Document Type

Article

Publication Date

12-2018

Publication Title

Fluids

Volume

3

Abstract

While there has been some recognition regarding the impact of thermal boundary conditions (adiabatic versus isothermal) on premixed flame propagation mechanisms in micro-channels (hydraulic diameters <10 mm), their impact in macro-channels has often been overlooked due to small surface-area-to-volume ratios of the propagating combustion wave. Further, the impact of radiative losses has also been neglected due to its anticipated insignificance based on scaling analysis and the high computational cost associated with resolving it’s spatial, temporal, directional, and wavelength dependencies. However, when channel conditions promote flame acceleration and deflagration-to-detonation transitions (DDT), large pressures are encountered in the vicinity of the combustion wave, thereby increasing the magnitude of radiative losses which in turn can impact the strength and velocity of the combustion wave. This is demonstrated for the first time through simulations of lean (equivalence ratio: 0.5) hydrogen-air mixtures in a macro-channel (hydraulic diameter: 174 mm) with obstacles (Blockage ratio: 0.51). By employing Planck mean absorption coefficients in conjunction with the P-1 radiation model, radiative losses are shown to affect the run-up distances to DDT in a long channel (length: 11.878 m). As anticipated, the differences in run-up distances resulting from radiative losses only increased with system pressure.

Issue

4

DOI

10.3390/fluids3040104

ISSN

2311-5521

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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