The Effects of Differential Diffusion on Turbulent Non-Premixed Flames LO 2 /CH 4 under Transcritical Conditions Using Large-Eddy Simulation

Siyuan Wang, Haiou Wang (), Kun Luo and Jianren Fan
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Siyuan Wang: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
Haiou Wang: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
Kun Luo: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
Jianren Fan: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China

Energies, 2023, vol. 16, issue 3, 1-17

Abstract: In this paper, a large-eddy simulation (LES) of turbulent non-premixed LO 2 /CH 4 combustion under transcritical conditions is performed based on the Mascotte test rig from the Office National d’Etudes et de Recherches A e ´ rospatiales (ONERA), and the aim is to understand the effects of differential diffusion on the flame behaviors. In the LES, oxygen was injected into the environment above the critical pressure while the temperature was below the critical temperature. The flamelet/progress variable (FPV) approach was used as the combustion model. Two LES cases with different species diffusion coefficient schemes—i.e., non-unity and unity Lewis numbers—for generating the flamelet tables were carried out to explore the effects of differential diffusion on the flame and flow structures. The results of the LES case with non-unity Lewis numbers were in good agreement with the experimental data. It was shown that differential diffusion had evident impacts on the flame structure and flow dynamics. In particular, when unity Lewis numbers were used to evaluate the species diffusion coefficient, the flame length was underestimated and the flame expansion was more significant. Compared to laminar counterflow flames, turbulence in jet flames allows chemical reactions to take place in a wider range of mixture fractions. The density distributions of the two LES cases in the mixture fraction space were very similar, indicating that differential diffusion had no significant effects on the phase transition under transcritical conditions.

Keywords: large-eddy simulation; transcritical conditions; differential diffusion; flame structure; flow dynamics (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
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