彭德其¹，刘 建¹，付 翁¹，俞天兰²， 谭卓伟¹， 吴淑英¹， 李 方¹

1. 湘潭大学 机械工程与力学学院， 湖南 湘潭 411105； 2. 湖南工业大学 机械工程学院， 湖南 株洲 412007

引用格式：彭德其， 刘建， 付翁， 等. 缩放管-液固两相流换热器的流场特征影响因素［J］. 中国粉体技术， 2025， 31（3）： 1-11.

PENG Deqi， LIU Jian， FU Weng， et al. Influencing factors of flow field characteristics of liquid-solid two-phase flow in converging-diverging tube heat exchangers［J］. China Powder Science and Technology， 2025， 31（3）： 1−11.

DOI：10.13732/j.issn.1008-5548.2025.03.006

收稿日期： 2024-08-06， 修回日期： 2025-03-03， 上线日期： 2025-03-26。

基金项目： 国家自然科学基金项目， 编号： 5217525； 湖南省自然科学基金项目， 编号： 2024JJ7546。

第一作者简介： 彭德其（1972—），男，教授，博士，博士生导师，研究方向为过程强化与节能环保。E-mail：pengshuaike@163. com。

通信作者简介： 谭卓伟（1990—），男，讲师，博士，硕士生导师，研究方向为动态流程下的强化传质过程研究。E-mail：tanzhuowei1990@126. com 。

摘要：【目的】研究缩放管内液固两相流的流场特征，实现缩放管-液固两相流换热器的优化设计。【方法】搭建可视化实验平台，采用粒子图像测速技术对立式上行缩放管内液固两相流流场特征进行研究，探索入口处流体速度、颗粒体积分数和颗粒粒径对缩放管内流体径向速度和涡量的影响规律。【结果】液固两相流的径向速度的峰值出现在轴向高度大约为0、6、24 mm处，即扩放段与收缩段的交接处；平均径向速度随着入口处流体速度、颗粒体积分数的增大而增大，随着颗粒粒径的增大而减小；涡量在管壁附近最大而在管中心处最小，整体平均涡量与近壁区域平均涡量均随着入口处流体速度、颗粒体积分数的增大而增大，随着颗粒粒径的增大而减小；在入口处流体速度为1.0 m/s、颗粒体积分数为5%、颗粒粒径为1.5 mm 的条件下，缩放管-液固两相流换热管内的流体运动最为剧烈，能有效促进管内传质与传热作用。【结论】在缩放管-液固两相流换热器中，液固两相流的平均径向速度的影响因素由强到弱依次为入口处流体速度、颗粒体积分数、颗粒粒径；近壁区域液固两相流的平均涡量的影响因素由强到弱依次为入口处流体速度、颗粒体积分数、颗粒粒径。

关键词： 缩放管； 液固两相流； 流场特征； 粒子图像测速技术； 换热器

Abstract

Objective　To optimize the design of the converging-diverging tube liquid-solid two-phase flow heat exchanger， a visual experimental platform was constructed. Particle image velocimetry （PIV） was employed to investigate the two-dimensional flow field characteristics within a vertical upward converging-diverging tube liquid-solid two-phase flow heat exchanger. The study analyzed the influence of inlet fluid velocity， particle size， and particle volume fraction on the radial velocity and vorticity of the fluid， aiming to elucidate the mechanisms of enhanced mass and heat transfer in the liquid-solid two-phase flow within the converging-diverging tube.

Methods　A visual experimental platform was established， utilizing tap water as the circulating liquid medium， spherical acrylic particles as the solid phase material， and quartz glass as the converging-diverging tube structure. Based on the general principles of particle settling velocity in engineering applications and considering the constraints of experimental conditions， three key parameters were selected， i. e. ， inlet fluid velocity， particle size， and particle volume fraction. Each parameter was set at five gradient levels. Two-dimensional PIV technology was employed to systematically investigate the flow field characteristics within a vertical upward converging-diverging tube liquid-solid two-phase flow heat exchanger. The influence of inlet fluid velocity， particle size， and particle volume fraction on the radial velocity and vorticity of the fluid was explored， and the optimal combination of operating conditions was determined.

Results and Discussion　The increase in the average radial velocity of the liquid-solid two-phase flow indicated enhanced radial fluid motion， which strengthened fluid exchange between different regions and promoted heat and mass transfer among these regions. Within a single pitch of the converging-diverging tube， the radial velocity of the liquid-solid two-phase flow at various radial positions exhibited positive and negative fluctuations as the axial height increased. The peak radial velocity occurred at axial heights of approximately 0， 6， and 24 mm， aligning with the junctions between the expanding and contracting sections of the tube. Along the radial direction， the radial velocity gradually increased from the tube center to the tube wall. The average radial velocity increased with higher inlet fluid velocity and volume fraction but decreased with larger particle sizes. The vorticity of the liquid-solid two-phase flow showed a symmetric positive-negative distribution along the radial direction， with larger vorticity values near the wall and lower values in the central region. Both the overall average vorticity and the near-wall average vorticity increased with higher inlet fluid velocity and volume fraction but decreased with larger particle size. At an inlet fluid velocity of 1. 0 m/s， the overall average vorticity was 80. 7 s^-1， and the near-wall average vorticity was 126. 4 s^-1. When the volume fraction ranged from 1% to 5%， the near-wall average vorticity was approximately 56. 6% to 69. 4% higher than the overall average vorticity. Under the conditions of an inlet fluid velocity of 1. 0 m/s， a volume fraction of 5%， and a particle size of 1. 5 mm，the fluid motion within the converging-diverging tube liquid-solid two-phase flow heat exchanger was the most intense， effectively enhancing mass and heat transfer within the tube.

Conclusion　The factors influencing the average radial velocity of the liquid-solid two-phase flow， in descending order of impact， are inlet fluid velocity， volume fraction， and particle size. Similarly， the factors affecting the average vorticity in the near-wall region， in descending order of influence， are inlet fluid velocity， volume fraction， and particle size.

Keywords： converging-diverging tube； liquid-solid two-phase flow； flow field characteristics； particle image velocimetry；heat exchanger

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