On Band Lumping, Radiation Reabsorption, and High-Pressure Effects in Laminar Flame Propagation
Effects of radiation reabsorption on the burning flux of freely propagating laminar premixed flames at atmospheric and elevated pressures were numerically investigated for CH4/O2/N2/CO2 mixtures. Models with SNBCK 9 bands and 7 bands based on the spectral band lumping for H2O, CO2, CO and CH4 were developed to improve the computational efficiency. It is found that the burning flux is promoted by the upstream radiation reabsorption and with increasing CO2 concentration. Furthermore, with increasing pressure, radiation reabsorption first increases and then reduces the burning flux because of the corresponding increases of the reabsorption efficiency and the optical thickness, respectively. The blockage of radiation emission from the burnt mixture due to the increased optical thickness is dominant with the addition of the stronger radiative species CO2 at higher pressures. Extensive computation further demonstrates that, compared with the benchmark case of 367 bands, the SNBCK 9 bands lumping retains good accuracy while substantially facilitates the computational efficiency.
S. Zheng et al., "On Band Lumping, Radiation Reabsorption, and High-Pressure Effects in Laminar Flame Propagation," Combustion and Flame, vol. 221, pp. 86-93, Elsevier Inc., Nov 2020.
The definitive version is available at https://doi.org/10.1016/j.combustflame.2020.07.042
Mechanical and Aerospace Engineering
Keywords and Phrases
Burning flux; Elevated pressures; Radiation reabsorption; SNBCK
International Standard Serial Number (ISSN)
Article - Journal
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01 Nov 2020