Patent Grant
9945232
The present invention relates to a profile for an airfoil of a gas turbine engine blade.
An overall efficiency of gas turbine engines utilizing rotating blades to extract energy from a flow of working fluid is greatly influenced by the exact shape of the blades airfoil. The exact shape of the airfoils determines an overall efficiency for the engine. Each airfoil's aerodynamic efficiency can be quantitatively analyzed using aerodynamic parameters such as an airfoil section pressure loss, suction surface diffusion, suction side leading edge overspeed, and pressure side leading edge overspeed etc. However, the aerodynamic environment within each stage of the engine varies, and thus it is unlikely that a single airfoil design will be the most efficient in every stage. Similarly, there is rarely a single airfoil profile that yields the most efficient rating for all of the aerodynamic parameters. As a result, airfoils may be specifically designed to meet the aerodynamic needs of the stage in which it operates. Once the aerodynamic needs of the selected stage are defined, a final airfoil design for the selected stage usually involves striking a balance between the aerodynamic parameters.
Often, however, the resulting balance may work best for one intended application, but subsequently the design may be implemented in other applications that have different parameters that affect aerodynamics, and hence the original design may not be optimal. In addition, knowledge of those in the art may improve over time, allowing for innovative design changes that improve aerodynamic efficiency within the intended application. For these, and any number of other reasons, there exists an ongoing need in the art to produce blades with airfoils having improved aerodynamic efficiency.
The invention is explained in the following description in view of the drawings that show:
An aerodynamically efficient airfoil substrate 10 disposed on an inner platform 12 is shown three dimensionally in
Nominal radial profiles 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, and 50 are substantially characterized by nominal Cartesian coordinates X and Y presented in tables 1-11 respectively. Each nominal profile is fully characterized by smooth, continuing curves that connect the nominal X and Y coordinates to form a smooth, continuous airfoil shape. An exterior surface of the airfoil is a smooth, continuing surface between the nominal profiles. The nominal X and Y coordinates are presented as unitless dimensions at ambient temperature, as opposed to operating temperature. In one embodiment the nominal X and Y coordinates represent inches. When the nominal coordinates represent inches, the airfoil substrate 10 may be suitable for use as part of a first stage turbine blade. However, the absolute value of the nominal X and Y coordinates may vary so long as the relative values are retained. In other words, the airfoil profile can be scaled up or down as desired. The coordinates provided below are for a baseline configuration. The nominal X and Y coordinates do not include any coating thickness, such as an MCrAlY, and/or TBC coating, but instead represent a substrate, such as a casting. The term “nominal” as used herein is meant to mean a design goal. As such, there is a manufacturing tolerance associated with casting the actual radial profiles manufactured to these nominal X and Y coordinates. An acceptable manufacturing tolerance for the cast substrate (only) is +/−0.015 inches in a direction normal to the exterior surface at that location.
−0.516103 *
0.310640 *
For example,
The bond coat 80 is shown as applied to the airfoil substrate 10 when the actual profile is disposed at the line representing the maximum outward variation 92, (i.e. when the airfoil substrate 10 is at the largest end of its manufacturing tolerance.) A thickness 96 of the bond coat 80 may vary from 0.006 inches up to 0.020 inches normal to the actual profile at that location. The TBC 82 is shown as applied a surface 98 of the bond coat 80. A thickness 100 of the TBC may also vary from 0.010 inches, and can reach up to 0.025 inches normal to the bond coat surface 98 at that location. Thus, a TBC surface 102 as shown in
A radial envelope 104 that spans from the maximum inward variation 90 of a bare airfoil substrate 10 to the TBC surface 102 shown therefore represents a range of actual profiles that may be manufactured using the nominal X and Y values in Tables 1-11 (i.e. based on the nominal X and Y values in Tables 1-11.) In particular, an inward boundary 106 of the radial envelope 104, defined by the maximum inward variation 90, represents the smallest airfoil substrate 10 that manufacturing tolerance will permit. Consequently, the inward boundary is 0.015 inches normal to the nominal profile 84 and inward at a given location. An outward boundary 108 of the radial envelope 104, defined by the TBC surface 102 in
The airfoil substrate 10 nominal profiles result in improved aerodynamics from prior art airfoil profiles. In addition, the airfoil substrate 10 may include a tip film cooling arrangement 120, shown in
The aerodynamics of the airfoil disclosed herein result in a relatively higher incidence tolerance, meaning improved robustness local to a leading edge of the airfoil. This allows for better airfoil aerodynamic performance with varying gas path flow inlet angles. Further, there is a relatively lower amount of aerodynamic losses on a suction side of the airfoil 10 due to reduced friction on the airfoil surfaces. In addition, there exists a relatively lower peak Mach number local to an airfoil trailing edge region which reduces trailing edge losses, thereby increasing the overall efficiency of the gas turbine engine.
Still further, the stacking of the airfoil disclosed herein generates a relatively lower mechanical load at an interface of the airfoil with an inner platform and at an interface of the airfoil with a root trailing edge region due to centrifugal loading of blade pull during operation. This results in increased fatigue life of these interfaces.
For at least the foregoing reasons, it can be seen that the inventors have created an airfoil profile that represents an improvement in that art.
While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.
This application is the US National Stage of International Application No. PCT/US2014/037657 filed May 12, 2014, and claims the benefit thereof. The International Application claims benefit of the 21 May 2013 filing date of U.S. provisional patent application No. 61/825,637. All applications are incorporated by reference herein. This application claims benefit of the 21 May 2013 filing date of U.S. provisional patent application No. 61/825,637, which is incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2014/037657 | 5/12/2014 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2015/020711 | 2/12/2015 | WO | A |
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| 20160102558 A1 | Apr 2016 | US |
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| 61825637 | May 2013 | US |
