US20090016871A1

US20090016871A1 - Systems and Methods Involving Variable Vanes

Info

Publication number: US20090016871A1
Application number: US11/775,523
Authority: US
Inventors: Michael G. McCaffrey
Original assignee: United Technologies Corp
Current assignee: RTX Corp
Priority date: 2007-07-10
Filing date: 2007-07-10
Publication date: 2009-01-15
Also published as: EP2014871B1; EP2014871A3; EP2014871A2

Abstract

Systems and methods involving vanes are provided. In this regard, a representative method for modifying the throat area between vanes of a gas turbine engine includes: directing a gas flow path of the gas turbine engine between a first vane and a second vane, wherein each of the first vane and the second vane has an outer surface and an interior; and emitting pressurized air from outlet ports communicating between the outer surface and the interior of the first vane, wherein the emitted pressurized air from the first vane modifies a throat area between the first vane and the second vane.

Description

BACKGROUND

1. Technical Field
The invention relates to gas turbine engines.
2. Description of the Related Art
Gas turbine engines use compressors to compress gas for combustion. In particular, a compressor typically uses alternating sets of rotating blades and stationary vanes to compress gas. Gas flowing through such a compressor is forced between the sets and between adjacent blades and vanes of a given set. Similarly, after combustion, hot expanding gas drives a turbine that has sets of rotating blades and stationary vanes.

SUMMARY

Systems and methods involving vanes are provided. In this regard, an exemplary embodiment of a gas turbine engine defining a gas flow path comprises: a first vane extending into the gas flow path and having: an interior operative to receive pressurized air; an outer surface; and outlet ports communicating between the outer surface and the interior of the first vane, the outlet ports being operative to receive the pressurized air from the interior and emit the pressurized air into the gas flow path such that a throat area defined, at least in part, by the first vane is modified.
An exemplary embodiment of a vane assembly comprises: a first vane having: an outer surface; an interior defining a cavity operative to receive pressurized air; and outlet ports communicating between the outer surface and the cavity, the outlet ports being operative to receive the pressurized air from the cavity and emit the pressurized air through the outer surface a valve assembly operative to regulate the pressurized air emitted by the first vane.
An exemplary embodiment of a method for modifying the throat area between vanes of a gas turbine engine comprises: directing a gas flow path of the gas turbine engine between a first vane and a second vane, wherein each of the first vane and the second vane has an outer surface and an interior; and emitting pressurized air from outlet ports communicating between the outer surface and the interior of the first vane, wherein the emitted pressurized air from the first vane modifies a throat area between the first vane and the second vane.
Other systems, features, and/or advantages will be or may become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, features, and/or advantages be included within this description and protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side cutaway view illustrating an exemplary embodiment of a turbine section of a gas turbine engine.

FIG. 2 is a side cutaway view of an exemplary embodiment of a vane.

FIG. 3 is a top cutaway view of an exemplary embodiment of vanes in a gas flow path.

FIG. 4 is a top cutaway view of another exemplary embodiment of vanes in a gas flow path.

FIG. 5 is a top cutaway view of another exemplary embodiment of vanes in a gas flow path.

