Experimental Study on Premixed Combustion of Dimethyl Ether-Hydrogen-Air Mixtures

The laminar combustion characteristics of dimethyl ether-hydrogen-air mixture were studied at various equivalence ratios, hydrogen fractions and initial pressures by using a constant volume combustion bomb.The influences of the equivalence ratio,the hydrogen fraction and the initial pressure on flame speed and combustion characteristics were analyzed.The results show that the flame speed,the laminar burning velocity and the mass burning rate increase with the increase of the hydrogen fraction.Increasing the hydrogen fraction will increase the peak combustion pressure and shorten the combustion duration.For small hydrogen fractions,the Markstein length decreases with the increase of the equivalence ratio,indicating that the lean mixture has higher flame front stability than the rich mixture.For large hydrogen fractions,the Markstein length increases with the increase of the equivalence ratio,indicating that the rich mixture has higher flame front stability than the lean mixture.Maximum combustion pressure increases with the increase of initial pressure,and initial pressure displays greater influence on combustion pressure than doping hydrogen.