Patent Application
20200340673
This disclosure relates to gas turbine engines. More specifically, this disclosure relates to an air tube for a gas turbine engine.
Gas turbine engines can use combustors with combustor liners that include air tubes. These air tubes can feed post compressor discharge air into a primary zone of the combustor liner and promote tangential swirl. The air tubes can be difficult and expensive to manufacture via convention manufacturing methods to manufacture, lack consistency, and degrade over time.
U.S. Pat. No. 6,729,141, to Ingram describes air tubes that are circumferentially spaced around the outer liner of an annular combustor for a microturbine engine in proximity to and downstream of a dam extending into the combustion chamber for reducing the emission of NOx. The air tubes are dimensioned so that the length to passage diameter is such that a swirling motion of the air injected into the combustion zone is normal to the center line of the annular combustor.
The present disclosure is directed toward overcoming one or more of the problems discovered by the inventors.
In general, this disclosure describes an air tube for a gas turbine including a combustor with an outer liner. The air tube comprises an inner tube, a strut, an outer plate, and an outer tube.
The inner tube circumferentially extends around an air tube axis longitudinal to the air tube. The inner tube has an outer surface, an inner tube inlet, and an inner tube outlet disposed opposite of the inner tube inlet, the inner tube outlet in fluid communication with the inner tube inlet. The strut is disposed adjacent to the outer surface of the inner tube and extends from proximate the inner tube inlet towards the inner tube outlet. The outer plate configured to be connected to the outer liner of the combustor. The outer tube connected to the strut and disposed outward of the inner tube.
The details of embodiments of the present disclosure, both as to their structure and operation, may be gleaned in part by study of the accompanying drawings, in which like reference numerals refer to like parts, and in which:
The detailed description set forth below, in connection with the accompanying drawings, is intended as a description of various embodiments and is not intended to represent the only embodiments in which the disclosure may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that embodiments of the invention can be practiced without these specific details. In some instances, well-known structures and components are shown in simplified form for brevity of description. In some instances, reference numbers are left out of the figures for ease of viewability.
In addition, the disclosure may generally reference a center axis 95 of rotation of the gas turbine engine, which may be generally defined by the longitudinal axis of its shaft 120 (supported by a plurality of bearing assemblies 150). The center axis 95 may be common to or shared with various other engine concentric components. All references to radial, axial, and circumferential directions and measures refer to center axis 95, unless specified otherwise, and terms such as “inner” and “outer” generally indicate a lesser or greater radial distance from center axis 95, wherein a radial 96 may be in any direction perpendicular and radiating outward from center axis 95.
A gas turbine engine 100 includes an inlet 110, a shaft 120, a compressor 200, a combustor 300, a turbine 400, an exhaust 500, and a power output coupling 600. The gas turbine engine 100 may have a single shaft or a dual shaft configuration.
The compressor 200 includes a compressor rotor assembly 210, compressor stationary vanes (stators) 250, and inlet guide vanes 255. The compressor rotor assembly 210 mechanically couples to shaft 120. As illustrated, the compressor rotor assembly 210 is an axial flow rotor assembly. The compressor rotor assembly 210 includes one or more compressor disk assemblies 220. Each compressor disk assembly 220 includes a compressor rotor disk that is circumferentially populated with compressor rotor blades. Stators 250 axially follow each of the compressor disk assemblies 220. Each compressor disk assembly 220 paired with the adjacent stators 250 that follow the compressor disk assembly 220 is considered a compressor stage. Compressor 200 includes multiple compressor stages. Inlet guide vanes 255 axially precede the compressor stages at the beginning of an annular flow path 115 through the gas turbine engine 100.
Once compressed air 10 leaves the compressor 200, it enters the combustor 300, where it is diffused and fuel is added. Air 10 and fuel are injected into a combustion chamber 320 via an injector and combusted. Energy is extracted from the combustion reaction via the turbine 400 by each stage of the series of turbine disk assemblies 420.
The turbine 400 includes a turbine rotor assembly 410 and turbine nozzles 450 within a turbine housing 430. The turbine rotor assembly 410 mechanically couples to the shaft 120. In the embodiment illustrated, the turbine rotor assembly 410 is an axial flow rotor assembly. The turbine rotor assembly 410 includes one or more turbine disk assemblies 420. Each turbine disk assembly 420 includes a turbine disk that is circumferentially populated with turbine blades. Turbine nozzles 450 axially precede each of the turbine disk assemblies 420. Each turbine disk assembly 420 paired with the adjacent turbine nozzles 450 that precede the turbine disk assembly 420 is considered a turbine stage. Turbine 400 includes multiple turbine stages.
