入口结构对三维凹壁面切向射流作用下离散颗粒行为的影响

doi:10.11949/0438-1157.20190177

化工学报 ›› 2019, Vol. 70 ›› Issue (8): 3021-3032.DOI: 10.11949/0438-1157.20190177

入口结构对三维凹壁面切向射流作用下离散颗粒行为的影响

张静^1,²(),王巍¹,宋姝宁³,龚斌¹(),李雅侠¹,王学平^1,²,吴剑华^1,²

1. 沈阳化工大学辽宁省化工新技术转移推广中心，辽宁沈阳 110142
2. 天津大学化工学院，天津 300072
3. 昆士兰大学化学与分子生物科学学院，澳大利亚布里斯班 4067

收稿日期:2019-03-03 修回日期:2019-04-30 出版日期:2019-08-05 发布日期:2019-08-05
通讯作者: 龚斌
作者简介:张静（1971—），女，博士，副教授，<email>2501474185@qq.com</email>
基金资助:
国家自然科学基金项目(51506133);辽宁省自然基金指导计划项目(1553734485448);辽宁省教育厅一般项目(LQ2017001)

Effect of inlet structures on discrete particles behavior based on concave-wall jet

Jing ZHANG^1,²(),Wei WANG¹,Shuning SONG³,Bin GONG¹(),Yaxia LI¹,Xueping WANG^1,²,Jianhua WU^1,²

1. Center of New Chemical Technology Transfer and Promotion of Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, Liaoning, China
2. School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, China
3. School of Chemistry and Molecular Bioscience, The University of Queensland, Brisbane 4067, Australia

Received:2019-03-03 Revised:2019-04-30 Online:2019-08-05 Published:2019-08-05
Contact: Bin GONG

摘要/Abstract

摘要：

液固分离是煤化工污水处理中的常规操作单元，待处理物料贴着圆筒体内壁面切向进入分离设备，形成三维凹壁面切向射流。为了比较射流入口结构对离散颗粒产生的影响，利用液固分离实验和离散相模型模拟研究了颗粒的轨迹和Reynolds数，并对加入颗粒前后凹壁面切向射流的湍动特性和壁面剪应力分布进行分析。研究结果表明，半圆形、方形、圆形入口与设备内壁面贴合长度依次缩短，颗粒沿径向分布范围依次加宽，流向行程依次缩短。而颗粒停留时间按照圆形、半圆形、方形依次缩短。其原因在于，半圆形入口切向最大速度比方形提高16.0%，圆形降低15.3%。近壁面一倍射流高度范围内的离心力平均值，半圆形入口比方形提高59.9%，圆形降低43.5%。三种入口结构下97%的颗粒Reynolds数在40～400范围内，Reynolds数为80的颗粒数量最多。颗粒受凹壁面切向射流的影响，入口周向10°～35°范围内，离散颗粒与壁面形成第一次冲击，最大壁面剪应力值出现持平趋势，超过 90°以后，颗粒沿壁面滚动下滑，壁面剪应力逐渐趋于0。经过计算，方形、半圆形、圆形三种入口结构加入离散颗粒后湍动强度分别提高27.1%、8.8%、62.7%，壁面剪应力分别提高23.7%、13.5%、15.2%。

关键词: 凹壁面切向射流, 离散相模型, 固相颗粒, 湍动强度, 壁面剪应力

Abstract:

Liquid-solid separation is a common operation unit in coal chemical wastewater treatment. The material to be treated is tangentially inserted into the separation device against the inner wall surface of the cylinder to form a three-dimensional concave wall tangential jet. In order to compare the influence of the jet inlet structures on discrete particles, the liquid-solid separation experiment and discrete phase model are used to calculate the trajectory and Reynolds number of the particles. The continuous phase turbulence characteristics are investigated under the influence of the particles, and the distribution of wall shear stress was analyzed. The results show that the fit length between inlet and wall are shortened for semi-circular, square and circular. The radial distribution range of particles is sequentially widened, and the distance of flow direction is sequentially shortened. The particle residence time is shortened in the order of circle, semi-circular, and square inlets. The reason is that the maximum tangential velocity of the semi-circular inlet is 16.0% higher than that of the square, and the circular shape is reduced by 15.3%. The average value of the centrifugal force of the semi-circular inlet is increased by 59.9% and the circle is reduced by 43.5% than the square in the near wall. 97% of the particles Reynolds number is in the range of 40—400, and the number of particles with Re = 80 is the highest for three inlets. The particles are affected by the concave-wall jet, the impact and rolling is formed between the discrete particles and the wall. The first impact is in the range of 10°—35° in the inlet circumferential direction, the maximum wall shear stress appears to be flat. The wall shear stress gradually approaches zero after the particles roll along the wall surface and the circumferential direction exceeds 90°. After calculations, the turbulence intensity increased 27.1%, 8.8%, and 62.7%, and the wall shear stress increased 23.7%, 13.5%, and 15.2% for square, semi-circular and circular inlet, respectively.

