Numerical study of the effect of turbulence on rate of reactions in the MILD combustion regime
Numerical study of the effect of turbulence on rate of reactions in the MILD combustion regime
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DOI：
10.1080/13647830.2011.561368
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发表时间：
2011-10
影响因子：
1.3
通讯作者：
A. Mardani;S. Tabejamaat;Mohammadreza Mohammadi
中科院分区：
文献类型：
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作者：
A. Mardani;S. Tabejamaat;Mohammadreza Mohammadi
本文研究了轻度燃烧条件下流场参数波动的重要性。因此，采用RANS轴对称方程，对CH4+H2喷射火焰在高温和不足共流空气中的湍流进行了模拟。采用EDC模型对湍流-化学相互作用进行了建模。采用DRM-22还原机理和GRI2.11完全机理描述H2/甲烷射流火焰的化学反应。结果表明，在MILD工况下，虽然温度场波动较小，反应区体积较大，但温度和物质浓度的波动对流场仍有影响。此外，不恰当地处理湍流对化学的影响，导致目前火焰的温度预测误差高达15%。通过降低热共流空气的O2浓度，流场参数的波动对火焰特性的影响仍然显著，对物质反应速率的影响不减小。另一方面，在一定的进口湍流强度下，虽然减小了进口雷诺数可以减小流场的波动，但在轻度燃烧条件下，湍流对物质分布和温度场的影响并不会降低。
In this paper, the importance of fluctuations in flow field parameters is studied under MILD combustion conditions. In this way, a turbulent non-premixed CH4+H2 jet flame issuing into a hot and deficient co-flow air is modeled using the RANS Axisymmetric equations. The modeling is carried out using the EDC model to describe the turbulence-chemistry interaction. The DRM-22 reduced mechanism and the GRI2.11 full mechanism are used to represent the chemical reactions of H2/methane jet flame. Results illustrate that although the fluctuations in temperature field are small and the reaction zone volume are large in the MILD regime, the fluctuations in temperature and species concentrations are still effective on the flow field. Also, inappropriate dealing with the turbulence effect on chemistry leads to errors in prediction of temperature up to 15% in the present flame. By decreasing of O2 concentration of hot co-flow air, the effect of fluctuations in flow field parameters on flame characteristics are still significant and its effect on species reaction rates does not decrease. On the other hand, although decreasing of jet inlet Reynolds number at constant inlet turbulence intensity addresses to smaller fluctuations in flow filed, it does not lead to lower the effect of turbulence on species distribution and temperature field under MILD combustion conditions.