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Lookup NU author(s): Dr Xinyi Chen, Freddie Young, Dr Umair AhmedORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Fully compressible numerical simulations of two-dimensional laminar lean hydrogen-air premixed flames have been performed, with the flame front subjected to acoustic forcing through the specification of a monopole-type sound source at the inflow. Simulations have been performed for acoustic frequencies ranging from 35 kHz to 500 kHz at two equivalence ratios, and . During the flame-acoustic interaction, the flame evolves from an initially weakly stretched state to exponential perturbation growth, wrinkle interaction, and the formation of non-linear cellular structures, with distinct linear and non-linear stages identified from Fourier mode analysis. The instability dynamics depend strongly on both forcing frequency and equivalence ratio. In the case of , the flame behaviour is strongly influenced by thermodiffusive instability, with a characteristic sequence of uniform cells, cell splitting, and cell merging. For , weaker thermodiffusive effects result in a response more strongly governed by hydrodynamic instability and large-scale wrinkle growth. At low forcing frequencies, flame corrugations remain relatively uniform, whereas at high frequencies the flame front becomes increasingly modulated and develops envelope-like structures, which can be interpreted as the interaction between an intrinsic standing cellular mode and the imposed acoustic disturbance. In the linear growth regime, the density-weighted displacement speed, , shows a linear correlation with total stretch rate, , for all forcing frequencies. While in the non-linear growth regime, two distinct branches appear, corresponding to weakly stretched flame segments and strongly negatively curved segments associated with flame pinch-off.
Author(s): Chen X, Young FW, Ahmed U, Cant RS
Publication type: Article
Publication status: Published
Journal: Proceedings of the Combustion Institute
Year: 2026
Volume: 42
Pages: 106011
Online publication date: 01/07/2026
Acceptance date: 05/06/2026
Date deposited: 02/07/2026
ISSN (print): 1540-7489
ISSN (electronic): 1873-2704
Publisher: Elsevier Inc.
URL: https://doi.org/10.1016/j.proci.2026.106011
DOI: 10.1016/j.proci.2026.106011
Data Access Statement: Supplementary data provided in a PDF file linked in article
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