Patent Application
20130115566
The subject matter disclosed herein relates to a combustor and, more particularly, to a combustor having wake air injection capability.
In gas turbine engines and other types of turbomachines, air flow is directed towards premixers in which fuel and air are mixed prior to being combusted in a combustion zone of a combustor. The fuel may be provided by way of fuel injectors disposed in the air flow whereby the mixing of the fuel and air is achieved at least partly as a result of cross flow velocities of the air flow being maintained at and around the fuel injectors.
It has been observed, however, that wakes can be generated by any streamlined or non-streamlined bodies disposed within the air flow. These wakes can disturb the air flow and lead to decreased cross flow velocities at and around the fuel injectors. The decreased cross flow velocities can negatively affect flame holding capability of the system. In some cases, fuel can be pulled up into recirculation zones in the combustion zone where mixed fuel can thus come in contact with hot surfaces of the combustor causing them to autoignite and initiate flame holding in flow sleeve liner annulus passages.
According to one aspect of the invention, a combustor having wake air injection is provided. The combustor includes a fuel nozzle, first and second vessels formed and disposed to define a flow path along which a first fluid flows in first and second opposite directions toward the fuel nozzle, a vane disposed in the flow path and an injector to inject a second fluid into wake formed by an obstruction disposed in the flow path upstream from the vane.
According to another aspect of the invention, a combustor having wake air injection is provided. The combustor includes a fuel nozzle configured to form a mixture of combustible materials to be supplied for combustion operations, first and second vessels formed and disposed about the fuel nozzle to define a flow path along which a first fluid flows in a first axial direction, then a radial direction and then a second axial direction, which is opposite the first axial direction, toward the fuel nozzle, a vane disposed in the flow path and an injector to inject a second fluid into wake formed by an obstruction disposed in the flow path at an axial location upstream from the vane.
According to yet another aspect of the invention, a wake air injection apparatus is provided and includes a first vessel having an end in which a mixture of combustible materials is formed and defining a combustion zone in which the mixture is combusted, a second vessel disposed about the first vessel to define a first space through which a flow of a first fluid is directed toward the end of the first vessel and in which an obstruction is disposed to form a wake in the flow of the first fluid and a third vessel disposed about the second vessel to define a second space to receive a second fluid. The second vessel defines an injector, by which the second fluid is injected from the second space to the first space, and which is positioned downstream from the obstruction relative to the flow of the first fluid and in substantial, circumferential alignment with the wake.
These and other advantages and features will become more apparent from the following description taken in conjunction with 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:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
With reference to
The second vessel 40 is disposed about the first vessel 30 and may be provided as a flow sleeve of the combustor 20. The second vessel 40, being disposed about the first vessel 30, may be formed to define a first space 400 in the annulus between the first vessel 30 and the second vessel 40 through which a flow of a first fluid, such as relatively low pressure impingement air, is directed toward the end 31 of the first vessel 30. In particular, the first space 400 forms a flow path along which the first fluid flows in a reverse flow pattern including a first axial direction at a radial location defined radially outwardly of the fuel nozzle 201, an inward radial direction axially forward of the fuel nozzle 201 and a second axial direction, which is opposite the first axial direction, at a radial location defined to be substantially radially aligned with the fuel nozzle 201.
The third vessel 50 may be disposed about the second vessel 40 and may be provided as a compressor discharge casing (CDC). The third vessel 50, being disposed about the second vessel 40, may be formed to define a second space 500 in the annulus between the second vessel 40 and the third vessel 50. A second fluid, such as relatively high pressure CDC air may be supplied to the second space 500.
At least one or more obstructions 70 and at least one or more vanes 80 may be disposed in the first space 400. The at least one or more vanes 80 may be provided, for example, as part of a quaternary fuel injection system and are disposed in a forward section of the first space 400. That is, each vane 80 may serve as a fuel injector by which fuel is injected into the flow of the first fluid. The at least one or more obstructions 70 may or may not be streamlined and are each disposed in the first space 400 at axial locations aft of the at least one or more vanes 80. In accordance with embodiments, as shown in
In order to counteract effects of the wake formed by the obstruction 70, the second vessel 40 is formed to define the injector 60 by which the second fluid is injected from the second space 500 to the first space 400 with an angle of injection of between about 20-80° relative to a centerline of the combustor or the exemplary gas turbine engine in accordance with embodiments. The injector 60 is positioned downstream from the obstruction 70 relative to the flow of the first fluid through the first space 400 or, in other words, at an axial location that is defined axially forward of the obstruction 70. The injector 60 is further positioned in substantial, circumferential alignment with the wake formed by the obstruction 70. Thus, the injection of the second fluid from the second space 500 may serve to reduce disturbances associated with the wake and thereby achieve necessary cross flow velocities at the corresponding one or more vanes 80 for acceptable flame holding margin.
With reference to
As shown in
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.
