General Electric Company

Samuel H Davison

Ambrose A Hauser

John J Ciokajlo

William F McGreehan

Kevin H Kast

Aidan William Clark

A rotatable turbine frame includes annular outer and inner bands having a plurality of circumferentially spaced apart struts extending therebetween. An annular drive shaft is fixedly joined to the inner band for transmitting output torque therefrom, and the struts are backwardly radially inclined relative to the direction of rotation of the frame so that gas flow between the struts tends to straighten the inclined struts to effect a compressive load component therein.

Rotatable turbine frame

A gas turbine engine rotor support system includes outer and inner rotors having respective outer and inner blades interdigitated in respective blade row stages. A stationary rear frame includes a rear support shaft. A rotatable aft frame is disposed forwardly of the rear frame includes an aft support shaft. And, a rotatable forward frame is disposed forwardly of the aft frame and includes a forward support shaft. The forward and aft frames support the outer and inner rotors, and a first bearing is disposed between the aft shaft and the rear shaft for supporting the aft shaft; a second bearing is disposed between the forward shaft and the aft shaft for supporting the forward shaft; and a third bearing is disposed between a core shaft of a core turbine and the forward shaft for supporting the core shaft thereon.

Gas turbine engine rotor support system

A lubrication system for a gas turbine engine includes first and second coaxially rotor shafts having at least one differential bearing disposed in outer and inner seats thereof. An annular first scoop extends axially from a first portion of the first shaft, and an annular second scoop extends axially from the inner seat of the second shaft. A plurality of first holes extend axially through the first shaft and radially below the first scoop, and a plurality of second holes extend axially through the inner seat of the second shaft and below the second scoop. An annular first shell extends axially between the second scoop and the first shaft from above the first holes. And, oil is injected under the first scoop for flow by centrifugal force from rotation of the first shaft through the first holes and along the first shell into the second scoop for flow through the second holes to lubricate the bearing.

Gas turbine engine lubrication system

An aircraft gas turbine engine is provided with a compressed air supply system generally used for meeting customer or aircraft bleed air requirements. The compressed air supply system comprises an auxiliary compressor, a means for mechanically driving the system from a rotor of the gas turbine rotor, and a cycle varying means, such as a variable speed drive, for operating the auxiliary compressor cycle independently of the aircraft gas turbine engine compressor cycle. The preferred embodiment provides a means for bleeding boundary layer air off the nacelle or another part of the aircraft outer skin and using it as a source of air for the auxiliary compressor. One embodiment includes an air turbine on a common shaft with the auxiliary compressor and a means to direct an unused portion of the airflow form the auxiliary compressor to the air turbine to help power the auxiliary compressor and another embodiment includes a means to direct compressed startling air to the air turbine for on ground and in flight starting of the gas turbine engine through the variable speed drive and a mechanical linkage to the high rotor of the gas turbine engine.

Aircraft engine starter integrated boundary bleed system

The invention relates to a control system which controls the diameter of a turbine shroud which surrounds a turbine in a gas turbine aircraft engine. The invention seeks to minimize the clearance between the turbine rotor and the shroud. Air is bled from the compressor in the engine and ducted to the shroud in order to heat or cool the shroud in order to, respectively, either expand or shrink the shroud to a proper diameter. The air temperature which is required is computed based on compressor speed and other engine parameters, but not upon directly measured rotor temperature, despite the fact that rotor temperature has a significant influence upon rotor diameter, and thus upon shroud diameter needed. Air at two different temperatures is bled from two different compressor stages in the engine and mixed together in a ratio which is determined according to flight conditions, in order to provide air of the required temperature for the shroud, and then ducted to the shroud in order to modify shroud size. Further, during accelerations and decelerations of the engine, a different air temperature is provided, as compared with that provided during steady state operation. In the event that the system just described should fail, back-up systems control shroud diameter. There exist two back-up systems, one for use during steady state, and the other for use during accelerations and decelerations.

Active clearance control

A system for controlling rotor blade tip clearances in a gas turbine engine supplies both heating air and cooling air to the rotor bore. The heating air flow is controlled by a valve and the cooling air flow is not controlled.

Clearance control system

Cooling airflow to the shroud support apparatus is varied in response to both rotor speed and elapsed time above a predetermined level by the selective use and mixture of two air sources at different temperatures. For steady-state operation, each of four different operating modes has its prescribed cooling air delivery mode such that, generally, as the engine speed and cycle temperatures increase, so does that of the cooling air. For transient operation, a timer is employed to sequence the desired cooling air delivery modes in such a manner as to maintain optimum rotor-to-shroud clearances during the transient period.

Rotor/shroud clearance control system

An inherent eccentricity between the rotor bearings and the stator shroud is reduced by intentionally fabricating into each of a pair of frame annuluses, outer and inner surfaces which are relatively eccentric, and then rotating the annuluses with respect to each other until the inherent eccentricity is substantially offset. A method is provided to determine the optimum relative rotational positions as a function of the measured inherent eccentricity, and restrictions in the number of possible rotational positions are considered.

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Milford, OH, United States of America

Samuel H Davison