Numerical simulation of hydraulic characteristics in axial flow pump type mixer

doi:10.11949/0438-1157.20231047

Abstract

Abstract:

The mixing and clarifying tank is an important extraction and separation equipment. In this study, computational fluid dynamics (CFD) method was used to study the fluid flow and shear force in a new type of axial flow pump type mixer (AFPM). The impact of the impeller type on average shear rate, spatial distribution of shear rate, and probability distribution of shear rate in the mixing chamber was analyzed. The results demonstrate that the combination of the conical pump and double blade yields significantly improved suction and shear force compared to traditional mixers. Furthermore, the six-bladed semi-closed turbine (SBSCT) blade can increase suction force by 87% and average shear rate by 90%. The axial flow pump also provides a more evenly distributed shear force within the mixing chamber.

Key words: numerical simulation, computational fluid dynamics, axial flow pump type mixer, extraction

摘要：

混合澄清槽是重要的萃取分离设备，采用计算流体力学（CFD）方法研究了一种新型轴流泵式混合澄清槽内流体流动与剪切力，确定了搅拌桨型对混合室内的平均剪切速率、剪切速率空间分布、剪切速率概率分布的影响，结果表明：与传统泵轮式混合室相比，轴流泵式混合室内锥形泵及双桨叶的搭配可以大幅提高混合室的抽吸力与剪切力，搭配六叶半闭式涡轮桨后抽吸力可提升87%，混合室平均剪切速率提升90%，同时轴流泵式混合室内剪切力的分布更加均匀。

关键词: 数值模拟, 计算流体力学, 轴流泵式混合室, 萃取

CLC Number:

TQ 051

Shiliang GU, Boren TAN, Quanzhong CHENG, Weijie YAO, Zhipeng DONG, Feng XU, Yong WANG. Numerical simulation of hydraulic characteristics in axial flow pump type mixer[J]. CIESC Journal, 2024, 75(3): 815-822.

谷世良, 谭博仁, 程全中, 姚玮洁, 董志鹏, 许峰, 王勇. 轴流泵式混合室内水力学特征的数值模拟[J]. 化工学报, 2024, 75(3): 815-822.

Figures/Tables 14

Fig.1 Axial flow pumptype mixer

Fig.2 Geometry of the impeller

Fig.3 Suction pressure of mixer with different rotating speeds

Fig.4 Geometry of mixer

Fig.5 Comparison of simulation results for three different grids

Table 1 Grid number of mixer with different structure

AFPM+Propeller	AFPM+SBSCT	TM+SBSCT
472658个	449610个	206706个

Fig.6 Contour of shear rates (N=390 r/min，D=6 cm，x=0)

Fig.7 Average shear rates at different rotate speeds

Fig.8 Probability distribution of shear rate for different structures (N=390 r/min)

Table 2 The ratio of average shear rate of mixers

设备名称	平均剪切速率比值
AFPM+Propeller	4.22
AFPM+SBSCT	4.59
TM+SBSCT	10.07

Fig.9 Suction pressure of mixer with different rotating speeds (CFD result)

Fig.10 Contour of pressure of different agitation structure

Fig.11 Vector plots of velocities of different mixer and impellers

Table 3 Average turbulent kinetic energy in mixer

设备名称	平均湍动能/(10^-3 m²/s²)
AFPM+Propeller	5.56
AFPM+SBSCT	5.14
TM+SBSCT	2.56

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