阅读说明：本技术 激光热成像法 (Laser thermal imaging method ) 是由 D.C.布丁 A.A.库尔卡尼 于 2018-04-03 设计创作，主要内容包括：提供一种用于涡轮机部件的状态评估的无损方法。该方法包括提供生成光脉冲的激光器,该光脉冲加热涡轮机部件。然后捕获加热的涡轮机部件的红外图像。然后可针对涡轮机部件的特定特性对涡轮机部件进行分析。还提供一种用于涡轮机部件的无损状态评估的系统。(A non-destructive method for condition assessment of a turbine component is provided. The method includes providing a laser that generates a pulse of light that heats a turbine component. An infrared image of the heated turbine component is then captured. The turbine component may then be analyzed for specific characteristics of the turbine component. A system for non-destructive condition assessment of a turbine component is also provided.)

1. A non-destructive method for condition assessment of a turbine component 120, comprising:

providing a laser 180 that generates a pulse of light 130, the pulse of light 130 heating the turbine component 120;

capturing at least one infrared image of the heated turbine component 120; and

analyzing turbine component characteristics on the at least one image.

2. The method of claim 1, further comprising,

activating the laser 180 at a first specified wavelength;

focusing the laser 180 to flash a desired region of the surface of the turbine component 120 for a first pulse duration; and

capturing an image of the desired region of the surface of the turbine component 120;

deactivating the laser 180 at the specified wavelength;

activating the laser 180 at a second specified wavelength;

focusing the laser 180 to flash the desired region of the sub-surface of the turbine component 120 for a second pulse duration; and

capturing a second image of the desired region of the sub-surface of the turbine component 120,

wherein the first image contains a first set of data about the desired region of the surface of the turbine component 120 and the second image contains a second set of data about the desired region of the sub-surface of the turbine component 120, an

Wherein the first specified wavelength and the second specified wavelength are different.

3. The method of claim 1, further comprising,

activating the laser at a first specified wavelength;

focusing the laser to flash a desired region of the surface of the turbine component 120 for a first pulse duration; and

capturing an image of the desired region of the surface of the turbine component 120;

deactivating the laser at the specified wavelength;

activating the laser at a second specified wavelength;

focusing the laser to flash the desired region of the sub-surface of the turbine component 120 for a second pulse duration; and

capturing a second image of the desired region of the sub-surface of the turbine component 120,

wherein the first image contains a first set of data about the desired region of the surface of the turbine component 120 and the second image contains a second set of data about the desired region of the sub-surface of the turbine component 120, an

Wherein the first specified wavelength and the second specified wavelength are the same.

4. The method of claim 2, wherein the first specified wavelength is in a range of 4 microns to 9 microns.

5. The method of claim 2, wherein the second specified wavelength is in a range of 9 microns to 11 microns.

6. The method of claim 5, wherein the second specified wavelength is in a range of 9.5 microns to 10.5 microns.

7. The method of claim 2, wherein the analyzing comprises comparing the first set of data to known material parameters to assess damage to the surface.

8. The method of claim 2, wherein said analyzing comprises comparing said second set of data with known material parameters in order to assess damage to said sub-surfaces 210, 220.

9. The method of claim 1, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

wherein the capturing is performed by an infrared camera 160, the infrared camera 160 comprising an infrared sensor for detecting thermal energy radiated by the turbine component 120, an

Wherein the radiated thermal energy is transferred to the infrared sensor 150 to enable generation of the infrared image.

10. The method of claim 1, wherein the pulse duration of the laser 180 is in the range of 1 ms to 30 ms.

11. The method of claim 1, wherein the surface of the turbine component 120 comprises a thermal barrier coating 220 and the sub-surface of the turbine component 120 comprises a bond coat 210 and/or a substrate 200.

