Journal ArticleDOI
Coupled interaction between unsteady flame dynamics and acoustic field in a turbulent combustor
Vedasri Godavarthi,Samadhan A. Pawar,Vishnu R. Unni,R. I. Sujith,Norbert Marwan,Jürgen Kurths,Jürgen Kurths,Jürgen Kurths +7 more
TLDR
A possible asymmetric bidirectional coupling between q ˙ ' and p ' is observed to exert a stronger influence on p ' than vice versa, and the directional property of the network measure, namely, cross transitivity is used to analyze the type of coupling existing between the acoustic field and the heat release rate fluctuations.Abstract:
Thermoacoustic instability is a result of the positive feedback between the acoustic pressure and the unsteady heat release rate fluctuations in a combustor. We apply the framework of the synchronization theory to study the coupled behavior of these oscillations during the transition to thermoacoustic instability in a turbulent bluff-body stabilized gas-fired combustor. Furthermore, we characterize this complex behavior using recurrence plots and recurrence networks. We mainly found that the correlation of probability of recurrence ( C P R), the joint probability of recurrence ( J P R), the determinism ( D E T), and the recurrence rate ( R R) of the joint recurrence matrix aid in detecting the synchronization transitions in this thermoacoustic system. We noticed that C P R and D E T can uncover the occurrence of phase synchronization state, whereas J P R and R R can be used as indices to identify the occurrence of generalized synchronization (GS) state in the system. We applied measures derived from joint and cross recurrence networks and observed that the joint recurrence network measures, transitivity ratio, and joint transitivity are useful to detect GS. Furthermore, we use the directional property of the network measure, namely, cross transitivity to analyze the type of coupling existing between the acoustic field ( p ′) and the heat release rate ( q ˙ ′) fluctuations. We discover a possible asymmetric bidirectional coupling between q ˙ ′ and p ′, wherein q ˙ ′ is observed to exert a stronger influence on p ′ than vice versa.Thermoacoustic instability is a result of the positive feedback between the acoustic pressure and the unsteady heat release rate fluctuations in a combustor. We apply the framework of the synchronization theory to study the coupled behavior of these oscillations during the transition to thermoacoustic instability in a turbulent bluff-body stabilized gas-fired combustor. Furthermore, we characterize this complex behavior using recurrence plots and recurrence networks. We mainly found that the correlation of probability of recurrence ( C P R), the joint probability of recurrence ( J P R), the determinism ( D E T), and the recurrence rate ( R R) of the joint recurrence matrix aid in detecting the synchronization transitions in this thermoacoustic system. We noticed that C P R and D E T can uncover the occurrence of phase synchronization state, whereas J P R and R R can be used as indices to identify the occurrence of generalized synchronization (GS) state in the system. We applied measures derive...read more
Citations
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Journal ArticleDOI
Convolutional neural networks to predict the onset of oscillatory instabilities in turbulent systems.
TL;DR: In this paper, the authors extract the peculiar pattern of phase space attractors during the regime of intermittency by constructing recurrence networks corresponding to the phase space topology and train a convolutional neural network to classify the periodic and aperiodic structures in the recurrence network and define a measure that indicates the proximity of the dynamical state to the onset of oscillatory instability.
Journal Article
Convolutional neural networks to predict the onset of oscillatory instabilities in turbulent systems
TL;DR: This paper extracts the peculiar pattern of phase space attractors during the regime of intermittency by constructing recurrence networks corresponding to the phase space topology and defines a measure that indicates the proximity of the dynamical state to the onset of oscillatory instability.
Journal ArticleDOI
Attenuation of thermoacoustic combustion oscillations in a swirl-stabilized turbulent combustor.
TL;DR: In this paper, a steady air jet from the injector rim was used to suppress combustion oscillations, and the loss of the primary hub in the turbulence network played an important role in the degeneration of combustion oscillation.
Journal ArticleDOI
Synchronization framework for modeling transition to thermoacoustic instability in laminar combustors
TL;DR: In this article, a model based on the framework of synchronization was proposed to describe a thermoacoustic system and capture the multiple bifurcations that such a system undergoes.
Journal ArticleDOI
Closeness-centrality-correlation for detecting interdependency between coupled systems
TL;DR: A novel method, called closeness-coding, which automates the very labor-intensive and therefore time-heavy and expensive process of synchronization between coupled systems.
References
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Journal ArticleDOI
Recurrence-plot-based measures of complexity and their application to heart-rate-variability data.
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