Stationary ethylene–air edge flames in a wedge-shaped region at low and high strain rates

ABSTRACT

Edge flames are a canonical two-dimensional flame structure appearing in lifted jet flames and in the growth and repair of flame holes in nonpremixed turbulent combustion. Computational studies of edge flames with hydrodynamic-coupling at high strains are difficult owing to difficulties defining a stationary state. A wedge-shaped counterflow configuration is here used to provide control over the position of the edge flame, and allowing access to stationary, hydrodynamically-coupled retreating flames (at low and high strains). ethylene–air edge flames are established in the resulting non-uniformly strained counterflow, with combustion modeled using a skeletal reduction of the USC Mech II. The details of the ethylene–air edge flame are discussed, and comparisons are made between stoichiometric, fuel-lean, and fuel-rich compositions. Mixture-fraction-based coordinates local to the flame front are developed and analysed for a range of edge-flame speeds and compositions. A strain-rate parameter is described that admits a speed-strain relationship that is insensitive to the mixture stoichiometry, and a model for retreating flame speeds at high strain rates is discussed.

Keywords:

• edge flame
• ethylene
• detailed chemistry
• eigenvalue problem
• flame speed

Acknowledgments

This material is based upon work supported by the Department of Energy, National Nuclear Security Administration, under Award Number DE-NA0002374.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This material is based upon work supported by the Department of Energy, National Nuclear Security Administration, under Award Number DE-NA0002374.