Effects of non-equilibrium plasma discharge on ignition and LTC of DME/O₂/Ar mixtures: A numerical investigation

The effects of nanosecond pulsed non-equilibrium plasma discharge on ignition characteristics of DME/O₂/Ar mixture are numerically investigated through self-consistent simulations in a plane-to-plane geometry at a reduced pressure of 76 Torr. This one-dimensional, multi-timescale plasma discharge model is used to study the two-stage ignition process and the NTC behavior of DME fuel. The kinetics model in this study consists of 69 species and 414 reactions, which combined combustion of plasma kinetics model and DME combustion kinetics model. The initial temperatures are set to be 550K and 800K, respectively. With the initial temperature of 550K, the ignition delay for plasma-assisted case is improved by approximately 250 times for the first stage, and 15 times overall. For the initial temperature of 800K, the overall ignition delay is shortened by approximately 75 times with plasma addition. Moreover, the results suggest that, plasma not only enhanced DME ignition characteristic delays dramatically by orders of magnitudes, but also alter reaction pathway and re-activates the disappeared two- stage ignition behavior in the 800K case.