Uncertainties for Thermoacoustics: A First Analysis

An Uncertainty Quantification analysis of a swirled stabilized combustor experiment is performed. The objective is to estimate the modal risk factor of the system, i.e. the probability of a thermoacoustic mode to be unstable, which may facilitate the development and optimization of suitable control methods. To propagate uncertainties, a Monte Carlo method is initially used based on 4000 Helmholtz-based thermoacoustic simulations with random perturbations on the flame input parameters. The analysis of the Monte Carlo database suggests that a reduced two-step Uncertainty Quantification strategy may be efficient to deal with thermoacoustic systems. First, three bilinear surrogate models are tuned from a moderate number of Helmholtz solutions (a few tens). Then, these algebraic models are used to perform a Monte Carlo analysis at reduced cost and approximate the risk factor of the mode. Good agreements are obtained when comparing the risk factor from the full Monte Carlo database and the risk factor from surrogate models.