VARIABLE AREA VANE HAVING MINIMIZED END GAP LOSSES

Airfoils are provided having a body having a leading edge, a trailing edge, a first end surface, and a second end surface opposite the first end surface, wherein (i) a first true chord length is a line extending from a first leading edge point to a first trailing edge point and (ii) a second true chord length is a line extending from a second leading edge point to a second trailing edge point, a first button located on the first end surface of the airfoil body, the first button having a first diameter and a first attachment device extending from the first button to enable rotation of the airfoil body about an attachment device axis. The first diameter is at least 15% of the first true chord length or the attachment device axis is located 10% of the first true chord length from the leading edge point.

BACKGROUND

The subject matter disclosed herein generally relates to gas turbine engines and, more particularly, to variable area vanes having minimized end gap losses for gas turbine engines.

In variable area turbines, throat area variation is achieved by incorporating rotating vanes. The vanes are rotated with an attachment device and button assembly (e.g., spindle and button assembly). This attachment device-button feature is designed to enable rotation of the vane to open and close the vane during operation. The attachment device is configured to define an attachment device axis about which the vane can rotate. The variable area vanes have end gaps between the vane and end-walls of a flow path through a gas turbine engine. The end gaps enable flow to leak from a pressure side to a suction side of the vane and may be a source of losses for variable area turbines.

SUMMARY

According to one embodiment, an airfoil for a gas turbine engine is provided. The airfoil includes an airfoil body having a leading edge, a trailing edge, a first end surface extending from the leading edge to the trailing edge, and a second end surface extending from the leading edge to the trailing edge and opposite the first end surface, wherein (i) a first true chord length is defined as a linear distance along the first end surface from a first leading edge point located at an intersection of the first end surface and the leading edge to a first trailing edge point located at an intersection of the first end surface and the trailing edge and (ii) a second true chord length is defined as a linear distance from a second leading edge point located at an intersection of the second end surface and the leading edge to a second trailing edge point located at an intersection of the second end surface and the trailing edge, a first button located on the first end surface of the airfoil body, the first button having a first diameter and configured to fit within a first recess of a flow path of a gas turbine engine, and a first attachment device extending from the first button and configured to attach to the gas turbine engine and enable rotation of the airfoil body about an attachment device axis that extends through the first attachment device, the first button, and the airfoil body, wherein the airfoil body is rotatable about the attachment device axis. The length of the first diameter is at least 15% of the first true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include a second button located on the second end surface of the airfoil body, the second button having a second diameter and configured to fit within a second recess of the flow path of the gas turbine engine and a second attachment device extending from the second button. The attachment device axis extends through the second button and the second attachment device.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the second diameter is at least 15% of the second true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the attachment device axis has a location on the second end surface of the airfoil body a distance along the second true chord length from the leading edge point that is at least 10% of the second true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the first diameter is greater than the second diameter.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the attachment device axis is located on the first end surface of the airfoil body a distance along the first true chord length from the leading edge point that is at least 10% of the first true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the airfoil body, the first button, and the first attachment device are an integral component.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the first true chord length is equal to the second true chord length.

According to another embodiment, an airfoil for a gas turbine engine is provided. The airfoil includes an airfoil body having a leading edge, a trailing edge, a first end surface extending from the leading edge to the trailing edge, and a second end surface extending from the leading edge to the trailing edge and opposite the first end surface, wherein (i) a first true chord length is defined as a linear distance along the first end surface from a first leading edge point located at an intersection of the first end surface and the leading edge to a first trailing edge point located at an intersection of the first end surface and the trailing edge and (ii) a second true chord length is defined as a linear distance from a second leading edge point located at an intersection of the second end surface and the leading edge to a second trailing edge point located at an intersection of the second end surface and the trailing edge, a first button located on the first end surface of the airfoil body, the first button having a first diameter and configured to fit within a first recess of a flow path of a gas turbine engine, and a first attachment device extending from the first button and configured to attach to the gas turbine engine and enable rotation of the airfoil body about an attachment device axis that extends through the first attachment device, the first button, and the airfoil body, wherein the airfoil body is rotatable about the attachment device axis. The attachment device axis is located on the first end surface of the airfoil body a distance along the first true chord length from the leading edge point that is at least 10% of the first true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include a second button located on the second end surface of the airfoil body, the second button having a second diameter and configured to fit within a second recess of the flow path of the gas turbine engine and a second attachment device extending from the second button. The attachment device axis extends through the second button and the second attachment device.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the attachment device axis has a location on the second end surface of the airfoil body a distance along the second true chord length from the second leading edge point that is at least 10% of the second true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the airfoil body, the first button, and the first attachment device are an integral component.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the first diameter is greater than the second diameter.

