Work

Cell size distributions of hydrogen–air flames during propagation in Hele–Shaw burners

Year: 2026

Type: article

Abstract: Flame instabilities in narrow channels produce cellular structures that strongly affect flame propagation. One of the key distinguishing factors between thermodiffusive and hydrodynamic instabilities is the characteristic cell size formed on the flame surface. This study quantifies flame cell size distributions in a Hele–Shaw burner for hydrogen–air mixtures across a wide range of equivalence ratios ϕ ∈ [ 0.4,2.3 ] , and channel gaps h ∈ [ 0.58,7 ] mm, using schlieren imaging combined with a cusp-detection algorithm. For very lean mixtures, thermodiffusive instabilities dominate, producing small, highly branched cells that are largely independent of h . In contrast, for rich mixtures, the cell size increases with h , revealing a strong sensitivity to confinement and highlighting the role of hydrodynamic instabilities, whose growth is reduced in narrow channels by heat losses to the walls. When normalized by their mean value, the cell-size distributions collapse, indicating that changes in operating conditions primarily affect the mean cell size while preserving the overall distribution shape. Smaller cell sizes are associated with higher normalized consumption rates, consistent with the enhanced flame surface generated by strongly corrugated fronts. Overall, the quantitative analysis of flame-cell size distributions provides a practical framework for distinguishing instability regimes in confined premixed flames and for evaluating the influence of confinement on flame behavior. Novelty and significance statement: This work provides the first systematic experimental quantification of flame-cell size distributions for premixed H 2 -air flames in Hele–Shaw cells over a broad range of equivalence ratios and channel gaps. By combining high-resolution schlieren imaging with an automated cusp-detection method, it establishes cell-size statistics as a practical metric to distinguish thermodiffusive- and hydrodynamic-dominated regimes under confinement. The proposed methodology improves the understanding of how confinement and heat losses control instability-driven flame structures in narrow channels.

Source: Proceedings of the Combustion Institute

DOI: 10.1016/j.proci.2026.106350

Authors: C.C. Mejía-Botero, L. Pratabuy Tran-Quang, C. Almarcha

Institutions: Centre National de la Recherche Scientifique, Aix-Marseille Université, Institut de Recherche sur les Phénomènes Hors Équilibre, Centrale Méditerranée

Language: English

Topic: Combustion and flame dynamics

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

SDG: Affordable and clean energy

Open Access status: hybrid

Estimated APC paid: $3,570