Sensitivity Analysis and Uncertainty Quantification of a Single Combusting Particle

Abstract This study explores the complex phenomena involved in simulations of unsteady solid fuel particle combustion. These simulations use models that depend on parameters from experiments or small-scale simulations, making it important to quantify the sensitivities and uncertainties of predicted quantities. The study focuses on combustion under different freestream compositions, such as air and oxy-fuel atmospheres. The first step involves identifying the most sensitive model parameters, a process developed in a previous study. The framework is extended to study the evolution of sensitivities over time for a single unsteady particle undergoing devolatilisation. The dominant model parameters affecting particle temperature and burning rate are identified for both air and oxy-fuel atmospheres. The impact of different devolatilisation models on sensitivities is also examined. Additionally, an adjoint-based active subspace method (AASM) is employed to quantify uncertainties in predictions. The results show that uncertainties in particle parameters are much greater than those in gas-phase reaction rates. Furthermore, uncertainties are larger in oxy-fuel atmospheres than in air, emphasising the effect of freestream composition on model predictions.