Effect of Plasma-Enhanced Low-Temperature Chemistry on Deflagration-to-Detonation Transition in a Microchannel

This study examines low-temperature chemistry (LTC) enhancement by nanosecond dielectric barrier discharge (ns-DBD) plasma on a dimethyl ether (DME)/oxygen O₂ ∕argon (Ar) premixture for deflagration-to-detonation transition (DDT) in a microchannel. It is found that non-equilibrium plasma generates active species and kinetically accelerates LTC of DME and DDT. In situ laser diagnostics and computational modeling examine the influence of the ns-DBDs on the LTC of DME and DDT using formaldehyde (CH₂ O) laser-induced fluorescence (LIF) and high-speed imaging. Firstly, high-speed imaging in combination with LIF is used to trace the presence of LTC throughout the flame front propagation and DDT. Then, competition between plasma-enhanced LTC of ignition and reduced heat release rate of combustion due to plasma-assisted partial fuel oxidation is studied with LIF. Observations of plasmaenhanced LTC effects on DDT are interpreted with the aid of detailed kinetic simulations. The results show that an appropriate number of ns-DBDs enhances LTC of DME and increases CH₂ O formation and low-temperature ignition, accelerating DDT. Moreover, it is found that, with many ns-DBDs, CH₂ O concentration decreases, indicating that excessive discharges may accelerate fuel oxidation in the premixture, reducing heat release and weakening shock–ignition coupling, inhibiting DDT.