Patent Description:
Turbomachines are utilized in a variety of industries and applications for energy transfer purposes. For example, a gas turbine engine generally includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section progressively increases the pressure of a working fluid entering the gas turbine engine and supplies this compressed working fluid to the combustion section. The compressed working fluid and a fuel (e.g., natural gas) mix within the combustion section and burn in a combustion chamber to generate high pressure and high temperature combustion gases. The combustion gases flow from the combustion section into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a rotor shaft connected, e.g., to a generator to produce electricity. The combustion gases then exit the gas turbine via the exhaust section.

Phased array ultrasonic testing (PAUT) is one type of scanning method /technique that is used to provide an image of an object or part to reveal flaws, defects, characteristics, or anomalies in the object (such as a gas turbine component). A phased linear array ultrasonic scanner has a plurality of electrically and acoustically independent ultrasonic transducers in a single linear array. By varying the timing of the electrical pulses applied to the ultrasonic transducers using delay criteria, a phased linear array ultrasonic probe can generate ultrasonic waves passing into the test object at different angles (e.g., from zero to one hundred eighty degrees) to try to detect anomalies and variances therein and to identify the orientation of those anomalies and variances.

In operation, the ultrasonic waves generated by the phased linear array ultrasonic probe are transmitted into the test object to which the probe is coupled. As the ultrasonic waves pass into the test object, various reflections, called echoes, occur as the ultrasonic waves interact with anomalies and other physical characteristics in the test object. Conversely, when the reflected ultrasonic waves are received by the piezoelectric surface of the ultrasonic transducers, it causes the transducers to vibrate which generates a voltage difference across the transducer electrodes that is detected as an electrical signal by signal processing electronics connected to the transducers through the cable. The signal processing circuits track the time difference between the transmission of the electrical pulses and the receipt of the electrical signals, and measure the amplitude of the received electrical signals to determine various attributes of any anomalies and characteristics of the object, such as depth, size, location, and orientation. <CIT> relates to a device for the non-destructive testing of a test object by means of ultrasound. The device comprises a control unit provided for driving a phased array ultrasonic test probe and a display. The control unit is configured to operate the phased array test probe in the pulse echo operation and to control the insonification angle Θ of the phased array test probe into the test object. The pulse echo from the test object received by the phased array test probe is analyzed by the control unit, wherein the control unit generates an A-scan or/and a B-scan of a received pulse echo on the display.

High pressure turbine blades in service are prone to cracking in and around cooling holes. Inspecting cooling passages pose considerable challenges as they are narrow and convoluted, making it difficult to use readily available probes or customize them to traverse through the convoluted space and provide reliable inspection. While ultrasonic methods have the advantage to probe these internal areas from blade's external surfaces, the complex external shapes pose extreme challenges for contact ultrasound method. Material anisotropy causes ghost echoes in the reflected ultrasonic signals. Given the cracks to detect are extremely small, signal to noise ratio from single element immersion ultrasonic technique is extremely poor and cannot be used. While <CIT> generally teaches to apply a phased array ultrasonic test probe for the non-destructive inspection of a test object by means of ultrasound in accordance with the TCG method, using a phased array ultrasonic test probe, <CIT> teaches to apply the therein suggested method for non-destructive inspection of a rectangular steel block of a known type of steel.

<CIT> is silent about any isuue related to anisotropy of the test object.

As such, an improved method of detecting defects in an anisotropic rotor blade using a phased array ultrasonic system is desired and would be appreciated in the art.

The herein claimed invention relates to the subject matter set forth in the claims. Aspects and advantages of the methods in accordance with the herein claimed invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the technology.

These and other features, aspects and advantages of the present methods will become better understood with reference to the following description and appended claims.

A full and enabling disclosure of the present methods, including the best mode of making and using the present systems and methods, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:.

Reference now will be made in detail to embodiments of the present methods, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, rather than limitation of, the technology. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present technology without departing from the scope or spirit of the claimed technology. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

The term "fluid" may be a gas or a liquid. The term "fluid communication" means that a fluid is capable of making the connection between the areas specified.

