The present invention relates to nozzles and injectors, and more particularly to swirlers for nozzles and injectors in gas turbine engines.
In a fuel nozzle for a gas turbine engine, compressor discharge air is used to atomize liquid fuel. More particularly, the air provides a mechanism to break up a fuel sheet into a finely dispersed spray that is introduced into the combustion chamber of an engine. Quite often the air is directed through a duct that serves to turn or impart swirl to the air. This swirling air flow acts to stabilize the combustion reaction.
There are many ways to develop swirl in a fuel nozzle. Historically, helically vaned swirlers were used because of their ability to effectively turn the air flow. These helical vanes generated acceptable air flow characteristics for many engine applications. Helically vaned air swirlers are traditionally placed upstream in the internal air path of a nozzle. Fuel injected into the swirling flow is mixed with air for combustion downstream.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for swirlers that allow for improved flow characteristics, thermal performance, and adaptability to specific applications. There also remains a need in the art for such swirlers that are easy to make and use. The present invention provides a solution for these problems.
The subject invention is directed to a new and useful swirler, such as for swirling air in a fuel injector of a gas turbine engine. The swirler includes a swirler body with opposed inlet and outlet ends with a swirler wall extending therebetween along a longitudinal axis. The inlet end of the swirler body defines an inlet opening. A plurality of swirl slots is defined through a portion of the swirler wall that converges toward the longitudinal axis in a direction from the inlet opening toward the outlet end of the swirler body. The swirl slots are radially off-set with respect to the longitudinal axis for imparting swirl on a flow passing from the inlet opening, through the swirl slots, and past the outlet end of the swirler body.
In accordance with certain embodiments, the swirl slots are elongated in a direction along the swirler wall. Each swirl slot can extend along the swirler wall in a direction oblique axially and circumferentially relative to the longitudinal axis. The swirler wall can define an axial cross-sectional profile that is bullet-shaped.
In certain embodiments, the swirler wall defines an axial cross-sectional profile that is trapezoidal. The outlet end of the swirler body can include a planar portion of the swirler wall that is substantially perpendicular to the longitudinal axis. The swirl slots can be cylindrical bores through the swirler wall.
In another aspect, it is contemplated that in certain embodiments the only flow path through the swirler wall is through the swirl slots. It is also contemplated that the outlet end of the swirler body can include at least one bore passing through the swirler wall in an axial direction relative to the longitudinal axis.
The invention also provides an injector having an injector body with opposed inlet and outlet ends. A liquid flow circuit passes through the injector body from the inlet end to the outlet end. An inner air circuit is defined through the injector body along a longitudinal axis. A swirler is mounted to the injector body. The swirler includes a swirler wall extending within the inner air circuit from an inlet opening of the swirler to a downstream end of the swirler along the longitudinal axis. A plurality of swirl slots is defined through the swirler wall. The swirl slots are radially off-set with respect to the longitudinal axis for imparting swirl as described above.
In certain embodiments, a flow passage is defined between the swirler wall and a wall of the inner air circuit of the injector body. The flow passage can have a cross-sectional area that increases in a direction along the longitudinal axis towards the downstream end of the swirler. The swirl slots can feed into the flow passage.
In another aspect, a swirler as described above can be mounted to an injector body, such as the injector body described above, upstream of the inner air circuit, e.g., with the swirler flipped axially relative to the orientation described above so the swirl slots are defined through a portion of the swirler wall that diverges relative to the longitudinal axis in a direction from the upstream end of the swirler to the downstream opening of the swirler.
These and other features of the systems and methods of the subject invention will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.
So that those skilled in the art to which the subject invention appertains will readily understand how to make and use the devices and methods of the subject invention without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:
Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject invention. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of an injector in accordance with the invention is shown in
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While injectors 100, 200, and 300 described above include swirlers having bullet-shaped cross-sectional profiles, any other suitable cross-sectional profile can be used as well. For example, injector 400 in
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While described above in the exemplary context of having a single set of swirl slots in each swirler, those skilled in the art will readily appreciate that multiple sets of swirl slots can be used in a swirler. For example, in injectors 300, 400, and 500 a single set of radially off-set cylindrical swirl slots is provided around the circumference of each swirler. However, additional sets of co- or counter-rotating swirl slots could be added in these swirlers to provide suitable flow characteristics for given applications.
While described above in the exemplary context of injectors with swirlers therein having swirler walls that converge, those skilled in the art will readily appreciate that any other suitable swirler wall profile can be used for a given application. For example,
One potential benefit of swirlers as described herein over traditional axial type swirlers, which typically include a centerline bluff body, is related to thermally induced stresses. Swirlers as described herein can tend to undergo relatively uniform temperature changes compared to traditional swirlers with bluff bodies. The bluff bodies tend to have large thermal masses, resulting in considerable thermal gradients across the swirl vanes, which is not necessarily the case with swirlers as described herein.
While shown and described in the exemplary context of air flow through inner air circuits for fuel injectors in gas turbine engines, those skilled in the art will readily appreciate that injectors and swirlers as described herein can be used in any other suitable application. Moreover, injectors and swirlers as described herein can be used to swirl any suitable fluid, including liquids, as needed for specific applications. Various embodiments are described herein with features that vary from embodiment to embodiment to provide different flow characteristics. Those skilled in the art will readily appreciate that any of these features can be adapted and/or used in combination to suit specific applications. Additionally, while the swirlers described herein are shown mounted in exemplary injector bodies, those skilled in the art will readily appreciate that swirlers as described herein can be used in any other suitable type of injector, nozzle, or other envelope without departing from the scope of the invention. In short, the swirlers described herein provide considerable design flexibility so that the flow characteristics can be tailored for specific applications.
The methods and systems of the present invention, as described above and shown in the drawings, provide for swirlers with superior properties including flow characteristics, thermal management, and adaptability for specific applications. While the apparatus and methods of the subject invention have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the spirit and scope of the subject invention.
This application is a divisional of U.S. patent application Ser. No. 13/783,832 filed Mar. 4, 2013 the contents of which are incorporated by reference herein in their entirety.
Number | Date | Country | |
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Parent | 13783832 | Mar 2013 | US |
Child | 16206302 | US |