12. The method of claim 1, wherein the laser 180 is a laser flash lamp.

13. A system for non-destructive condition assessment of a turbine component, comprising:

a laser source 180, wherein the laser source 180 generates optical pulses 130 that heat the turbine component 120;

an infrared camera 160 comprising an infrared sensor 150 for detecting thermal energy radiated by the turbine component 120, wherein the radiated thermal energy is transmitted to the infrared sensor 150 to enable generation of the infrared image; and

the turbine component 120 is a part of a turbine,

wherein the infrared sensor 150 captures at least one image of the turbine component 120.

14. The system of claim 13, further comprising a mirror 140 that focuses the light pulses 130 onto the turbine component 120.

15. The system of claim 13, wherein the turbine component 120 comprises a thermal barrier coating 220 and/or a bond coating 210 overlying a substrate 200.

Technical Field

The present disclosure relates generally to methods and systems for non-destructive inspection of components, and more particularly, to methods and systems for non-destructive inspection of turbine components using laser thermal imaging.

Background

In many industrial applications, non-destructive testing methods are used to evaluate components without causing damage. One such application of non-destructive testing uses flash thermography to test components of a turbine engine, such as turbine blades or vanes, combustor baskets, or transition components. These components typically consist of a substrate coated with a thermal barrier coating that protects the substrate from the high temperatures and corrosive environments. For example, a coated gas turbine component may require testing to determine the thickness of the thermal barrier coating, or whether the coating has any cracks or delamination, i.e., a section where the coating layer has separated from the substrate. During normal operation of the turbine, severe cracking or delamination may cause the component to fail.

Inspection and testing of coated turbine components can currently be performed using the flash thermography method, which is a commonly used non-destructive testing method in which the component surface is heated by a light pulse typically lasting only a few milliseconds. Under normal conditions, the part will cool after flash heating because the heat deposited on the surface will flow to the cooler interior. However, internal anomalies in the test piece (such as voids, inclusions, delamination, moisture, or changes in thickness or density) can cause changes in the surface cooling rate. An infrared camera is then used to capture the infrared radiation emitted by the component to form a thermal imaging image. The internal anomalies referred to above will be visible in the thermographic image.

Although the flash thermography method enables non-destructive testing of components, there are some drawbacks to using a flash lamp as the light/heat source. For example, flash lamps are bulky and generate light/heat over a larger area of the component than the area of possible interest for the test sample. The heat generated decays over time and generates a significant amount of background noise, making it necessary to use filters to attenuate the signal in order to filter out this background noise. In addition, flash lamps require a significant amount of time to heat the components to the desired temperature. In contrast, the laser will quickly reach the desired temperature. Furthermore, information about the surface layer or thermal barrier coating of the turbine component is more readily obtained using flash thermography than with sub-surface layers. It is possible to obtain information about the subsurface layer using flash thermography, however, capturing much data during an examination requires a lot of time to analyze the captured data.

Therefore, there is a need for a non-destructive inspection method that will overcome these disadvantages.

Disclosure of Invention

Briefly described, aspects of the present disclosure relate to non-destructive methods and systems for condition assessment of turbine components.

A non-destructive method for condition assessment of a turbine component is provided. The method includes providing a laser that generates a pulse of light that heats a turbine component. An infrared image of the heated turbine component is then captured. The turbine component may then be analyzed for specific characteristics of the turbine component.

A system for non-destructive condition assessment of a turbine component is provided. The system includes a laser source that generates pulses of light that heat turbine components. An infrared camera comprising an infrared sensor for detecting thermal energy radiated by the turbine component is used to capture at least one image of the turbine component. The radiated thermal energy is transmitted to an infrared sensor to enable generation of an infrared image.

Drawings

Figure 1 shows a side partial cut-away view of an axial flow gas turbine,

figure 2 shows a laser thermal imaging system for imaging a turbine component,

FIG. 3 shows a coated turbine component for non-destructive evaluation using laser thermography, an

FIG. 4 shows a flow chart including the steps involved in a non-destructive method for condition assessment of a turbine component.

Detailed Description

To facilitate an understanding of the embodiments, principles and features of the present disclosure, they are explained below with reference to embodiments in illustrative embodiments. However, embodiments of the present disclosure are not limited to use in the described systems or methods.

