Development of a computational testbed for numerical simulation of combustion instability

A synergistic hierarchy of analytical and computational fluid dynamic techniques is used to analyze three-dimensional combustion instabilities in liquid rocket engines. A mixed finite difference/spectral procedure is employed to study the effects of a distributed vaporization zone on standing and spinning instability modes within the chamber. Droplet atomization and vaporization are treated by a variety of classical models found in the literature. A multi-zone, linearized analytical solution is used to validate the accuracy of the numerical simulations at small amplitudes for a distributed vaporization region. This comparison indicates excellent amplitude and phase agreement under both stable and unstable operating conditions when amplitudes are small and proper grid resolution is used. As amplitudes get larger, expected nonlinearities are observed. The effect of liquid droplet temperature fluctuations was found to be of critical importance in driving the instabilities of the combustion chamber

Automated construction of pressure-dependent gas-phase kinetic models : new pathways for old problems

Advancement in the understanding and design of such important gas-phase processes as light hydrocarbon cracking, combustion, and partial oxidn. hinges, in part, on the development of correct, detailed chem. kinetic models. But the size and complexity of the required chem. mechanisms makes them extremely difficult to construct by hand. Chemists and engineers have thus turned to software tools that attempt to build these large mechanisms automatically. But these tools cannot treat pressure-dependent reaction networks, nor do they systematically terminate the otherwise combinatorial growth of a computer-generated chem. mechanism -- limiting their usefulness. We present a new, elementary-step-based mechanism generation algorithm which combines an integrated approach to pressure-dependent reactions with a rational, flux-based criteria for truncating mechanism growth. Examples for methane and ethane pyrolysis reveal important new pathways, not previously considered by other researchers, and suggest the power of explicit, elementary-step based mechanism generation in solving industrially relevant problems. [on SciFinder(R)

sj-pptx-1-gut-10.1177_26345161221137089 – Supplemental material for The Epidemiology of Surgically Managed Hiatal Hernia: A Nine Year Review of National Trends

Supplemental material, sj-pptx-1-gut-10.1177_26345161221137089 for The Epidemiology of Surgically Managed Hiatal Hernia: A Nine Year Review of National Trends by Brian M. Till, Shale J. Mack, Gregory Whitehorn, Micaela Langille Collins, Chi-Fu Jeffrey Yang, Tyler Grenda, Nathaniel R. Evans and Olubenga Okusanya in Foregut: The Journal of the American Foregut Society</p

sj-docx-1-gut-10.1177_26345161221137089 – Supplemental material for The Epidemiology of Surgically Managed Hiatal Hernia: A Nine Year Review of National Trends

Supplemental material, sj-docx-1-gut-10.1177_26345161221137089 for The Epidemiology of Surgically Managed Hiatal Hernia: A Nine Year Review of National Trends by Brian M. Till, Shale J. Mack, Gregory Whitehorn, Micaela Langille Collins, Chi-Fu Jeffrey Yang, Tyler Grenda, Nathaniel R. Evans and Olubenga Okusanya in Foregut: The Journal of the American Foregut Society</p