Power plants – Reaction motor – Interrelated reaction motors
Reexamination Certificate
2002-04-29
2004-05-25
Kim, Ted (Department: 3747)
Power plants
Reaction motor
Interrelated reaction motors
C060S268000, C060S039162
Reexamination Certificate
active
06739120
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a counterrotatable fan section and counterrotatable booster compressor for a gas turbine engine and, in particular, to a fan blade assembly of a counterrotatable fan section which also functions as a compressor blade in the booster compressor.
Gas turbine engines are continuously being improved so as to achieve greater thrust with lower noise and greater operating efficiency. One approach has become known as the bypass turbofan engine, where the airflow is divided into two separate and concentric flow streams. An outer flow stream is compressed only by a fan section of the engine and is utilized to provide most of the overall thrust, while an inner flow stream passes through the fan, core engine, and turbine to provide power in which to drive the fan. In order to achieve an increase in fan pressure ratio and maintain fan efficiency with lower relative noise, the fan section includes two stages or rows of fan blades which rotate in opposite direction so as to be a counterrotatable fan. For lower noise and greater efficiency, it has become desirable to separate the two rows of fan blades axially to allow attenuation of the wake between them.
To reduce the extra length necessitated by the spacing of the fan blade rows, the inner and outer flow streams are separated at a location axially between such fan stages and the booster compressor positioned within the inner diameter of the second fan stage. Initial configurations of the booster compressor utilized in bypass turbofan engines included various stages of rotor blades which rotated in accordance with the first fan stage, as well as a stator vane stage positioned between each pair of rotor blades (see U.S. Pat. No. 6,220,012 to Hauser et al., for example). Thereafter, as seen in U.S. Pat. No. 4,860,537 to Taylor, U.S. Pat. No. 5,307,622 to Ciokajlo et al., and U.S. Pat. No. 4,790,133 to Stuart, the booster compressor was designed so as to have counterrotatable blade rows or sections therein which rotate in accordance with corresponding stages of the counterrotatable fan.
It has been found that driving the separate blade rows of the booster compressor introduces certain mechanical complexities. In addition, support for the second fan stage is required which does not unduly disrupt sealing of the outer and inner flow streams, particularly since the inner flow stream through the booster compressor must pass through the second fan stage. Thus, in light of the foregoing, it would be desirable for a counterrotatable fan section and counterrotatable booster compressor be developed which simplifies rotation of the second fan stage and the corresponding row of booster compressor blades. It would also be desirable for the disk retaining the second fan stage blades to be located closer to a central axis of the engine to better maintain tip clearances.
BRIEF SUMMARY OF THE INVENTION
In a first exemplary embodiment of the invention, a fan blade assembly for a gas turbine engine having a counterrotatable fan section and a counterrotatable booster compressor is disclosed as including a disk connected to a drive shaft, a fan blade row retained within the disk, a first platform member integral with each fan blade at a first location so as to form an inner flowpath for the counterrotatable booster compressor, and a second platform member integral with each fan blade at a second location so as to form an outer flowpath for the counterrotatable booster compressor, wherein a portion of each fan blade extending between the first and second platform members functions as a compressor blade in a compressor blade row of the counterrotatable booster compressor.
In a second exemplary embodiment of the invention, a counterrotatable booster compressor assembly for a gas turbine engine having a counterrotatable fan section with a first fan blade row connected to a first drive shaft and a second fan blade row axially spaced from the first fan blade row and connected to a second drive shaft is disclosed. The counterrotatable booster compressor assembly includes a first compressor blade row connected to the first drive shaft and a second compressor blade row interdigitated with the first compressor blade row and connected to the second drive shaft, wherein a portion of each fan blade of the second fan blade row extends through a flowpath of the counterrotatable booster compressor so as to function as a compressor blade in the second compressor blade row.
In a third exemplary embodiment of the invention, a gas turbine engine is disclosed as including a high pressure rotor including a high pressure turbine, a low pressure turbine located aft of the high pressure rotor having counterrotating low pressure inner and outer rotors effective for rotating first and second drive shafts, a counterrotatable fan section completely forward of the high pressure rotor including a first fan blade row connected to the first drive shaft and a second fan blade row axially spaced from the first fan blade row and connected to the second drive shaft, and a counterrotatable booster compressor including a first compressor blade row connected to the first drive shaft and a second compressor blade row interdigitated with the first compressor blade row and connected to the second drive shaft, whereby each low pressure turbine rotor respectively drives both a fan blade row and a compressor blade row, wherein a portion of each fan blade of the second fan blade row extends through a flowpath of the counterrotatable booster so as to function as a compressor blade in the second compressor blade row of the counterrotatable booster compressor.
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Moniz Thomas Ory
Orlando Robert Joseph
Andes William Scott
Davidson James P.
General Electric Company
Kim Ted
LandOfFree
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