DETAILED DESCRIPTION

Systems and methods involving vanes of gas turbine engines are provided. In this regard, several exemplary embodiments will be described. Notably, gas passing through a gas turbine engine enters a turbine that includes rotating blades and stationary vanes. The gas, following the gas flow path, is forced between adjacent vanes. The vanes are often shaped like airfoils and, therefore, have aerodynamic properties similar to airfoils. The flow of gas between adjacent vanes results in a throat area determined by, for example, the shape and relative position of the vanes. Often, the angle of the vanes relative to the gas flow path may be mechanically changed to vary the location and/or size of the throat area and alter the efficiency of the engine. However, it may be desirable, either additionally or alternatively, to alter the location and/or size of the throat area aerodynamically. In some embodiments, the gas turbine engine is configured as a turbofan.
Referring now in detail to the drawings, FIG. 1 is a schematic side view illustrating an exemplary embodiment of a turbine section 100 of a gas turbine engine. In turbine section 100, rotating blades 104 are attached to a disk that is rotated by a shaft 106. Stationary vanes 108 are attached to the casing of the engine between the blades 104. In operation, gas enters the turbine section along gas flow path 102 and drives the blades 104. The gas exits the turbine section 100 along gas flow path 102.
FIG. 2 is a simplified, side cutaway view of vane assembly 200 that includes a vane airfoil 202 and a valve assembly 208. Note that vane airfoil 202 typically is mounted to and spans between an outer diameter vane platform and an inner diameter vane platform, neither of which is depicted in FIG. 2.
In the embodiment of FIG. 2, valve assembly 208 includes a piston 204 and solenoid 220, which is used to actuate the piston. Inlet ports 218 provide gas to the valve assembly so that actuation of the piston pressurizes the received gas.
Vane airfoil 202 includes an interior cavity 214 that receives pressurized air from the inlet ports via the piston, and outlet ports 216 that are used to emit the pressurized air into the gas flow path. In particular, the gas emitted by the outlet ports 216 affects the throat area formed between vane airfoil 202 and an adjacent vane airfoil. This is in contrast to emission of pressurized gas from ports of a vane airfoil for performing film cooling. Notably, the pressure of the pressurized gas emitted from the outlet ports 216 is greater than that used for performing film cooling. As such, the pressurized gas from the outlet ports 216 urges the gas flow path, which flows about the vane airfoil during operation of the gas turbine engine, away from the exterior surface of the vane airfoil to a greater extent than that caused by pressurized gas involved in film cooling. In fact, in those embodiments that additionally include film cooling, the boundary layer formed by the film-cooling air also is urged away from the exterior of the vane airfoil. Typically, the pressure of the gas required to alter the throat is not available from the compressor alone. Thus, piston 204 is used in the embodiment of FIG. 2 to increase the pressure of the gas provided to the outlet ports. In other embodiments, various other mechanisms could be used to increase the gas pressure.
The shape of the vane assembly 200 illustrated in FIG. 2 is merely an illustration of but one possible embodiment. The shape of the vane assembly 200 may vary depending on a variety of factors including, but not limited to, the component to which the vane assembly 200 is attached, the location of the vane assembly 200 in the gas turbine engine, the gas flow path around the vane assembly 200 at particular gas flow velocities, desired design characteristics of the gas turbine engine, and materials used in the fabrication of the gas turbine engine.
In FIG. 2, a controller 212 also is provided. The controller 212 is used to open and close the valve assembly 208. In one mode of operation, the valve assembly 208 is left open such that the outlet ports 216 emit a constant flow of pressurized air. Additionally, or alternatively, the valve assembly 208 may be opened and closed intermittently. In this mode of operation, the pressurized air may be emitted from the outlet ports 216 in pulses. Notably, operation in a pulsed mode allows the pressure of the pressurized air to increase prior to being emitted into a gas flow path. In some of these embodiments, the controller 212 may be set to control the frequency of the pulses of emitted pressurized air. Controlling the frequency of the pulses may be desirable because a change in the throat area based on a frequency of pulses may allow the aerodynamic characteristics of the engine to be adjusted.
Specifically, the frequencies of the pulses may be controlled to modify one or more throat areas in a specific region of an engine to control local pressure ratios and/or local temperatures. The pulse frequencies may also be timed to adjust for resonance in the engine that may result in vane and blade vibrations. These pulses may be used to add a canceling frequency that may effectively cancel engine resonance, for example.