As used herein, the terms "upstream" (or "forward") and "downstream" (or "aft") refer to the relative direction with respect to fluid flow in a fluid pathway. However, the terms "upstream" and "downstream" as used herein may also refer to a flow of electricity. The term "radially" refers to the relative direction that is substantially perpendicular to an axial centerline of a particular component, the term "axially" refers to the relative direction that is substantially parallel and/or coaxially aligned to an axial centerline of a particular component and the term "circumferentially" refers to the relative direction that extends around the axial centerline of a particular component.

Terms of approximation, such as "about," "approximately," "generally," and "substantially," are not to be limited to the precise value specified. For example, the approximating language may refer to being within a <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent margin in either individual values, range(s) of values and/or endpoints defining range(s) of values. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, "generally vertical" includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.

For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive- or and not to an exclusive- or.

Referring now to the drawings, <FIG> illustrates a schematic diagram of one embodiment of a turbomachine, which in the illustrated embodiment is a gas turbine <NUM>. Although an industrial or land-based gas turbine is shown and described herein, the present disclosure is not limited to a land-based and/or industrial gas turbine, unless otherwise specified in the claims. For example, the rotor blade as described herein may be used in any type of turbomachine including, but not limited to, a steam turbine, an aircraft gas turbine, or a marine gas turbine.

As shown, the gas turbine <NUM> generally includes an inlet section <NUM>, a compressor section <NUM> disposed downstream of the inlet section <NUM>, a plurality of combustors (not shown) within a combustor section <NUM> disposed downstream of the compressor section <NUM>, a turbine section <NUM> disposed downstream of the combustor section <NUM>, and an exhaust section <NUM> disposed downstream of the turbine section <NUM>. Additionally, the gas turbine <NUM> may include one or more shafts <NUM> coupled between the compressor section <NUM> and the turbine section <NUM>.

The compressor section <NUM> may generally include a plurality of rotor disks <NUM> (one of which is shown) and a plurality of rotor blades <NUM> extending radially outwardly from and connected to each rotor disk <NUM>. Each rotor disk <NUM> in turn may be coupled to or form a portion of the shaft <NUM> that extends through the compressor section <NUM>.

The turbine section <NUM> may generally include a plurality of rotor disks <NUM> (one of which is shown) and a plurality of rotor blades <NUM> extending radially outwardly from and being interconnected to each rotor disk <NUM>. Each rotor disk <NUM> in turn may be coupled to or form a portion of the shaft <NUM> that extends through the turbine section <NUM>. The turbine section <NUM> further includes an outer casing <NUM> that circumferentially surrounds the portion of the shaft <NUM> and the rotor blades <NUM>, thereby at least partially defining a hot gas path <NUM> through the turbine section <NUM>.

During operation, a working fluid such as air flows through the inlet section <NUM> and into the compressor section <NUM> where the air is progressively compressed, thus providing pressurized air to the combustors of the combustor section <NUM>. The pressurized air is mixed with fuel and burned within each combustor to produce combustion gases <NUM>. The combustion gases <NUM> flow through the hot gas path <NUM> from the combustor section <NUM> into the turbine section <NUM>, wherein energy (kinetic and/or thermal) is transferred from the combustion gases <NUM> to the rotor blades <NUM>, causing the shaft <NUM> to rotate. The mechanical rotational energy may then be used to power the compressor section <NUM> and/or to generate electricity. The combustion gases <NUM> exiting the turbine section <NUM> may then be exhausted from the gas turbine <NUM> via the exhaust section <NUM>.

As may be seen in <FIG>, the turbomachine <NUM> may define an axial direction A and a circumferential direction C, which extends around the axial direction A. The turbomachine <NUM> may also define a radial direction R perpendicular to the axial direction A.

<FIG> provides a perspective view of an exemplary rotor blade <NUM>. The rotor blade <NUM> may be the rotor blade <NUM> or the rotor blade <NUM> described above with reference to <FIG>. As shown in <FIG>, the rotor blade <NUM> generally includes a mounting or shank portion <NUM> having a mounting portion or dovetail <NUM> and an airfoil <NUM> that extends outwardly, e.g., generally along the radial direction R, from a substantially planar platform <NUM>. The platform <NUM> generally serves as the radially inward boundary for the hot gases of combustion <NUM> flowing through the hot gas path <NUM> of the turbine section <NUM> (<FIG>). The platform <NUM> extends along the axial direction A from a leading face <NUM> to a trailing face <NUM>. As shown in <FIG>, the mounting portion <NUM> of the mounting or shank portion <NUM> may extend radially inwardly from the platform <NUM> and may include a root structure, such as a dovetail, configured to interconnect or secure the rotor blade <NUM> to a rotor disk <NUM> (<FIG>). The mounting portion <NUM> may further define a root face <NUM>, which may be the radially innermost surface of the rotor blade <NUM>. The root face <NUM> may be generally planar (i.e., flat), and one or more cooling passage inlets <NUM> may be defined within the root face <NUM>.

