Adjoint-based sensitivity analysis of char combustion surface reaction kinetics

Abstract

Simulations of solid particle combustion rely on models to approximate the reactions on the surface of the particle and in the surrounding gas. These models, in turn, depend on many model parameters, which are determined, most commonly, by experiments and contain a certain level of uncertainty. It is therefore essential to correctly determine the sensitivities of measured quantities of interest, with respect to the existing model parameters. This study, concentrates on a one-step model describing the heterogeneous reaction on the surface of a char particle, and in particular, the surface model presented by Schiemann et al. [24]. Adjoint-based methods are then employed to extract sensitivities of various quantities of interests, including the burning rate and total heat release, with respect to surface model parameters, such as, the activation energy, and the pre-exponential factor. The variation of these sensitivities are then assessed as the particle size and free stream composition are varied.