US20140137560A1 - Turbomachine with trapped vortex feature - Google Patents

Abstract

A turbomachine with a trapped vortex feature includes a unibody liner formed to define a flow path for combustion products, the unibody liner including first and second portions defining first radial planes, a third portion defining a second radial plane and fourth and fifth portions extending substantially radially between proximal ends of the first and third portions and proximal ends of the second and third portions, respectively, and an injector configured to deliver a fuel or a fuel/air mixture to a space partially bound by the third, fourth and fifth portions.

Description

BACKGROUND OF THE INVENTION
• The subject matter disclosed herein relates to turbomachines and, more particularly, to turbomachines with trapped vortex features.
• A typical turbomachine includes a compressor to compress inlet air, a combustor in which the compressed inlet air is combusted along with fuel, a turbine in which products of the combustion are receivable for power generation purposes and a transition piece. The transition piece is fluidly interposed between the combustor and the turbine.
• In some cases, the typical turbomachine is configured to support axially staged or late lean injection. In these cases, fuel and air are injected into downstream sections of the combustor or the transition piece in order to cause secondary combustion within the downstream sections of the combustor or the transition piece. This secondary combustion tends to reduce emissions of pollutants, such as oxides of nitrogen.
BRIEF DESCRIPTION OF THE INVENTION
• According to one aspect of the invention, a unibody liner formed to define a flow path for combustion products, the unibody liner including first and second portions defining first radial planes, a third portion defining a second radial plane and fourth and fifth portions extending substantially radially between proximal ends of the first and third portions and proximal ends of the second and third portions, respectively, and an injector configured to deliver a fuel or a fuel/air mixture to a space partially bound by the third, fourth and fifth portions.
• According to another aspect of the invention, a turbomachine is provided and includes a unibody liner formed to define a flow path for combustion products, the unibody liner being formed to define a trapped vortex feature into which a portion of combustion products flow, and an injector configured to deliver a fuel or a fuel/air mixture to the trapped vortex feature.
• According to yet another aspect of the invention, a turbomachine is provided and includes a combustor liner defining a first interior in which combustion occurs and a second interior through which products of combustion flow, a transition piece disposed downstream from the combustor liner, the transition piece defining a third interior, which is receptive of the products of combustion and through which the products of combustion continue to flow, at least one of the combustor liner and the transition piece being formed to define a recess into which a portion of the products of combustion flow and an injector configured to deliver combustible materials to the recess whereby the combustible materials and the portion of the products of combustion form respectively trapped vortices.
• These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
• FIG. 1 is a schematic illustration of a turbomachine; and
• FIG. 2 is an enlarged view of a portion of the turbomachine ofFIG. 1.
• The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
• With reference toFIGS. 1 and 2, aturbomachine10 includes acompressor11 to compress inlet air, acombustor12 in which the compressed inlet air is combusted along with fuel, aturbine13 in which products of combustion are receivable for power generation purposes and atransition piece14. Thetransition piece14 is fluidly interposed between thecombustor12 and theturbine13. Theturbomachine10 is configured to support axially staged injection or late lean injection (LLI) whereby fuel and air are injected into downstream sections of thecombustor12 or thetransition piece14 in order to cause secondary combustion processes. This secondary combustion tends to reduce emissions of pollutants, such as oxides of nitrogen, from theturbomachine10.
• In some axially staged injection or LLI configurations, it has been found that almost all of the air available for turbomachine operations is utilized for combustion in one form or another and that little to no air is bypassed in the form of combustor dilution air. This means that air used for axially staged injection or LLI robs the head end of thecombustor12 of some portion of air that could have otherwise been used to improve head end performance for a given amount of fuel. Accordingly, theturbomachine10 is provided with a trapped vortex feature (which is described below) that allows most of the air available for combustion to be provided through the pre-mixers at the head end of thecombustor12 and then be re-utilized later for axially staged injection or LLI.
• With reference toFIG. 2, thecombustor12 includes acombustor liner20 and aflow sleeve21. Thecombustor liner20 is formed to define afirst interior201, in which a first stage of the combustion occurs, and asecond interior202. The products of combustion flow through thesecond interior202 toward theturbine13. Thefirst interior201 is generally defined proximate to a head end of thecombustor12 at an axially upstream location and thesecond interior202 is defined fluidly and axially downstream from thefirst interior201. Theflow sleeve21 is disposed about thecombustor liner20 to define afirst annulus22.
• Thetransition piece14 is disposed fluidly and axially downstream from thecombustor12 and includes atransition piece liner30 and animpingement sleeve31. Thetransition piece liner30 is formed to define athird interior301, which is fluidly interposed between thesecond interior202 and an interior of theturbine13. Thus, thethird interior301 is receptive of the products of combustion from thesecond interior202 of thecombustor12 and provides for a flow path along or through which the products of combustion can continue to flow toward theturbine13. Theimpingement sleeve31 is disposed about thetransition piece liner30 to define asecond annulus32. Thesecond annulus32 is fluidly coupled with thefirst annulus22. Theimpingement sleeve31 is formed to defineimpingement holes310.
• For purposes of clarity and brevity, in the following description and claims, thecombustor liner20 and thetransition piece liner30 may be referred to separately or as a unibody liner. Thus, it will be understood that a unibody liner includes at least portions of both thecombustor liner20 and thetransition piece liner30.
• Compressed air is exhausted from thecompressor11 and enters a compressor discharge casing (CDC). From an interior of the CDC, the compressed air enters thesecond annulus32 via theimpingement holes310. The compressed air then flows from thesecond annulus32 through thefirst annulus22 toward the head end of thecombustor12 where the compressed air is mixed with fuel and combusted.
