Fluid dynamics and photoionization contribution to plasma-assisted combustion models

The coupling between the plasma fields and ionization waves has two fundamental modes, one driven by preionization, which generally supports smooth and deterministic fronts, and one driven by photoionization, which supports the stochastic process. High-speed aerodynamics affects (weaken) the first path but not the second. This research investigates how the coupling between fluid and plasma wave is affected by Mach number variations for regimes (altitude) of interest to scramjet combustion. We will be studying the effect of photoionization on the propagation of streamers with combustion to improve the combustion ignition probability inside scramjets. We have modified a code typically used in astrophysics simulations to fully couple emission, photoionization, and combustion. The emissions are calculated using Bolsig, a code that calculates the electron energy distribution function using a two-term expansion of the Boltzmann equation. Photoionization is handled with a diffuse ray trace solver using Monte Carlo ray tracing. We have done some tests against a simplified method based on approximations of Green's function for shear layers relevant to cavity flow in scramjet condition. We will be investigating the effect of electrode geometry on shock formation during ignition.