Turbo-machinery with flow deflector system   

Abstract: The present application provides a turbo-machine. The turbo-machine may include a number of buckets, a number of nozzles, and a flow deflector system. The flow deflector system may include a bucket deflector and a nozzle deflector so as to limit leakage flow losses therethrough.

TECHNICAL FIELD

The present application and the resultant patent relate generally to turbo-machinery and more particularly relate to a steam turbine with a flow deflector system having extensions to restrict leakage flow in both axial and radial directions for improved efficiency.

BACKGROUND OF THE INVENTION

Generally described, turbo-machinery such as steam turbines, gas turbines, and the like include alternating rows of rotating airfoils or buckets and rows of stationary airfoils or nozzles. Each row of rotating airfoils may be attached to a rotor for rotation therewith. Each row of stationary airfoils may be attached at one end to a casing with each of the stationary airfoil extending radially inward toward a packing ring and the rotor. The packing ring may have seal strips extending from both the rotating and stationary surfaces so as to form a clearance therebetween. Other configurations may be used.

In operation, the rotating and the stationary airfoils expand the flow of fluid therethrough. As the fluid passes axially through the turbine, the pressure of the fluid decreases. For example, the fluid pressure on the downstream side of a row of stationary airfoils is less than the pressure on the upstream side of the same row. The fluid will seek the path of least resistance such that leakage may occur through the packing ring clearance between the stationary airfoil and the rotor. This leakage flow may enter radially into the main flow path upstream of the rotating airfoil. The leakage flow may mix randomly with the mainstream flow and cause increase mixing or intrusion losses. Both the random mixing of the clearance flow with the main flow caused by intrusion and the higher packing ring clearance flow losses will degrade overall turbine performance and efficiency.

There is therefore a desire for improved turbo-machinery so as to limit both intrusion losses and overall clearance leakage flows so as to improve overall efficiency. Limiting such leakage flow results in more of the working fluid producing useful work. Preferably, such clearance leakage flow improvements may be provided without the use of expensive and complex brush seals or other types of components subject to wear and tear.

SUMMARY

The present application and the resultant patent thus provide a turbo-machine. The turbo-machine may include a number of buckets, a number of nozzles, and a flow deflector system. The flow deflector system may include a bucket deflector and a nozzle deflector so as to limit leakage flow losses therethrough so as to improve overall efficiency.

The present application and the resultant patent further provide a method of limiting leakage flow losses in a turbine. The method may include the steps of flowing a leakage flow through a nozzle clearance, placing a bucket extension into an axial gap between a bucket and a nozzle adjacent to the nozzle clearance, overlapping the bucket extension in the axial gap with a nozzle extension so as to limit the leakage flow therethrough, and directing the leakage flow exiting the axial gap in a direction of a main flow.

The present application and the resultant patent further provide a flow deflector system. The flow director system may include a bucket deflector positioned about a bucket, a nozzle deflector positioned about a nozzle, and a nozzle abradable positioned about the nozzle deflector and/or a bucket abradable positioned about the bucket deflector.

These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims. The several embodiments shown herein are by way of example only.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a section of a turbine.

FIG. 2 is a schematic view of a portion of a turbine with a flow deflector system as may be described herein.

FIG. 3 is a partial side cross-sectional view of the flow deflector system of FIG. 2.

FIG. 4 is a partial side cross-sectional view of an alternative embodiment of a flow deflector system as may be described herein.

FIG. 5 is a partial side plan view of an alternative embodiment of a flow deflector system as may be described herein.

FIG. 6 is a partial side plan view of an alternative embodiment of a flow deflector system as may be described herein

FIG. 7 is a partial side plan view of an alternative embodiment of a flow deflector system as may be described herein.

FIG. 8 is a partial side plan view of an alternative embodiment of a flow deflector system as may be described herein.

FIG. 9 is a partial side plan view of an alternative embodiment of a flow deflector system as may be described herein.

FIG. 10 is a partial side plan view of an alternative embodiment of a flow deflector system as may be described herein

FIG. 11 is a partial side plan view of an alternative embodiment of a flow deflector system as may be described herein.

FIG. 12 is a schematic view of a portion of a compressor with a flow deflector system as may be described herein.

DETAILED DESCRIPTION

Referring now to the drawings, in which like numerals refer to like elements throughout the several views, FIG. 1 shows a portion of a turbo-machine 10. In this example, the turbo-machine 10 may be a steam turbine 15. A gas turbine and other configurations and types of turbo-machinery also may be used herein. As described above, the steam turbine 15 includes a number of rotating airfoils or buckets 20. The rotating airfoils 20 may be attached to a rotor 25 for rotation therewith. The rotating airfoils 20 may be positioned between rows of a number of stationary airfoils or nozzles 30. The stationary airfoils 30 extend from a casing 35 on one end to a packing ring 40 on the other. The packing ring 40 may have a number of seal strips 45 positioned on both the stationary airfoil 30 and the rotor 25. A packing ring clearance 50 may extend between the stationary airfoil 30 and the rotor 25. A leakage flow 55 may extend therethrough. The nature of the leakage flow 55 may vary. Other components and other configurations may be used herein.

FIG. 2 shows a portion of a turbo-machine 100 as may be described herein. As above, the turbo-machine 100 may be a steam turbine 110. Gas turbines and other turbo-machinery also may be used herein. The steam turbine 110 may include a number of rotating airfoils or buckets 120. The buckets 120 may be attached to a rotor 130 and a disk 140. Likewise, the steam turbine 110 may include a number of stationary airfoils or nozzles 150. The nozzles 150 may extend radially towards the rotor 130 and a packing ring 160 on one end thereof. A packing ring clearance 170 may extend between the packing ring 160 and the rotor 130. While a main flow 180 may pass between the buckets 120 and the nozzles 150, a leakage flow 190 may seek to escape via the packing ring clearance 170 and into an axial gap 195 between the buckets 120 and the nozzles 150.

