TY - JOUR
T1 - 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
AU - Faghih, Mahdi
AU - Valera-medina, Agustin
AU - Chen, Zheng
AU - Paykani, Amin
N1 - © 2023 The Author(s). Published by Elsevier Inc. on behalf of The Combustion Institute. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
PY - 2023/11/30
Y1 - 2023/11/30
N2 - 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 and P = 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.
AB - 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 and P = 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.
KW - Laminar flame speed
KW - NH-air
KW - NH/CH-air
KW - NH/H-air
KW - Radiation
KW - Spherically propagating flame
UR - http://www.scopus.com/inward/record.url?scp=85169827839&partnerID=8YFLogxK
U2 - 10.1016/j.combustflame.2023.113030
DO - 10.1016/j.combustflame.2023.113030
M3 - Article
AN - SCOPUS:85169827839
SN - 0010-2180
VL - 257
JO - Combustion and Flame
JF - Combustion and Flame
M1 - 113030
ER -