Characteristics and Measurement of Air Velocity and Particulate Matter Mass Concentration Distribution in Upstream and Downstream of 90° Elbow

doi:10.12068/j.issn.1005-3026.2025.20230307

Abstract

Abstract:

To solve the problem of difficulty in accurately measuring ventilation parameters at non-ideal test sections of ventilation systems， based on the numerical simulation method， the effects of pipe diameter， air velocity， curvature-diameter ratio， particulate matter mass concentration， particle size， density and other factors on the airflow and particle concentration distribution in the 90° circular bend are explored. The measurement errors and rules of the equal-area ring method and the center point method on the non-ideal test section are analyzed. The results show that the air velocity distribution in the bend is only affected by the curvature-diameter ratio， and the particulate matter mass concentration is affected by the curvature-diameter ratio， particle size and density. The maximum error of air velocity at the elbow outlet measured by the equal area ring method is 7.8%. When the curvature-diameter ratio is fixed， there is a functional relationship between the error of each measured section and the pipe diameter， and there is a linear relationship between the wind speed of the pipe center and the average air velocity of the section. The particulate matter mass concentration errors of the elbow inlet and outlet measured by the equal-area ring method are all below 10%. This study can provide a reference for the monitoring of air velocity and particulate matter mass concentration in non-ideal measurement section.

Key words: numerical simulation, 90°bend, air velocity distribution, pipeline air velocity, particulate matter mass concentration

CLC Number:

TB 24

Xiu-li LIN, Min FAN, Jin-shuo YANG, Jing-xian LIU. Characteristics and Measurement of Air Velocity and Particulate Matter Mass Concentration Distribution in Upstream and Downstream of 90° Elbow[J]. Journal of Northeastern University(Natural Science), 2025, 46(5): 113-125.

Figures/Tables 14

Fig.1 Geometric model

Fig.2 Geometric model meshing diagram

Fig.3 Comparison of experimental and simulated values at a typical cross section

Fig.4 The effect of the number of meshes on the calculation result

Fig.5 Position diagram of different sections

Fig.6 Sectional air velocity distribution at different inlet air velocities

Fig.7 Particulate matter mass concentration distribution at different inlet velocities

Fig.8 Particulate matter mass concentration distribution under different particle sizes

Fig.9 Particulate matter mass concentration distribution under polydisperse phases

Fig.10 Air velocity and particulate matter mass concentration distribution under different curvature-diameter ratios

Fig.11 Measurement error of equal area doughnut method under different conditions

Fig.12 Wind speed error fitting curves at the inlet and outlet of the elbow under different curvature-diameter ratios

Fig.13 Fitting curves of central wind speed and average wind speed of different sections of the pipe

Table 1 Measurement error of two equal area ring methods

参数		等面积圆环法						加密等面积圆环法
		与弯头入口距离		与弯头出口距离				与弯头入口距离		与弯头出口距离
		0	2D	0	2D	4D	6D	0	2D	0	2D	4D	6D
$风速 m · s - 1$	18	0.7	2.1	2.9	-7.1	-2.0	11.6	-0.4	0.3	-5.5	-2.5	-0.9	3.1
$风速 m · s - 1$	20	2.4	1.0	0.2	-7.2	0.6	3.5	0.0	0.0	-3.7	-0.5	0.9	5.9
$粒径 µ m$	2.50	-2.9	-6.2	1.8	-8.0	3.3	3.1	0.5	-1.3	0.1	-5.6	-1.0	8.2
	9.69	5.9	5.0	-3.5	-4.1	-2.0	5.7	1.6	1.1	-3.9	-1.8	-1.6	3.3
	10.00	3.0	1.5	-3.6	-3.0	0.9	4.5	1.8	-1.5	0.2	2.6	-1.6	1.4
	25.00	0.9	2.1	8.9	9.0	-0.5	-6.3	1.2	-0.3	13.8	1.5	-4.1	-9.6
$颗粒物密度 g ⋅ c m - 3$	2.0	3.2	0.1	1.1	-4.0	-1.1	7.9	-5.0	-0.7	0.7	-1.9	1.7	4.7
$颗粒物密度 g ⋅ c m - 3$	0.6	-8.5	1.4	3.1	-3.5	2.4	1.2	-0.7	-0.6	-1.5	-2.3	0.2	1.8
$颗粒物质量浓度 m g ⋅ m - 3$	10	3.4	-2.2	-3.5	-4.2	-2.4	5.4	4.3	-1.2	-3.9	-1.9	1.4	5.8
$颗粒物质量浓度 m g ⋅ m - 3$	20	2.3	0.0	1.2	-4.7	-3.6	3.0	-2.2	0.6	-0.9	-2.7	-3.3	2.9