In addition to one or more of the features described above, or as an alternative, further embodiments of the airfoil may include that the first true chord length is equal to the second true chord length.

According to another embodiment, a gas turbine engine is provided. The gas turbine engine includes a variable area turbine having a variable area vane. The vane has an airfoil body having a leading edge, a trailing edge, a first end surface extending from the leading edge to the trailing edge, and a second end surface extending from the leading edge to the trailing edge and opposite the first end surface, wherein (i) a first true chord length is defined as a linear distance along the first end surface from a first leading edge point located at an intersection of the first end surface and the leading edge to a first trailing edge point located at an intersection of the first end surface and the trailing edge and (ii) a second true chord length is defined as a linear distance from a second leading edge point located at an intersection of the second end surface and the leading edge to a second trailing edge point located at an intersection of the second end surface and the trailing edge, a first button located on the first end surface of the airfoil body, the first button having a first diameter and configured to fit within a first recess of a flow path of a gas turbine engine, and a first attachment device extending from the first button and configured to attach to the gas turbine engine and enable rotation of the airfoil body about an attachment device axis that extends through the first attachment device, the first button, and the airfoil body, wherein the airfoil body is rotatable about the attachment device axis. The length of the first diameter is at least 15% of the first true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include a second button located on the second end surface of the airfoil body, the second button having a second diameter and configured to fit within a second recess of the flow path of the gas turbine engine and a second attachment device extending from the second button. The attachment device axis extends through the second button and the second attachment device.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include that the second diameter is at least 15% of the second true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include that the attachment device axis has a location on the second end surface of the airfoil body a distance along the second true chord length from the leading edge point that is at least 10% of the second true chord length.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include that the first diameter is greater than the second diameter.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include that the attachment device axis is located on the first end surface of the airfoil body a distance along the first true chord length from the leading edge point that is at least 10% of the first true chord length.

According to another embodiment, a gas turbine engine is provided. The gas turbine engine includes a variable area turbine having a variable area vane. The vane includes an airfoil body having a leading edge, a trailing edge, a first end surface extending from the leading edge to the trailing edge, and a second end surface extending from the leading edge to the trailing edge and opposite the first end surface, wherein (i) a first true chord length is defined as a linear distance along the first end surface from a first leading edge point located at an intersection of the first end surface and the leading edge to a first trailing edge point located at an intersection of the first end surface and the trailing edge and (ii) a second true chord length is defined as a linear distance from a second leading edge point located at an intersection of the second end surface and the leading edge to a second trailing edge point located at an intersection of the second end surface and the trailing edge, a first button located on the first end surface of the airfoil body, the first button having a first diameter and configured to fit within a first recess of a flow path of a gas turbine engine, and a first attachment device extending from the first button and configured to attach to the gas turbine engine and enable rotation of the airfoil body about an attachment device axis that extends through the first attachment device, the first button, and the airfoil body, wherein the airfoil body is rotatable about the attachment device axis. The attachment device axis is located on the first end surface of the airfoil body a distance along the first true chord length from the leading edge point that is at least 10% of the first true chord length.

Technical effects of embodiments of the present disclosure include variable area vanes with decreased end gap losses. Further technical effects include variable area vanes having increased diameter buttons that are configured to minimize end gap losses. Further technical effects include variable area vanes having spindle axis locations configured to minimize end gap losses.

DETAILED DESCRIPTION

As shown and described herein, various features of the disclosure will be presented. Various embodiments may have the same or similar features and thus the same or similar features may be labeled with the same reference numeral, but preceded by a different first number indicating the Figure Number to which the feature is shown. Thus, for example, element “a” that is shown in FIG. X may be labeled “Xa” and a similar feature in FIG. Z may be labeled “Za.” Although similar reference numbers may be used in a generic sense, various embodiments will be described and various features may include changes, alterations, modifications, etc. as will be appreciated by those of skill in the art, whether explicitly described or otherwise would be appreciated by those of skill in the art.

FIG. 1Aillustrates a general schematic view of a gas turbine engine10such as a gas turbine engine for propulsion. While a particular turbofan engine is schematically illustrated in the disclosed non-limiting embodiment, it should be understood that the disclosure is applicable to other gas turbine engine configurations, including, for example, gas turbines for power generation, turbojet engines, low bypass turbofan engines, turboshaft engines, etc.

