Effects of the K-value solution schemes on radiation heat transfer modelling in oxy-fuel flames using the full-spectrum correlated K-distribution method

Abstract

Radiation heat transfer in oxy-fuel flames is more important than in conventional fuel-air flames. The Full-Spectrum Correlated K-distribution methods (FSCK) with the original correlated-K solution scheme (Modest and Zhang, 2002) and a newly proposed one (Cai and Modest, 2014), and the Rank Correlated Full-Spectrum K-distribution method (RC-FSK) are used in radiative calculations of oxy-fuel flames. Twelve one-dimensional flames, including fuel-air, dry and wet oxy-fuel flames with various length scales, as well as a two-dimensional dry oxy-fuel flame are studied. The results show that the reference temperature has a non-negligible impact on the accuracy of original scheme and the emission-weighted temperature leads to a good accuracy. The accuracy of the new scheme is almost unaffected by the reference temperature, except for smallscale dry oxy-fuel flames. The error of the new scheme is mainly in the low-temperature region, and its accuracy depends on the length scale of computational domain. A hybrid correlated-K scheme using either the original or the new scheme according to local temperature is proposed. It combines the advantages of two schemes in different temperature regions, and is independent of the reference temperature. In addition, the RC-FSK demonstrates almost the same accuracy as FSCK with the hybrid scheme when the Planck temperature is set equal to the reference temperature.

Influence of gas radiative property models on Large Eddy Simulation of 1 m methanol pool fires

“…The RCFSK preserves the total emission and does not require any specification of a reference state [29]. In configurations relevant for combustion applications, the RCFSK was found to provide an overall very good agreement with reference LBL or Narrow Band calculations in both emission and absorption dominated problems [29,59,60]. Consequently, it will be used as reference in the present study.…”

On the symmetric and skew-symmetric K-distributions

“…Since its introduction by Jakeman and Pusey (1976), the K-distribution has proved to be remarkably useful for modeling the complex dynamics of various systems, such as wireless communications channel modeling and radar applications (e.g., Bithas et al (2006); Wang et al (2019); Zhao et al (2016)). Over the last couple of years, various derivative distributions of the K distribution have attracted attention due to their successful use in machine learning-based ultrasound image reconstruction, as well as heat transfer (e.g., Zhou et al (2020); Liu et al (2020)).…”