Patent ID: 12253031

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

FIG.1schematically illustrates an embodiment of an aircraft100. The aircraft100includes an airframe102and one or more gas turbine engines10mounted on the airframe102to provide propulsion and/or electrical power generation for the aircraft100.

An exemplary embodiment of a gas turbine engine10for the aircraft100is illustrated inFIG.2. The gas turbine engine10is disclosed herein as a two-spool turbofan that generally incorporates a fan section12, a compressor section14, a combustor section16and a turbine section18. Alternative engines might include other systems or features. The fan section12drives air along a bypass flow path B in a bypass duct, while the compressor section14drives air along a core flow path C for compression and communication into the combustor section16then expansion through the turbine section18. Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures.

The exemplary engine10generally includes a low speed spool20and a high speed spool22mounted for rotation about an engine central longitudinal axis A relative to an engine static structure26.

The low speed spool20generally includes an inner shaft30that interconnects a fan32, and a low pressure turbine36. The high speed spool22includes an outer shaft40that interconnects an impeller42and high pressure turbine44. A combustor90is arranged in exemplary gas turbine10between the impeller42and the high pressure turbine44. The inner shaft30and the outer shaft40are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes.

The core airflow is compressed by the impeller42, mixed and burned with fuel in the combustor90, then expanded over the high pressure turbine44and low pressure turbine36. The turbines36,44rotationally drive the respective low speed spool20and high speed spool22in response to the expansion. It will be appreciated that each of the positions of the fan section12, compressor section14, combustor section16, and turbine section18, may be varied. While the structure described herein is a two-spool gas turbine engine10, one skilled in the art will readily appreciate that the present disclosure may be similarly applied to a single spool or three or more spool gas turbine engine10. The core flow path C is separated from the bypass flowpath B by a core casing46that encloses the compressor section14, the combustor section16and the turbine section18. The compressor section14includes two or more compressor stages, with each compressor stage including at least a compressor rotor48. In some embodiments, one or more of the compressor rotors48is an impeller.

A bleed-off valve (BOV)50is disposed in the core casing46. The BOV50is disposed at a bleed opening52that extends through an outer casing wall54of the core casing46so that when the BOV is moved into an opened position, at least a portion of airflow from the core flowpath C is vented from the core flowpath C and into the bypass flowpath B via the bleed opening52.

An embodiment of a BOV50is illustrated inFIG.3. The BOV50includes a slider56that is disposed at an inner casing wall58of the core casing46, which is opposite the outer casing wall54. The slider56is mounted on a track60and is configured to move circumferentially in the track60, relative to the engine central longitudinal axis A. When the BOV50is in a closed position, the slider56covers the bleed opening52, while when the BOV50is in an open position, the slider56is moved circumferentially such that the bleed opening52is at least partially uncovered thereby allowing a bleed airflow64to exit the core flowpath C through the bleed opening52and enter the bypass flowpath B.

Referring now toFIG.4, in some embodiments the track60is formed on the inner casing wall58. The track60may include a first track element66, which is substantially L-shaped and is configured to receive a first axial side68of the slider56and an opposing L-shaped second track element70configured to receive a second axial side72of the slider56. Additionally, the BOV50is configured to be self-scaling. The fluid pressure of the core flowpath C is greater than the fluid pressure of the bypass flowpath B during operation of the gas turbine engine10. As a result of this differential in pressure during operation of the gas turbine engine10, when the slider56is in the closed position, the slider56is urged radially outwardly in the track60and is pushed against the inner casing wall58. This acts to seal the bleed opening50preventing leakage therethrough.