Table 1 Measurement error of two equal area ring methods

参数		等面积圆环法						加密等面积圆环法
		与弯头入口距离		与弯头出口距离				与弯头入口距离		与弯头出口距离
		0	2D	0	2D	4D	6D	0	2D	0	2D	4D	6D
$风速 m · s - 1$	18	0.7	2.1	2.9	-7.1	-2.0	11.6	-0.4	0.3	-5.5	-2.5	-0.9	3.1
$风速 m · s - 1$	20	2.4	1.0	0.2	-7.2	0.6	3.5	0.0	0.0	-3.7	-0.5	0.9	5.9
$粒径 µ m$	2.50	-2.9	-6.2	1.8	-8.0	3.3	3.1	0.5	-1.3	0.1	-5.6	-1.0	8.2
	9.69	5.9	5.0	-3.5	-4.1	-2.0	5.7	1.6	1.1	-3.9	-1.8	-1.6	3.3
	10.00	3.0	1.5	-3.6	-3.0	0.9	4.5	1.8	-1.5	0.2	2.6	-1.6	1.4
	25.00	0.9	2.1	8.9	9.0	-0.5	-6.3	1.2	-0.3	13.8	1.5	-4.1	-9.6
$颗粒物密度 g ⋅ c m - 3$	2.0	3.2	0.1	1.1	-4.0	-1.1	7.9	-5.0	-0.7	0.7	-1.9	1.7	4.7
$颗粒物密度 g ⋅ c m - 3$	0.6	-8.5	1.4	3.1	-3.5	2.4	1.2	-0.7	-0.6	-1.5	-2.3	0.2	1.8
$颗粒物质量浓度 m g ⋅ m - 3$	10	3.4	-2.2	-3.5	-4.2	-2.4	5.4	4.3	-1.2	-3.9	-1.9	1.4	5.8
$颗粒物质量浓度 m g ⋅ m - 3$	20	2.3	0.0	1.2	-4.7	-3.6	3.0	-2.2	0.6	-0.9	-2.7	-3.3	2.9