Key words: concave-wall jet, discrete phase model, solid particle, turbulence intensity, wall shear stress

中图分类号:

O 358

张静, 王巍, 宋姝宁, 龚斌, 李雅侠, 王学平, 吴剑华. 入口结构对三维凹壁面切向射流作用下离散颗粒行为的影响[J]. 化工学报, 2019, 70(8): 3021-3032.

Jing ZHANG, Wei WANG, Shuning SONG, Bin GONG, Yaxia LI, Xueping WANG, Jianhua WU. Effect of inlet structures on discrete particles behavior based on concave-wall jet[J]. CIESC Journal, 2019, 70(8): 3021-3032.

图/表 18

图1 凹壁面切向射流模型结构

Fig.1 Model of concave-wall jet

表1 射流入口结构形式

Table 1 Inlet structures of wall jet

射流入口	结构	参数
	方形	B=20 mm
	半圆形	B=20 mm
	圆形	B=20 mm

表2 流体与颗粒的物性参数

Table 2 Physical parameters of fluid and particles

连续相参数	数值	离散相参数	数值
温度/K	298	d_p/mm	0.75
黏度/(m²·s^-1)	1.005×10^-6	形状	球形
密度 ρ/(kg·m^-3)	998.2	密度 ρ_p/(kg·m^-3)	2250
u_in/(m·s^-1)	1.0—5.0	总流率/(kg·s^-1)	5×10^-4
Re范围	19900—121571	颗粒类型	inert

图2 监测截面上颗粒质量分数变化

Fig.2 Particle mass percentage variation of monitoring surface (D0=600 mm；uin=2.0 m?s-1)

图3 块结构化网格

Fig.3 Block-structured grid

图4 实验装置

Fig.4 Experiment system

图5 出口截面颗粒统计

Fig.5 Statistics of particles on outlet section

图6 90%的颗粒在出口截面上位置分布及停留时间统计

Fig.6 Statistics of particle distribution on outlet section and residence time with cumulative percentage of 90%

图7 离散颗粒轨迹与Reynolds数

Fig.7 Trajectory and Reynolds number of discrete particles (D0=600 mm；uin=2.0 m?s-1)

图8 离散颗粒分布统计

Fig.8 Particle distribution statistics in separator(D0=600 mm；uin=2.0 m?s-1)

图9 离散颗粒Reynolds数统计

Fig.9 Statistics of particles Reynolds number (D0=600 mm；uin=2.0 m?s-1)

图10 水平对称面上最大切向速度

Fig.10 Maximum tangential velocity at Z/B = 0 (D0=600 mm；uin=2.0 m?s-1)

图11 流向半值宽

Fig.11 Half value width of streamwise at Z/B = 0 (D0=600 mm；uin=2.0 m?s-1)

图12 近壁面湍动强度分布

Fig.12 Distribution of turbulence intensity at (R0-r)/B=0.5 (D0=600 mm；uin=2.0 m?s-1)

图13 湍动强度的比较分析

Fig.13 Comparative analysis of turbulence intensity (D0=600 mm；uin=2.0 m?s-1)

图14 壁面剪应力分布

Fig.14 Wall shear stress (D0=600 mm；uin=2.0 m?s-1)

表3 壁面剪应力

Table 3 Wall shear stress

入口结构	无离散颗粒		含离散颗粒
入口结构	最大值/Pa	均值/Pa	最大值/Pa	均值/Pa
方形	14.33	0.396	15.54	0.490
半圆形	14.31	0.532	15.04	0.604
圆形	12.26	0.271	12.00	0.312

图15 周向最大壁面剪应力

Fig.15 Maximum wall shear stress along circumferential direction (D0=600 mm；uin=2.0 m?s-1)

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入口结构对三维凹壁面切向射流作用下离散颗粒行为的影响

Effect of inlet structures on discrete particles behavior based on concave-wall jet

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