A-posteriori analysis of a data-driven filtered wrinkled flamelet model for thermodiffusively unstable premixed flames

Abstract

State-of-the-art turbulent combustion models do not account for the effects of intrinsic flame instabilities, which are known to have a non-negligible effect, under technically relevant conditions, in thermodiffusively unstable flames such as those of hydrogen-based fuels. In this work, a data-driven modeling framework for filtered, laminar, self-wrinkling flames subject to intrinsic instabilities is presented and proposed as a stepping stone for the development of turbulent combustion models for large eddy simulation. In this context, data-driven refers to the use of small- and medium-sized resolved simulations, explicitly filtered in physical space, as data sources for the development of filtered tables. For consistency, all the unclosed terms of the filtered governing equations are then written according to the filtered tabulated chemistry formalism. The a-posteriori analysis of the modeling framework indicates that medium-scale simulations, which conversely to the small-scale ones feature at least one characteristic flame-finger, are needed for the generation of the data-driven tables. Furthermore, a laminar wrinkling factor, accounting for the sub-filter cellular wrinkling, should also be used. The presented results show promise for the extension of this modeling framework to the simulation of turbulent flames, as well as to multi-step chemistry and detailed thermo-transport modeling. Statement of SignificanceIt is nowadays well-known that intrinsic flame instabilities have a leading order impact on the propagation of premixed flames in thermodiffusively unstable mixtures, such as lean hydrogen-air premixed flames. This work presents the first a-posteriori analysis of a combustion model for filtered, albeit laminar, large-scale, intrinsically unstable premixed flames. The novelty of the presented data-driven model lies in the use of data obtained from filtering direct numerical simulations performed for paradigmatic small and medium-scale cases, instead of standard one-dimensional flamelets.