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Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames
Published on: June 1, 2016
Characterization of unconventional hydrogen flame propagation in narrow gaps
Jorge Yáñez Escanciano1, Mike Kuznetsov1, Fernando Veiga-López2
1Institute for Thermal Energy Technology and Safety, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
Abstract:
The physical limits of the unconventional flame propagation regimes recently discovered [Veiga-Lopez et al., Phys. Rev. Lett. 124, 174501 (2020)PRLTAO0031-900710.1103/PhysRevLett.124.174501] are analyzed. These regimes appear in combustible gaseous mixtures approaching the lean quenching limit of hydrogen-air flames in narrow gaps. They are characterized by a split of the flame front into a dendritic and a bifurcating set of flame cells separated by nonburned material. A feature selection analysis utilizing dimensionless numbers is applied to reveal the most significant parameters governing the separation between unconventional and traditional flame propagation regimes. It is concluded that (a) the outbreak of unconventional propagation is mostly due to heat losses, (b) the phenomenon is governed by the Peclet number and only appears in thin channels, and (c) the Lewis number does not determine the propagation regime. Additionally, an equation describing the optimal border of the unconventional regime is derived from experiments.
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