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dc.contributor.advisor Kielb, Robert E en_US
dc.contributor.author Clark, Stephen Thomas en_US
dc.date.accessioned 2010-05-13T17:52:22Z
dc.date.available 2010-05-13T17:52:22Z
dc.date.issued 2010 en_US
dc.identifier.uri http://hdl.handle.net/10161/2506
dc.description Thesis en_US
dc.description.abstract <p>In the vast majority of measured turbomachinery blade flutter occurrences, the response occurs predominately in a single mode. The primary reason for this single-mode flutter is that for turbomachinery applications the combination of high mass ratio, high solidity, and large natural frequency separation results in only slight mode coupling. </p> <p> The increased importance of fuel efficiency is driving the development of improved turbofans and open-rotor fans. These new designs use fewer blades and will incorporate composite materials or hollowed airfoils in their fan blade designs. Both of these design changes result in lower mass ratio, lower solidity fan blades that may cause multi-mode flutter, rather than single-mode flutter as seen on traditional fan blades. Thus, a single mode flutter design analysis technique may not be adequate. The purpose of this study is to determine initial guidelines for deciding when a coupled-mode analysis is necessary. </p> <p> The results of this research indicate that mass ratio, frequency separation, and solidity have an effect on critical rotor speed. Further, guidelines were developed for when a multi-mode flutter analysis is required. These guidelines define a critical mass ratio that is a function of frequency separation and solidity. For blade mass ratios lower than this critical value, a multi-mode flutter analysis is required. Finally, the limitations of aerodynamic strip-theory have been revealed in a three-dimensional coupled-mode flutter analysis.</p> en_US
dc.format.extent 5774693 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US
dc.subject Engineering, Aerospace en_US
dc.subject Engineering, Mechanical en_US
dc.subject Coupled-Mode en_US
dc.subject Fan en_US
dc.subject Flutter en_US
dc.subject mass ratio en_US
dc.subject open-rotor en_US
dc.subject solidity en_US
dc.title Coupled-Mode Flutter for Advanced Turbofans en_US
dc.type Thesis en_US
dc.department Mechanical Engineering and Materials Science en_US

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