While in the embodiment ofFIG.4, the track60is formed directly on the inner casing wall58, in other embodiments such as inFIGS.5-7, the track60may have other configurations. In the embodiment ofFIG.5, the L-shaped track elements66and70are not formed directly on the inner casing wall58, but are formed separately and installed to the inner casing wall58via one or more fasteners74, such as bolts, screws, rivets, and/or adhesives. In this embodiment, the track elements66,70may include an additional fastening arm76which is located against the inner casing wall58, and through which the fasteners74extend. In another embodiment, illustrated inFIG.6, casing ribs78extend radially inwardly from the casing inner wall54, and are in some embodiments formed integral to the inner casing wall58. The track elements66and70are each secured to a casing rib78by fasteners74extending through the track elements66and70and at least partially through the casing rib78. In another embodiment, shown inFIG.7, the track elements66,70are C-shaped such that the sealing surface of the slider56is not the inner casing wall58, but is a sealing arm80of the track elements66,70. The track elements66,70further may include fastening arms76through which the fasteners74extend into the core casing46to secure the track elements66,70thereto. In some embodiments, the track elements66,70may be formed from a low-friction composite material to reduce friction during operation of the slider56and or to improve sealing performance of the slider56to the sealing arm80. The track elements66,70may be formed from, for example, milling, 3D printing or other additive manufacturing processes, or electrical discharge machining (EDM). Further, coatings may be utilized on the track elements66,70and/or on the slider56to reduce friction or improve sealing performance. Additionally, in some embodiments, the slider56may be manufactured to be somewhat flexible to improve sealing performance. In one embodiment, the slider is formed from stainless steel sheet metal. One skilled in the art will readily appreciate that the embodiments shown inFIGS.3-7are merely exemplary and that other configuration of track60may be utilized.

Referring now toFIG.8, in some embodiments the slider56may be configured to extend only partially around a circumference of the core casing46, having an included angle of about 45 degrees or less between circumferential ends of the slider56, such as shown inFIG.8. In such embodiments, there may be only one bleed opening52, with the slider56operated to control bleed airflow64through the bleed opening52. In other embodiments, such as shown inFIG.9, the slider56may extend around a greater portion of the circumference of the core casing46, having an included angle between circumferential ends of the slider56of 270 degrees or more. In such embodiments, the core casing46may have multiple bleed openings52arrayed circumferentially about the core case46, all axially aligned with the slider56. The slider56has multiple slider openings82, each slider opening82corresponding to a bleed opening52. With this configuration, circumferential movement of the slider56controls bleed airflow64through the plurality of bleed openings52. Depending on desired bleed airflow performance, the bleed openings52may all be identical in shape and size, or may vary in shape and/or cross-sectional area depending on circumferential position of the bleed opening52. Similarly, in some embodiments the slider openings82are identical in size and/or shape, while in other embodiments the shape and/or cross-sectional area of the slider openings82varies depending on circumferential location of the slider opening82.

Referring now toFIG.10, in some embodiments, two or more BOV50arrangements may be utilized with a first BOV50aat a first axial location and a second BOV50bat a second axial location. While in some embodiments the first bleed openings52aof the first BOV50aare circumferentially aligned with the second bleed openings52bof the second BOV50b, in other embodiments as illustrated inFIG.10the first bleed openings52amay be circumferentially offset from the second bleed openings52b. In some embodiments, two or more sliders56are utilized with a first slider56aoperating in the first BOV50aand a second slider56boperating in the second BOV50b, with the first slider56aand the second slider56bbeing independently operable. In other embodiments, the two BOVs50aand50bare operated via a common slider56, with second bleed openings52baxially offset from the first bleed openings52a.

Referring again toFIG.9, to control and drive movement and position of the slider56thus controlling the bleed airflow64, the slider56is operable connected to an actuator84, which is configured to drive the slider56circumferentially along the track60. In some embodiments the actuator84is connected to the slider56via a linkage arm86at or near a circumferential end of the slider56. The operation of the actuator84is controlled by an engine controller88, which in some embodiments is a full authority digital engine control (FADEC). One skilled in the art will readily appreciate that this configuration is merely exemplary and that other configurations may be utilized. In the embodiments ofFIG.10, the first slider56aand the second slider56bmay be operated by a common actuator84connected to each of the sliders56aand56b, or alternatively may be operated by separate, independent actuators84.

The BOC50disclosed herein includes relatively few moving parts, is self-sealing, and is a cost effective solution to improve bleed performance of the gas turbine engine10.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of +8% or 5%, or 2% of a given value.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.