Global and Local Synchronization During Thermoacoustic Instability in a Swirl Combustor

Global and Local Synchronization During Thermoacoustic Instability in a Swirl Combustor | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Global and Local Synchronization During Thermoacoustic Instability in a Swirl Combustor Samadhan A. Pawar, Ankit Dutta, Swetaprovo Chaudhuri This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6323502/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Synchronization, along with various other collective behaviors, is a widely studied phenomenon in systems of coupled oscillators across diverse fields of science and engineering. In such systems, the global dynamics are governed by complex local interactions among spatially distributed oscillators, nonlinearly coupled through different mechanisms. In this paper, we investigate both the global and local interactions between the acoustic pressure field and the unsteady heat release rate in the flame of a swirl-stabilized turbulent combustion system during a self-oscillatory state known as thermoacoustic instability. These instabilities are typically characterized by large-amplitude limit cycle oscillations in the acoustic field of the combustor. While the global characteristics of flame-acoustic interactions during thermoacoustic instability have been well understood over the years, the local interactions leading to the observed global dynamics remain elusive. Through experimental analyses of simultaneously measured acoustic pressure and heat release rate fluctuations (captured via CH* chemiluminescence imaging of the flame) in the combustor, we demonstrate that these fluctuations globally phase synchronize with a finite time delay during thermoacoustic instability. However, the local interaction of these coupled oscillations exhibits coherent patterns of phase-locking, resulting in the formation of space-invariant phase clusters along the flame surface. Thus, we observe that the local clustered synchronization of acoustic pressure and heat release rate fluctuations in the reaction field sustains the global order in the combustor during thermoacoustic instability. Finally, we propose a phenomenological phase oscillator model, based on Kuramoto’s model for coupled phase oscillators, to uncover the potential underlying network structure governing flame-acoustic interactions and driving synchronization transitions in the swirl combustion system. Synchronization Coupled Phenomena Thermoacoustic Instability Swirl Combustion Phase Oscillator Modeling Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6323502","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":435434517,"identity":"c0423ffa-1b8a-41eb-8b7a-3f63f5c7140e","order_by":0,"name":"Samadhan A. 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Through experimental analyses of simultaneously measured acoustic pressure and heat release rate fluctuations (captured via CH* chemiluminescence imaging of the flame) in the combustor, we demonstrate that these fluctuations globally phase synchronize with a finite time delay during thermoacoustic instability. However, the local interaction of these coupled oscillations exhibits coherent patterns of phase-locking, resulting in the formation of space-invariant phase clusters along the flame surface. Thus, we observe that the local clustered synchronization of acoustic pressure and heat release rate fluctuations in the reaction field sustains the global order in the combustor during thermoacoustic instability. 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