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Bayesian Machine Learning for the Prognosis of Combustion Instabilities from Noise

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Rasmussen, CE 
Juniper, MP 

Abstract

jats:titleAbstract</jats:title> jats:pExperiments are performed on a turbulent swirling flame placed inside a vertical tube whose fundamental acoustic mode becomes unstable at higher powers and equivalence ratios. The power, equivalence ratio, fuel composition, and boundary condition of this tube are varied and, at each operating point, the combustion noise is recorded. In addition, short acoustic pulses at the fundamental frequency are supplied to the tube with a loudspeaker and the decay rates of subsequent acoustic oscillations are measured. This quantifies the linear stability of the system at every operating point. Using this data for training, we show that it is possible for a Bayesian ensemble of neural networks to predict the decay rate from a 300 ms sample of the (unpulsed) combustion noise and therefore forecast impending thermoacoustic instabilities. We also show that it is possible to recover the equivalence ratio and power of the flame from these noise snippets, confirming our hypothesis that combustion noise indeed provides a fingerprint of the combustor's internal state. Furthermore, the Bayesian nature of our algorithm enables principled estimates of uncertainty in our predictions, a reassuring feature that prevents it from making overconfident extrapolations. We use the techniques of permutation importance and integrated gradients to understand which features in the combustion noise spectra are crucial for accurate predictions and how they might influence the prediction. This study serves as a first step toward establishing interpretable and Bayesian machine learning techniques as tools to discover informative relationships in combustor data and thereby build trustworthy, robust, and reliable combustion diagnostics.</jats:p>

Description

Keywords

40 Engineering, 4017 Mechanical Engineering, 4002 Automotive Engineering, Bioengineering, Machine Learning and Artificial Intelligence

Journal Title

Journal of Engineering for Gas Turbines and Power

Conference Name

Journal ISSN

0742-4795
1528-8919

Volume Title

143

Publisher

ASME International

Rights

All rights reserved
Sponsorship
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (766264)
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