Reduced-kinetic mechanisms for hydrogen and syngas combustion including autoignition

• Autores: Pierre Boivin
• Directores de la Tesis: M. Carmen Jiménez Sánchez (dir. tes.), Antonio Luis Sánchez Pérez (dir. tes.)
• Lectura: En la Universidad Carlos III de Madrid ( España ) en 2011
• Idioma: inglés
• Tribunal Calificador de la Tesis: Forman Arthur Williams (presid.), Vadim Kourdioumov (secret.), Amable Liñán Martínez (voc.), Paul Clavin (voc.), Bénédicte Cuenot (voc.)
• Materias:
  • Física
    • Física de fluidos
  • Ciencias tecnológicas
    • Tecnología energética
• Enlaces
  • Tesis en acceso abierto en: e-Archivo
• Resumen

  • Reduced chemical-kinetic mechanisms are investigated for hydrogen and syngas combustion to fill the need for simplified chemistry able to describe with accuracy both premixed and diffusion flames and also autoignition, necessitated for instance in computational work that addresses turbulent combustion or the transition from deflagration to detonation. The reduced descriptions incorporate steady-state assumptions for O and OH, which are found to be reasonably accurate for flames but much less accurate for hightemperature autoignition. A detailed description of ignition histories, both above and below the second explosion limit, provides explicit analytic expressions for the ignition time of hydrogen-air mixtures, valid in a wide range of pressure, temperature, and equivalence ratios, and also leads to a correction for the rates of the reduced chemistry that improves accuracy of predicted high-temperature ignition times while keeping the simplification associated with the steady-state assumptions for O and OH. The resulting reduced mechanisms, which consist of three overall steps for hydrogen combustion and one additional CO-oxidation step for syngas combustion, possess reasonable accuracy for most computational purposes, as is demonstrated through extensive validation exercises including comparisons with detailed-chemistry computations and experimental measurements of flame-propagation velocities, extinction strain rates, and ignition times. The three-step mechanism is used also to investigate a turbulent, supersonic, autoignition-stabilized, hydrogenair lifted flame, enabling reduced-chemistry capabilities to be tested in a large scale simulation including turbulence modelling. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------