Effect of pressure on the lean limit flames of H2-CH4-air mixture in tubes
Hernandez Perez, Francisco
van Oijen, Jeroen A.
de Goey, Laurentius P.H.
KAUST DepartmentClean Combustion Research Center
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AbstractThe lean limit flames of H2-CH4-air mixtures stabilized inside tubes in a downward flow are experimentally and numerically investigated at elevated pressures ranging from 2 to 5 bar. For the shapes of lean limit flames, a change from ball-like flame to cap-like flame is experimentally observed with the increase of pressure. This experimentally observed phenomenon is qualitatively predicted by numerical simulations. The structure of ball-like and cap-like lean limit flames at all tested pressures is analysed in detail based on the numerical predictions. The results show that the lean limit flames are located inside a recirculation zone at all tested pressures. For the leading edges of the lean limit flames at all tested pressures, the fuel transport is controlled by both convection and diffusion. For the trailing edge of the ball-like lean limit flame at 2 bar, the fuel transport is dominated by diffusion. However, with increasing pressure, the transport contribution caused by convection in the trailing edges of the lean limit flames increases. Finally, the influence of transport and chemistry on the predicted ultra lean flames and lean flammability limit is analysed at elevated pressures.
CitationZhou Z, Shoshin Y, Hernández-Pérez FE, van Oijen JA, de Goey LPH (2017) Effect of pressure on the lean limit flames of H 2 -CH 4 -air mixture in tubes. Combustion and Flame 183: 113–125. Available: http://dx.doi.org/10.1016/j.combustflame.2017.05.011.
SponsorsThis work was supported by the Dutch Technology Foundation (STW) (project 13549). The authors thank Prof. Clinton Groth for providing access to the CFFC (Computational Framework for Fluids and Combustion) code.
JournalCombustion and Flame