• In some cases, a portion of the compressed air entering thesecond annulus32 may be used as a coolant for thetransition piece liner30 within thethird interior301. In such cases, thetransition piece liner30 may include aflange33 that is sealed to thetransition piece liner30 byhula seal34. Theflange33 is formed to define acooling path35 by which the portion of the compressed air can be delivered to thethird interior301 along an interior surface of thetransition piece liner30.
• At least one or both of thecombustor liner20 and thetransition piece liner30 is formed to define a substantially annular recess40 proximate to a connection of thecombustor liner20 and thetransition piece liner30. The recess40 acts as a trapped vortex feature41 that extends radially outwardly from thesecond interior202 and/or thethird interior301. Thus, as the products of combustion travel downstream through thesecond interior202 and then through thethird interior301 as a main flow, a portion of the products of combustion flow into the recess40 with a flow pattern (i.e., a second trapped vortex70) to be described below. In accordance with embodiments, the portion of the products of combustion include air provided through the pre-mixers at the head end of thecombustor12 and which is to be re-utilized in the recess40/trapped vortex feature41.
• In being formed to define the recess40, the at least one of thecombustor liner20 and thetransition piece liner30 includes a firstaxial portion401, a secondaxial portion402, a thirdaxial portion403, a fourthradial portion404 and a fifthradial portion405 with the recess at least partially bounded by the thirdaxial portion403, the fourthradial portion404 and the fifthradial portion405. The firstaxial portion401 may be disposed upstream from the secondaxial portion402. The first and secondaxial portions401 and402 may have annular shapes while respectively defining first radial planes, RP1, which may be but need not be substantially similar to one another. The thirdaxial portion403 may have an annular shape and defines a second radial plane, RP2, which is displaced radially outwardly from the first radial planes, RP1, by a predefined amount. The fourthradial portion404 and the fifthradial portion405 each extend substantially radially to connect the first and secondaxial portions401 and402 to the thirdaxial portion403. That is, the fourthradial portion404 extends substantially radially between proximal ends of the firstaxial portion401 and the thirdaxial portion403 while the fifthradial portion405 extends substantially radially between proximal ends of the secondaxial portion402 and the thirdaxial portion403.
• In accordance with embodiments, the recess40 may have a substantially rectangular cross-sectional shape. In accordance with further embodiments, the corners of the recess40 (i.e., the connections between the firstaxial portion401 and the fourthradial portion404, the fourthradial portion404 and the thirdaxial portion403, the thirdaxial portion403 and the fifthradial portion405 and the fifthradial portion405 and the second axial portion402) may be rounded to facilitate smooth fluid flow into and out of the recess40.
• Theturbomachine10 further includes aninjector50. Theinjector50 is configured to deliver combustible materials, such as a fuel or a fuel and air mixture, to the recess40. In so doing, the combustible materials form a first trappedvortex60 while the portion of the products of combustion that have flown into the recess40 form the second trappedvortex70. The combustible materials may include, for example, fuel and a quantity of air derived from the CDC. As such, the combustible materials have a pressure, P_CD, which is substantially similar to the pressure in the CDC interior.
• As shown, the combustible materials forming the first trappedvortex60 tend flow in a first vortical pattern and the portion of the products of combustion forming the second trappedvortex70 tends to flow in a second vortical pattern. The first and second vortical patterns may be substantially oppositely oriented. Thus, as the first andsecond vortices60 and70 are adjacent to one another, the respective fluids in each one mix along theshear line80 such that the combustible materials injected into the recess40 by theinjector50 auto-ignite due to the temperatures and pressures of the portion of the products of combustion. The respective fluids, including the auto-ignited combustible materials, are then returned to the main flow and proceed to flow toward theturbine13.
• With the auto-ignited combustible materials returned to the main flow, axially staged injection or LLI processes may be engaged. This allows for secondary combustion to occur with the associated advantages in terms of reduced pollutant emissions, for example, but without the need to deprive the head end of thecombustor12 of any of the air necessary for a given amount of fuel.
• Theinjector50 may include avane51 and a fuel source52. Thevane51 is formed to define aflowpath510 by which the compressed air is transmittable from the CDC to the recess40. The fuel source52 may include a flexible hose520 and is configured to provide a supply of fuel to theflowpath510. Thevane51 is substantially radially oriented and traverses thefirst annulus22 and/or thesecond annulus32. Thevane51 may be cylindrical or otherwise aerodynamically formed to generate as little a disturbance as possible in compressed air moving through thefirst annulus22 or thesecond annulus32. Thevane51 may include amicromixer511 that is formed to mix the combustible materials to be injected into the recess40 and to prevent or substantially reduce the possibility of flameholding in the recess40 or thevane51.
• For most of the radial length of thevane51, theflowpath510 is oriented substantially radially. At a radially inward location, however, thevane51 may be configured such that the flowpath510 runs along the axial dimension of theturbomachine10. In this way, theinjector50 is configured to inject the combustible materials into the recess40 in a substantially axial direction thus facilitating the formation of the first trappedvortex60.
• In accordance with further embodiments, the fifthradial portion405 may be formed to define through-hole53 by which compressed air may flow from thesecond annulus32 into the recess40. In this way, additional air may be provided to enhance the combustion of the fuel injected by theinjector50. Moreover, since the through-hole53 is defined through the fifthradial portion405, the through-hole has a substantially axial orientation whereby the compressed air flowing through the through-hole53 flows in the axial direction and thereby facilitates the formation of the first trappedvortex60. It will be understood that a similar effect can be achieved with the through-hole53 defined through a downstream section of the thirdaxial portion403. In this case, the compressed air flowing into the recess flows in the radial direction and again facilitates the formation of the first trappedvortex60.
• While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims (20)

