A chemical time scale approach for FPI modeling

Abstract

In most reactive CFD codes, the set of resolved governing equations is not compatible with the original formulation of the "Flame Prolongation of ILDM" (so-called FPI) tabulation technique. In the absence of an explicit continuity equation, the total mass conservation may be expressed implicitly, through the transport of each species. The corresponding reaction rates are then to be evaluated in the FPI database. With this procedure, any chemical source term perturbation often results in very poor predictions of the flame inner structure. In the present work, we propose a chemical-time based formulation aimed at correcting the table interpolated species reaction rates. The very good agreement obtained by this modified approach on an elementary 1D premixed laminar flame bench-mark validates the effective improvement of the FPI model.

Detailed modeling of planar transcritical H2–O2–N2flames

“…Planar flames are important from a theoretical point of view but are also the basis of numerous turbulent combustion models [32,33]. We first establish that, at sufficiently low temperatures, fresh mixtures of H 2 -O 2 -N 2 are thermodynamically unstable.…”

A method to extend flamelet manifolds for prediction of NOx and long time scale species with tabulated chemistry

“…Thus, laminar flamelet reaction rates are stored in a chemistry table. In order to prevent deviation of local composition from the table due to three-dimensional diffusive and convective effects, a correction term is introduced following the previous work of Savre et al (2008) and the reaction rates of the chemical species are generally introduced in the transport equations in the following form:…”

“…The difference with the work of Savre et al (2008) is that a single characteristic time τ is used since deviations from table composition are driven by three-dimensional diffusive and convective effects common to all species. It can be verified in the calculations that in each cell of the mesh, the local composition is close to the tabulated one.…”

Soot and radiation modeling in laminar ethylene flames with tabulated detailed chemistry

“…A computationally affordable method consists in tabulating the chemistry as a function of a reduced set of variables. In particular, the FPI method was investigated by Galpin et al [38] and Savre et al [39] for combustion in industrial devices. For this method, a onedimensional laminar premixed flame is pre-processed with the PREMIX code [40] involving complex detailed chemistry and detailed transport.…”