Date of Award
Spring 2016
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Mechanical Engineering
First Advisor
Allen, Casey M.
Second Advisor
Singer, Simcha
Third Advisor
Borg, John
Abstract
Accurate chemical kinetic models, which predict species evolution and heat release rates in chemically reactive systems, are essential for further advancements in fuel and combustion technology. An experimental facility that is widely used for evaluating the accuracy of kinetic models is a rapid compression machine (RCM), which creates a well-defined reaction environment by compressing a reactive mixture inside a chamber. Generally, RCM experiments are conducted in order to obtain ignition delay data. However, chemical speciation data provides greater insight into reaction pathways, and is therefore a more rigorous benchmark for validating kinetic models. In order for a chemical kinetic model to be evaluated using RCM data, the kinetic model must be coupled with a thermodynamic model that can predict the temporally varying conditions that evolve during an RCM experiment. The most common approach is to utilize a thermally and compositionally homogeneous 0-dimensional reactor model (HRM), which predicts conditions inside the hot core region of the main combustion chamber of an RCM, where a significant portion of the chemical reaction in an RCM takes place. This approach requires an effective volume profile, which is derived from the pressure profile of either a non-reactive experiment with similar transport properties as the condition of interest, or a separate multi-zone model (MZM), via the relationship between pressure and volume for an isentropic process. While HRMs have been shown to yield adequate ignition delay predictions, they cannot be used to predict average speciation data, since the conditions in the core region vary considerably from the average conditions of the total reaction chamber. This work introduces a modified MZM, which simulates chemical reaction throughout the entire temperature-varying main combustion chamber of an RCM, in addition to boundary work, conduction, and crevice flows as the traditional MZM approach. Simulating chemistry in the MZM allows for average speciation predictions, and eliminates the need for an HRM. The new approach is shown to yield similar average speciation data as CFD simulations (within 15% difference) for the combustion of primary reference fuels at various conditions.