# US 5,706,647 A · Airfoil structure

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- Number: US 5,706,647 A
- Document ID: US5706647A
- Status: Granted
- Kind: A
- Application number: 08/339,527
- Filed: 1994-11-15
- Granted: 1998-01-13
- Earliest claimed: 1994-11-15
- Assignees: Solar Turbines Incorporated
- Inventors: Gary A. Frey; Christopher Z. Twardochleb
- Web page: https://patentgrep.com/patent/US5706647A

## CPC

- F01D 9/02: Nozzles; Nozzle boxes; Stator blades; Guide conduits {, e.g. individual nozzles (nozzle boxes F01D9/047)}
- F01D 5/141: {Shape, i.e. outer, aerodynamic form (F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147)}
- F05D 2200/11: Sum
- F05D 2300/21: Oxide ceramics
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

Past airfoil configurations have been used to improve aerodynamic performance and engine efficiencies. The present airfoil configuration further increases component life and reduces maintenance by reducing internal stress within the airfoil itself. The airfoil includes a chord and a span. Each of the chord and the span has a bow being summed to form a generally "C" configuration of the airfoil. The generally "C" configuration includes a compound bow in which internal stresses resulting from a thermal temperature gradient are reduced. The structural configuration reduces internal stresses resulting from thermal expansion.

## Claims

### Claim 1

An airfoil defining a chord having a preestablished chord length and a span having a preestablished radial span length, each of said chord and said span having a curvature which when summed, forms a generally "C" configuration defining a compound bow including an axial bow and a tangential bow and said tangential bow being about 20 percent of the preestablished radial span length.

### Claim 2 (depends on 1)

The airfoil of claim 1 wherein said chord length and said span length are equal.

### Claim 3 (depends on 2)

The airfoil of claim 2, wherein said axial bow is about 10 percent of the preestablished radial span length.

### Claim 4

An airfoil defining a chord having a preestablished chord length and a span having a preestablished radial span length, each of said chord and said span having a curvature which when summed, forms a generally "C" configuration defining a compound bow including an axial bow and a tangential bow and said tangential bow being about twice the axial bow.

### Claim 5

A gas turbine engine having a compressor section, a combustor section and a turbine section, comprising:
said turbine section including a nozzle and shroud assembly being supported within the engine to a mounting structure having a preestablished rate of thermal expansion;
said nozzle and shroud assembly having a preestablished rate of thermal expansion being less than that of the mounting structure;
said nozzle and shroud assembly including an inner annular ring member, an outer annular ring structure and a plurality of airfoils being positioned therebetween; and
said plurality of airfoil defining a chord having a preestablished chord length and a span having a preestablished radial span length, each of said chord and said span defining a curvature which when summed forms a generally "C" configuration defining a compound bow including an axial bow and a tangential bow and said tangential bow is about 20 percent of the preestablished radial span length.

### Claim 6 (depends on 5)

The gas turbine engine of claim 5, wherein said axial bow is directed toward the combustor section.

### Claim 7 (depends on 5)

The gas turbine engine of claim 5, wherein said axial bow is about 10 percent of the preestablished span length.

### Claim 8 (depends on 5)

The gas turbine engine of claim 5 wherein said plurality of airfoils are fixedly positioned between the inner annular ring member and the outer annular ring structure.

### Claim 9 (depends on 5)

The gas turbine engine of claim 5 wherein said nozzle and shroud assembly includes a plurality of segments.

### Claim 10

A gas turbine engine having a compressor section, a combustor section and a turbine section, comprising:
said turbine section including a nozzle and shroud assembly being supported within the engine to a mounting structure having a preestablished rate of thermal expansion;
said nozzle and shroud assembly having a preestablished rate of thermal expansion being less than that of the mounting structure;
said nozzle and shroud assembly including an inner annular ring member, an outer annular ring structure and a plurality of airfoils being positioned therebetween; and
said plurality of airfoils defining a chord having a preestablished chord length and a span having a preestablished radial span length, each of said chord and said span defining a curvature which when summed forms a generally "C" configuration defining a compound bow including an axial bow and a tangential bow and said tangential bow is about twice the axial bow.

### Claim 11 (depends on 6)

The gas turbine engine of claim 6 wherein said plurality of airfoils are fixedly positioned between the inner annular ring member and the outer annular ring structure.

### Claim 12 (depends on 6)

The gas turbine engine of claim 6 wherein said nozzle and shroud assembly includes a plurality of segments.