The engine10includes a core engine section that houses a low spool14and high spool24. The low spool14includes a low pressure compressor16and a low pressure turbine18. The core engine section drives a fan section20connected to the low spool14either directly or through a gear train. The high spool24includes a high pressure compressor26and high pressure turbine28. A combustor section30is arranged between the high pressure compressor26and high pressure turbine28. The low spool14and high spool24rotate about an axis of rotation A of the engine10.

The gas turbine engine10functions in a conventional manner, as known in the art. Air drawn through an intake32is accelerated by the fan section20and divided along a bypass flow path and a core flow path. The bypass flow path bypasses the core engine section and is exhausted to atmosphere to provide propulsive thrust. The core flow path compresses the air in the low pressure compressor16and the high pressure compressor26and is mixed with fuel to be combusted in the combustor section30. The resultant hot combustion products then expand through, and thereby drive the low pressure turbine18and the high pressure turbine28before being exhausted to atmosphere through an exhaust nozzle34to provide additional propulsive thrust. The low pressure turbine18and the high pressure turbine28, in response to the expansion, drive the respective low pressure compressor16and high pressure compressor26and fan section20.

FIG. 1Bis a schematic view of a turbine section that may employ various embodiments disclosed herein. Turbine100includes a plurality of airfoils, including, for example, one or more blades101and vanes102. The airfoils101,102extend from an inner diameter106to an outer diameter108within an air flow path. The blades101and the vanes102can include platforms110located proximal to the inner diameter106thereof. A root or attachment118of the airfoils101can be connected to or be part of the platform110. The platform110, as shown, is mounted to an attachment118of a turbine disk112.

Turning now toFIG. 2, a schematic illustration of an airfoil in accordance with a non-limiting embodiment of the present disclosure is shown. InFIG. 2, a vane202is located within a portion of a turbine200. The vane202is a variable area vane that is configured to rotate within a flow path C to thus control a variable flow through the flow path C. As shown, a blade201is located downstream from the vane202. The flow path C is defined, in part, between an inner diameter end wall220and an outer diameter end wall222. The end walls220,222can be formed from part of the turbine200and may include, in some embodiments, vane rings that are configured to support the vane202at an inner diameter and an outer diameter of the vane202.

In variable area turbines, such as turbine200, a throat area variation is achieved by incorporating rotating vanes similar to vane202. The vane202is rotated with an attachment device-button assembly that extends from an airfoil body224. For example, in some embodiments, the attachment device-button assembly may be configured as a spindle-button assembly. The attachment device-button assembly is designed for inner diameter206and outer diameter208rotation about an attachment device axis X, as shown inFIG. 2. The attachment device-button assembly, in the embodiment shown inFIG. 2, includes an inner portion and an outer portion. For example, as shown inFIG. 2, the vane202includes a first button226and a first attachment device228located at an outer diameter208of the vane202. Similarly, the vane202includes second button230and a second attachment device232located at an inner diameter206of the vane202. As shown, the airfoil body224is located within the flow path C and the portions of the attachment device-button assembly (e.g., buttons226,230; attachment devices228,232) extend into the end walls220,222of the turbine200.

As shown inFIG. 2, the vane202has a first true chord length L1at the outer diameter208of the vane202. As used herein, the true chord length is a linear length extending from a leading edge point to a trailing edge point of the airfoil at a specific span-wise location. The leading edge point and the trailing edge point of a single true chord length at a position in the span-wise direction of an airfoil defines a constant or fixed length. For example, the leading edge point and the trailing edge point can be points at a span-wise position along the span of the airfoil where a camber line exits the leading edge and trailing edge, respectively. Stated another way, the leading edge point and the trailing edge point are points at a span-wise position along the leading edge and the trailing edge of the airfoil where the radius of curvature of the edges is the smallest. Those of skill in the art will appreciate that, inFIG. 2, the span-wise direction is a length/direction of the vane202extending from the inner diameter206to the outer diameter208.

In the configuration shown inFIG. 2, a first leading edge point P1Lis located at a junction or intersection of a leading edge234of the airfoil202and a first end surface S1of the airfoil202(e.g., at the outer diameter208). For example, seeFIG. 3B, providing a top-down, plan illustration of an airfoil. Similarly, a first trailing edge point P1Tis located at a junction or intersection of a trailing edge236of the airfoil202and the first end surface S1(e.g., at the outer diameter208). Further, a second leading edge point P2Lis located at a junction or intersection of a leading edge234of the airfoil202and a second end surface S2of the airfoil202(e.g., at the inner diameter206), as shown, and a second trailing edge point P2Tis located at a junction or intersection of a trailing edge236of the airfoil202and the second end surface of S2(e.g., at the inner diameter206).

