Simulation of Flow in Continuous-Flow Cloud Condensation Nuclei Counter (DMT-CCNC)

doi:10.13209/j.0479-8023.2017.015

Abstract

Abstract:

The velocity, temperature and humidity in the chamber of the Continuous Flow Streamwise Thermal-Gradient CCN Counter manufactured by DMT were successfully simulated using the computational fluid dynamics software ANSYS FLUENT. With velocity of 0.0164, 0.0185, 0.0205, 0.0226, 0.0246 m/s and temperature settings of ΔT 2, 8 and 17 K, the influence of velocity and temperature on the flow were tested. Results show that, velocity and temperature setting of CCNC influenced both velocity field and temperature field. When ∆T=8 K, v=0.0205 m/s, the supersaturaiton on the centerline was about 0.27%. Supersaturation in the CCNC chamber was simulated successfully.

Key words: CCNC, ANSYS FLUENT, velocity field, temperature field, water vapor field

摘要：

运用计算流体力学模型 ANSYS FLUENT, 对 DMT 公司的恒流热梯度云凝结核计数器(CCNC)云室内的流场、温度场以及水汽场进行模拟。依据外场观测和室内实验中的常用进气流速 0.0164, 0.0185, 0.0205, 0.0226 和 0.0246 m/s 以及云室温差 2, 8 和 17 K, 对比不同进气流速和云室温差对云室内流场的影响。结果显示, 云室内的速度场和温度场均受进气流速和云室温差的影响。当云室温差为 8 K, 进气流速为 0.0205 m/s时, 模拟出的云室中心线的过饱和度约为0.27%, 较好地模拟出云室内的水汽过饱和状态。

关键词: 云凝结核计数器(CCNC), ANSYS FLUENT, 速度场, 温度场, 水汽场

Renjie YU, Chunsheng ZHAO, Huiwen XUE, Nan MA, Jiangchuan TAO, Shizuo FU, Jianpeng ZHANG, Ye KUANG, Hongjian LIU, Yuxuan BIAN. Simulation of Flow in Continuous-Flow Cloud Condensation Nuclei Counter (DMT-CCNC)[J]. Acta Scientiarum Naturalium Universitatis Pekinensis, 2017, 53(5): 817-824.

于仁杰, 赵春生, 薛惠文, 马楠, 陶江川, 付仕佐, 张健鹏, 旷烨, 刘宏剑, 边宇轩. FLUENT对云凝结核计数器云室内气流特征的模拟研究[J]. 北京大学学报自然科学版, 2017, 53(5): 817-824.

Figures/Tables 9

Fig. 1 CCNC chamber

Fig. 2 Theory of supersaturation generation of CCNC chamber

Fig. 3 Velocity field in CCNC chamber when ∆T is set respectively at 2, 8, 17 K, and inlet flow velocity is 0.0205 m/s

Fig. 4 Velocity results in the middle of CCNC chamber when ∆T is set respectively at 2, 8, 17 K, and inlet flow velocity varies from 0.0164 m/s to 0.0246 m/s

Fig. 5 Temperature field in CCNC chamber when ∆T is set respectively at 2, 8, 17 K, and inlet flow velocity is 0.0205 m/s

Fig. 6 Temperature in the middle of CCNC chamber when ∆T is set respectively at 2, 8, 17 K, and inlet flow velocity varies from 0.0164 m/s to 0.0246 m/s

Fig. 7 Vapor pressure field in CCNC chamber when ∆T is set at 8 K, and inlet flow velocity is 0.0205 m/s

Fig. 8 Saturation vapor pressure field in CCNC chamber when ∆T is set at 8 K, and inlet flow velocity is 0.0205 m/s

Fig. 9 Relative humidity field in CCNC chamber when ∆T is set at 8 K, and inlet flow velocity is 0.0205 m/s

References 17

[1]	Lohmann U, Feichter J. Global indirect aerosol effects: a review. Atmospheric Chemistry and Phy-sics, 2005, 5(3):715-737
[2]	Solomon S.Climate change 2007 — the physical science basis. Working GroupⅠ: Contribution to the fourth assessment report of the IPCC. New York: Cambridge University Press, 2007: Vol. 4
[3]	Rose D, Gunthe S S, Mikhailov E, et al.Calibration and measurement uncertainties of a continuous-flow cloud condensation nuclei counter (DMT-CCNC): CCN activation of ammonium sulfate and sodium chloride aerosol particles in theory and experiment. Atmospheric Chemistry and Physics , 2008, 8(5):1153-1179
[4]	Stratmann F, Herrmann E, Petaja T, et al. Modelling Ag-particle activation and growth in a TSI WCPC Model3785. Atmospheric Measurement Techniques,2010, 3(1): 273‒281
[5]	Herrmann E, Lihavainen H, Hyvarinen A P, et al. Nucleation simulations using the fluid dynamics software FLUENT with the fine particle model FPM. The Journal of Physical Chemistry A, 2006, 110(45):12448-12455
[6]	Herrmann E, Hyvarinen A P, Brus D, et al. Re-evaluation of the pressure effect for nucleation in laminar flow diffusion chamber experiments with FLUENT and the fine particle model.The Journal of Physical Chemistry A, 2009, 113(8):1434-1439
[7]	Lance S, Medina J, Smith J N, et al. Mapping the operation of the DMT continuous flow CCN counter.Aerosol Science and Technology, 2006, 40(4):242- 254
[8]	Roberts G, Nenes A. A continuous-flow streamwise thermal-gradient CCN chamber for atmospheric measurements.Aerosol Science and Technology, 2005, 39(3):206-221
[9]	ANSYS Inc. ANSYS FLUENT 12.0 user’s guide [EB/OL]. (2009‒04) [2014‒12‒05].
[10]	王福军. 计算流体动力学分析: CFD 软件原理与应用. 北京: 清华大学出版社, 2004: 160‒183
[11]	李进良, 李承曦, 胡仁喜. 精通FLUENT 6.3 流场分析.北京: 化学工业出版社, 2009: 12‒50
[12]	吴望一. 流体力学(上、下).北京: 北京大学出版社, 1990: 145‒199
[13]	马楠. 华北平原气溶胶光学和活化特性研究[D]. 北京: 北京大学, 2013
[14]	邓兆泽, 赵春生, 马楠, 等一种快速测量高粒径分辨率气溶胶活化率曲线的方法.北京大学学报: 自然科学版, 2012, 48(3):386-392
[15]	Wang Z B, Su H, Wang X, et al. Scanning supersaturation CPC applied as a nano-CCN counter for size-resolved analysis of the hygroscopicity and chemical composition of nanoparticles.Atmospheric Measurement Techniques Discussions, 2014, 7(11):11137-11168
[16]	Lathem T L, Nenes A. Water vapor depletion in the DMT continuous-flow CCN chamber: effects on supersaturation and droplet growth.Aerosol Science and Technology, 2011, 45(5):604-615
[17]	盛裴轩, 毛节泰, 李建国, 等. 大气物理学.北京: 北京大学出版社, 2003: 290‒352