Optimized single-step (OSS) chemistry for auto-ignition of heterogeneous mixtures

Luis Carbajal-Carrasco (1) , Zakaria Bouali (1) , Arnaud Mura (1)

1 CT - Structures de flammes et combustion [Institut Pprime]

With the objective of recovering the values of ignition delays of reactive heterogeneous mixtures a single- step chemistry model has been developed. The corresponding model extends a recent optimization procedure introduced to describe flame propagation in heterogeneous media featuring composition variations (equivalence ratio and temperature) in the fresh reactants or containing residual burned gases (RBG). It is based on the use of an optimized virtual species and a tabulation of the pre-exponential coefficient of an Arrhenius law. The main results of high activation energy asymptotics (AEA) are first recalled to put in evidence the key parameters and the dependence of the ignition delay on the corresponding quantities. The optimization procedure is then applied to these parameters, namely, the pre-exponential factor K and the activation energy Ea of the associated single-step Arrhenius law. An efficient tabulation method benefiting from both rapid access and low storage is proposed for the composition variable (the mixture fraction, in the present case). Finally, the restitution of both ignition and propagation features is ensured through the consideration of the cross-over temperature. The performance of the resulting model is then assessed through comparisons with data obtained from detailed chemistry computations used as refer- ence in several conditions of increasing complexity.

Mots clés: Single-step chemistry; auto-ignition; ignition delay; premixed combustion; turbulent flames

Domaines: Milieux fluides et réactifs

Luis Carbajal-Carrasco, Zakaria Bouali, Arnaud Mura. Optimized single-step (OSS) chemistry for auto-ignition of heterogeneous mixtures. Combustion and Flame, 2021, 227, pp.11-26. ⟨10.1016/j.combustflame.2020.12.026⟩. ⟨hal-03101255⟩