Over-cambered stage design for steam turbines

• US 5,326,221 A
• Filed: 08/27/1993
• Issued: 07/05/1994
• Est. Priority Date: 08/27/1993
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Berrahou, Philip F., Amyot, Joseph W., Orlando, Robert J., Ruggles, Stephen G.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): LARSON, JAMES
• Application Number:
  US08/112,365
• Time in Patent Office: 312 Days
• Field of Search: 416/223 A, 415/181, 415/191
• US Class Current: 415/191
• 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 5/145 Means for influencing boundary layers or secondary circulations for compressors F04D29/68
• CPC Class Codes: F05D 2240/301 Cross-sectional characteristics

Abstract

Steam turbine nozzle blades and buckets are profiled in accordance with Tables I and II or multiples of the X,Y and R coordinates of the charts. The profiles of the nozzle blades impose a parabolic flow distribution at the throat and the buckets accommodate the incoming flow. The nozzle blades and buckets are over-cambered at their roots and tips to constrict flow from the roots and tips into the mid-regions of the blades and buckets. Improved aerodynamic efficiencies are obtained by directing the flow away from the end walls of the blades and buckets toward the efficient mid-region of the blades and buckets whereby flow velocity and angle leaving the nozzle has a non-linear distribution and the bucket velocity leaving angles are similarly non-linear.

Claims

1. A nozzle for a steam turbine having a pair of adjacent blades having leading and trailing edges, blade bodies therebetween, and root and tip portions with a mid-region therebetween, said adjacent blades defining a throat therebetween measured by a series of straight lines extending from the trailing edges of a blade to the closest adjacent surface along the body of the adjacent blade and defining a pitch in the circumferential spacing between blades, the ratios of the throat to the pitch at successive profiles along said blades increasing from the root portions toward a mid-blade region and then decreasing from the mid-blade region to the tip portion, the blades being one of nozzle or bucket blades.

2. A nozzle for a steam turbine having a blade profile in accordance with Table I.

3. A stage for a steam turbine having a plurality of nozzles each having a blade profile according to claim 2 and a plurality of buckets each having a bucket profile in accordance with Table II.

4. A nozzle for a steam turbine having nozzle blade profiles in accordance with Table I scaled by multiplying X,Y and R coordinates thereof by a predetermined number.

5. A stage for a steam turbine having a plurality of nozzles each having a blade profile according to claim 4 and a plurality of buckets each having a bucket profile in accordance with Table II scaled by multiplying X,Y and R coordinates thereof by said predetermined number.

6. A bucket for a steam turbine having a bucket profile in accordance with Table II.

7. A bucket for a steam turbine having a bucket profile in accordance with Table II scaled by multiplying X,Y and R coordinates thereof by a predetermined number. blades being one of nozzle or bucket blades.