The exhaust 500 includes an exhaust diffuser 520 and an exhaust collector 550 that can collect exhaust gas 90. The power output coupling 600 may be located at an end of shaft 120.
Fuel nozzles 340 can be circumferentially disposed around the outer liner 330 and be in flow communication with the combustion chamber 320. Air tubes 350 can be circumferentially disposed around the outer liner 330 and be in flow communication with the combustion chamber 320. The air tubes 350 can be oriented at an angle with respect to the outer liner 330 such as less than 90 degrees with respect to the outer liner 330. The fuel nozzles 340 can be spaced between the air tubes 350 and may be spaced evenly. The air tubes 350 can comprise a wide variety of metals, including sheet metal and metals used for additive manufacturing such as Nickel based alloys.
The outer tube 380 can have an outer tube inlet 382 and an outer tube outlet 384. The outer tube inlet 382 can be disposed outward of the outer liner 330 with respect to the center axis 95 and may not be located within the combustion chamber 320. The outer tube inlet 382 can be in flow communication with the compressor 200. The outer tube outlet 384 can be disposed inward of the outer liner 330 with respect to the center axis 95 and may be located within the combustion chamber 320. The outer tube outlet 384 can be in flow communication with the outer tube inlet 382. In other words, a portion of the outer tube 380 can extend through the outer liner 330.
The outer plate 370 can be disposed outward of and circumferentially connected to the outer tube 380 with respect to the air tube axis 355. The outer plate 370 can be angled with respect to the outer tube 380. The outer plate 370 can be configured to be connected to the outer liner 330 of the combustor 300. The outer plate 370 can be connected to the outer liner 330 via brazing, welding, mechanical fasteners or other connections of the like.
The inner tube 360 can include an inner tube outer surface 365 facing outwards with respect to the air tube axis 355. The inner tube 360 can include struts 366 that are disposed proximate to the inner tube inlet 362 and extend outward from the inner tube outer surface 365 with respect to the air tube axis 355. The struts 366 can be positioned circumferentially around the inner tube 360 and be evenly spaced apart. Alternatively the struts 366 can vary in spacing and not be evenly spaced apart. The struts 366 can extend from the inner tube inlet 362 towards the inner tube outlet 364 generally parallel with the air tube axis 355. The struts can extend along a portion of the outer tube 380. Alternatively the struts may extend the full length of the outer tube 380. A portion of the struts 366 may connect with the outer tube 380. In other words, the struts 366 can couple the inner tube 360 to the outer tube 380.
The outer tube 380 can circumferentially extend around the air tube axis 355 and generally be shaped as a hollow cylinder extending along the air tube axis 355. The outer tube 380 can be disposed radially outward from the inner tube 360 with respect to the air tube axis 355. The outer tube 380 can include flares 385 disposed proximate to the outer tube inlet 382. The flares 385 can be shaped similar to a crown with each of the crown points extending along one of the struts 366. The flares 385 can connect with the struts 366 and may generally radially contour the shape of the struts 366 with respect to the air tube axis 355.
The air tube 350 can include a first transition portion 374 that may be disposed at an obtuse angle formed by outer tube 380 and the outer plate 370. The first transition portion 374 can arcuately extend from the outer tube 380 to the outer plate 370.
The outer tube 380 can include an inner surface 383 facing inwards towards the inner tube 360 and the air tube axis 355. The outer tube 380 can include fins 386 that can extend inward from the inner surface 383 towards the inner tube 360 with respect to the air tube axis 355. In an embodiment, the fins 386 extend to proximate the inner tube 360 but do not connect with the inner tube 360. In an alternate example, the fins 386 extend from the outer tube 380 and connect with the inner tube 360.
