Method and system for detecting a crack on a turbomachine blade

Abstract

Method (400) for detecting a possible crack in a blade (110, 115) located in a compressor section (105) of a turbomachine (100), wherein the method (400) comprises: Providing a turbomachine (100) comprising: a compressor section (105) wherein the compressor section (105) has several blades (110, 115); and an acoustic detection device (170) configured to monitor the compressor section (105) while the turbomachine (100) is operating, wherein the acoustic detection device (170) receives acoustic data (410) relating to the several blades (110, 115); Using the acoustic data to generate an acoustic signature (420) corresponding to the multiple scoops (110, 115); Retrieving a related acoustic signature from a storage device (430); Comparing the acoustic signature with the related acoustic signature (420, 430); and Determine whether the acoustic signature is within a permissible range (420); where a finding that the acoustic signature is outside the permissible range indicates a probability of a crack in at least one of the several blades (110, 115); characterized by the fact that the related acoustic signature is derived from at least one other turbomachine (100) and / or a fleet of turbomachines.

Description

BACKGROUND TO THE INVENTION

[0001] The present invention relates generally to a compressor section of a turbomachine and, more particularly, to a method for detecting a possible crack on a blade of the compressor section.

[0002] Turbomachinery, such as, but not limited to, air-breathing combustion turbines, has a compressor section with multiple blades arranged in multiple rotor stages. During normal operation, the tip speed of these blades can be sonic or supersonic. A crack in one blade can seriously damage the entire turbomachinery if that blade detaches during normal operation.

[0003] Currently known crack detection methods are typically performed through a static inspection process while the turbomachinery is out of operation. However, these methods require the turbomachinery to be shut down, which turbine operators are reluctant to stop.

[0004] DE 41 27 395 A1 describes a method and system for detecting a possible crack in a turbine blade, which have the features of the preambles of independent claims 1 and 5. A sound spectrum of the turbine blade is generated and recorded on the turbine casing by means of a sound sample and compared with a stored reference spectrum from the original state of the turbine.

[0005] US 2002 / 0 059 831 A1 describes a system and method for the acoustic inspection of a bladed impeller, wherein a blade of the rotating impeller is subjected to a mechanical excitation, an electrical signal is generated from the recorded acoustic response and a frequency response is determined therefrom by FFT, characteristic frequencies of the frequency response are compared with those of an ideal frequency response and as a result of the comparison defects, e.g. cracks, are detected in the blade.

[0006] US 2002 / 0 157 471 A1 describes a system and method for monitoring the condition of a thermal protection coating on guide or rotor blades of a turbine by monitoring the change in the amplitude of the electrical signals obtained from received acoustic signals in the time domain and / or by monitoring the change in the amplitude of the sound waves at specific frequencies by means of a spectrum analyzer.

[0007] JP S62-22 060 A describes a system and method for detecting cracks in a turbine blade based on recorded sound waves and a comparison with normal or standard measured values.

[0008] There remains a need for an improved method for detecting a crack in a rotor blade. The method should be capable of detecting a potential crack while the turbomachine is operating, allowing the turbomachine to operate longer between out-of-service inspections for cracking in the blade. BRIEF DESCRIPTION OF THE INVENTION

[0009] In one embodiment of the present invention, a method for detecting a possible crack on a blade disposed in a compressor section of a turbomachine is provided, the method comprising: providing a turbomachine comprising: a compressor section, wherein the compressor section has a plurality of blades, and an acoustic detection device configured to monitor the compressor section while the turbomachine is operating, wherein the acoustic detection device receives acoustic data related to the plurality of blades; using the acoustic data to generate an acoustic signature corresponding to the plurality of blades; retrieving a related acoustic signature from a storage device; comparing the acoustic signature with a related acoustic signature;and determining whether the acoustic signature is within an acceptable range; wherein a determination that the acoustic signature is outside the acceptable range indicates a likelihood of a crack in at least one of the plurality of blades. According to the invention, the related acoustic signature is derived from at least one other turbomachine and / or a fleet of turbomachines.

