Flow field characteristics in stirred tank equipped with punched and four-pitched blade combined impeller

doi:10.16085/j.issn.1000-6613.2023-2214

Abstract

Abstract:

The flow characteristics of the punched and four-pitched blade combined impellers in the stirred tank were simulated by using large eddy simulation based on computational fluid dynamics (CFD) and the simulation results were validated by the results of particle image velocimetry (PIV) experiments. The effects of different rotational speeds, installation height of impellers, and punched hole diameter on the flow field characteristics were investigated. The research results showed that the increasing of rotational speed can enhance the pumping effect of the lower blade and then promoted the mixing effect of the flow field. However, the excessive increasing of rotational speed can cause chaos in the flow pattern, and the simulation results showed that the optimal speed was N=100r/min. The increasing of the installation height of impellers would improve the velocity distribution in the top area of the tank. When the ratio of installation height of impellers to vessel diameter was 0.29, a vortex favorable for mixing was formed in the flow field, and the distribution of flow velocity in the top and lower areas was appropriate, indicating a better distance from the bottom. The connection flow between two blades was mainly affected by the punched hole diameter. When the punched hole diameter was 4mm, the connection flow in the mixing tank was more stable and the overall high-speed zone area distribution was more appropriate, which can promote the overall circulation effect in the mixing tank. The research results can provide a reference for the application of punched and four-pitched blade combined impeller in practical industrial processes.

Key words: four-pitched blade-punched combined impellers, particle image velocimetry(PIV), flow field, computational fluid dynamics(CFD)

摘要：

基于计算流体力学（CFD）中的大涡模拟方法对穿流-四斜叶组合桨槽内流动特性进行了模拟研究，并采用粒子成像测速（PIV）技术进行了实验验证。研究了不同转速、离底距和桨叶开孔直径对流场的影响。结果表明，转速的增加可以提升下桨叶的轴流作用进而增强流场的混合效果，但转速过高会使流场内流型变得混乱，模拟结果显示较优转速为N=100r/min；离底距的增加会改善槽内顶部区域的速度分布，当离底距与液位高度比为0.29时，流场内形成了有利于混合的涡旋，搅拌槽顶部及下层区域流场速度分布合理，为较优的离底距；穿流孔径主要影响两桨叶之间的连接流，当穿流孔径为4mm时，搅拌槽内的连接流更稳定，整体高速区面积分布更为合理，能促进搅拌槽内整体的循环效果。研究结果可为穿流-四斜叶组合桨的实际工业生产应用提供数据参考。

关键词: 穿流-四斜叶组合桨, 粒子成像测速, 流场, 计算流体力学

CLC Number:

TQ027

XU Yang, YANG Qizhou, PAN Yueyue, ZHOU Yongjun. Flow field characteristics in stirred tank equipped with punched and four-pitched blade combined impeller[J]. Chemical Industry and Engineering Progress, 2025, 44(1): 38-47.

徐阳, 杨其洲, 潘跃跃, 周勇军. 穿流-四斜叶组合桨搅拌槽内的流场特性[J]. 化工进展, 2025, 44(1): 38-47.

Figures/Tables 18

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参考	数值/mm	参考	数值/mm
H	670	d	40
T	430	h₀	40
h	620	t	2
D	240	D₂	210
D₁	200	B₂	30
B₁	30	R	30

参考	数值/mm	参考	数值/mm
H	670	d	40
T	430	h₀	40
h	620	t	2
D	240	D₂	210
D₁	200	B₂	30
B₁	30	R	30

网格数	功率准数N_P	相对偏差/ %
7.6×10⁵	4.12	—
8.7×10⁵	4.37	+6.068
9.7×10⁵	4.52	+3.432
1.04×10⁶	4.58	+1.327
1.10×10⁶	4.62	+0.873

网格数	功率准数N_P	相对偏差/ %
7.6×10⁵	4.12	—
8.7×10⁵	4.37	+6.068
9.7×10⁵	4.52	+3.432
1.04×10⁶	4.58	+1.327
1.10×10⁶	4.62	+0.873

转速N/r·min^-1	计算功率/W	实验功率/W	误差/ %
60	1.0061	1.0865	7.99%
80	2.6887	2.9165	8.47%
100	3.9899	4.3701	9.53%
120	6.6103	7.2671	9.93%