Fully coupled simulations of plasma assisted combustion using nanosecond pulsed discharges

There has been a growing interest towards utilizing nanosecond pulsed non-thermal plasma discharges as a potentially new ignition technology for combustion based applications. Traditional spark plug based ignition, used in internal combustion engines, relies on a millisecond timescale spark channel to deposit thermal energy into a small activated volume within the fuel air mixture. This technique however, suffers from several limitations such as low fuel consumption efficiency and high pollutant emission. In this regard, non-thermal plasma discharges present an interesting prospect as a technology that can overcome these limitations and further, help achieve increased ignition tunability, flame stabilization and lower temperature/leaner combustion. Several theories have been proposed to explain the manner in which non-equilibrium plasmas enhance ignition, such as the production of active radicals and ultra fast-gas heating over relatively short nanosecond timescales. This paper presents a fully coupled numerical modeling study of a plasma assisted ignition process to obtain insight into the dominant pathways through which the plasma discharge influences ignition. A high-fidelity, multi-dimensional, non-equilibrium plasma solver- VizGlow is used to model the dynamics of the nanosecond pulsed plasma. As the external voltage pulse driving plasma production is switched off, all the solution variables from the discharge are incorporated into the initial conditions of a multi-dimensional combustion simulation that then consistently models the spatio-temporal evolution of a flame kernel.