The steam turbine 110 also may include a leakage flow deflector system 200. The leakage flow deflector system 200 may include a bucket deflector 210. The bucket deflector 210 may include an upstream bucket extension 220 on an upstream side 230 thereof and a downstream bucket extension 240 on a downstream side thereof. The bucket extensions 220, 240 may extend from the disk 140 beneath the bucket 120 and extend into the axial gap 195. Although the bucket extensions 220, 240 are shown as having a largely rectangular, blunted shape 260 any desired size or shape may be used herein.

The flow deflector system 200 also may include a nozzle deflector 270 positioned about each nozzle 150. The nozzle deflector 270 may include an upstream nozzle extension 280 positioned on an upstream side 290 thereof and a downstream nozzle extension positioned on a downstream side 310 thereof. The nozzle extensions 280, 300 may extend into the axial gap 195. The blade extensions 220, 240 and the nozzle extensions 280, 300 may overlap each other to a varying extent. Although the nozzle extensions 280, 300 are shown as having a rectangular blunt shape 320, any size or shape may be used herein. Likewise, although the blade extensions 220, 240 are shown on top of the nozzle extensions 280, 300, the nozzle extensions 280, 300 may be on top and/or one blade extension 220, 240 may be on top and one nozzle extension 280, 300 may be on top in any configuration.

The nozzle deflector 270 also may include a honeycomb or an amount of abradable material positioned under the nozzle extensions 280, 300 and in line with the bucket extensions 220, 240 as a nozzle abradable 330. The use of the abradable material prevents possible damage to the blade extensions 220, 240. The abradable material may be of a conventional nature. The nozzle abradable 330 may have different sizes and shapes. The abradable material may be applied directly to the nozzle cavity or attached to a plate that may be positioned within the nozzle cavity. Other types of attachment methods may be used herein.

In use, the leakage flow 190 may pass through the packing ring clearance 170. As the leakage flow 190 reaches the downstream side 310 of the nozzle 150, the overlap of the downstream nozzle extension 300 and the upstream bucket extension 220 creates resistance to the leakage flow 190 passing into the axial gap 195. Such increased resistance thus limits the leakage flow 190 therethrough. Further, the leakage flow 190 that does pass therethrough is now directed in the same direction as the main flow 180. As a result, intrusion losses caused by random mixing between the leakage flow 190 and the main flow 180 may be reduced. The reduction in both the volume of the leakage flow 190 and the random mixing caused by the intrusion of the leakage flow 190 into the main flow 180 thus promotes overall turbo-machine efficiency.

Various modifications and embodiments may be used herein. As is shown in FIG. 3, for example, the blade extensions 220, 240 may extend in close proximity to the nozzle abradable 330 of the nozzles 150. Alternatively, the spacing of the blade extensions 220 and the nozzle abradable 330 may be increased as is shown in FIG. 4 so as to provide for an extension gap 340 therebetween. Different sizes, spacings, and configurations may be used herein.

Likewise, the extensions themselves may have different shapes. As is shown in FIG. 5, the blade extensions 220, 240 may extend to a sharp tip 350 (similar to FIG. 9). As is shown in FIG. 6, a vertical tip 355 also may be used. The vertical tip 355 may extend upwardly or downwardly. Likewise, the blade extensions 220, 240 also may use a blade abradable 360 thereon as is shown in FIG. 7 (similar to FIG. 12). Similarly, the nozzles 150 may include a nozzle cavity 370 instead of the use of the nozzle abradable 330. Likewise, the nozzle extensions 280, 300 may extend into a downward flange 380 as is shown in FIG. 8, a blunt tip 390 as is shown in FIG. 9, a sharp vertical tip 400 (upward or downward) as shown in FIG. 10, or a sharp tip 410 as shown in FIG. 11. Many different configurations and designs may be used herein.

The flow deflector system 200 thus reduces the total leakage flow 190 and the losses caused by the intrusion of the leakage flow 190 into the main flow 180. Such reductions provide an increase in overall system efficiency without the use of expensive or complex brush seals. The flow deflector system 200 limits both radial and axial clearances and redirects the leakage flow 190 in the direction of the main flow 180. Moreover, overall blade loading may be improved. The flow deflector system 200 may be used with high pressure, intermediate pressure, and/or low pressure sections of the steam turbine 110 and otherwise. The flow deflector system 200 also may be used with any type of turbo-machinery 100.

FIG. 12 shows a further embodiment of a turbo-machine 100 as may be described herein. In this example, the turbo-machine 100 may be in the form of a compressor 420. The compressor 420 may use the flow deflection system 200 as described above with the bucket deflector 210 and the nozzle deflector 270. In this case, the nozzle 150 includes the upstream nozzle extension 280, the downstream nozzle extension 300, and the nozzle abradable 330. Likewise, the bucket deflector 210 includes the upstream bucket extension 220, the downstream bucket extension 240, and the bucket abradable 360.

In this example, the main flow 180 is compressed such that the pressure is increased as the flow moves downstream. The leakage flow 190 thus is leaked from the downstream side 250 of the bucket 120 and heads toward the upstream side 290. The leakage flow 190 thus may be blocked by the upstream nozzle extension 280 in combination with the downstream bucket extension 240 and the bucket abradable 360. Other components and other configurations may be used herein.

It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.