[0010] In another embodiment of the present invention, a system is provided for detecting the presence of a crack on a rotor blade within a gas turbine, the system comprising: a gas turbine having a plurality of rotor blades; an acoustic detection device configured to monitor operation of the gas turbine, the acoustic detection device receiving acoustic data relating to the plurality of blades and disposed adjacent to the compressor section; a control system, the control system performing the steps of: using the acoustic data to generate an acoustic signature corresponding to the plurality of blades; retrieving a related acoustic signature from a storage device; comparing the acoustic signature to a related acoustic signature; and determining whether the acoustic signature is within an acceptable range.According to the invention, the related acoustic signature is derived from at least one other gas turbine and / or a fleet of gas turbines. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a schematic representation of an environment in which an embodiment of the present invention may operate. Fig. Figure 2 shows a schematic cross-sectional view of an example of a rotating blade of the Fig. 1 illustrated compressor section. Fig. 3 is a diagram illustrating an example of a frequency response curve generated according to an embodiment of the present invention. Fig. 4 shows a block diagram illustrating a method for monitoring a compressor of a turbomachine according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention has the technical effect of monitoring an operating turbomachine for the possibility of a crack in a turbomachine blade. The turbomachine may take the form of an air-breathing combustion turbine, such as, but not limited to, a heavy-duty gas turbine, an aeroderivative gas turbine, an aircraft engine, or any other engine, powerplant, or other machine or equipment that includes a compressor, and the like. Furthermore, although embodiments of the present invention are described with respect to a gas turbine, the application of the present invention is not limited to a gas turbine. Embodiments of the present invention may be applied to other machines that have multiple blades that may not be described herein.Although embodiments of the present invention are described with respect to a compressor section blade in a turbomachinery application of the present invention, the present invention is not limited to a turbomachinery having a compressor section with multiple blades. Embodiments of the present invention may be applied to turbomachinery that does not have a compressor section, such as, but not limited to, a steam turbine or the like.

[0012] Example embodiments are described in detail herein. However, specific structural and functional details disclosed herein are merely representative for the purpose of describing example embodiments. However, example embodiments may be embodied in many alternative forms and should not be construed as limited solely to the embodiments disclosed herein.

[0013] While exemplary embodiments are susceptible to various modifications and alternative forms, the embodiments thereof are illustrated in the figures by way of example and described in detail herein. It should be understood, however, that there is no intention to limit the exemplary embodiments to the specific forms disclosed; on the contrary, the exemplary embodiments are intended to include all modifications, equivalents, and alternatives falling within the spirit and scope of the exemplary embodiment.

[0014] It should be understood that although the terms "first", "second", etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used merely to distinguish one element from another. For example, a first element could be referred to as a second element, and similarly, a second element could be referred to as a first element, without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes each element and all combinations of one or more of the associated enumerated elements.

[0015] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the example embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is further to be understood that the terms "comprises," "having," "includes," and / or "containing," as used herein, specify the presence of the stated features, integers, steps, operations, elements, and / or components, and do not preclude the presence or inclusion of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0016] It should also be noted that in some alternative implementations, the mentioned functions / effects may occur in a different order than that mentioned in the figures. For example, two consecutive functions / effects may be performed substantially simultaneously according to the figures, or they may sometimes be performed in the reverse order depending on the functionality or operations involved.

[0017] Reference will now be made to the figures, in which different reference characters designate like parts throughout the several views. Fig. Figure 1 shows a schematic representation of an environment in which an embodiment of the present invention may operate. Embodiments of the present invention may include a turbomachine 100 that generates acoustic data 175 that is received by a crack detection system 180. Stored acoustic data 185 may also be sent to the crack detection system 180, which may provide an indication or notification 190 regarding the possibility of a crack in at least one blade of the compressor section 105.

[0018] In Fig. 1, the turbomachine in the form of a gas turbine 100 includes: a compressor section 105; a combustion system 130; and a turbine section 150. Generally, the compressor section 105 includes a plurality of stationary vanes 110 and rotor blades 115 structured to compress air drawn in at the inlet section 125. The compressor section 105 may further include at least one acoustic detection device 170. Here, the acoustic detection device 170 may, as a non-limiting example, take the form of a microphone or other sound wave detecting device. Embodiments of the present invention may be applied to a compressor section 105 integrated with a fan or turbofan section (in Fig. 1 not illustrated).

[0019] The combustion section 130 may include a plurality of canned combustors 135 (only one of which is illustrated), a plurality of fuel nozzles 140, and a plurality of transition sections 145 (only one of which is illustrated). The plurality of canned combustors 135 may be connected to a fuel source (not illustrated). Within each canned combustor 135, compressed air is received from the compressor section 105 and mixed with fuel received from the fuel source. The air and fuel mixture is ignited, creating a working fluid. The working fluid flows substantially downstream from the aft end of the plurality of fuel nozzles 140 through the transition section 145 into the turbine section 150.

