Numerical Study of Nanosecond Pulsed Discharge Effects on Flame Speed and Emissions in Ammonia Flames

Plasma-assisted combustion of ammonia leverages non-equilibrium electrical discharges to modify flame dynamics and emissions. In this work, we perform a numerical investigation using a one-dimensional model to examine the influence of nanosecond-repetitively pulsed discharges on the propagation of stoichiometric ammonia-air flames at atmospheric conditions. The model incorporates detailed plasma chemistry solved with ZDPlasKin. In particular, we look into the influence of pulse repetition frequency on laminar flame speed and NOx emissions. The simulations reveal unexpected behavior in the spatial distribution of plasma energy deposition within the flame. The plasma is found to significantly speed up the flame, up to +140%, although some numerical challenges prevented us from exploring operation at higher frequencies. The chemical kinetics used also predict a small decrease in NO in the product region of the flame.