Visualization Tool for Chemical Kinetic Pathways in Plasma-Assisted Combustion

Chemical kinetic mechanisms for combustion are represented by hundreds of reactions and tens of species. By introducing plasma discharges to combustion, the plasma chemistry can be exploited to enhance combustion regimes that are difficult to stabilize. In the context of plasma-assisted combustion, energetic electrons prompt electron impact reactions that provoke excitation in the mixture. By employing plasma-assistance, the combustion pro- cesses can be modified to achieve high-speed combustion as well as combustion with low emissions. Because computational simulations of these kinetic mechanisms have to account for the many reactions and species, the main numerical barrier lies in solving a stiff system of equations that includes the mass and energy conservation equations for all relevant species. In higher dimensional computational models, runtimes can take upwards of several hours even when the programs for these simulations are parallelized and run on supercomputer clusters. By understanding how each of the reaction pathways in the kinetic model influence the results of the simulation, an algorithm that determines the importance of each reaction can be developed. By generating an algorithm that can quantitatively assess the importance of the reaction to relevant values of the simulation such as ignition delay time (IDT), the overall kinetic model of plasma-assisted combustion and other plasma-based kinetic models can be interpreted in large parametric explorations and, subsequently, can be reduced. Ul- timately, a reaction pathways analysis can be used as a kinetic model reduction tool for the simulated engineering design toolbox already present in the Aerospace Plasma Group at the Massachusetts Institute of Technology.