On conditions for self-sustained combustion of pulverised coal particle-laden mixtures following localised forced ignition: A Direct Numerical Simulation analysis
On conditions for self-sustained combustion of pulverised coal particle-laden mixtures following localised forced ignition: A Direct Numerical Simulation analysis
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发表时间：
2015
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通讯作者：
T. Brosh;F. Marincola;D. Wacks;D. Patel;N. Chakraborty
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作者：
T. Brosh;F. Marincola;D. Wacks;D. Patel;N. Chakraborty
随着高性能计算技术的发展，数值模拟在煤燃烧分析中发挥着越来越重要的作用。Luo等人最近对含煤颗粒的湍流混合物进行了直接数值模拟（DNS）。在缺乏足够的挥发性气体热化学表征的情况下，Luo等人认为煤中释放的挥发性气体具有甲烷的性质，将煤颗粒作为点源，并以拉格朗日方式对其进行跟踪。最近，Brosh和Chakraborty[2]使用载体相的三维DNS来分析颗粒加载（即颗粒等效比，Φp，根据颗粒相中可用的挥发性燃料来定义）、背景气体中一次挥发性燃料的等效比Ф和均方根湍流速度波动u对煤粉颗粒混合物局部强制点火后燃烧早期阶段的影响。本文扩展了Brosh和Chakraborty[2]的分析，分析了成功点火后燃烧初期微混合对燃烧程度的影响。微混合速率是由标量耗散率决定的，尽管已知标量耗散率在液滴燃烧过程中具有重要影响，但现有文献尚未分析其对含煤颗粒混合物燃烧程度的影响[3,4]。本分析通过在不同颗粒直径的Φp， Ф和u值范围内对含煤粉颗粒混合物进行局部强制点火的三维DNS模拟，解决了上述差距。
Numerical simulations are playing an increasingly important role in the analysis of coal combustion as a result of the recent advances in high performance computing. Luo et al. [1] recently carried out Direct Numerical Simulations (DNS) of turbulent coal particle-laden mixtures. In the absence of an adequate thermochemical representation of the volatile gas, Luo et al. [1] considered the volatile gas released from the coal to have the properties of methane, treating the coal-particles as point sources, and tracking them in a Lagrangian manner. Recently, Brosh and Chakraborty [2] used three-dimensional DNS for the carrier phase to analyse the effects of particle loading (i.e. particle equivalence ratio, Φp, which was defined based on the volatile fuel available in the particulate phase), equivalence ratio of primary volatile fuel in the background gas, Ф, and root-mean-square turbulent velocity fluctuation, u, on the early stages of combustion following localised forced ignition of pulverised coal particle-laden mixtures. This paper extends the analysis of Brosh and Chakraborty [2] to analyse the influences of micro-mixing on the extent of burning during the early stages of combustion following successful ignition. The rate of micro-mixing is determined by the scalar dissipation rate and its effects on the extent of burning in coal particle-laden mixtures are yet to be analysed in the existing literature, despite the fact that the scalar dissipation rate is known to have important influences in droplet-laden combustion processes [3,4]. The present analysis addresses the aforementioned gap by carrying out three-dimensional DNS simulations of localised forced ignition of pulverised coal particle-laden mixtures for a range different values of Φp, Ф and u for different particle diameters, ap.