Bucket for next-to-the-last stage of a turbine

• US 5,445,498 A
• Filed: 06/10/1994
• Issued: 08/29/1995
• Est. Priority Date: 06/10/1994
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Williams, John C., Ruggles, Stephen G.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): LARSON, JAMES
• Application Number:
  US08/258,042
• Time in Patent Office: 445 Days
• Field of Search: 416/190, 416/191, 416/193 R, 416/223 A, 416/DIG. 2
• US Class Current: 416/191
• CPC Class Codes: F01D 5/141 Shape, i.e. outer, aerodynamic form F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147
• CPC Class Codes: F01D 5/22 Blade-to-blade connections, e.g. for damping vibrations
• CPC Class Codes: F05D 2240/301 Cross-sectional characteristics

Abstract

A next-to-the-last stage steam turbine bucket has a profile according to the table set forth in the specification. The buckets also include continuous couplings at the bucket mid-point including nubs on each bucket projecting from opposite sides thereof in generally circumferentially extending directions. A sleeve is disposed between each pair of adjacent buckets and has open opposite ends for receiving the nubs of the adjacent buckets. The cross-sections of the nubs and open ends of the sleeve are generally complementary and non-circular to prevent sleeve rotation during turbine operation. The buckets have a continuous cover including cover elements having tenons projecting from opposite sides for reception in corresponding openings in the tips of adjacent buckets.

Claims

1. A bucket for a steam turbine having a profile in accordance with Table I inclusive as set forth in the specification.

2. A plurality of buckets, each constructed in accordance with claim 1, and spaced circumferentially about an axis of a turbine wheel, said buckets having tips, and covers continuously coupling said tips one to the other about said axis.

3. A plurality of buckets according to claim 2 wherein each said cover includes a first tenon projecting toward an admission side of the turbine wheel and a tenon projecting toward the discharge side of the turbine wheel, the tips of adjacent buckets having openings for receiving the tenons for coupling the tips one to the other.

4. A plurality of buckets according to claim 3 wherein each tenon on a bucket admission side is peened over to provide a rigid connection with an adjoining bucket tip and the tenon on a bucket discharge side has an opening in its end enabling the tenon to be flared, affording a loose connection between the cover and adjoining bucket.

5. A plurality of buckets according to claim 3 including a continuous sealing rib extending radially outwardly on the surface of each bucket tip and said cover.

6. A plurality of buckets, each constructed in accordance with claim 1, and spaced circumferentially about an axis of a turbine wheel, said buckets having intermediate portions, each intermediate portion of each bucket including a nub projecting in a generally circumferential direction toward an adjacent bucket, a sleeve open at opposite ends receiving the nubs of adjacent buckets affording a continuous coupling at the intermediate portions of the buckets.

7. A plurality of buckets according to claim 6 wherein each sleeve has an axis, the ends of the sleeves being formed at an angle to the axis other than 90°

to permit the sleeves to rock as the relative positions of the adjacent nubs change during operation of the turbine.

8. A plurality of buckets according to claim 6 wherein each nub has a non-circular cross-section and the sleeve has a generally corresponding non-circular cross-section to preclude sleeve rotation during turbine operation.

9. A plurality of buckets according to claim 6 wherein the buckets have tips and means for continuously coupling said tips one to the other about the turbine axis.