The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that will perform the same or similar function as the materials described herein are intended to be included within the scope of embodiments of the present disclosure.

The laser can provide intense energy using short pulses, primarily due to the on/off switch. This significantly reduces the background intensity achieved with conventional flash sources (e.g., flashlights). Thus, the laser can be used to heat the surface of the material very quickly. In addition, the laser beam is highly controllable, with a very local focal region. Accordingly, methods for thermographic non-destructive testing of coated gas turbine components using a laser as a heat source are presented.

Multiple laser wavelengths are available so that the same test setup can be used to see the surface properties as well as the sub-surface properties of the part. Since the cover layer (also referred to as surface layer), such as the thermal barrier coating of the coated component, is transparent to certain wavelengths, the test sample information can be tailored such that at these wavelengths a subsurface temperature increase can be induced in the component. The temperature signal of the sub-surface layer can be digitally recorded by infrared imaging or active thermography.

Referring to FIG. 1, an industrial gas turbine engine 10 is shown. The engine 10 includes a compressor section 12, a combustor section 14, and a turbine section 16 arranged along a horizontal centerline axis 18. The combustor section 14 includes a plurality of combustors 28. Hot working gas is delivered from the combustor section 14 through to the turbine section 16.

As the gas travels along the hot gas path in the turbine 10, the sections of the turbine 10 exposed to the hot gas may include ceramic-based coatings that may be used to minimize exposure of the alkali metal of the component (such as the airfoil alkali metal) to high temperatures that may cause oxidation of the alkali metal. This coating may be a known Thermal Barrier Coating (TBC) applied over a bond coat formed on the alkali metal.

The turbine 10 is typically operated for long periods of time. During operation of the turbine 10, the TBC layer or both the TBC and bond coat may undesirably degrade or delaminate. This exposes the alkali metal to high temperatures, which may cause oxidation of the alkali metal. The turbine 10 is inspected at regular intervals to check for wear damage and other undesirable conditions that may have occurred to the various internal components. In addition, TBCs and bond coats are routinely inspected to determine the degree of degradation of the TBCs and bond coats (i.e., the remaining thickness of the layers) and other undesirable conditions before the turbine is shut down or assembled.

Referring now to FIG. 2, a system for non-destructive 100 state assessment of a turbine component 120 is shown, according to an embodiment. The laser source 180 generates light pulses 130 that heat the turbine component 120. The system includes an Infrared (IR) camera 160 having an infrared sensor 150, the infrared sensor 150 for detecting thermal energy in the infrared region of the electromagnetic spectrum. The detected thermal energy is radiated by the turbine component 120 and transmitted to the infrared sensor 150. The IR camera 160 is configured to capture IR images of the turbine component 120. Mirror 140 may be used to focus light pulses 130 from laser source 180 onto turbine component 120. In the illustrated embodiment, the turbine blades are shown as turbine components 120, however, those skilled in the art will appreciate that other turbine components may also be used. The IR sensor 150 is communicatively coupled to the computer 170 by an electrical or wireless connection.

The computer 170 may include a central processing unit, memory, and input/output interfaces. The computer is typically coupled through an I/O interface to a display for visualization and various input devices (such as a keyboard) that enable a user to interact with the computer 170. For example, a user may load a component 120 from the I/O interface into the computer 170 by identifying the type of component to be inspected. Using the identified component type, the computer 170 may automatically position the camera 160 according to preprogrammed positions stored in memory in order to capture the desired image.

As previously discussed, the turbine component 120, particularly a turbine blade or vane, may include a base layer, also referred to as a substrate, covered with a bond coat layer, to which a TBC is applied. FIG. 3 shows a cross-section of this coated turbine component 120. The substrate 200 is covered with a bond coat 210, and a thermal barrier coating 220, TBC, is applied to the bond coat 210. The substrate 200 may include a superalloy material.

