公开(公告)号：US11359549B2

公开(公告)日：2022-06-14

申请号：US17331020

申请日：2021-05-26

Applicant: ROLLS-ROYCE PLC

Inventor： Matthew Silvester ,  Geoffrey Hughes

IPC: F02C7/36 ,  F04D29/40 ,  B64D27/10 ,  F02C3/073 ,  F04D25/02 ,  F02K3/06

Abstract: A gas turbine engine for an aircraft includes a fan system having a reverse travelling wave first flap mode, Fan RTW, and including a fan located upstream of the engine core; a fan shaft; and a front engine structure arranged to support the fan shaft and having a front engine structure nodding mode comprising a pair of modes at similar, but not equal, natural frequencies in orthogonal directions; and a gearbox. An LP rotor system including the fan system and a gearbox output shaft arranged to drive the fan shaft has a first reverse whirl rotor dynamic mode, Rotor RW, and a first forward whirl rotor dynamic mode, 1FW. The engine has a maximum take-off speed, MTO. A backward whirl frequency margin of: the ⁢ ⁢ lowest ⁢ ⁢ frequency ⁢ ⁢ of ⁢ ⁢ either ⁢ ⁢ mode ⁢ ⁢ Fan ⁢ ⁢ RTW ⁢ ⁢ or ⁢ ⁢ Rotor ⁢ ⁢ RW ⁢ ⁢ at the ⁢ ⁢ MTO ⁢ ⁢ speed the ⁢ ⁢ MTO ⁢ ⁢ speed may be in the range from 15 to 50%.

公开(公告)号：US11352958B2

公开(公告)日：2022-06-07

申请号：US17331989

申请日：2021-05-27

Applicant: ROLLS-ROYCE PLC

Inventor： Matthew Silvester ,  Geoffrey Hughes

IPC: F02C7/36 ,  F04D29/40 ,  B64D27/10 ,  F02C3/073 ,  F04D25/02 ,  F02K3/06

Abstract: 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: ⁢ the ⁢ ⁢ frequency ⁢ ⁢ difference ⁢ ⁢ between ⁢ ⁢ mode ⁢ ⁢ ⁢ ⁢ FSN ⁢ ⁢ and ⁢ ⁢ the ⁢ ⁢ highest ⁢ ⁢ frequency ⁢ ⁢ of ⁢ ⁢ either ⁢ ⁢ ⁢ ⁢ synchronous ⁢ ⁢ Fan ⁢ ⁢ RTW ⁢ ⁢ or ⁢ ⁢ synchronous ⁢ ⁢ Rotor ⁢ ⁢ RW ⁢ the ⁢ ⁢ lowest ⁢ ⁢ natural ⁢ ⁢ frequency ⁢ ⁢ of ⁢ ⁢ ⁢ ⁢ the ⁢ ⁢ front ⁢ ⁢ structure ⁢ ⁢ nodding ⁢ ⁢ pair ⁢ ⁢ of ⁢ ⁢ modes is in the range from 5 to 50%.