At the inner diameter208of the vane202, as shown, the vane202has a second true chord length L2. The first and second true chord lengths L1, L2are the linear length of the vane202from (i) the leading edge point P1Lto the trailing edge point P1Tand (ii) the leading edge point P2Lto the trailing edge point P2T, respectively. That is, the first true chord length L1and the second true chord length L2are straight line lengths from the respective leading edge points to the respective trailing edge points.

As shown inFIG. 2, the first true chord length L1is greater than the second true chord length L2. Accordingly, the true chord length of the vane from the respective leading edge points to the respective trailing edge points can be different in length at different span-wise positions along the airfoil. Because of the different true chord lengths of the vane202, as shown inFIG. 2, an attachment device axis position P, of the attachment device axis X is different relative to or with respect to the leading edge234along the span-wise direction. Those of skill in the art will appreciate that, on a span-wise or section basis, the true chord length is always fixed.

In the embodiment ofFIG. 2, the attachment device axis position P, increases in dimension (e.g., length, distance, dimension) as the position P, extends from the inner diameter206to the outer diameter208of the vane202. Although shown with a specific configuration inFIG. 2, those of skill in the art will appreciate that other vane configurations are possible without departing from the scope of the present disclosure. For example, in some embodiments, the first true chord length can be less than the second true chord length, and in other embodiments the first true chord length can be equal to the second true chord length along the span of the airfoil (e.g., a constant true chord length along the span of the airfoil).

Further, as shown, the first button226of the vane202has a first diameter D1and the second button230has a second diameter D2. The first diameter D1, in the embodiment ofFIG. 2, is greater than the second diameter D2. The buttons226,230are thus round buttons with a uniform diameter that are configured to enable the vane202to rotate within the flow path C about the attachment device axis X. The buttons226,230are configured to fit within a recess or other cavity in the end walls220,222of the flow path C. Similarly, the attachment devices228,232are round (although other geometries and/or shapes can be used) and are configured and engageable to rotate the vane202.

Also shown inFIG. 2, the variable area vane202defines end gaps between the vane202and the end walls220,222(both inner and outer diameter end walls). As shown, a first end gap G1is formed between the vane202at the outer diameter208and the outer end wall222, and a second end gap G2is formed between the vane202at the inner diameter206and the inner end wall220. The height of the end gaps G1, G2is defined as a distance between an exposed or end surface S1, S2of the vane202and an end wall (e.g.,220,222) of the flow path C, and a length of the end gaps G1, G2is defined as a distance between a leading edge point P1L, P2L, or a trailing edge point P1T, P2Tand an edge of a respective button226,223.

The end gaps G1, G2allow flow to leak from a pressure side to a suction side of the vane202and are thus a source of additional losses for variable area turbines. As shown inFIG. 2, the end gaps G1, G2, are formed between the buttons226,230and the trailing edge236of the vane202. In some embodiments, the buttons226,230can be integrally formed with and are part of the vane202which can result in no end gap existing at the location of the buttons226,230. By selecting a size and/or position of the buttons in the attachment device-button assemblies, the amount of gap can be minimized.

Embodiments of the present disclosure are directed to attachment device-buttons assembly features that are configured to reduce end gap losses. For example, the buttons226,230are sized and configured to reduce the end gaps G1, G2. As noted, the end gaps G1, G2for a rotating vane in a variable area turbine can be the source of aerodynamic loss. The end gaps G1, G2can be reduced by increasing a button diameter (e.g., diameters D1, D2) and/or by moving the attachment device axis X as aft as possible from the leading edge234of the vane202. The combination (or individual design features) of attachment device axis location and increased button diameter can close the gap near the trailing edge236of the airfoil202(e.g., where the leakage losses can be high).

Although show and described with respect to a specific or particular airfoil shape, geometry, and configuration, those of skill in the art will appreciate that embodiments provided herein can be employed with airfoil having different configurations. For example, curved airfoils, variable airfoils, etc., can all be configured with embodiments of the present disclosure.