FIG. 3 is a top cutaway view of a pair of vanes in an embodiment of a gas turbine engine. As shown in FIG. 3, gas is forced between the vanes 300 along gas flow path 302, forming a throat area 304. The shape of the adjacent vanes 300, their proximity to each other, and the angle of incidence to the gas flow path 302 are possible factors that can influence the location and size of the throat area 304.
FIG. 4 depicts a top cutaway view of another embodiment of a vane assembly. In this embodiment, vanes 406 and 412 are adjacent vanes. Vane 406 has an interior cavity 404 that is connected to a pressurized air source (not shown). Outlet ports 410 are located on the surface of vane 406 and are in communication with interior cavity 404.
Pressurized air emitted from the outlet ports 410 in vane 406 defines a boundary layer 408 that has an aerodynamic effect on the gas flow path 402. Notably, the boundary layer 408 associated with the pressurized air from the outlet ports modifies the location and/or size of the throat area 416. Also note that the outlet ports of this embodiment are oriented such that the flow from the outlet ports is generally in a direction of the gas flow path. In other embodiments, however, the orientation can be different, such as by providing a perpendicular (see FIG. 5) or counter flow (not shown).
Modifying the throat area of an engine may affect the flow of gasses through the engine. For instance, such modifying can affect the pressure ratio of the compressor and change the relationship between the flow and the pressure ratio. For example, a lower flow rate can increase the pressure ratio.
FIG. 5 depicts a top cutaway view of another embodiment of a vane assembly. In the illustrated embodiment, vane assembly 500 incorporates two adjacent vanes, a first vane 501 and a second vane 503. The first vane 501 and the second vane 503 are spaced from each other to define a gas flow path 502. The first vane 501 includes three chambers—a film-cooling chamber 504, a suction side chamber 505 and a pressure side chamber 507. The film-cooling chamber 504, suction side chamber 505 and the pressure side chamber 507 include ports, such as ports 506, 509 and 511, respectively.
In operation, the film-cooling chamber 504 receives cooling pressurized air that is emitted from the associated ports, e.g., port 506. This air creates a relatively thin boundary layer 530 that is located adjacent to the exterior of the vane 501 to serve as a barrier against the hot gas flowpath 502. The suction side chamber 505 and the pressure side chamber 507 also receive pressurized air, which is at a higher pressure than that provided to chamber 504, that is emitted from associated ports, e.g., ports 509 and 511. The pressurized air emitted from chamber 507 creates a boundary layer 513 along the pressure surface 515 of the first vane 501 that affects the throat area 550. Notably, the boundary layer 513 tends to urge the boundary layer 530 away from the pressure surface 515, thereby causing the boundary layer 530 to dissipate and mix with the gas of the gas flow path 502.
The second vane 503 also includes three chambers—a film-cooling chamber 532, a suction side chamber 510 and a pressure side chamber 512. The film-cooling chamber 532, suction side chamber 510 and the pressure side chamber 512 include ports, such as ports 534, 522 and 514, respectively.
In operation, the film-cooling chamber 532 receives cooling pressurized air that is emitted from the associated ports, e.g., port 534. This air creates a relatively thin boundary layer 536 that is located adjacent to the exterior of the vane 503. The suction side chamber 510 and the pressure side chamber 512 also receive pressurized air, which is at a higher pressure than that provided to chamber 534, that is emitted from associated ports, e.g., ports 522 and 514. The pressurized air emitted from chamber 510 creates a boundary layer 525 along the suction surface 506 of the vane 503 that affects the throat area 550. Notably, the boundary layer 525 tends to urge the boundary layer 536 away from the suction surface 506, thereby causing the boundary layer 536 to dissipate and mix with the gas of the gas flow path 502.
The suction side chambers 505 and 510 and the pressure side chambers 507 and 512 may be separate and unconnected to each other so that the air emitted from each of the chambers may be controlled independently. Alternatively, the suction side chambers 505 and 510 and the pressure side chambers 507 and 512 may be in communication, and therefore, dependently controlled.
It should be emphasized that the above-described embodiments are merely possible examples of implementations. Many variations and modifications may be made to the above-described embodiments. By way of example, although a solenoid is described with respect to the embodiment of FIG. 2, other types of actuation could be used. As another example, a pressurized line could be used to provide gas to a valve assembly. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the accompanying claims.