The fins 386 can be positioned circumferentially around a portion of the outer tube 380 such as less than 180 degrees with respect to the circumference of the outer tube 380. Alternatively the fins 386 can be positioned greater than 180 degrees of the circumference of the outer tube 380. The fins 386 can be spaced apart along the outer tube 380 at a fin arc length L2. In an embodiment, the fins 386 are evenly spaced apart. Alternatively the fins 386 can vary in arc length L2 spacing and may not be evenly spaced apart. The fins 386 can extend from the outer tube outlet 384 towards the outer tube inlet 382 and be generally parallel with the air tube axis 355. The fins 386 can have a generally triangular shaped that is wider adjacent the outer tube 380 and narrower inward of the outer tube 380 with respect to the air tube axis 355. The fins 386 can have a concave fillet shape with the outer tube 380 such as a “T” fillet. Alternatively the fins 386 can be shaped as pin fins, wavy fins, rectangular cross-sectional fins, or a wide variety of other geometries that can provide different heat transfer characteristics.
In an embodiment eleven fins 386 are shown. However there is no limit to the number of fins 386 that can be included. One, two, three, four, five, six, or more fins 386 may be included.
The struts 366 can be positioned circumferentially around inner tube 360 and extend to the outer tube 380. The struts 366 can be spaced apart along the outer tube 380 at a strut arc length L1. In an embodiment, the struts 366 are evenly spaced apart. Alternatively the struts 366 can vary in arc length L1 spacing and may not be evenly spaced apart. The struts can have a generally “I” shape with concave fillets joining the outer tube 380 and the inner tube 360. In an embodiment six struts 366 are shown. However there is no limit to the number of struts 366 that can be included. One, two, three, four, five, seven, eight, or more struts 366 may be included.
The outer tube 380 and the inner tube 360 can be radially spaced apart at a distance D3. Distance D3 can be the difference between the inward tube radius R1 and the outer tube radius R2.
The first fin 386a can extend from the outer tube outlet 384 at a distance of Da. Second fins 386b can be disposed circumferentially proximate to the first fin 386a. The second fins 386b can extend from the outer tube outlet 384 at a distance of Da.
The third fins 386c can be disposed circumferentially proximate to the second fins 386b, opposite from the first fin 386a. The third fins 386c can extend from the outer tube outlet 384 at a distance of Dc.
The fourth fins 386d can be disposed circumferentially proximate to the third fins 386c, opposite from the first fin 386a. The fourth fins 386d can extend from the outer tube outlet 384 at a distance of Dd.
The fifth fins 386e can be disposed circumferentially proximate to the fourth fins 386d, opposite from the first fin 386a. The fifth fins 386e can extend from the outer tube outlet 384 at a distance of De.
The sixth fins 386f can be disposed circumferentially proximate to the fifth fins 386e, opposite from the first fin 386a. The sixth fins 386f can extend from the outer tube outlet 384 at a distance of De.
Though the fins 386 are shown as a specific set of lengths, the fins 386 may vary in length and position or may have the same length as other fins 386. Alternatively the fins 386 do not have to be continuous along their length. The fins 386 can be broken up into several segments along the air tube axis 355. The fins 386 can be individually projects oriented in an organized matrix or as a dispersed pattern.
During operation a gas turbine engine 100 combusts a fuel-air mixture in a combustion chamber 320 of a combustor 300 and drives one or more turbines 400 with the resulting hot combustion gas. The high temperatures of the combustion gas can cause wear and potential damage to various components within the gas turbine engine 100. In some gas turbine engines 100, the combustor 300 can include air tubes 350, 390.
The air tubes 350, 390 are formed and can be positioned to receive post compressor discharge air. The post compressor discharge air can be routed into the inner tube inlet 362 and the outer tube inlet 382 and exit the inner tube outlet 364 and outer tube outlet 384, respectively. In other words the inner tube 360 and outer tube 380 can form dual concentric flow circuits for delivering discharge air from the compressor 200 to the combustion chamber 320. The outer plate 370 can be angled with respect to the outer tube 380 which can angle the air tube 350, 390 into position with the outer liner 330 and inner liner 310 such that the exiting air from the inner tube outlet 364 and outer tube outlet 384 provides a tangential swirling motion of the gas within a primary zone of the combustion chamber 320. An embodiment of the air tube 390 can include an igniter tube 394 that is shaped to provide access for an igniter (not shown) to ignite the air and fuel mixture located in the combustion chamber 320.
