Measurement and application of conserved scalars in combustion chemistry

The two principal contributions to flame structure are the dynamics of high-temperature fluid flows and the chemical mechanisms by which the molecular components of that flow may react. This study uses the nonreacting, spatially independent variable, mixture fraction, as a simplifying link between fluid dynamics and chemistry as investigated both experimentally and numerically.;Acetone is tested for use as a fluorophore to experimentally track mixture fraction. Highly attractive because of its low toxicity and small seeding concentrations, its use is limited by thermal decomposition before it reaches the flame reaction zone. This behavior is confirmed with calculations assuming one-step, infinitely fast chemistry. Hence, while acetone fluorescence marking provides no information about the high temperature region of a diffusion flame, it does show promise as a tracer in time-varying and turbulent flames where cooler pockets of fuel have been observed.;Also investigated is the use of hydroxyl radical fluorescence thermometry. By fitting the Boltzmann population of rotational states for ;The application of the mixture fraction-based, species conservation equations for combustion is investigated for use in modeling the nitrogen chemistry of a flame. Modeling of these systems has often lagged behind experimentation due to the large computational requirements of detailed chemistry in the study of reacting flows. To address this issue, the mixture fraction form of the conservation equations is first shown to be an efficient tool to perform reaction rate analysis of nitrogen oxidation reaction mechanisms. As a further step, these mixture fraction-based equations are then used as part of an algebraic simplification procedure to form a closed set of five linear equations that accurately describe the bulk of the nitrogen oxidation in a diffusion flame.