Propagation and extinction of premixed dimethyl-ether/air flames

Laminar flame speeds and extinction strain rates of dimethyl-ether/air mixtures were measured at room temperature and atmospheric pressure over a wide range of equivalence ratios. The experiments were performed in the counterflow configuration, and included the use of digital particle image velocimetry and laser Doppler velocimetry. The laminar flame speeds were experimentally determined using a new non-linear extrapolation technique, which utilizes simulations obtained using detailed chemistry and transport. Compared to literature experimental data, the measured laminar flame speeds were found to be in good agreement with the majority of measurements using spherically expanding flames, and they are lower compared to measurements reported by other groups using the stagnation flame technique. An updated kinetic model of dimethyl-ether oxidation is also proposed, which entails a number of adjustments to reactions involving methane chemistry. Compared to previous versions of the model, improved agreement was found with the experimental data. Sensitivity analyses with respect to reactions and binary diffusion coefficients were conducted to provide insight into the controlling physico-chemical processes. Additionally, reaction pathway analyses were used to interpret the results, and to identify the high temperature reaction pathways of dimethyl-ether oxidation.