Mutual synchronization of hydrodynamic and thermoacoustic oscillations in a turbulent premixed combustor

Mutual synchronization of hydrodynamic and thermoacoustic oscillations in a turbulent premixed 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 Mutual synchronization of hydrodynamic and thermoacoustic oscillations in a turbulent premixed combustor Manikandan Balasubramaniyan, Haiqing Wang, Peijin Liu, Yu Guan, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3963225/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 The presence of global hydrodynamic instability (GHI) in turbulent premixed flames has been shown to reduce the sensitivity of heat-release-rate (HRR) responses to external acoustic forcing, suggesting that GHI could passively weaken thermoacoustic oscillations detrimental to combustion systems. This study adopts a mutual synchronization approach to investigate the coupled interactions between a bluff-body stabilized turbulent premixed flame containing GHI and the acoustic modes of its surrounding combustor. In the absence of external forcing, flame HRR oscillations and combustor acoustic modes can mutually synchronize , but the impact of mutual synchronization on resulting flame response or acoustic pressure amplitude remains unclear. Therefore, this study systematically investigates mutual synchronization, its dynamical states, and subsequent flame response/acoustic pressure amplitude using temporal and spatial analysis. Simultaneous CH* chemiluminescence imaging and unsteady pressure measurements were conducted in a bluff-body stabilized lean-premixed turbulent combustor. By increasing the combustor length (1200 mm ⩽ L ⩽ 2700 mm) while maintaining a fixed equivalence ratio (ϕ = 0.65) and Reynolds number (Re = 10785), four distinct flame modes were observed: (i) a self-sustained vortex shedding mode due to GHI at L = 1200 mm, also known as the hydrodynamic mode; (ii) a self-sustained 1 combustor mode due to thermoacoustic instability at L = 1700 mm; (iii) a hybrid mode at L = 2500 mm, where both the GHI and thermoacoustic modes coex-ist; and (iv) a mutually synchronized mode at L = 2700 mm, where GHI and thermoacoustic modes are locked into each other. Temporal analysis reveals the coexistence of various dynamical states during mutual synchronization, including a simultaneous increase in the amplitudes of flame HRR and acoustic pressure oscillations. Similarly, spatial analysis reveals strong HRR fluctuations occurring at the recirculation zone due to large-scale vortex roll-up. Lastly, two distinct mechanisms causing flame blowoff are identified: (i) a few cycles of flame pinch-off followed by global flame blowoff when ϕ falls below the lean flammability limit and (ii) flame pinch-off and flame-wall quenching together cause global flame blowoff. Synchronization Flame oscillations Premixed flame Lock-in 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-3963225","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":273806488,"identity":"3e20ed81-5c46-4854-981b-9acd8a414f86","order_by":0,"name":"Manikandan Balasubramaniyan","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAy0lEQVRIiWNgGAWjYDACCSD6gCrCRliL5AwIk7EBzCdGizQPSVp0Zzc/vG1TY5Nnzt78/AFjW10dg3RbAl4tZneOGVvnHEsrtuw5ZtjA2HZYgkHm2AH8Wm4kmEnnNhxO3HAjhxGo5QDQYekNBLSkf5O2BGm5/wakpY4YLTlm0oxgW3hAWpiBWtIIOOzOGZA30hI3nEkznJFw7rBkm0RaAn4tt9s33vhRY5O44fjhBx8+lNXx80ukGeDVggpAxhOKyFEwCkbBKBgFRAAA8s1HTOUY9r4AAAAASUVORK5CYII=","orcid":"","institution":"Hong Kong University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Manikandan","middleName":"","lastName":"Balasubramaniyan","suffix":""},{"id":273806489,"identity":"85411640-7863-4ba1-ab5d-02a90bc7396c","order_by":1,"name":"Haiqing Wang","email":"","orcid":"","institution":"Northwestern Polytechnical University","correspondingAuthor":false,"prefix":"","firstName":"Haiqing","middleName":"","lastName":"Wang","suffix":""},{"id":273806490,"identity":"d248bb26-ea83-4476-a7b4-12a83eec3968","order_by":2,"name":"Peijin Liu","email":"","orcid":"","institution":"Northwestern Polytechnical University","correspondingAuthor":false,"prefix":"","firstName":"Peijin","middleName":"","lastName":"Liu","suffix":""},{"id":273806491,"identity":"ecf2d300-59e2-4f34-9949-921050cb010c","order_by":3,"name":"Yu Guan","email":"","orcid":"","institution":"Hong Kong Polytechnic