Experimental study on combustion characteristics of dimethyl ether-air premixed mixtures at elevated pressure and temperature

Laminar burning velocity and the Markstein length of the dimethyl ether-air premixed mixtures were measured in a constant volume bomb under different equivalence ratios and initial temperatures at initial pressure of 0.5 MPa. The effect of flame stretch on the flame speed was analyzed and a two-zone model was used to analyze the combustion characteristics of the premixed combustion. The results showed that the laminar burning velocity was increased with the increase of the initial temperature and there exists a maximum value of the laminar burning velocity for the mixture slightly richer than the stoichiometric mixture for a given initial pressure and temperature. The Markstein length was decreased with the increase of equivalence ratio and initial temperature, indicating an increase of instability of the flame front with the increase of the equivalence ratio and initial temperature. Maximum combustion pressure was decreased with the increase of the initial temperature while the rate of pressure rise was increased with the increase of the initial temperature.