Flame propagation in gas feeding pipelines to the IC engine

Results from experimental investigation on flame propagation in a pipeline filled with gaseous combustible mixture consisted of hydrogen, methane or 20% hydrogen-methane is presented in the article. The mixture was prepared in separate cylinders and premixed before filling the pipeline. The tests were conducted under various relative equivalence ratio – lambda from 1.0 to 3.0 at pressure of 1 bar and temperature of 25ºC. Hydrogen and methane were selected because these gases are main combustible fractions in several gaseous engine fuels (e.g. natural gas, syngas, biogas). Additionally, the mixture 20% hydrogen and methane, as potential engine fuel, was also under investigation. Flame front was detected with aid of IR photodetectors. Hence, the flame speed was resulted from distance divided by time. As observed, the flame propagation speed was over 100 m/s for both hydrogen and methane premixed mixtures. It was several times higher if compared with the laminar flame speed for these gases. It can be explained by additional acoustic effects (standing waves) taking place inside the pipeline. Results from this investigation can be useful in design and construction of the gas feeding system in the gas fuelled internal combustion engine.