Symmetric and Nonsymmetric Flame Spread between Parallel Plates of Thick Combustible Solid

ABSTRACT

To identify the occurrence conditions of a symmetry-breaking phenomenon, numerical simulations of flame spread along parallel, combustible plates are performed. Two-dimensional, time-dependent conservation equations for gas-phase with a one-step global reaction coupled to one-dimensional heat conduction for the solid-phase are simultaneously solved. The flame spread having two leading edges was successfully simulated and the behaviors were examined under various flow velocities and channel heights. Based on the time histories of the leading edges, the simulated flame behaviors are distinguished into three modes: symmetric, asymmetric and oscillation, in addition to the extinction. The occurrence conditions of those modes are summarized. The results indicate that the local extinction caused by an excess of the scalar dissipation rate is a key process of the symmetry-breaking. Since coexistence of flames in narrow channel is unstable, the local extinction occurs to achieve a stable state for the system to burn.

KEYWORDS:

• Flame spread
• Narrow channel
• Combustion instability
• Symmetry-breaking
• Fire Dynamics Simulator

Nomenclature

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Acknowledgments

This work was supported by JSPS KAKENHI Grant Numbers JP16K16365 and JP17H02051.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science [JP16K16365,JP17H02051].