Large-eddy simulations of a lean hydrogen premixed turbulent jet flame with tabulated chemistry

TL;DR

This study employs large-eddy simulations with tabulated chemistry to accurately model a lean hydrogen turbulent jet flame, capturing complex thermodiffusive effects and validating results against direct numerical simulations.

Contribution

The paper introduces an LES approach using a tabulated flamelet model that includes detailed transport and thermodiffusion, validated against DNS for predictive accuracy.

Findings

LES accurately reproduces flow structures and thermodiffusive effects.

Global flame characteristics are well captured with limited mesh sensitivity.

Thermodiffusion significantly influences flame reactivity and should be included.

Abstract

Large-eddy simulations (LES) of a planar turbulent lean hydrogen-air jet flame at Re = 11000 are performed using a tabulated flamelet model based on mixture-averaged diffusion that incorporates detailed transport, including differential and preferential diffusion, wall heat loss, and thermodiffusion. The approach is extended to turbulent combustion in LES using a presumed-shape probability density function formulation that accounts for sub-filter effects. The flame exhibits a highly corrugated front, driven by local variations of mixture fraction induced by strong thermodiffusive transport. These effects significantly alter both the flame structure and morphology. The LES results are systematically compared to a reference direct numerical simulation across varying LES filters through different mesh resolutions to evaluate the predictive capability of the model. The LES accurately reproduces instantaneous flow structures and thermodiffusive effects. Global flame characteristics including flame length, surface area, and consumption speed, are well captured and show limited sensitivity to mesh resolution. The role of thermodiffusion is also examined, showing that its incorporation leads to a more reactive flame and should not be neglected in the formulation. Heat losses are incorporated into the tabulated chemistry framework for completeness but are found to have a negligible impact, consistent with the walls weak influence in the present configuration. Overall, the results demonstrate that the proposed approach provides reliable predictions of the main flame characteristics, with remaining discrepancies primarily associated with unresolved sub-filter effects that deserve further investigation.