| This research focuses on the time-accurate simulation and analysis of high-pressure mixing and combustion processes in turbulent mixing layers. The objectives are: (1) to provide insight with respect to the many uncertainties associated with modeling turbulent, reacting, multiphase flow at near-critical pressures; (2) to establish a baseline theoretical framework and criteria which addresses model performance and accuracy requirements; and (3) to analyze high-pressure phenomena at the operating conditions typically employed in state of the art combustors. Results address fundamental issues related to modeling and understanding unsteady reacting flow dynamics at near-critical conditions by focusing on mixing and combustion processes in hydrogen-oxygen systems.; The approach follows four fundamental steps: (1) the development of a generalized theoretical framework; (2) the specification of detailed property evaluation schemes and consistent closure methodologies; (3) the implementation of an efficient and time-accurate numerical framework; and (4) the presentation and analysis of a systematic series of case studies which focus on model performance and accuracy requirements, Lagrangian-Eulerian treatments of transcritical spray field dynamics, and pure Eulerian treatments of transcritical and supercritical mixing and combustion processes. The theoretical framework is based on the large-eddy-simulation technique, employs state of the art correlations to model the particulate phase, and employs a recently optimized 24-step finite-rate kinetics mechanism. The numerical framework is based on a preconditioned, density-based, finite-volume methodology that takes full account of thermodynamic nonidealities and transport anomalies and accommodates any arbitrary equation of state.; Case studies focus on model performance and accuracy requirements, Lagrangian-Eulerian treatments of transcritical spray field dynamics, and pure Eulerian treatments of transcritical and supercritical mixing and combustion processes. The Lagrangian-Eulerian calculations demonstrate the effects of particle damping, propellant striations, and mixture induced enhancement of turbulent diffusion processes on the evolutionary structure of the flow. The pure Eulerian calculations demonstrate the effects of the momentum flow ratio on flame holding dynamics, the dominating effect of the interfacial density gradient, and the impact of diminished mass diffusion rates which accompany the liquid like behavior of near-critical fluids. |
