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首页> 外文期刊>Environmental Science & Technology >Analyses of Turbulent Flow Fields and Aerosol Dynamics of Diesel Engine Exhaust Inside Two Dilution Sampling Tunnels Using the CTAG Model
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Analyses of Turbulent Flow Fields and Aerosol Dynamics of Diesel Engine Exhaust Inside Two Dilution Sampling Tunnels Using the CTAG Model

机译：基于CTAG模型的两条稀释采样隧道内柴油机排气湍流流场和气溶胶动力学分析。

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Experimental results from laboratory emission testing have indicated that particulate emission measurements are sensitive to the dilution process of exhaust using fabricated dilution systems. In this paper, we first categorize the dilution parameters into two groups: (1) aerodynamics (e.g., mixing types, mixing enhancers, dilution ratios, residence time); and (2) mixture properties (e.g., temperature, relative humidity, particle size distributions of both raw exhaust and dilution gas). Then we employ the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model to investigate the effects of those parameters on a set of particulate emission measurements comparing two dilution tunnels, i.e., a T-mixing lab dilution tunnel and a portable field dilution tunnel with a type of coaxial mixing. The turbulent flow fields and aerosol dynamics of particles are simulated inside two dilution tunnels. Particle size distributions under various dilution conditions predicted by CTAG are evaluated against the experimental data. It is found that in the area adjacent to the injection of exhaust, turbulence plays a crucial role in mixing the exhaust with the dilution air, and the strength of nudeation dominates the level of particle number concentrations. Further downstream, nudeation terminates and the growth of particles by condensation and coagulation continues. Sensitivity studies reveal that a potential unifying parameter for aerodynamics, i.e., the dilution rate of exhaust, plays an important role in new particle formation. The T-mixing lab tunnel tends to favor the nudeation due to a larger dilution rate of the exhaust than the coaxial mixing field tunnel. Our study indicates that numerical simulation tools can be potentially utilized to develop strategies to reduce the uncertainties assoriated with dilution samplings of emission sources.
机译：实验室排放测试的实验结果表明，使用制造的稀释系统，颗粒物排放测量对废气的稀释过程很敏感。在本文中，我们首先将稀释参数分为两类：（1）空气动力学（例如，混合类型，混合增强剂，稀释比，停留时间）; （2）混合物特性（例如，温度，相对湿度，原始废气和稀释气体的粒径分布）。然后，我们使用综合湍流气溶胶动力学和气体化学（CTAG）模型来研究这些参数对一组颗粒物排放测量值的影响，该测量比较了两个稀释通道，即T混合实验室稀释通道和便携式现场稀释通道，一种同轴混合。在两个稀释通道中模拟了颗粒的湍流场和气溶胶动力学。根据实验数据评估了CTAG预测的各种稀释条件下的粒径分布。已经发现，在与废气注入相邻的区域中，湍流在将废气与稀释空气混合中起着至关重要的作用，并且裸露的强度主导着颗粒数浓度的水平。在更下游，裸露终止并且通过凝结和凝结的颗粒生长继续。敏感性研究表明，潜在的空气动力学统一参数，即废气的稀释率，在新颗粒的形成中起着重要作用。 T型混合实验室隧道倾向于排气，因为排气的稀释率比同轴混合场隧道大。我们的研究表明，数值模拟工具可以潜在地用于开发策略，以减少与排放源稀释采样相关的不确定性。

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  • 来源
    《Environmental Science & Technology》 |2013年第2期|889-898|共10页
  • 作者

    Yan Jason Wang; Bo Yang; Eric M. Lipsky; Allen L. Robinson; K. Max Zhang;

  • 作者单位

    Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, United States;

    College of Automotive Engineering, Jilin University, Changchun, China;

    Engineering, Pennsylvania State University Greater Allegheny, McKeesport, Pennsylvania, United States;

    Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States;

    Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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