Premixed Flames Under Microgravity and Normal Gravity Conditions
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Premixed conical CH4-air flames were studied experimentally and numerically under normal straight, reversed gravity conditions and microgravity. Low-gravity experiments were performed in Drop tower. Classical Bunsen-type burner was used to find out features of gravity influence on the combustion processes. Mixture equivalence ratio was varied from 0.8 to 1.3. Wide range of flow velocity allows to study both laminar and weakly turbulized flames. High-speed flame chemoluminescence video-recording was used as diagnostic. The investigations were performed at atmospheric pressure. As results normalized flame height, laminar flame speed were measured, also features of flame instabilities were shown. Low- and high-frequency flame-instabilities (oscillations) have a various nature as velocity fluctuations, preferential diffusion instability, hydrodynamic and Rayleigh-Taylor ones etc., that was explored and demonstrated.
KeywordsMethane-air mixture Combustion Microgravity Flame instability
The authors would like to thank K.V. Klinkov and C. Eigenbrod for their help in performing experiments under microgravity conditions.
The experimental work has been supported by the German Aerospace Center (DLR) Office for Research under Space Conditions under Grant No. 50WM1125 within the project: “Droplet-Droplet Interactions” which is gratefully acknowledged.
The treatment and analysis of experimental results work was supported by the Ministry of education and science of the Russian Federation within the framework of the research activities on the subject of “Investigation of electrophysical and thermal processes in multiphase and reactive environments”, state registration number AAAA-A-16-116051810083-4.
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