@Article{BourginAlvYanFacBau:2017:EfLeNu,
               author = "Bourgin, E. and Alves, M. M. and Yang, C. and Fachini Filho, 
                         Fernando and Bauwens, L.",
          affiliation = "MBDA and {University of Calgary} and {University of Calgary} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {University 
                         of Calgary}",
                title = "Effects of Lewis numbers and kinetics on spontaneous ignition of 
                         hydrogen jets",
              journal = "Proceedings of the Combustion Institute",
                 year = "2017",
               volume = "36",
               number = "2",
                pages = "2833--2839",
             keywords = "Jet ignition, Lewis number, Chain-branching, Hydrogen.",
             abstract = "The transient process following a hydrogen leak into the 
                         atmosphere initiates as a contact surface appears separating air 
                         heated by the leading shock from hydrogen cooled by expansion. 
                         Diffusion of heat and species produces reactive mixture, 
                         potentially leading to ignition. Reactions being very 
                         temperature-sensitive, their rate peaks close to the hot air-rich 
                         side of the interface, where the small fuel concentration depends 
                         upon the fuel Lewis number. If the Lewis number is less than 
                         unity, diffusion brings in more fuel than temperature-controlled 
                         chemistry consumes. If greater, diffusion does not bring in as 
                         much fuel as chemistry would burn. Results from the current 
                         analysis for multistep kinetics also show that the role of the H 
                         Lewis number is crucial. In the short time limit, the evolution of 
                         the diffusion layer appears as a perturbation superimposed to the 
                         self-similar non-reactive diffusion solution. Initiation is very 
                         slow compared with steps consuming one reactant and an 
                         intermediate species, while some steps associated with termination 
                         are extremely fast. The approximation being made, assuming 
                         initiation much smaller than most rates, and termination much 
                         faster, is very accurate since the corresponding ratios are of the 
                         order of 10(5). The resulting problem still requires a numerical 
                         solution. A time-splitting algorithm combines exact solutions to 
                         three subproblems, avoiding issues such as stiffness of the 
                         kinetics. The problem is formulated not in physical space but in 
                         the similarity variable of the diffusion problem, hence avoiding 
                         difficulties associated with the initial singularity when the 
                         layer has zero thickness, and the resulting uncertainties. These 
                         are distinct advantages over numerical simulations, which however 
                         will retain a reasonable accuracy at later times. Results confirm 
                         the role of the Lewis number. They also show two distinct regimes: 
                         an early one mainly controlled by initiation, and a later one 
                         controlled by chain-branching, with a sharp transition.",
                  doi = "10.1016/j.proci.2016.06.175",
                  url = "http://dx.doi.org/10.1016/j.proci.2016.06.175",
                 issn = "1540-7489",
             language = "en",
           targetfile = "bourgin_effects.pdf",
        urlaccessdate = "27 abr. 2024"
}