University","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Guan","suffix":""},{"id":273806492,"identity":"c3e4da7d-493d-4368-b594-31b1e501f5dc","order_by":4,"name":"Larry K.B. Li","email":"","orcid":"","institution":"Hong Kong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Larry","middleName":"K.B.","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2024-02-17 05:49:53","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3963225/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3963225/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":68443859,"identity":"ede9dc50-af56-4ab7-85da-a3154c7ba0a1","added_by":"auto","created_at":"2024-11-07 10:17:35","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":15108194,"visible":true,"origin":"","legend":"","description":"","filename":"FlowTurbulenceandCombustion.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3963225/v1_covered_3f373334-78eb-469e-98d8-fc02ebc3f273.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Mutual synchronization of hydrodynamic and thermoacoustic oscillations in a turbulent premixed combustor","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Synchronization, Flame oscillations, Premixed flame, Lock-in","lastPublishedDoi":"10.21203/rs.3.rs-3963225/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3963225/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The presence of global hydrodynamic instability (GHI) in turbulent premixed flames has been shown to reduce the sensitivity of heat-release-rate (HRR) responses to external acoustic forcing, suggesting that GHI could passively weaken thermoacoustic oscillations detrimental to combustion systems. This study adopts a mutual synchronization approach to investigate the coupled interactions between a bluff-body stabilized turbulent premixed flame containing GHI and the acoustic modes of its surrounding combustor. In the absence of external forcing, flame HRR oscillations and combustor acoustic modes can mutually synchronize , but the impact of mutual synchronization on resulting flame response or acoustic pressure amplitude remains unclear. Therefore, this study systematically investigates mutual synchronization, its dynamical states, and subsequent flame response/acoustic pressure amplitude using temporal and spatial analysis. Simultaneous CH* chemiluminescence imaging and unsteady pressure measurements were conducted in a bluff-body stabilized lean-premixed turbulent combustor. By increasing the combustor length (1200 mm ⩽ L ⩽ 2700 mm) while maintaining a fixed equivalence ratio (ϕ = 0.65) and Reynolds number (Re = 10785), four distinct flame modes were observed: (i) a self-sustained vortex shedding mode due to GHI at L = 1200 mm, also known as the hydrodynamic mode; (ii) a self-sustained 1 combustor mode due to thermoacoustic instability at L = 1700 mm; (iii) a hybrid mode at L = 2500 mm, where both the GHI and thermoacoustic modes coex-ist; and (iv) a mutually synchronized mode at L = 2700 mm, where GHI and thermoacoustic modes are locked into each other. Temporal analysis reveals the coexistence of various dynamical states during mutual synchronization, including a simultaneous increase in the amplitudes of flame HRR and acoustic pressure oscillations. Similarly, spatial analysis reveals strong HRR fluctuations occurring at the recirculation zone due to large-scale vortex roll-up. Lastly, two distinct mechanisms causing flame blowoff are identified: (i) a few cycles of flame pinch-off followed by global flame blowoff when ϕ falls below the lean flammability limit and (ii) flame pinch-off and flame-wall quenching together cause global flame blowoff.","manuscriptTitle":"Mutual synchronization of hydrodynamic and thermoacoustic oscillations in a turbulent premixed combustor","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-22 03:06:32","doi":"10.21203/rs.3.rs-3963225/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"05ad1b23-4575-4f4d-8659-0f2443de65e5","owner":[],"postedDate":"February 22nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-11-07T10:08:55+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-22 03:06:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3963225","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3963225","identity":"rs-3963225","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}