Ph.D. Advisor: Prof. Hong G. Im

External Examiner: Prof. Benoît Fiorina (University Paris-Saclay, CentraleSupélec)

Committee Chair: Prof. Hussein Hoteit

4th Committee Member: Prof. Deanna A. Lacoste

Nonthermal plasma (NTP) has emerged as a powerful lever for lowering ignition barriers, accelerating radical production, and stabilizing ultra-lean flames, yet quantitative design of NTP-assisted combustors is still limited by the disparity of relevant time and length scales. This dissertation resolves that gap by developing and deploying a high-performance computational framework that couples plasma physics with reactive-flow chemistry from the zero-dimensional (0D) limit to full multi-dimensional (multiD) computational fluid dynamics (CFD).

At the engineering scale, a phenomenological plasma-energy deposition model is embedded in laminar flame simulations of a jet-wall burner to systematically analyze the respective roles of ultrafast electronic heating, vibrational relaxation, and O-atom injection in nanosecond repetitively pulsed (NRP) discharge assisted methane flames. The study reveals that O-radical chemistry, rather than thermal or hydrodynamic effects, dominates flame displacement and stabilization, in agreement with benchmark experiments.

At the kinetics scale, the open-source code ChemPlasKin is created by integrating the electron Boltzmann equation solver CppBOLOS with the combustion library Cantera. ChemPlasKin performs fully time-resolved 0D simulations of coupled gas-plasma chemistry, capturing both rapid electronic heating and slower vibrational-translational relaxation. Comprehensive verification shows the reliability, accuracy and efficiency of ChemPlasKin, demonstrating its utility in advancing gas-plasma kinetic studies.

At the flow-physics scale, the thesis introduces reactPlasFoam, an AMR-enabled, MPI-parallel extension of OpenFOAM that integrates ChemPlasKin and solves electron Boltzmann equation on the fly. The solver adaptively switches between streamer, spark, reacting-flow, and ionic-wind modes, and updates the electron energy distribution function locally without resorting to pre-calculated electron properties. After benchmarking against established codes, reactPlasFoam is further applied to model spark discharge in airflow, demonstrating the flame-guided streamer propagation, and examining the ionic wind effect of non-breakdown AC electric fields on a counterflow diffusion flame.

Finally, the framework is exercised on modeling a single nanosecond pulse in laminar premixed CH4/air and NH3/air flames stabilized between a McKenna burner and a high-voltage plate. In both cases, the positive streamer head expands and decelerates upon reaching the flame front, and a weakly ionized regime forms throughout the burnt gases.

Collectively, these contributions deliver a scalable toolkit spanning kinetic analysis to transport phenomena, from streamer propagation to flame dynamics, offering both fundamental insights and practical guidance for next-generation plasma-assisted combustors.