Effect of radiation on laminar flame speed determination in spherically propagating NH3-air, NH3/CH4-air and NH3/H2-air flames at normal temperature and pressure
Effect of radiation on laminar flame speed determination in spherically propagating NH3-air, NH3/CH4-air and NH3/H2-air flames at normal temperature and pressure
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DOI：
10.1016/j.combustflame.2023.113030
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发表时间：
2023-11
影响因子：
4.4
通讯作者：
Mahdi Faghih;Agustin Valera-Medina;Zheng Chen;Amin Paykani
中科院分区：
文献类型：
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作者：
Mahdi Faghih;Agustin Valera-Medina;Zheng Chen;Amin Paykani
球形传播火焰通常用于测量NH3-空气、NH3/CH 4-空气和NH3/H2-空气混合物中的层流火焰速度。然而，这种混合物中辐射引起的不确定性尚未得到彻底研究。由于氨混合物的层流火焰速度较低，预计这种混合物的辐射效应相当大。本研究旨在填补这一空白，进行数值模拟，使用不同的化学机制和绝热和光学薄辐射模型来研究辐射对球形传播的NH3-空气，NH3/CH 4-空气和NH3/H2-空气火焰的影响。模拟是在常温常压下（Tu=298 K andP= 1 atm）和宽当量比范围内进行的。球形火焰中的辐射引起的不确定性进行了量化，并与平面火焰相比。球形火焰中的辐射诱导流动和热效应的重要性进行了比较不同的混合物和相关性的开发，以确定球形NH3-空气火焰的辐射校正的火焰速度。考虑到NH3-空气中的辐射效应，发现使用不同的机理导致层流火焰速度的测定存在相当大的差异。一些机制表明，球形火焰中的辐射诱导的火焰速度被低估了2倍以上的平面火焰相比，和贫和富球形传播的NH3-空气火焰的辐射诱导的不确定性超过20%。然而，辐射引起的不确定性在常温常压下球形传播的NH3/CH 4-空气和NH3/H2-空气火焰是不太重要的，不超过11%。最后，提出了一个更新的相关性，以确定辐射校正的火焰速度为NH3-空气火焰，可以直接用于球形火焰实验测量层流火焰速度。
The use of spherically propagating flames is common for measuring the laminar flame speed in NH3-air, NH3/CH4-air and NH3/H2-air mixtures. However, the radiation-induced uncertainty in such mixtures has not been thoroughly investigated. Due to the low laminar flame speed of ammonia mixtures, it is anticipated that the radiation effect is considerable for such mixtures. This study aims to fill this gap by conducting numerical simulations using different chemical mechanisms and the adiabatic and optical thin radiation models to examine the effects of radiation on spherically propagating NH3-air, NH3/CH4-air and NH3/H2-air flames. The simulations are performed for mixtures at normal temperature and pressure (Tu=298 K andP= 1 atm) and wide range of equivalence ratios. The radiation-induced uncertainty in spherical flames is quantified and compared to planar flames. The importance of the radiation-induced flow and thermal effects in spherical flames is compared between different mixtures and a correlation is developed to determine the radiation-corrected flame speed for spherical NH3-air flames. Considering the radiation effect in NH3-air, it was found that using different mechanisms results in considerable discrepancies in laminar flame speed determination. Some mechanisms showed that the radiation-induced flame speed in spherical flames was underpredicted by more than two times compared to planar flames, and the radiation-induced uncertainty for lean and rich spherically propagating NH3-air flames exceeds 20%. However, the radiation-induced uncertainty at normal temperature and pressure in spherically propagating NH3/CH4-air and NH3/H2-air flames was less significant, not exceeding 11%. Finally, an updated correlation is proposed to determine the radiation-corrected flame speed for NH3-air flames that can be directly used in spherical flame experiments measuring the laminar flame speed.