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Abstract
Increasing concerns regarding environmental pollution and the challenge of meeting stringent emission regulations associated with NOx and Soot have prompted the combustion community to give significant attention to the design of more efficient engines without sacrificing performance standards. Experimental combustion study is mainly governed by fundamental combustion properties such as ignition characteristics, laminar burning velocities and time histories of product formation at various temperatures. Additionally, with the advancement of computational speed and improved numerical methods, Computer Fluid Dynamics (CFD) modeling and simulation to understand fuel performance and combustion characteristics have also gained substantial amount of interest from the combustion research community in the last couple of decades. Although, numerous experimental studies have been conducted in multiple devices such as rapid compression machines and/or shock tubes, majority of them were carried out under low-pressure, high temperature and/or highly dilute conditions (diluted with air, nitrogen, argon or helium). However, robust data from extreme conditions (e.g., high pressure) would significantly inform our quest towards maximizing the engine efficiency with minimum toxic emissions. Therefore, a computational method is required which can fill in the gaps of the insights obtained from experimental and modeling studies of combustion in extreme conditions. The ReaxFF reactive force field, combined with Molecular Dynamics, has the capability to simulate the combustion process and obtain atomistic data about the underlying complex physical and chemical phenomena as well as capture the possible reaction pathways without any prior user input. The ReaxFF force field is typically trained against Quantum Mechanics (QM) data and is well suited to carry out large-scale molecular dynamics simulation (>> 1000 atoms) of dynamic/reactive systems. In this dissertation, ReaxFF reactive force field simulations have been used across the three stages of combustion, namely pyrolysis, oxidation, and incipient soot formation.