References 19

[1]	国家卫生健康委发布2021年全国职业病报告［J］. 职业卫生与应急救援， 2022， 40（4）： 416.
	National Health Commission released 2021 national occupational disease report ［J］. Journal of Occupational Health and Emergency Rescue， 2022， 40（4）： 416.
[2]	Oberdoester G， Oberdoester E， Oberdoester J. Nanotoxicology： an emerging discipline evolving from studies of ultrafine particles ［J］. Environmental Health Perspectives， 2005， 113（7）： 823-839.
[3]	刘殿武. 用速度场系数简化风速测量方法［J］. 煤矿安全， 2005 （5）： 42-43.
	Liu Dian-wu. Simplifying wind speed measurement method with velocity field coefficient［J］. Safety in Coal Mines， 2005 （5）： 42-43.
[4]	Gladyszewska-Fiedoruk K， Demianiuk A B， Gajewski A， et al. Measurement of velocity distribution for air flow through perforated plastic foil ducts ［J］. Energy and Buildings， 2011， 43（2/3）： 374-378.
[5]	Ostrowski P， Remiorz L. Measurement of gas flow in short ducts， also rectangular ［J］. Flow Measurement and Instrumentation， 2013， 30： 1-9.
[6]	Care I， Bonthoux F， Fontaine J R. Measurement of air flow in duct by velocity measurements［C］// Proceedings of the 16th International Congress of Metrology. Paris： EDP Sciences， 2013： 00010.
[7]	Chow J C， Watson J G， Wang X， et al. Review of filters for air sampling and chemical analysis in mining workplaces ［J］. Minerals， 2022， 12（10）：1314.
[8]	Pampena J D， Cauda E G， Chubb L G， et al. Use of the field-based silica monitoring technique in a coal mine： a case study ［J］. Mining Metallurgy & Exploration， 2020， 37（2）： 717-726.
[9]	Molaie S， Lino P. Review of the newly developed， mobile optical sensors for real-time measurement of the atmospheric particulate matter concentration ［J］. Micromachines， 2021， 12（4）：416.
[10]	Molaie S， Lino P. Theoretical design of the scattering based sensor for analysis of the vehicle tailpipe emission ［J］. Micromachines， 2020， 11（12）：1085.
[11]	Bezantakos S， Costi M， Baempoinis K， et al. Qualification of the Alpha sense optical particle counter for inline air quality monitoring ［J］. Aerosol Science and Technology， 2020， 55（3）： 361-370.
[12]	梁艳，张增福，陈文亮，等. 基于β射线法的新型PM_2.5自动监测系统研究［J］. 传感技术学报， 2014， 27（10）： 1418-1422.
	Liang Yan， Zhang Zeng-fu， Chen Wen-liang， et al. Research of new type PM_2.5 automated monitoring system based on β-ray method ［J］. Chinese Journal of Sensors and Actuators， 2014， 27（10）： 1418-1422.
[13]	Chen J G， Li D W， Liu G Q， et al. Development of a coal dust concentration sensor based on the electrostatic induction method ［J］. ACS Omega， 2023， 8（14）： 13059-13067.
[14]	Ribalko A N， Charty P V， Shemanin V G. Dust concentration measurement laser instrument at industrial conditions［C］// Proceedings of the International Conference on Lasers for Measurements and Information Transfer. St Petersburg： SPIE， 2000： 130-136.
[15]	Abou Khousa M A， Aldurra A， Alwahedi K， et al. Hermetically sealed microwave probe for in-situ detection of black powder in gas pipelines ［C］// Proceedings of the IEEE International Instrumentation and Measurement Technology Conference （I2MTC）. Montevideo， 2014： 1115-1119.
[16]	李立，姬忠礼，许乔奇，等. 新型高压天然气管道内固体颗粒物在线检测装置及其应用［J］. 天然气工业， 2012， 32（12）： 81-84.
	Li Li， Ji Zhong-li， Xu Qiao-qi， et al. On-line detection device for solid particulate matter in novel high-pressure natural gas pipeline and its application［J］. Natural Gas Industry， 2012， 32（12）： 81-84.
[17]	Sudo K， Sumida M， Hibara H. Experimental investigation on turbulent flow in a circular-sectioned 90-degree bend ［J］. Experiments in Fluids， 1998， 25（1）： 42-49.
[18]	Kim J， Yadav M， Kim S. Characteristics of secondary flow induced by 90 degree elbow in turbulent pipe flow ［J］. Engineering Applications of Computational Fluid Mechanics， 2014， 8（2）： 229-239.
[19]	熊攀，鄢曙光. 基于Rosin-Rammler函数的数值模拟对旋风除尘器粒径分布规律的研究［J］. 粉末冶金工业， 2019， 29（2）： 29-32.
	Xiong Pan， Yan Shu-guang. Numerical simulation of particle size distribution of cyclone dust collector based on Rosin-Rammler function ［J］. Powder Metallurgy Industry， 2019， 29（2）： 29-32.