[0020] The turbine section 150 may include a plurality of rotating components 155, a plurality of stationary components 160, and a plurality of impeller gap regions 165. Generally, the turbine section 150 converts the working fluid into mechanical torque used to drive a load (not illustrated).

[0021] Fig. 2 shows a schematic cross-section showing an example of a rotor blade 115 of the Fig. 1 illustrated compressor section 105. Fig. Figure 2 provides general information regarding certain dimensional characteristics of a typical blade 115 that may be located within a stage of the compressor section 105. The cross-section illustrates a portion of the blade 115 near the radially outer tip that experiences sonic or supersonic speeds. The angle θ represents a stagger angle of the blade 115 in the particular section illustrated. The stagger angle lies between the true chord 119 in the section and the rotational axis XX of the gas turbine 100. As illustrated, "t" denotes the thickness at a location 120 and represents the leading edge thickness of the section. Location 120 is a location on the blade 115 that is indicative of the blade thickness at which the airflow 117 engages.

[0022] When the rotor blades 115 operate at supersonic tip speeds, shock waves are generated. The shock waves are the result of small differences in the geometry of adjacent rotor blades 115. The shock waves generate an acoustic signature commonly referred to as multiple pure tones (MPT). An MPT acoustic signature is created by acoustic tones generated at integer multiples of the shaft speed. The amplitude of these acoustic tones is unique for the particular stagger angle of each rotor blade 115 within each stage of the compressor section 105.

[0023] Embodiments of the present invention provide a method for determining whether the stagger angle is changing, which may indicate the presence of a crack on the blade 115. Embodiments of the present invention may monitor the MPT signature of the compressor section 105 and automatically detect a change in the MPT signature. This change may indicate that the stagger angle of at least one blade 115 is changing, suggesting that a crack is developing in the blade 115. Embodiments of this method may monitor the compressor section 105 while the gas turbine 100 is operating.

[0024] Fig. 3 shows a diagram 300 illustrating an example of a frequency response curve generated according to an embodiment of the present invention. Fig. 3 illustrates how an MPT signature may be generated according to an embodiment of the present invention. Frequency band amplitude 305 represents shock wave data acquired at a 1 / 3 octave band level. Acoustic signature 310 represents shock wave data acquired at a narrower spectrum of frequency band amplitude. These shock waves may propagate upstream through inlet section 125, resulting in acoustic signature 310. The narrower frequency band amplitude spectrum associated with a specific acoustic signature 310 may provide narrowband tones that are highly sensitive to changes in stagger angle. Frequency band amplitude 305 and acoustic signature 310 are typically unique to geometric variations between blades and the stagger angle among the rotor blades 115.

[0025] The present invention can generate a reference MPT signature for a new or "healthy" (healthy) gas turbine 100 in real time while the gas turbine 100 is operating. Changes from this reference MPT signature may be indicative of a change in the geometry and stagger angle of the blade 115. As a crack develops, the deflection of the tip of the blade 115 may change, thereby changing the MPT signature.

[0026] As will be understood, the present invention may be implemented as a method, system, or computer program product. Accordingly, the present invention may take the form of an embodiment implemented entirely in hardware, an embodiment implemented entirely in software (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware features, all of which are generally referred to herein as a "circuit," "module," or "system." Further, the present invention may take the form of a computer program product on a computer-usable storage medium having computer-usable program code embedded in the medium.As used herein, the terms "software" and "firmware" are interchangeable and include any computer program stored in memory for execution by a processor, including RAM, ROM, EPROM, EEPROM, and non-volatile RAM (NVRAM). The foregoing types of memory are merely exemplary and not limiting as to the types of memory that may be used to store a computer program.

[0027] Any suitable computer-readable medium may be used. The computer-usable or computer-readable medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor-based system, device, apparatus, or propagation medium. More specific examples (a non-exhaustive list) of computer-readable media would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a transmission medium such as those supporting the Internet or an intranet, or a magnetic storage device.It should be noted that the computer-usable or computer-readable medium could even be paper or other suitable medium on which the program is printed, since the program can be electronically captured, for example, by optically scanning the paper or other medium, subsequently compiled, interpreted, or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory. In the context of this document, a computer-usable or computer-readable medium can be any medium that can contain, store, transmit, propagate, or transport the program for use by or in connection with the system, device, or apparatus for executing instructions.

[0028] The term processor, as used herein, refers to central processing units, microprocessors, microcontrollers, reduced instruction set circuits (RISCs), application specific integrated circuits (ASICs), logic circuits, and any other circuitry or processors capable of performing the functions described herein.

