Experimental Characterization of a Rotor to Dynamic Collective Pitch Inputs in Hover

Experimental Characterization of a Rotor to Dynamic Collective Pitch Inputs in Hover | 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 Experimental Characterization of a Rotor to Dynamic Collective Pitch Inputs in Hover Patrick Mortimer, Jayant Sirohi This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4596101/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 24 May, 2025 Read the published version in Experiments in Fluids → Version 1 posted 9 You are reading this latest preprint version Abstract Experiments were performed on a two-meter diameter, four-bladed rotor to extract the coefficients of a dynamic inflow model. The frequency response of rotor induced velocity to rotor thrust was found by introducing stepped-sine collective pitch inputs at frequencies of 0.2 per revolution to 0.7 per revolution, where the rotor rotational frequency was 14 Hz. The induced velocity field was measured using phase-resolved, two-dimensional, three-component particle image velocimetry (PIV) over a large region of interest (0.84 m x 0.77 m) in a radial slice of the rotor flow field. The rotor thrust was measured using a hub-mounted load cell. Limited by the frame rate of the cameras, PIV was performed using an under-sampling technique in which one image pair was captured during each rotor revolution, and the time history was recreated from the phase-resolved measurements. The thrust amplitude was found to increase with input frequency, reaching 27.4% of the steady thrust at the highest input frequency. The induced velocity amplitude followed the opposite trend, decreasing to 2.0% of the steady value at the highest input frequency. Dynamic inflow states were extracted and fit to a first-order transfer function. The gain and corner frequency of the transfer function were found to be K = 34.7 +/- 1.52 dB and b = 4.08+/-0.19 rad/s, respectively, which followed a similar trend to computational studies reported in the literature. Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 24 May, 2025 Read the published version in Experiments in Fluids → Version 1 posted Editorial decision: Revision requested 10 Sep, 2024 Reviews received at journal 06 Aug, 2024 Reviews received at journal 06 Aug, 2024 Reviewers agreed at journal 20 Jul, 2024 Reviewers agreed at journal 17 Jul, 2024 Reviewers invited by journal 17 Jul, 2024 Editor assigned by journal 18 Jun, 2024 Submission checks completed at journal 18 Jun, 2024 First submitted to journal 17 Jun, 2024 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. 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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-4596101","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":321856548,"identity":"9873551b-b02c-4788-a8cf-242d74f3e8d0","order_by":0,"name":"Patrick Mortimer","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8ElEQVRIiWNgGAWjYLCCBAjF+IDBAESzMRwgoIGxAaqF2YB4LVAGmwSUxq9et733+YOHOTb5DNLNz6oLCuzs+dmPJR5gqLGJxqXF7Mxxw4bEbWmWDTLHzG7PMEhOnNmTduAAw7G03AZcWm6kMQK1HDZgkMhhu81jwJxgcIO94QBjw2FCWv6DtRTzGNTb2xOp5QBYCzOPwWHGDRJsB/BrOXOMcUbitmQDBpljxtIzDI4nzjiTlnAgAZ9fjrcxfPy5zc4AGGIPPxf8qbbnbz9m/OFDjQ1OLXBgfwMYl3BeAiHlYCCBrGUUjIJRMApGARIAAPnKWVJvhT1hAAAAAElFTkSuQmCC","orcid":"","institution":"Piasecki Aircraft Corporation","correspondingAuthor":true,"prefix":"","firstName":"Patrick","middleName":"","lastName":"Mortimer","suffix":""},{"id":321856549,"identity":"a99c4207-88d9-43f0-a982-16f3e7764f08","order_by":1,"name":"Jayant Sirohi","email":"","orcid":"","institution":"The University of Texas at Austin","correspondingAuthor":false,"prefix":"","firstName":"Jayant","middleName":"","lastName":"Sirohi","suffix":""}],"badges":[],"createdAt":"2024-06-17 21:23:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4596101/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4596101/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00348-025-04037-6","type":"published","date":"2025-05-24T15:58:43+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":83460161,"identity":"b5c37e84-12ae-4b8d-af55-826e4277d64c","added_by":"auto","created_at":"2025-05-26 16:11:23","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5711968,"visible":true,"origin":"","legend":"","description":"","filename":"ExperimentsinFluid2024.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4596101/v1_covered_48b0c1f6-ee0c-446c-a11e-c40c24b1e398.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Experimental Characterization of a Rotor to Dynamic Collective Pitch Inputs in Hover","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"experiments-in-fluids","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"exif","sideBox":"Learn more about [Experiments in Fluids](http://link.springer.com/journal/348)","snPcode":"348","submissionUrl":"https://submission.nature.com/new-submission/348/3","title":"Experiments in Fluids","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4596101/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4596101/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Experiments were performed on a two-meter diameter, four-bladed rotor to extract the coefficients of a dynamic inflow model. The frequency response of rotor induced velocity to rotor thrust was found by introducing stepped-sine collective pitch inputs at frequencies of 0.2 per revolution to 0.7 per revolution, where the rotor rotational frequency was 14 Hz. The induced velocity field was measured using phase-resolved, two-dimensional, three-component particle image velocimetry (PIV) over a large region of interest (0.84 m x 0.77 m) in a radial slice of the rotor flow field. The rotor thrust was measured using a hub-mounted load cell. Limited by the frame rate of the cameras, PIV was performed using an under-sampling technique in which one image pair was captured during each rotor revolution, and the time history was recreated from the phase-resolved measurements. The thrust amplitude was found to increase with input frequency, reaching 27.4% of the steady thrust at the highest input frequency. 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