Modeling of the nonlinear flame response of a Bunsen-type flame via multi-layer perceptron

Tathawadekar, Nilam; Doan, Nguyen Anh Vu; Silva, Camilo; Thuerey, Nils

doi:10.1016/j.proci.2020.07.115

Cited by 7 publications

(2 citation statements)

References 19 publications

(37 reference statements)

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“…While this is inherently the case for the flame resolved by CFD, the LOM must also include non-linear flame models representing the dynamics of all remaining flames. However, non-linear flame models, which are valid for a wide range of frequencies and amplitudes -the relevant frequencies and amplitudes are typically not known in advance -are generally very costly to determine [17][18][19] or are only of qualitative nature. 20 Instead, here we propose to identify the non-linear flame models "on-the-fly", based on a linear model of flame dynamics plus observations of non-linear flame dynamics in CFD during the simulation of the selfexcited configuration.…”

Section: Introductionmentioning

confidence: 99%

Hybrid CFD/low-order modeling of thermoacoustic limit cycle oscillations in can-annular configurations

Haeringer

Polifke

2022

International Journal of Spray and Combustion Dynamics

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We propose a hybrid strategy for modeling non-linear thermoacoustic phenomena, e.g. limit-cycle (LC) oscillations, in can-annular combustion systems. The suggested model structure comprises a compressible CFD simulation limited to the burner/flame zone of one single can, coupled to a low-order model (LOM) representing the remaining combustor. In order to employ the suggested strategy for modeling non-linear phenomena like LC oscillations, the LOM must capture non-linear flame dynamics in the cans, which are not resolved by CFD. Instead of identifying such non-linear flame models in preliminary simulations, we aim at learning the non-linear dynamics “on-the-fly”, while simulating the self-excited system under consideration. Based on the observation of flame dynamics in the CFD domain, the parameters of the employed non-linear models are estimated during run time. The present study reveals that block-oriented models, which comprise a linear dynamic part followed by a static non-linear function, are well suited for this purpose. The proposed hybrid model is applied to a laminar can-annular combustor. Results agree well with the monolithic CFD simulation of the entire combustor, while the computational cost is drastically reduced. The employed flame models, whose parameters are identified during the simulation of the self-excited LC oscillation, represent well the relevant non-linear dynamics of the considered flame.

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Section: Introductionmentioning

confidence: 99%

Hybrid CFD/low-order modeling of thermoacoustic limit cycle oscillations in can-annular configurations

Haeringer

Polifke

2022

International Journal of Spray and Combustion Dynamics

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“…Recently, a different modelling strategy was introduced for the modelling of the non-linear flame response in the time domain (Tathawadekar et al 7 ). The derived model is obtained relatively easy from data and is more general than the FDF as it accounts for interaction between frequencies.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear flame response modelling by a parsimonious set of ordinary differential equations

Doehner

Haeringer

Silva

2022

International Journal of Spray and Combustion Dynamics

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In this work we present a parsimonious set of ordinary differential equations (ODEs) that describes with satisfactory precision the linear and non-linear dynamics of a typical laminar premixed flame in time and frequency domain. The proposed model is characterized by two ODEs of second-order that can be interpreted as two coupled mass-spring-damper oscillators with a symmetric, nonlinear damping term. This non-linear term is identified as function of the rate of displacement following [Formula: see text]. The model requires only four constants to be calibrated. This is achieved by carrying out an optimization procedure on one input and one output broadband signal obtained from high-fidelity numerical simulations (CFD). Note that the Transfer Function (FTF) or describing function (FDF) of the flame under investigation are not known a-priori, and therefore not used in the optimization procedure. Once the model is trained on CFD input and output time series, it is capable of recovering with quantitative accuracy the impulse response of the laminar flame under investigation and, hence, the corresponding frequency response (FTF). If fed with harmonic signals of different frequency and amplitude, the trained model is capable of retrieving with qualitative precision the flame describing function (FDF) of the studied flame. We show that the non-linear term [Formula: see text] is essential for capturing the gain saturation for high amplitudes of the input signal. All results are validated against CFD data.

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Modeling of the nonlinear flame response of a Bunsen-type flame via multi-layer perceptron

Cited by 7 publications

References 19 publications

Hybrid CFD/low-order modeling of thermoacoustic limit cycle oscillations in can-annular configurations

Hybrid CFD/low-order modeling of thermoacoustic limit cycle oscillations in can-annular configurations

Nonlinear flame response modelling by a parsimonious set of ordinary differential equations

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