Massively parallel high-fidelity simulations of plasma-assisted ignition of hydrocarbon fuels using nanosecond pulsed discharges

A series of numerical studies are conducted using the adaptive mesh refinement (AMR) compressible reactive flow solver PeleC, built on the AMReX software infrastructure, to investigate the ignition and propagation of axisymmetric atmospheric air streamers. A range of conditions and configurations are explored to better understand the streamer, with an emphasis on the cathode sheath region, which supports steep gradients in charged species number densities as well as strong electric fields. The formation of the cathode sheath is shown to be a consequence of processes at the cathode surface, driven by electron losses at the boundary, and a strong dependence on the emission of secondary electrons. Next, a reduced version of the mechanism is used to carry out axisymmetric pin-to-pin simulations of ethylene/air ignition. In each simulation, a series of NSPD are delivered to the gap through the application of a time-varying voltage to the anode until an ignition event occurs. It is observed that the highest temperatures and radical populations during the initial pulse are located near the electrode tips. A range of pulsing parameters are explored in order to assess the ideal conditions for rapid ignition and stable combustion. It is found that there is only a minor dependece of active particle creation on pulse frequency, with lower frequencies leading to greater populations of active particles.