The airfoil <NUM> includes a pressure side wall <NUM> and an opposing suction side wall <NUM>. The pressure side wall <NUM> and the suction side wall <NUM> extend substantially radially outwardly from the platform <NUM> in span from a root <NUM> of the airfoil <NUM>, which may be defined at an intersection between the airfoil <NUM> and the platform <NUM>, to a tip <NUM> of the airfoil <NUM>. The pressure side wall <NUM> is connected to the suction side wall <NUM> at a leading edge <NUM> of the airfoil <NUM> and a trailing edge <NUM> downstream of the leading edge <NUM>, and the airfoil <NUM> thus extends between the leading edge <NUM> and the trailing edge <NUM>. The pressure side wall <NUM> generally comprises an aerodynamic, concave external surface of the airfoil <NUM>. Similarly, the suction side wall <NUM> may generally define an aerodynamic, convex external surface of the airfoil <NUM>. The tip <NUM> is disposed radially opposite the root <NUM>. As such, the tip <NUM> may generally define the radially outermost portion of the rotor blade <NUM> and, thus, may be configured to be positioned adjacent to a stationary shroud or seal (not shown) of the turbomachine <NUM>. The tip <NUM> may include a tip cavity <NUM>.

As shown in <FIG>, the rotor blade <NUM> may be at least partially hollow, e.g., the rotor blade <NUM> may include a cooling circuit <NUM> defined therein. The cooling circuit <NUM> may include a plurality of cooling passages <NUM> (shown partially in dashed lines in <FIG>), which may be circumscribed within the rotor blade <NUM> for routing a coolant <NUM> through the airfoil <NUM> between the pressure side wall <NUM> and the suction side wall <NUM>, thus providing convective cooling thereto. The cooling passages <NUM> may be at least partially defined by and between a plurality of ribs <NUM>. The ribs <NUM> extend partially through the cooling circuit <NUM> generally along the radial direction R, e.g., as illustrated in <FIG>. The ribs <NUM> may extend fully through the cooling circuit <NUM> between the pressure side wall <NUM> and the suction side wall <NUM>. The plurality of ribs <NUM> may thereby partition the cooling circuit <NUM> and at least partially form or define the cooling passages <NUM>. For example, each rib <NUM> may radially terminate near one of a root turn <NUM> or a tip turn <NUM>. The root turn <NUM> may be partially defined by a floor <NUM>, which defines the radially inward most boundary of the root turn <NUM>. Similarly, the tip turn <NUM> may be partially defined by a ceiling <NUM>, which may define the radially outermost boundary of the tip turn <NUM>.

The coolant <NUM> may include a portion of the compressed air from the compressor section <NUM> (<FIG>) and/or steam or any other suitable gas or other fluid for cooling the airfoil <NUM>. One or more cooling passage inlets <NUM> are disposed along the rotor blade <NUM>. In some embodiments, one or more cooling passage inlets <NUM> are formed within, along or by the mounting portion <NUM>. The cooling passage inlets <NUM> are in fluid communication with at least one corresponding cooling passage <NUM>. A plurality of coolant outlets <NUM> may be in fluid communication with the tip cavity <NUM>. Each cooling passage <NUM> is in fluid communication with at least one of the coolant outlets <NUM>. In some embodiments, the tip cavity <NUM> may be at least partially surrounded by a pressure side tip rail <NUM> and a suction side tip rail <NUM>.

As may be seen in <FIG>, the cooling passages <NUM> extend within each of the shank portion <NUM> and the airfoil portion <NUM>. For example, the cooling passages <NUM> may extend between the shank portion <NUM> and the airfoil portion <NUM>, e.g., from the shank portion <NUM> to the airfoil portion <NUM>, such as from the one or more cooling passage inlets <NUM> in the shank portion <NUM> to the at least one coolant outlet <NUM> in the tip <NUM> of the airfoil portion <NUM>.

