Large Eddy Simulation on Blow-Off Limit of Methane and Hydrogen-Mixed Gas

Abstract

The blow-off limits of methane and hydrogen-mixed gas on the Sydney inhomogeneous inflow jet burner were calculated and studied by large eddy simulation. The GRI 3.0 detailed reaction mechanism, 28-step and 19-step methane simplified reaction mechanisms were used to calculate the laminar premixed flames under the condition of different hydrogen-mixed fuel gases, which demonstrates the good performance of the 19-step simplified mechanism. A dynamic thickening flame combustion model was combined with the 19-step reaction mechanism to compute the Sydney partially premixed jet flame burner with a hydrogen-mixed gas (the volume ratio of V(H2):V(CH4):V(CO):V(CO2) = 0.2:0.2:0.27:0.33). The blow-off limits in FA and FJ layouts of hydrogen-mixed gas are 90 m/s and 109 m/s, while for pure methane flames are 74 m/s and 128 m/s, respectively. The difference of blow-off limits between the two fuels is related to the inhomogeneity of fuel and air mixing in different layouts. This study shows that the combustion stability can be improved by optimizing the inlet layout and mixing process of fuel gas and air.

Keywords

• partially premixed flame
• blow-off limit
• hydrogen-mixed gas
• thickened flame model
• large eddy simulation