High efficiency stator for the first phase of a gas turbine

• US 7,387,490 B2
• Filed: 04/07/2005
• Issued: 06/17/2008
• Est. Priority Date: 04/09/2004
• Status: Expired due to Fees

• Current Assignee: Nuovo Pignone SPA (Nuovo Pignone International SRL)
• Original Assignee: Nuovo Pignone SPA (Nuovo Pignone International SRL)
• Inventors: Noera, Federico
• Primary Examiner(s): EDGAR, RICHARD A
• Application Number:
  US11/100,615
• Publication Number:
  US 20050241287A1
• Time in Patent Office: 1,167 Days
• Field of Search: None
• 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 9/02 Nozzles; Nozzle boxes; Stator blades; Guide conduits , e.g. individual nozzles nozzle boxes F01D9/047
• CPC Class Codes: F01D 9/041 using blades F01D5/148 takes precedence
• CPC Class Codes: F05D 2220/3212 the first stage of a turbine
• CPC Class Codes: F05D 2230/90 Coating; Surface treatment manufacture with deposition of material F05D2230/30
• CPC Class Codes: F05D 2250/70 Shape
• CPC Class Codes: F05D 2250/74 given by a set or table of xyz-coordinates
• CPC Class Codes: Y10S 416/02 Formulas of curves

Abstract

A stator for the first phase of a low-pressure turbine has a series of blades each defined by coordinates of a discreet combination of points, in a Cartesian reference system (X, Y, Z) wherein the axis (Z) is a radial axis intersecting the central axis of the turbine. The profile of each blade is identified by means of a series of closed intersection curves between the profile itself and planes (X, Y) lying at distances (Z) from the central axis. Each blade has an average throat angle defined by the cosine arc of the ratio between the average throat length at mid-height of the blade and the circumferential pitch evaluated at the radius of the average throat point; the average throat angle ranges from 57° to 60°.

Claims

1. A stator for the first phase of a low-pressure turbine having a series of blades each defined by coordinates of a discreet combination of points, in a Cartesian reference system (X,Y,Z), wherein the axis (Z) is a radial axis intersecting the central axis of the turbine, the profile of each blade being identified by means of a series of closed intersection curves between the profile itself and planes (X,Y) lying at distances (Z) from the central axis, each blade having an average throat angle defined by the cosine arc of the ratio between the average throat length at mid-height of the blade and the circumferential pitch evaluated at the radius of the average throat point, wherein said average throat angle ranges from 57°

to 60°

, and further wherein said closed curves are defined according to Table I, whose values refer to a room temperature profile and are divided by the value, expressed in millimeters, of the axial chord referring to the most external distance (Z) of the blade (1).

2. The stator according to claim 1, wherein said average throat angle is 58.5°

.

3. The stator according to claim 1, wherein each of said closed curves has a throat angle defined by the cosine arc of the ratio between the throat length and the circumferential pitch, evaluated at the radius corresponding to the distance (Z) from the central axis of the closed curve itself, and characterized in that each blade has a distribution of throat angles along the height (Z) of the blade, said distribution with respect to said average throat angle having a shift ranging from +1°

to −

1°

.

4. The stator according to claim 1, wherein the profile of each blade has a tolerance of +/−

0.3 mm in a normal direction with respect to the profile of the blade itself.

5. The stator according to claim 1, wherein the profile of each blade includes an anti-wear coating.

6. The stator for the first phase of a low-pressure turbine according to claim 5, wherein said coating has a thickness ranging from 0 to 0.5 mm.