1. A turbomachine with a trapped vortex feature, comprising:

a unibody liner formed to define a flow path for combustion products, the unibody liner comprising:

first and second portions defining first radial planes, a third portion defining a second radial plane and fourth and fifth portions extending substantially radially between proximal ends of the first and third portions and proximal ends of the second and third portions, respectively; and

an injector configured to deliver a fuel or a fuel/air mixture to a space partially bound by the third, fourth and fifth portions.

2. The turbomachine according toclaim 1, wherein the injector is configured to deliver the fuel or the fuel/air mixture to the space in a substantially axial direction.

3. The turbomachine according toclaim 1, wherein the unibody liner comprises a combustor liner and a transition piece liner and the space is defined proximate to a connection of the combustor liner and the transition piece.

4. The turbomachine according toclaim 1, wherein the space has an annular shape.

5. The turbomachine according toclaim 1, wherein the space has a substantially rectangular cross-sectional shape.

6. A turbomachine, comprising:

a unibody liner formed to define a flow path for combustion products;

the unibody liner being formed to define a trapped vortex feature into which a portion of combustion products flow; and

an injector configured to deliver a fuel or a fuel/air mixture to the trapped vortex feature.

7. The turbomachine according toclaim 6, wherein the injector is configured to deliver the fuel or the fuel/air mixture to the trapped vortex feature in a substantially axial direction.

8. The turbomachine according toclaim 6, wherein the unibody liner comprises a combustor liner and a transition piece liner and the trapped vortex feature is defined proximate to a connection of the combustor liner and the transition piece.

9. The turbomachine according toclaim 6, wherein the trapped vortex feature has an annular shape.

10. The turbomachine according toclaim 6, wherein the trapped vortex feature has a substantially rectangular cross-sectional shape.

11. A turbomachine, comprising:

a combustor liner defining a first interior in which combustion occurs and a second interior through which products of combustion flow;

a transition piece liner disposed downstream from the combustor liner, the transition piece liner defining a third interior, which is receptive of the products of combustion and through which the products of combustion continue to flow,

at least one of the combustor liner and the transition piece liner being formed to define a recess into which a portion of the products of combustion flow; and

an injector configured to deliver combustible materials to the recess whereby the combustible materials and the portion of the products of combustion form respectively trapped vortices.

12. The turbomachine according toclaim 11, wherein the combustible materials comprise fuel or a fuel mixed with compressor discharge casing air.

13. The turbomachine according toclaim 11, further comprising:

a flow sleeve disposed about the combustor liner to define a first annulus; and

an impingement sleeve disposed about the transition piece liner to define a second annulus,

the second annulus being fluidly coupled to the first annulus.

14. The turbomachine according toclaim 11, wherein the injector comprises:

a vane formed to define a flowpath by which air is transmitted from a compressor discharge casing to the recess; and

a fuel source configured to provide a supply of fuel to the flowpath.

15. The turbomachine according toclaim 14, wherein the vane comprises a micromixer.

16. The turbomachine according toclaim 14, wherein the fuel source comprises a flexible hose.

17. The turbomachine according toclaim 11, wherein the injector is configured to deliver the combustible materials to the recess in a substantially axial direction.

18. The turbomachine according toclaim 11, wherein the recess is defined proximate to a connection of the combustor liner and the transition piece liner.

19. The turbomachine according toclaim 11, wherein the recess has an annular shape.

20. The turbomachine according toclaim 11, wherein the recess has a substantially rectangular cross-sectional shape.

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