Experimental and kinetic study on ignition delay times of dimethyl ether at high temperatures

An experimental investigation was performed on the effects of the temperature, pressure, equivalence ratio, and fuel concentration on ignition delay times of dimethyl ether (DME)/O₂/Ar mixtures behind the reflected shock wave. Experimental conditions used temperatures over 1000-1600 K, pressures of 1.2-20 atm, and equivalence ratios of 0.5-2.0, with fuel concentrations of 0.5-2.457%. The measurements showed that the DME mixtures have different global activation energies under different equivalence ratios. Thus, correlations were derived under different equivalence ratios based on all experimental data, which fits fairly well with the experimental data. Four recently developed models were compared to the measurements, and their predictabilities were thoroughly discussed. Finally, a systematic kinetic chemical analysis was performed to chemically interpret the observed equivalence ratio dependence and to ascertain the key reactions that control ignition of DME, which are the potential candidates for improvement of LLNL DME Mech.