Referring to fig. 1-4, a non-destructive method for condition assessment of a turbine component is also provided. A laser source 180 may be provided, the laser source 180 generating optical pulses 130 that heat the turbomachine component 120. An infrared image of a desired portion of the turbine component 120 may be captured. The characteristics of the turbine component 120 on the infrared image may then be analyzed. FIG. 3 illustrates an embodiment of a light pulse generated from a light source that is focused onto a coated turbine component. An infrared camera captures infrared radiation emitted from the coated turbine component and captures data in the form of infrared images.

To capture data about the thermal barrier coating 220 on the surface of the turbine component 120 and data about the sub-surface that may include the substrate 200 and/or bond coat 210, the method may be used by varying the wavelength of the laser source 180. For example, the laser source 180 may be activated at a first specified wavelength in order to capture data about the thermal barrier coating 220. The laser source 180 is then focused to flash a desired area of the surface of the turbine component 120 for a first pulse duration. The IR camera 160 may be used to capture a desired area of the surface of the turbine component 120. The laser source 180 may then be deactivated at the first specified wavelength. Next, to obtain data about the sub-surface that may include the bond coat 210 and/or the substrate 200, the laser source 180 may be activated at a second specified wavelength. The bond coat 210 and the substrate 200 generally have similar characteristics such that they heat similarly. The laser source 180 is then focused to flash the desired area of the surface of the turbine component 120 for a second pulse duration. The infrared camera 160 may be used to capture a desired area of a sub-surface of the turbine component 120. The laser source 180 may then be deactivated at a second designated wavelength.

The laser source 180 may be a laser flash lamp that provides duration pulses of broadband light of different wavelengths and high radiation intensity. The laser source 180 may emit wavelengths between 4 microns and 9 microns (considered mid-wave) and between 9 microns and 15 microns (considered long-wave). The surface or thermal barrier coating is opaque at wavelengths between 4 microns and 9 microns so that TBC properties can be captured in thermal images in this range. However, the material properties of the thermal barrier coating make the TBC transparent to laser wavelengths of about 9 to 11 microns. Thus, at laser wavelengths in the range of 9 microns to 11 microns, sub-surface or bond coat 210 and/or substrate 200 data can be captured in the thermal image. In an embodiment, the wavelength of the laser may be set to 9.5 to 10.5 microns. The duration of the light pulse 130 depends on the turbine characteristics to be analyzed, however, the duration of the light pulse 130 may be in the range of 1 ms to 30 ms. For certain regions, the first pulse duration and the second pulse duration may be the same in the case of uniform ceramic and metal thickness, or may be different in the case of large layer thickness differences.

The acquired data may be analyzed to assess the condition of the turbine component 120. The analysis may be accomplished by running an algorithm on the computer 170 to process the acquired pixelated data. The analysis may include examining thermal decay over time in the desired region, and may convert the spatiotemporal information into depth information. Evaluating the condition of the turbine component 120 may include comparing the acquired data for the desired area to known parameters to determine defects on the component, such as delamination. Defects or discontinuities will manifest themselves in the thermal imaging map as temperature changes that are different from the normal surface or subsurface states. Likewise, the condition of the turbine component 120 may be evaluated by measuring the thickness of the thermal barrier coating 220 on the substrate 200 of the turbine component 120. In an embodiment, the thickness of the thermal barrier coating 220 on the component 120 at different inspection intervals may be tracked over the life of the component.

Advantages of laser thermal imaging compared to flash thermal imaging include: better light source temperature control and shorter laser heating time periods reduce the amount of time required to inspect a component. Furthermore, the use of a laser provides flexibility in changing the wavelength so that the substrate can be more easily inspected simply by switching the wavelength of the laser. Thus, two inspections, namely, the inspection of the thermal barrier coating and the inspection of the substrate, can be performed at a time in the same test setup. It can be appreciated that the data collected on the turbine components can be stored and referenced for future use, such as statistical analysis of the turbine components. The statistical data may be used by a computer to track the health of the turbine component over time.

Although the embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the appended claims.