[0029] The computer program code for carrying out the operations according to the present invention may be written in an object-oriented programming language, such as Java7, Smalltalk or C++ or the like. However, the computer program code for carrying out the operations according to the present invention may also be written in conventional procedural programming languages, such as the "C" programming language or a similar language. The program code may be executed entirely on the user computer, partially on the user computer, as a stand-alone software package, partially on the user computer and partially on a remote computer, or entirely on the remote computer. In the latter case, the remote computer may be connected to the user computer via a local area network (LAN) or a wide area network (WAN), or the connection may be to an external computer (e.g.via the Internet using an Internet service provider).

[0030] The present invention is described below with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of the blocks in the flowchart illustrations and / or block diagrams, may be implemented by computer program instructions.These computer program instructions may be supplied to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine such that the instructions, when executed by the processor of the computer or other programmable data processing device, produce means for implementing the functions / effects specified in the flowchart and / or the block or blocks of the block diagram.

[0031] These computer program instructions may further be stored in a computer-readable memory. These instructions may instruct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means that implement the functions / effects specified in the flowchart and / or the block or blocks of the block diagram. The computer program instructions may further be loaded onto a computer or other programmable data processing device. These instructions may cause the computer or other programmable device to perform a series of operational steps to produce a computer-implemented process.Here, the instructions executed on the computer or other programmable device result in steps for implementing the functions / effects specified in the flowchart and / or block diagram blocks.

[0032] Referring again to the figures, Fig. 4 is a block diagram illustrating a method 400 for monitoring a compressor of a turbomachine according to an embodiment of the present invention. In one embodiment of the present invention, an operator may use a control system to monitor or control operation according to method 400 via a graphical user interface (GUI) or the like.

[0033] An embodiment of the method 400 may include at least one algorithm that may perform the following steps. As described, each compressor section 105 may have a unique MPT signature. The algorithm may first establish the MPT reference signature of the compressor section 105. This step should occur when the compressor section 105 is in a new or "healthy" (sound) condition. While the turbomachine 100 is operating, the acoustic detection device 170 may continuously monitor the acoustic signature, and a processor may then calculate the acoustic frequency spectrum to generate the MPT reference signature.

[0034] Next, the algorithm can compare the real-time MPT signature with a reference MPT signature. The algorithm can then determine the narrowband or proportional octave band frequency spectrum. The algorithm can then determine the individual frequency components. The amplitude of each frequency component can then be compared with the amplitude of the corresponding reference frequency component. If the amplitude of the frequency component begins to deviate by a predetermined threshold, an embodiment of the present invention can notify the operator that there is a potential for crack initiation.

[0035] In one embodiment of the present invention, the comparison of the frequency components may be performed on a band-by-band basis or by comparing a group of adjacent bands. In another embodiment of the present invention, the comparison may involve considering a wide range of frequencies and detecting changes in the overall spectral shape.

[0036] An embodiment of the method 400 may perform the following steps. In step 410, the method 400 may receive the acoustic data from at least one acoustic detection device. In one embodiment of the present invention, the acoustic detection device may be located in the inlet section of the compressor section. As described, the acoustic detection device may take the form of a microphone or a sound wave sensing device. The acoustic detection device may be capable of receiving the acoustic data. Furthermore, the acoustic detection device may be capable of transmitting the acoustic data to the control system by means of an electrical signal or the like.

[0037] In step 420, method 400 may receive the current acoustic data transmitted in step 410. Next, an acoustic signature, such as, but not limited to, an MPT signature, may be generated. In one embodiment of the present invention, method 400 may store the newly generated MPT signature on a local storage device and / or on a remote storage device.

[0038] In step 430, method 400 may transmit historical acoustic data, such as, but not limited to, an MPT signature separate from step 420. According to the present invention, the historical acoustic data is derived from another gas turbine and / or a fleet of gas turbines. Method 400 may then employ an algorithm that analyzes and compares the MPT signatures from the operating machine and the historical acoustic data transmitted in step 430.

[0039] In step 440, the method 400 may determine whether a notification should be generated. In one embodiment of the present invention, the notification may indicate that the current MPT is not within a desired range of the reference MPT, indicative of a possible crack in a blade. If a notification should be generated, the method 400 may then proceed to step 450; otherwise, the method 400 may return to step 420, where the monitoring process may continue.

