Experimental study on premixed combustion of dimethyl ether-hydrogen-air mixtures

The laminar combustion characteristics of DME-hydrogen-air premixed mixture were studied at different equivalence ratios, ratios of hydrogen to DME plus hydrogen, and initial pressures by using a constant volume combustion bomb. The influences of the equivalence ratio, the hydrogen addition, and the initial pressure on flame speed and combustion characteristics are analyzed. The results show that the flame speed, the laminar burning velocity, and the mass burning rate increase with the increase of hydrogen addition. Increasing the ratio of hydrogen to DME plus hydrogen will shorten the combustion duration. In the case of small hydrogen addition, the Markstein length decreases with the increase of equivalence ratio, and this reveals that lean mixture has better flame front stability compared with that of the rich mixture. In the case of large hydrogen addition, the Markstein length increases with the increase of equivalence ratio, and this indicates that the rich mixture has better flame front stability than the lean mixture. Maximum combustion pressure increases with the increase of initial pressure, and initial pressure has larger influence on combustion pressure than that from hydrogen addition. The flame development duration decreases with the increase of hydrogen addition and the increase of equivalence ratio.