Radiative Extinction of Laminar Diffusion Flame above the Flat Porous Burner in Microgravity: A Computational Study
| Autor: | A. Yu. Snegirev, Ekaterina Markus, Egor Kuznetsov |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Mass flux
Materials science 010304 chemical physics General Chemical Engineering Diffusion flame General Physics and Astronomy Energy Engineering and Power Technology Laminar flow General Chemistry Mechanics medicine.disease_cause Combustion 01 natural sciences Soot 010406 physical chemistry 0104 chemical sciences Fuel Technology Extinction (optical mineralogy) 0103 physical sciences Combustor medicine Radiative transfer |
| Zdroj: | Combustion, Explosion, and Shock Waves. 56:394-411 |
| ISSN: | 1573-8345 0010-5082 |
| DOI: | 10.1134/s0010508220040036 |
| Popis: | Transient dynamics of formation and extinction of methane- and ethylene-fueled flames above the flat porous burner in an oxidizing atmosphere is numerically investigated. The simulated scenarios replicate the experimental conditions of the BRE (Flamenco) project of the ACME program focusing on combustion research in microgravity. The 3D unsteady model includes the multi-step and multi-component chemical mechanisms of fuel oxidation, formation and oxidation of soot, and the radiative transfer. The model is validated for the methane-fueled jet laminar diffusion flame in normal gravity and for the ethylene flame developing in short-duration free-fall microgravity in the drop tower. The microgravity flames are then simulated at longer times, and the range of fuel mass fluxes characteristic of solid and liquid combustibles is explored. In all the cases considered, combustion is essentially unsteady, in spite of the constant fuel supply rate. During the initial stage of flame growth, the temperature in the reaction zone persistently decreases due to the radiative losses down to the level causing local extinction, oscillations, and complete extinguishment of the flame. The effect of fuel type and mass flux at the burner surface on the flame lifetime and on its disintegration dynamics is demonstrated. The sensitivity of the results to the chemical mechanism used in the simulations is examined. The radiative fraction in the microgravity flames is found to be by an order of magnitude higher than that in the normal gravity flames produced by the same burner. The radiative losses are shown to be the reason for extinction and instability in the microgravity flames considered in this work. |
| Databáze: | OpenAIRE |
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