[0040] In one embodiment of the present invention, the gas turbine can be integrated into a remote monitoring and diagnostic system (RMD). The RMD system can receive the acoustic data and can directly contact the gas turbine operator, thereby providing direct notification of a potential crack.

[0041] In step 450, method 400 may generate the notification. Here, the notification may be in the form of an audible and / or visual alarm or another commonly used form of communication.

[0042] As described, embodiments of the present invention can provide real-time monitoring of the compressor section for the possibility of cracking on a rotor blade. The present invention does not require a gas turbine shutdown and can be automated to automatically issue an alarm if the compressor's acoustic signature changes in a manner consistent with cracking on a rotor blade.

[0043] As one skilled in the art will understand, the widely different features and configurations described above with respect to the various exemplary embodiments can be further selectively applied to form other possible embodiments in accordance with the present invention. Those skilled in the art will further understand that all possible variations of the present invention have not been indicated or explained in detail, even if all combinations and all possible embodiments are intended to be encompassed by the various claims below or otherwise to form a part of the present application. Furthermore, from the above description of various exemplary embodiments of the invention, those skilled in the art will recognize improvements, changes, and modifications.Such improvements, changes, and modifications within the skill of the art are intended to be encompassed by the appended claims. Furthermore, it should be understood that the foregoing relates only to the described embodiments of the present invention, and that numerous changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined by the following claims and their equivalents.

[0044] Embodiments of the present invention may enable real-time monitoring of a compressor section 105 to determine the possibility of cracking on a blade 110, 115. The present invention does not require shutting down the engine 100. The present invention may be configured to automatically trigger an alarm if the acoustic signature of the compressor section 105 changes in a manner consistent with cracking on a blade 110, 115. Parts list: 100 Turbomachine 105 Compressor section 110 stationary shovel 115 rotating blade, rotor blade 117 Airflow 119 tendon 120 positions 125 Inlet section 130 Combustion system 135 tube combustion chamber 140 Fuel nozzle 145 Transition section 150 turbine section 155 rotating components 160 stationary components 165 Wheel space area 170 acoustic detection device 175 acoustic data 180 crack detection system 185 stored acoustic data 190 Notification of possible defect 300 diagram 305 Frequency band amplitude 310 acoustic signature 400 procedures

Claims

[1] A method (400) for detecting a possible crack on a blade (110, 115) located in a compressor section (105) of a turbomachine (100), the method (400) comprising: Providing a turbomachine (100) comprising: a compressor section (105), wherein the compressor section (105) has a plurality of blades (110, 115); and an acoustic detection device (170) configured to monitor the compressor section (105) while the turbomachine (100) is operating, wherein the acoustic detection device (170) receives acoustic data (410) relating to the plurality of blades (110, 115); Using the acoustic data to generate (420) an acoustic signature corresponding to the plurality of blades (110, 115); retrieving a related acoustic signature from a storage device (430); Comparing the acoustic signature with the related acoustic signature (420, 430); and Determine whether the acoustic signature is within an acceptable range (420); wherein a determination that the acoustic signature is outside the allowable range indicates a likelihood of a crack in at least one of the plurality of blades (110, 115); characterized by , that the related acoustic signature is derived from at least one other turbomachine (100) and / or a fleet of turbomachines. [2] The method (400) of claim 1, wherein the acoustic detection device (170) is disposed adjacent to an inlet portion of the compressor section (105). [3] The method (400) of claim 1, further comprising the step of generating a notification (440, 450) of a result of the step of determining whether the acoustic signature is within an acceptable range. [4] The method (400) of claim 1, further comprising the step of transmitting the acoustic signature to a remote monitoring and diagnostic center (450). [5] A system for detecting the presence of a crack on a blade (110, 115) in a gas turbine (100), the system comprising: a gas turbine (100) having a plurality of blades (110, 115); an acoustic detection device (170) configured to monitor operation of the gas turbine (100), the acoustic detection device (170) receiving acoustic data relating to the plurality of blades (110, 115) and being disposed adjacent to a compressor section (105) of the gas turbine (100); a control system (180), wherein the control system (180) is configured to perform the steps: Using the acoustic data to generate (420) an acoustic signature corresponding to the plurality of blades (110, 115); and retrieving a related acoustic signature from a storage device (430); Comparing the acoustic signature with the related acoustic signature (420, 430); and Determine whether the acoustic signature is within an acceptable range (420); characterized by , that the related acoustic signature is derived from at least one other gas turbine (100) and / or a fleet of gas turbines.

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