstract:

In order to reduce the isolation zone, expand the chaotic mixing zone and strengthen the fluid mixing process. Based on the self-similarity of fractal theory, a kind of impeller with fractal arranged perforated holes was proposed to strengthen the fluid chaotic mixing behavior. The power consumption characteristics, velocity distribution, shear strain rate distribution, isolation zone structure and Poincare section during the fluid mixing process were investigated by using computational fluid dynamics (CFD) combined with experiments. Results showed that FAPT impeller could effectively reduce the power consumption and power number compared with RT at the same Reynolds number, and the power consumption and power number could be further decreased with the increase of fractal iteration number of perforated holes. Compared with RT system, the power number of FAPT-1 system was reduced by 6.57%~12.50%, the power number of FAPT-2 system was reduced by 10.95%~19.32%, and the power number of FAPT-3 system was reduced by 15.25%~24.66%. FAPT impeller could enhance the shear effect on the fluid, increase the shear strain rate of fluid, reduce the isolation zone, shorten the mixing time, and improve the fluid mixing efficiency compared with Rushton turbine under the same power consumption, and this effect was more obvious with the increase of fractal iteration number of perforated holes.

Key words: fractal-arranged perforated impeller, mixing, flow field, computational fluid dynamics

中图分类号:

TQ 027.2

谷德银, 李昌树, 杨豪, 刘作华. 分形排布式穿流搅拌桨强化流体混沌混合行为研究[J]. 化工学报, DOI: 10.11949/0438-1157.20240488.

Deyin GU, changshu LI, Hao YANG, Zuohua LIU. Study on fluid chaotic mixing behavior intensified by a fractal-arranged perforated impeller[J]. CIESC Journal, DOI: 10.11949/0438-1157.20240488.

图/表 14

图1 搅拌装置图

Fig.1 Stirred device diagram

图2 搅拌桨结构图

Fig.2 Impeller structure diagram

图3 桨叶结构示意图

Fig.3 Impeller blade structure diagram

图4 网格无关性验证

Fig.4 Grid independence verification

图5 FAPT-3体系功耗模拟值与实验值

Fig.5 Numerical simulation predicted power consumption with experimental data in FAPT-3 system

图6 不同搅拌桨体系中功耗、功率准数以及Reynolds数与功率准数乘积随Reynolds数的变化

Fig.6 Variation of power consumption and power number with Reynolds number in different impeller systems

图7 不同搅拌桨体系中z/H =0.5处的径向速度和轴向速度（P = 9.2 W）

Fig.7 Radial velocity and axial velocity at z/H =0.5 in different impeller systems (P = 9.2 W)

图8 搅拌桨所在平面（z = 0.16 m）的速度分布（P = 9.2 W）

Fig.8 Velocity distribution on the impeller plane (P = 9.2 W)

图9 搅拌桨桨叶垂直平面的速度分布（P = 9.2 W）

Fig.9 Velocity distribution on vertical plane of impeller blade（P = 9.2 W）

图10 搅拌桨所在平面（z = 0.16 m）的剪切应变率分布（P = 9.2 W）

Fig.10 Shear strain rate distribution on the impeller plane (P = 9.2 W)

图11 不同搅拌体系中r/R = 0.8处的剪切应变率分布（P = 9.2 W）

Fig.11 Shear strain rate distribution at r/R = 0.8 in different impeller systems (P = 9.2 W)

图12 不同搅拌桨在不同单位体积功耗下的混合时间

Fig.12 Mixing time of different impeller system under different unit volume power consumption

图13 不同搅拌桨体系的可视化图（P = 9.2 W）

Fig.13 Visualization of different impeller systems (P = 9.2 W)

图14 不同搅拌桨体系的庞加莱截面（P = 9.2 W）

Fig.14 Poincare cross sections for different impeller systems (P = 9.2 W)

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