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A unified model for premixed flames as gasdynamic discontinuities / Ein vereinheitlichtes Modell fuer Vormischflammen als gasdynamische Diskontinuitaet

  • Class, A.G.
  • Forschungszentrum Karlsruhe GmbH Technik...
  • karlsruhe, forschungszentrum
Publication Date
Jan 01, 2003
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In this habilitation thesis tensor algebra is applied to derive a unified model, consisting of a new flame speed relation and new jump conditions, which is applicable for arbitrary Lewis numbers. In appropriate limits the models of Sivashinsky and Matalon-Matkowsky are recovered. Moreover a new distinguished limit allows for larger Lewis number deviations form unity as compared to the Matalon-Matkowsky theory thus bridging the Matalon-Matkowsky and the Sivashinsky theory. Considering shortwave corrugations of the flame not considered previously, results in new terms coupling neighboring flame elements. These terms damp short wave perturbations of the flame surface, and thus in contrast to previous theories the unified theory is applicable when the flame is unstable with respect to shortwave pulsating instabilities. Remarkable is the fact, that the flame speed relation and jump conditions depend on the precise location of the discontinuity surface. When Gibbs (1879) studied the free interface problem of two adjacent immiscible fluids, he made a similar observation. Depending on the choice of the interface an excess surface mass must be assigned to the interface. In contrast to previous theories the surface is chosen to yield a vanishing excess surface mass. This results in substantially simplified jump conditions. In numerical simulations using the unified model, mass must not be added or subtracted from the flow as the simulation progresses, which is required in the Matalon-Matkowsky model. (orig.) / SIGLE / Available from TIB Hannover: ZA 5141(6807) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische Informationsbibliothek / DE / Germany

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