An aircraft gas turbine engine includes a fan system having a reverse traveling wave first flap mode, Fan RTW, and including a fan upstream of the engine core; a fan shaft; and a front engine structure to support the shaft and having a front engine structure nodding mode FSN including two modes at similar, but unequal, natural frequencies in orthogonal directions; and a gearbox. The engine includes a gearbox, and a gearbox output shaft to couple output of the gearbox to the fan shaft. An LP rotor system including the fan system and the gearbox output shaft has a first reverse whirl rotor dynamic mode, Rotor RW. A frequency margin of:thefrequencydifferencebetweenmodeFSNandthehighestfrequencyofeithersynchronousFanRTWorsynchronousRotorRWthelowestnaturalfrequencyofthefrontstructurenoddingpairofmodesis in the range from 5 to 50%.
Aircraft gas turbine engine with improved response to rotor unbalance
2022-06-07
Patent
Electronic Resource
English
Aircraft Engine Response Due to Fan Unbalance
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