Effect of Fluctuating Aerosol Concentration on the Aerosol Distributions in a Turbulent Jet
Effect of Fluctuating Aerosol Concentration on the Aerosol Distributions in a Turbulent Jet
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DOI：
10.4209/aaqr.2019.11.0556
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发表时间：
2020
影响因子：
4
通讯作者：
Hailin Yang;Jianzhong Lin;T. Chan
中科院分区：
文献类型：
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作者：
Hailin Yang;Jianzhong Lin;T. Chan
本文应用雷诺平均法推导了基于湍流动能的平均粒子通用动力学方程（APGDE），该方程模拟了气溶胶浓度波动对凝结的影响，称为波动凝结项（FCT）。的APGDE数值求解采用泰勒级数展开法的时刻为湍流射流的方程，然后通过比较一些结果与实验值进行验证。得到了加入和不加入FCT时气溶胶粒子数浓度、质量浓度、平均直径和几何标准差的分布和演变规律，发现当x/D = 5时，浓度波动对凝结的贡献成为一个因素，当x/D = 20时，浓度波动对凝结的贡献达到稳定状态。当考虑FCT时，数量浓度、平均直径和几何标准差分别明显较低、较大和较大。浓度波动强化了混凝作用，降低了数浓度，增大了平均粒径。因此，湍流射流中的这种波动不能忽略。
ABSTRACT We apply the Reynolds averaging method to derive the averaged particle general dynamic equation (APGDE), which models the effect of fluctuations in aerosol concentrations on coagulation, referred to as the fluctuating coagulation term (FCT), based on the turbulent kinetic energy. The APGDE is numerically solved using the Taylor-series expansion method of moments for a turbulent jet; the equation is then validated by comparing some of the results with experimental values. Obtaining the distribution and evolution of the aerosol particle number concentration, mass concentration, mean diameter and geometric standard deviation both when the FCT is incorporated and when it is excluded, we find that the contribution of fluctuating concentrations to the coagulation becomes a factor when x/D = 5 and reaches a stable state when x/D = 20. When the FCT is considered, the number concentration, mean diameter and geometric standard deviation are clearly lower, larger and greater, respectively. The fluctuating concentrations intensify the coagulation, reduce the number concentration and increase the mean diameter. Therefore, such fluctuations in a turbulent jet cannot be neglected.