TURBOMACHINE COMPONENT DAMPING STRUCTURE AND METHOD OF DAMPING VIBRATION OF A TURBOMACHINE COMPONENT

Abstract

A turbomachine component includes a main body having a surface, and a damping structure mounted to the surface of the main body. The damping structure is formed from a material having a temperature dependent damping characteristic.

Description

BACKGROUND OF THE INVENTION

Exemplary embodiments of the present invention relate to the art of turbomachines and, more particularly, to a damping structure for a turbomachine component.

Turbomachines include a multitude of components, many of which rotate at high speed during operation. The operation of the turbomachine subjects many of the turbomachine components to stresses resulting from vibration. This includes compressor components, hot gas path (HGP) components, combustor sections and turbine components. Stresses resulting from vibration cause fatigue that shortens operational life of turbomachine components.

BRIEF DESCRIPTION

In accordance with an exemplary embodiment of the invention, a turbomachine component includes a main body having a surface, and a damping structure mounted to the surface of the main body. The damping structure is formed from a material having a temperature dependent damping characteristic.

In accordance with another exemplary embodiment of the invention, a method of damping vibration of a turbomachine component including mounting a damping structure to a surface of the turbomachine component. The damping structure is formed from a material having a temperature dependent damping characteristic.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a turbine bucket including a damping structure in accordance with an exemplary embodiment of the invention.

DETAILED DESCRIPTION

Referring to FIG. 1, a turbine component, shown in the form of a turbine bucket, constructed in accordance with exemplary embodiments of the invention is indicated generally at 2. Turbine bucket 2 is formed from a high temperature alloy such as, but not limited to, alloys of nickel and includes an airfoil or blade portion 4 and a base portion 6. Blade portion 4 includes a main body 10 having a first end section 12 that extends to a second end section 14 through an intermediate or airfoil section 16. Airfoil section 16 includes a suction side surface 18 and a pressure side surface 20. Base portion 6 includes a main body member 30 having a first end portion 32 that extends to a second end portion 34 through an intermediate portion 36. Intermediate section 36 includes a first angel wing 40 that defines a first trench cavity 42 and a second, opposing angel wing 44 that defines a second trench cavity 46. Turbine bucket 2 is configured to be mounted to a rotor disk (not shown) adjacent a plurality of additional turbine buckets to form a turbine section.

In accordance with the exemplary embodiment shown, turbine bucket 2 includes a damping structure 60 secured to pressure side surface 20 of airfoil section 16. As will become more fully evident below, damping structure 60 provides vibration damping characteristics when applied to airfoil section 16. In accordance with the exemplary embodiment, damping structure 60 is formed from a material having temperature dependent vibration damping characteristics. More specifically, damping structure 60 includes a first damping characteristic at a first temperature and a second damping characteristic at a second temperature. The first damping characteristic changes to the second damping characteristic at a damping transition temperature. In this manner, turbine bucket 2 is provided with a first level of damping during start up and, as operating temperatures and speeds increase, damping structure 60 passes through the transition temperature to provide an increased level of vibration damping.

In accordance with one aspect of the exemplary embodiment, damping structure 60 is formed from a stainless steel alloy having a damping transition temperature at about 900° F. (482.2° C.). Damping structure 60 is secured to a surface of, for example airfoil section 16. The amount of damping provided by damping structure 60 is dependent upon the temperature at which a vibratory response occurs. That said, below about 900° F. (482.2° C.) the damping is at a first level and above about 900° F. (482.2° C.), damping is at a second, higher level. The above described system provides a 2-14 times increase in damping to turbine bucket 2. Of course it should be realized that the above described range is but an exemplary embodiment of the invention. Other materials having similar or different damping characteristics could also be employed. The particular materials employed depend upon desired damping characteristics at particular operating parameters/temperatures of the turbomachine.

At this point it should be understood that while damping structure 60 is described as being formed from stainless steel, other alloys, including glass alloys, that have a damping transition temperature in a range of about 800° F.-1400° F. (426.6° C.-760° C.) can also be employed. It should also be understood that the particular mounting location of damping structure 60 can also vary. That is, instead of covering an entire airfoil section, damping structure 60 can be selectively applied in high strain areas for maximum stress reduction. In addition, a thermal barrier coating 70 can be applied over an interface between damping structure 60 and airfoil section 16 to provide protection from spallation and oxidation.

Damping structure 60 can be applied to the desired turbomachine component by a number of appropriate joining techniques depending on the materials to be joined. For example, damping structure 60 can be applied to airfoil section 16 using welding, brazing or plasma spray techniques. More over, damping structure 60 can be applied in a single layer, multiple layers or combined with a damping structure having damping properties tied to structural characteristics of the damping material such as taught by co-pending U.S. patent application Ser. No. 11/844,462, entitled “Structures for Damping of Turbine Components” filed on Aug. 24, 2007 incorporated herein by reference in the entirety.

In general, this written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of exemplary embodiments of the present invention if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. A turbomachine component comprising:

a main body having a surface; and

a damping structure mounted to the surface of the main body, the damping structure formed from a material having a temperature dependent damping characteristic.

2. The turbomachine component according to claim 1, wherein the damping structure includes a first damping characteristic at a first temperature and a second damping characteristic at a second temperature, the second temperature being distinct from the first temperature.

3. The turbomachine component according to claim 2, wherein the damping structure includes a damping transition temperature, the damping transition temperature being between the first and second temperatures.

4. The turbomachine component according to claim 3, wherein the damping transition temperature is in a range between about 800° F. (426.6° C.) to about 1400° F. (760° C.).

5. The turbomachine component according to claim 4, wherein the damping transition temperature is about 900° F. (482.2° C.).

6. The turbomachine component according to claim 1, wherein the damping structure comprises stainless steel.

7. The turbomachine component according to claim 1, wherein the turbomachine component includes at least one turbine bucket, the damping structure being mounted to a surface of the at least one turbine bucket.

8. The turbomachine component according to claim 1, wherein the damping structure is mounted to a portion of the surface of the at least one turbine bucket.

9. The turbomachine component according to claim 1, wherein the damping structure is mounted to the surface of the turbomachine component by one of welding, brazing and plasma spraying.

10. A method of damping vibration of a turbomachine component, the method comprising:

mounting a damping structure to a surface of the turbomachine component, the damping structure formed from a material having a temperature dependent damping characteristic.

11. The method of claim 10, wherein the damping structure is mounted to the surface of the turbomachine component by one of welding, brazing and plasma spraying.

12. The method of claim 10, further comprising: damping vibration at a first level when the turbomachine component is at a first temperature, and damping vibration at a second level when the turbomachine component is at a second temperature, the second temperature being distinct from the first temperature.

13. The method of claim 12, wherein damping the vibration at the first level occurs when the turbomachine component in a range between about 800° F. (426.6° C.) to about 900° F. (482.2° C.).

14. The method of claim 12, wherein damping the vibration at the second level occurs when the turbomachine component in a range between about 900° F. (482.2° C.) to about 1400° F. (760° C.).

15. The method of claim 10, wherein mounting the damping structure to the surface of the turbomachine component comprises mounting the damping structure to a turbomachine bucket.

16. The method of claim 10, wherein mounting the damping structure to a surface of the turbomachine component comprises mounting a material including stainless steel to the surface of the turbomachine component.