Numerical Simulation on Combustion Characteristics of Methane–Air Premixed Flame Impacted by Hydrogen Jet

Abstract

Low-concentration coalbed methane is an efficient and clean unconventional natural gas with abundant reserves. It can greatly lessen the problem of energy scarcity when used to produce combustion power. Nevertheless, the engine finds it challenging to burn low-concentration coalbed methane directly due to its low and fluctuating CH4 concentration. This study suggests using a hydrogen jet to ignite low-concentration coalbed methane. The simulation method is used in this article. To investigate the effects of various ignition injection strategies on the combustion characteristics of low-concentration coalbed methane ignited by a hydrogen jet, a constant volume bomb model was developed. The results show that when the ignition and hydrogen injection interval is 2.0 ms, the cold jet of hydrogen does not burn immediately when it reaches the premixed flame, and there is a transition process from the premixed flame to the jet flame. The larger the interval between ignition and hydrogen injection, the more waste gas is produced after the premixed flame combustion, which has a certain inhibition effect on the formation of the jet flame. With the decrease in the interval between ignition and hydrogen injection, the combustion duration is obviously shortened. Therefore, the earlier hydrogen is involved in the ignition, the faster the combustion speed.