Turning now toFIGS. 3A-3B, schematic illustrations of a vane302in accordance with a non-limiting embodiment of the present disclosure are shown.FIG. 3Ashows a side elevation view of the vane302andFIG. 3Bshows a top-down view of the vane302along the line B-B ofFIG. 3A. The vane302is similar to that shown and described with respect toFIG. 2. Accordingly, the vane302is a variable area vane for a variable area turbine. The vane302includes an airfoil body324that extends from a leading edge334to a trailing edge336, with a first end surface S1and a second end surface S2. As shown, the airfoil body324can be curved to form a desired airfoil shape. Although a particular airfoil geometry is shown, those of skill in the art will appreciate that other geometries, shapes, curvatures, dimensions, etc., can employ embodiments of the present disclosure, and the illustrations are not to be limiting.

The vane302includes a first button326and a respective first attachment device328, as shown at an outer diameter308of the vane302. The vane302also includes a second button330and a respective second attachment device332, as shown at an inner diameter306of the vane302. An attachment device axis X extends through the vane302from the first attachment device328to the second attachment device332and defines an axis of rotation for the vane302.

Similar to the configuration ofFIG. 2, the first button326has a first diameter D1and the vane302has a first true chord length L1, as show at the outer diameter308. The second button330has a second diameter D2and the vane302has an second true chord length L2, as shown at the inner diameter306. As described above, the true chord lengths L1, L2are linear lengths that extend from leading edge points P1L, P2Lon the leading edge334to respective trailing edge points P1T, P2Ton the trailing edge336of the airfoil302.

Also shown in the embodiment ofFIG. 3A, an attachment device axis position P, of the attachment device axis X is variable extending from the inner diameter306to the outer diameter308. Although shown with increasing attachment device axis position P, from the inner diameter306to the outer diameter308, those of skill in the art will appreciate that the attachment device axis position P, can be increasing from the outer diameter308to the inner diameter306, can be constant from the inner diameter306to the outer diameter308, or some other geometric configuration (e.g., increasing distance toward the inner and outer diameters from a point between). The attachment device axis position P, is a distance of the attachment device axis X from the leading edge along the true chord length from the leading edge. For example, as shown inFIG. 3B, the attachment device axis position Px1defines a distance of the attachment device axis X at the first button326. This position or distance is defined as a length along the first true chord length L1to a point where a normal or 90° line is drawn from the attachment device axis X through the first true chord length L1(e.g., as shown inFIG. 3B).

In accordance with some embodiments, the relationship between the diameters D1, D2of the buttons326,330and the true chord lengths L1, L2of the vane302can impact the leakage losses at the end gaps (e.g., end gaps G1, G2, shown inFIG. 2). For example, in accordance with some non-limiting embodiments, the diameters D1, D2of the buttons326,330can be 15% or greater in dimension of the respective true chord length Li, Loof the vane302. That is, the first diameter D1of the first button326is a length or dimension that is 15% or greater of the first true chord length L1. Similarly, the second diameter D2of the second330is a length or dimension that is 15% or greater of the length or dimension of the second true chord length L2. By configuring the buttons326,330with a diameter that is 15% or greater than a respective true chord length L1, L2, the end gaps can be reduced, and thus end gap losses can be minimized. Stated another way, by having button diameters with such dimensions, a surface area of the first end surface S1of the airfoil302can be minimized or reduced and thus limiting the amount of end gap losses (e.g., as shown inFIG. 3B)

Another factor that can impact the amount of end gap losses can be the location or distance of the attachment device axis position P, from the leading edge334. The location of the attachment device axis position P, of the attachment device axis X defines the positions of the buttons326,330, because the buttons326,330are located between the attachment devices328,332along the attachment device axis X. As shown, the first button326can have a first button position Px1relative to the first leading edge point P1Land the second button330can have a second button position Px2relative to the second leading edge point P2L. In accordance with embodiment of the present disclosure, the button positions Px1, Px2can be 10% or greater than the respective true chord length L1, L2.

Advantageously, embodiments provided herein enable covering of an end gap of a variable area vane of a gas turbine engine to decrease losses due to end gaps of the vanes. For example, various embodiments provide an increased diameter button that reduces the amount of exposed vane surface area of end surfaces to form an end gap, thus reducing the end gap losses. Further, embodiments provided herein include a variable area vane having an attachment device axis location that is aftward (as compared to prior vane configurations), which can reduce the amount of end gap that is formed between the vane and an end wall of a flow path in a gas turbine engine.

For example, although an aero or aircraft engine application is shown and described above, those of skill in the art will appreciate that turbine disk configurations as described herein may be applied to industrial applications and/or industrial gas turbine engines, land based or otherwise.