Numerical Study on the Effects of Diluents on the Laminar Burning Velocity of Methane–Air Mixtures

Abstract

The effect of diluents on the laminar burning velocity of the premixed methane–air–diluent flames was numerically studied using the Chemkin package. The mechanisms of dilution, thermal-diffusion, and chemical effects of diluents on the laminar burning velocity were analyzed quantitatively at different dilution ratios for different diluents. Results show that the laminar burning velocity is decreased in the order from helium, argon, nitrogen, and carbon dioxide. In the case of N2, the thermal-diffusion and chemical effects can be negligible and the decrease of the laminar burning velocity is largely caused by the dilution effect. The dilution, thermal-diffusion, and chemical effects of CO2 suppress the laminar burning velocity, where the dilution effect plays a dominant effect among them. For helium and argon diluents, the chemical effect can be negligible and the thermal-diffusion effect enhances the laminar burning velocity. Therefore, the dilution effect has a much larger suppression effect on decreasin...