Experimental and numerical study of cap-like lean limit flames in H2-CH4-air mixtures
| Autor: | Laurentius P.H. de Goey, Yuriy Shoshin, Jeroen A. van Oijen, Francisco E. Hernández-Pérez, Zhen Zhou |
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| Přispěvatelé: | Power & Flow, Group De Goey, Group Van Oijen |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Leading edge
Low Lewis number Laminar flame speed 020209 energy General Chemical Engineering Analytical chemistry General Physics and Astronomy Energy Engineering and Power Technology 02 engineering and technology 01 natural sciences 010305 fluids & plasmas Physics::Fluid Dynamics 0103 physical sciences 0202 electrical engineering electronic engineering information engineering Physics::Chemical Physics Flammability limit Premixed flame Hull speed Chemistry Diffusion flame Lean combustion limit General Chemistry Mechanics Negative flame displacement speed Flame speed Adiabatic flame temperature Fuel Technology Cap-like flame |
| Zdroj: | Combustion and Flame, 189, 212-224. Elsevier |
| ISSN: | 0010-2180 |
| Popis: | Lean limit flames of H2-CH4-air mixtures stabilized inside a tube with an inner diameter of 30 mm in a downward flow are studied experimentally and numerically. A transition from bubble-like flames, with a long decaying skirt, to cap-like flames with a sharp visible flame edge at the bottom is observed as the lean flammability limit is approached. This transition is accompanied by formation of a secondary weak flame front inside the cap-like flame. The CH* chemiluminescence distribution of the studied flames is recorded and the velocity field of the lean limit flames is measured using Particle Image Velocimetry (PIV). The flame temperature field is measured utilizing the Rayleigh scattering method. Numerical prediction with a mixture-averaged transport model and skeletal mechanism for CH4 qualitatively reproduces the above experimentally observed phenomena. The presence of negative flame displacement speed for the entire leading edge of the cap-like flames is numerically predicted and experimentally demonstrated. The secondary weak flame front is located in a region with reverse upward flow of the recirculation zone, which is found to support the propagation of the leading edge with a negative flame displacement speed. Furthermore, radiative heat loss has a significant influence on the lean flammability limit of the cap-like flames. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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