Motion Distribution Characteristics of Regular Tetrahedral Particle Population in Vertical Uppipe

doi:10.12141/j.issn.1000-565X.240222

Abstract

Abstract:

Liquid-solid two-phase flow technology is widely applied to the heat transfer enhancement in heat exchanger design, the key lies in guiding low-volume-fraction particles to the wall region to disrupt the thermal boundary layer and thereby improve the heat transfer efficiency. The movement behavior of particles is a key factor for deep analysis of heat transfer enhancement mechanism. Non-spherical particles have better disturbance effects and more complex movement behaviors due to the anisotropy of their shapes. This paper takes regular tetrahedral particle groups as the research subject to analyze their motion and distribution law in liquid-solid two-phase flow in vertical uppipe. In the investigation, the effects of particle inlet volume fraction (1%, 2%, 3%, 4% and 5%) and liquid inlet velocity (1.0, 1.2, 1.5, 1.8 and 2.0 m/s) on the average velocity and relative volume fraction distribution of particle groups in tubes are simulated based on CFD-DEM (Computational Fluid Dynamics-Discrete Element Model) coupling method, and the accuracy of the numerical simulation is verified by PIV (Particle Image Veloci-metry) experiments. The results show that, within the studied parameter range, the average velocity of particle groups exhibits axial fluctuations, with a fluctuation amplitude intensifying as the liquid inlet velocity increases, and decreases radially from the pipe center to the wall. Furthermore, the velocity distribution becomes increasingly centralized as the fluid flow develops axially. Along the radial direction, the relative volume fraction of particles follows the double peak law, that is, being higher in the central area and near the wall of the tube, while being lower in the transition area. When the particle inlet volume fraction is 1% and the liquid inlet velocity is 2.0 m/s, the particle volume fraction near the pipe wall is the highest.

Key words: liquid-solid two-phase flow, regular tetrahedral particle, motion characteristic, velocity distribution, volume fraction distribution

CLC Number:

TK124

PENG Deqi, ZHOU Jingqiang, FENG Yuan, HUANG Zhizhong, TAN Zhuowei, TANG Mingcheng, PENG Jianguo, CHEN Ying. Motion Distribution Characteristics of Regular Tetrahedral Particle Population in Vertical Uppipe[J]. Journal of South China University of Technology(Natural Science Edition), 2025, 53(5): 130-138.

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对象	具体设置
求解器	基于压力的瞬态求解器
湍流模型	Realizable k-ε湍流模型
进出口条件	速度进口，z轴正方向；压力出口，出口静压为0，参考压力为大气压；湍流强度依据模拟条件计算选取；设置管径32 mm为水力直径
壁面条件	Enhanced Wall Treatment，非滑移壁面，壁温恒定为350 K

参数	数值		数值
颗粒泊松比	0.29	颗粒-颗粒恢复系数	0.3
颗粒剪切模量/Pa	1×10⁸	颗粒-颗粒静摩擦系数	0.3
颗粒密度/（kg·m^-3）	2 500	颗粒-颗粒滚动摩擦系数	0.02
管壁（钢）泊松比	0.28	颗粒-管壁恢复系数	0.45
管壁（钢）剪切模量/Pa	7×10¹⁰	颗粒-管壁静摩擦系数	0.5
管壁（钢）密度/（kg·m^-3）	7 800	颗粒-管壁滚动摩擦系数	0.05

流速/（m·s^-1）	管段	不同颗粒群进口体积分数下的标准差
流速/（m·s^-1）	管段	1%	2%	3%	4%	5%
1.0	2	0.029 9	0.027 7	0.025 7	0.022 1	0.023 9
	13	0.014 1	0.013 5	0.013 0	0.012 5	0.012 0
	19	0.012 3	0.011 6	0.010 9	0.010 2	0.009 6
1.2	2	0.029 5	0.027 4	0.023 6	0.025 4	0.022 9
	13	0.013 3	0.012 8	0.012 3	0.011 8	0.011 4
	19	0.011 4	0.010 7	0.010 1	0.009 5	0.008 9
1.5	2	0.027 0	0.025 1	0.022 3	0.023 2	0.021 1
	13	0.012 1	0.011 7	0.011 2	0.010 8	0.010 4
	10	0.011 3	0.010 6	0.010 0	0.009 4	0.008 8
1.8	2	0.026 1	0.025 2	0.022 5	0.022 8	0.019 3
	13	0.011 2	0.010 7	0.010 3	0.009 9	0.009 6
	19	0.010 9	0.010 2	0.009 6	0.009 0	0.008 5
2.0	2	0.025 4	0.025 7	0.023 5	0.020 5	0.019 2
	13	0.010 2	0.009 8	0.009 4	0.009 1	0.008 7
	19	0.010 2	0.009 6	0.008 5	0.008 7	0.007 9

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