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dc.contributor.authorTraverso, Ten
dc.contributor.authorMagri, Lucaen
dc.date.accessioned2019-04-16T23:30:33Z
dc.date.available2019-04-16T23:30:33Z
dc.date.issued2019-01-01en
dc.identifier.isbn9783030227463en
dc.identifier.issn0302-9743
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/291717
dc.description.abstractWhen the heat released by a flame is sufficiently in phase with the acoustic pressure, a self-excited thermoacoustic oscillation can arise. These nonlinear oscillations are one of the biggest challenges faced in the design of safe and reliable gas turbines and rocket motors~\cite{Magri2019_amr}. In the worst-case scenario, uncontrolled thermoacoustic oscillations can shake an engine apart. Reduced-order thermoacoustic models, which are nonlinear and time-delayed, can only qualitatively predict thermoacoustic oscillations. To make reduced-order models quantitatively predictive, we develop a data assimilation framework for state estimation. We numerically estimate the most likely nonlinear state of a Galerkin-discretized time delayed model of a horizontal Rijke tube, which is a prototypical combustor. Data assimilation is an optimal blending of observations with previous system’s state estimates (background) to produce optimal initial conditions. A cost functional is defined to measure (i) the statistical distance between the model output and the measurements from experiments; and (ii) the distance between the model’s initial conditions and the background knowledge. Its minimum corresponds to the optimal state, which is computed by Lagrangian optimization with the aid of adjoint equations. We study the influence of the number of Galerkin modes, which are the natural acoustic modes of the duct, with which the model is discretized. We show that decomposing the measured pressure signal in a finite number of modes is an effective way to enhance state estimation, especially when nonlinear modal interactions occur during the assimilation window. This work represents the first application of data assimilation to nonlinear thermoacoustics, which opens up new possibilities for real-time calibration of reduced-order models with experimental measurements.
dc.publisherSpringer Verlag
dc.rightsAll rights reserved
dc.titleData Assimilation in a Nonlinear Time-Delayed Dynamical System with Lagrangian Optimizationen
dc.typeConference Object
prism.endingPage168
prism.publicationDate2019en
prism.publicationNameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)en
prism.startingPage156
prism.volume11539 LNCSen
dc.identifier.doi10.17863/CAM.38877
dcterms.dateAccepted2019-03-15en
rioxxterms.versionofrecord10.1007/978-3-030-22747-0_12en
rioxxterms.versionAM
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2019-01-01en
dc.contributor.orcidMagri, Luca [0000-0002-0657-2611]
dc.identifier.eissn1611-3349
rioxxterms.typeConference Paper/Proceeding/Abstracten
pubs.funder-project-idRoyal Academy of Engineering (RAEng) ()
cam.orpheus.successThu Nov 05 11:53:49 GMT 2020 - Embargo updated*
rioxxterms.freetoread.startdate2020-01-01


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