Article Dans Une Revue Proceedings of the Combustion Institute Année : 2025

The effect of low-temperature chemistry in nitrogen-diluted flames under microgravity

Résumé

In this work, a flame propagation behavior analysis was conducted for outwardly propagating flames of diethoxymethane (DEM) and ethanol as exemplary fuels with and without low-temperature chemistry (LTC). Flame temperatures were decreased by N2-dilution of the oxidizer to enhance the possible low-temperature chemistry effect, leading to decreased flame propagation speed. Slowly expanding spherical flames are known to be affected by radiation and particularly by buoyancy, deforming the flame’s shape and violating underlying existing post-processing assumptions. Experiments were conducted under microgravity conditions during parabolic flight campaigns aboard the Airbus A310 Zero-G to isolate the effects of radiation from buoyancy induced flame deformation. Extracted unstretched laminar flame speeds at initial pressures of 3 to 10 bar were compared with planar flame simulations. The approach by Yu et al. (2014) was used to correct the experimental laminar flame speeds for radiation. For lean mixtures, significant flame acceleration was observed with a strong nonlinear propagation speed dependence on stretch for both fuels. In contrast, rich DEM/oxidizer mixtures consistently maintain self-sustained flame propagation, while ethanol/oxidizer mixtures tend to extinguish. This is linked to the effectiveness of low-temperature branching reactions in DEM oxidation. Flame structure analyses for DEM/oxidizer mixtures revealed that the reaction zone broadening is correlated to the distribution of oxidized DEM radicals predominantly present at a lower temperature of T ∼ 800 K.

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hal-05410523 , version 1 (11-12-2025)

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Roman Glaznev, Christian Schwenzer, Fabien Halter, Raik Hesse, Christian Chauveau, et al.. The effect of low-temperature chemistry in nitrogen-diluted flames under microgravity. Proceedings of the Combustion Institute, 2025, 41, pp.105986. ⟨10.1016/j.proci.2025.105986⟩. ⟨hal-05410523⟩
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