Measurement of laminar burning velocity of methane-air premixed flame at different initial temperatures

The laminar burning velocity of methane-air mixtures was measured under different initial temperatures and equivalence ratios by using the outwardly expanding flame and high-speed schlieren photography. The results show that the stretched flame propagation speed, the unstretched flame propagation speed and the laminar burning velocity are increased with the increase of initial temperature. The Markstein length is increased with the increase of equivalence ratio, but it decreases slightly with the increase of initial temperature. Flame front of the rich premixed mixture combustion shows higher stability than that of the lean mixture combustion. The laminar burning velocities reach their maximum values at the stoichiometric equivalence ratio regardless of initial temperature. Based on the experimental data, an explicit expression for the laminar burning velocity to initial temperature and equivalence ratio is correlated.