During operation of the gas turbine engine 100 and within the outer liner 330, the inner tube 360 and outer tube 380 can experience different temperatures, which cause them to undergo thermal expansion at different rates. The struts 366 can connect the inner tube 360 to the outer tube 380 and can experience varying levels of stress in different directions from the differently expanding inner tube 360 and outer tube 380. The height of the struts 366 from the inner tube 360 to the outer tube 380 can be designed shorter to help reduce the stress experienced in the struts. The struts 366 can be formed to position the outer tube 380 with respect to the inner tube 360 at a spacing D3. The spacing D3 can be selected to change the effective area between the outer tube 380 and the inner tube 360 and tune for desired performance characteristics such as to enhance overall combustion performance or for tuning the temperature performance of specific areas and features of the air tube 350, 390 during operation of the gas turbine engine 100. The spacing D3 may be dictated by the effective area required and any assembly constraints for the existing outer liner 330 design. The inner tube 360 can extend beyond the outer tube 380 which provides an emersion depth D1. The emersion depth D1 can be can be selected to tune the temperature performance of air tube 350, 390 features such as the inner tube 360. The emersion depth D1 can be selected to mitigate any potential ignition complications.
The number of struts 366 can be selected to change the effective area between the outer tube 380 and the inner tube 360 and tune the temperature performance of the air tube 350, 390. The struts can also provide the necessary structural support for positioning the outer tube 380 with respect to the inner tube 360. The radial cross sectional area of the struts 366 with respect to the air tube axis 355 can be selected to change the effective area between the outer tube 380 and the inner tube 360 and tune the temperature performance of the air tube 350, 390. The radial cross sectional shape of the struts 366 with respect to the air tube axis 355 can be selected to change the air flow mechanics and tune the temperature performance of the air tube 350, 390. The generally parallel length of the struts 366 with respect to the air tube axis 355 can be selected to tune the temperature performance of the air tube 350, 390. For example, the struts 366 may extend a partial length, the entire length, or beyond the length of the outer tube 380.
The fins 386, 386a, 386b, 386c, 386d, 386e, 386f can be used to increase the surface area of the outer tube 380 and used to improve the temperature performance of the outer tube 380 such as lowering the experienced metal temperatures during operation of the gas turbine engine 100. The number of fins 386, 386a, 386b, 386c, 386d, 386e, 386f can be selected to tune the temperature performance of the air tube 350, 390. The height and arc length L2 of the fins 386, 386a, 386b, 386c, 386d, 386e, 386f can be selected to tune the temperature performance of the air tube 350, 390. The radial cross sectional area of the fins 386, 386a, 386b, 386c, 386d, 386e, 386f with respect to the air tube axis 355 can be selected to tune the temperature performance of the air tube 350, 390. The radial cross sectional shape of the fins 386, 386a, 386b, 386c, 386d, 386e, 386f with respect to the air tube axis 355 can be selected to tune the temperature performance of the air tube 350, 390. The generally parallel length of the fins 386 with respect to the air tube axis 355 can be selected to tune the temperature performance of the air tube 350, 390. The fins 386, 386a, 386b, 386c, 386d, 386e, 386f can be positioned less than 180 degrees with respect to the circumference of the outer tube 380 to reduce the maximum temperature of the outer tube 380 proximate to the higher heat effected zone of the outer tube 380, while minimizing the restriction of flow caused by the reduction in effective area.
The air tubes 350, 390 may be made from a variety of manufacturing methods including the use of sheet metal and brazing or additive manufacturing. Additive manufacturing, also known as 3D printing, can facilitate the manufacturing of desired air tube feature geometry to achieve the desired performance. Additive manufacturing may provide other functional benefits. The surface texture provided by additive manufacturing can allow for a stronger brazing bond between the surface of the outer plate 370 and the outer liner 330 in comparison to brazing with another material such as sheet metal. Additive manufacturing allows for the air tube 350, 390 to be manufacture as one piece, whereas using sheet metal can require brazing multiple pieces of metal together and can create eccentricities that effect temperature performance of the air tube 350, 390.
Although this invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention. Accordingly, the preceding detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. In particular, the described embodiments are not limited to use in conjunction with a particular type of gas turbine engine 100. For example, the described embodiments may be applied to stationary or motive gas turbine engines 100, or any variant thereof. Furthermore, there is no intention to be bound by any theory presented in any preceding section. It is also understood that the illustrations may include exaggerated dimensions and graphical representation to better illustrate the referenced items shown, and are not consider limiting unless expressly stated as such.
It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that have any or all of the stated benefits and advantages.