Claims

1. A gas turbine engine defining a gas flow path, the gas turbine engine comprising:

a first vane extending into the gas flow path and having:

an interior operative to receive pressurized air;

an outer surface; and

outlet ports communicating between the outer surface and the interior of the first vane, the outlet ports being operative to receive the pressurized air from the interior and emit the pressurized air into the gas flow path such that a throat area defined, at least in part, by the first vane is modified.

2. The turbine engine of claim 1, wherein the throat area is modified by moving the throat area upstream.

3. The turbine engine of claim 1, wherein the first vane further comprises film cooling ports operative to receive cooling pressurized air at a pressure lower than that provided to the outlet ports and to emit the cooling pressurized air from the first vane such that the first vane is film cooled.

4. The turbine engine of claim 1, further comprising a valve assembly operative to regulate the pressurized air emitted by the ports.

5. The turbine engine of claim 1, further comprising a second vane, the throat area being defined by the first vane and the second vane.

6. The turbine engine of claim 5, further comprising a valve assembly operative to control the pressurized air emitted by the first vane and the second vane.

7. The turbine engine of claim 6, further comprising a second throat area defined, at least in part, by the second vane, wherein the throat area and the second throat area are modified independently by the valve assembly.

8. The turbine engine of claim 1, wherein the valve assembly is operative to intermittently provide the pressurized air to the ports.

9. The turbine engine of claim 1, wherein the engine is a turbofan.

10. A vane assembly comprising:

a first vane having:

an outer surface;

an interior defining a cavity operative to receive pressurized air; and

outlet ports communicating between the outer surface and the cavity, the outlet ports being operative to receive the pressurized air from the cavity and emit the pressurized air through the outer surface a valve assembly operative to regulate the pressurized air emitted by the first vane.

11. The vane assembly of claim 10, further comprising a control assembly operative to control the valve assembly.

12. The vane assembly of claim 10, further comprising:

a second vane operative to define a throat area between the first vane and the second vane, wherein the pressurized air emitted from the outlet ports of the first vane is operative to modify the throat area between the first vane and the second vane.

13. The vane assembly of claim 10, wherein the first vane further comprises film cooling ports operative to receive cooling pressurized air at a pressure lower than that provided to the outlet ports and to emit the cooling pressurized air from the first vane such that the first vane is film cooled.

14. The vane assembly of claim 10, wherein the valve assembly comprises a piston and a solenoid, the piston and the solenoid being operative to increase the pressure of air provided to the valve assembly.

15. A method for modifying the throat area between vanes of a gas turbine engine comprising:

directing a gas flow path of the gas turbine engine between a first vane and a second vane, wherein each of the first vane and the second vane has an outer surface and an interior; and

emitting pressurized air from outlet ports communicating between the outer surface and the interior of the first vane, wherein the emitted pressurized air from the first vane modifies a throat area between the first vane and the second vane.

16. The method of claim 15, further comprising film cooling the first vane using lower pressure air than the emitted pressurized air used to modify the throat area.

17. The method of claim 15, wherein the step of emitting the pressurized air from outlet ports further comprises emitting the pressurized air in pulses.

18. The method of claim 15, further comprising emitting pressurized air from outlet ports communicating between the outer surface of the second vane and the interior of the second vane such that the emitted pressurized air from the second vane also modifies the throat area between the first vane and the second vane.

19. The method of claim 15, wherein the step of emitting the pressurized air from outlet ports further comprises emitting the pressurized air in a direction corresponding to the flow of the gas flow path.

20. The method of claim 15, wherein the step of emitting the pressurized air from ports further comprises emitting the pressurized air to reduce engine resonance.