In many embodiments, the rotor blade <NUM> may be composed an anisotropic media (e.g., the rotor blade may be referred to as an "anisotropic rotor blade"), particularly when the rotor blade <NUM> is used in the turbine section <NUM> because the anisotropic material allows the rotor blade <NUM> to withstand greater temperatures/- stresses. Anisotropy is the property of a material which allows it to assume different properties in different directions, as opposed to isotropic materials. Particularly, the rotor blade <NUM> may be formed from a single crystalline alloy such as nickel-based alloys.

Referring particularly to <FIG>, a phased array ultrasonic system <NUM>, which may be used for detecting defects in an anisotropic rotor blade <NUM> is illustrated in accordance with embodiments of the present disclosure. In exemplary implementations of the phased array ultrasonic system <NUM>, the anisotropic rotor blade <NUM> for the turbine section <NUM>, which may have the same or a similar configuration as the rotor blade <NUM> described above with reference to <FIG>. Defects that may be detected by the present phased array ultrasonic system <NUM> and method are cracks, corrosion, voids, pin-holes, air pockets, and others.

The phased array ultrasonic system <NUM> includes a probe <NUM> having transducer array <NUM> comprised of a plurality of separately driven transducer elements or transducers <NUM> which each produce a burst of ultrasonic energy when energized by a pulse produced by a transmitter <NUM>. The ultrasonic energy reflected back to transducer array <NUM> from the subject under study is converted to an electrical signal by each transducer element <NUM> and applied separately to a receiver <NUM> through a set of switches <NUM>. Transmitter <NUM>, receiver <NUM> and switches <NUM> are operated under control of a digital controller <NUM> (which may be responsive to the commands input by a human operator). A complete scan is performed by acquiring a series of echoes in which transmitter <NUM> is gated on momentarily to energize each transducer element <NUM>, switches <NUM> are then gated on to receive the subsequent echo signals produced by each transducer element <NUM>, and these separate echo signals are combined in receiver <NUM> to produce a single echo signal which is employed to produce a pixel or a line in an image on a display <NUM>.

Transmitter <NUM> drives the transducer array <NUM> such that the ultrasonic energy produced is directed, or steered, in a beam. A B-scan can therefore be performed by moving this beam through a set of angles from point-to-point rather than physically moving transducer array <NUM>. To accomplish this, transmitter <NUM> imparts a time delay (Tk) to the respective pulses <NUM> that are applied to successive transducer elements <NUM>. If the time delay is zero (Tk =<NUM>), all the transducer elements <NUM> are energized simultaneously and the resulting ultrasonic beam is directed along a central axis <NUM> normal to the transducer face and originating from the center of transducer array <NUM>. The beam is focused at an infinite range. As the time delay (Tk) is increased, the ultrasonic beam is directed downward from central axis <NUM> by an amount θ. The relationship between the time delay increment Tk which is added successively to each kth signal from one end of the transducer array (k=<NUM>) to the other end (k=N) is given by the following relationship: <MAT>.

Where d is the spacing between centers of adjacent transducer elements <NUM>, c is the velocity of sound in the object under study, R<NUM> is the range at which transmit beam is focused and Tk is the delay offset which insures that all calculated values (Tk) are positive values.

The time delays Tk in equation (<NUM>) have the effect of steering the beam in the desired angle θ, and causing it to be focused at a fixed range R<NUM>. A sector scan is performed by progressively changing the time delays Tk in successive excitations. The angle θ is thus changed in increments to steer the transmitted beam in a succession of directions, but the focal distance R<NUM> remains fixed. When the direction of the beam is above central axis <NUM>, the timing of pulses <NUM> is reversed, but the formula of equation (<NUM>) still applies. Multiple depths (e.g., multi-depth focusing) may be scanned in succession, and the resulting echoes may be stitched together to form a full sector scan image viewable by the display system <NUM>.

The echo signals produced by each burst of ultrasonic energy emanate from reflecting objects located at successive positions (R) along the ultrasonic beam. These are sensed separately by each transducer element <NUM> of transducer array <NUM> and a sample of the magnitude of the echo signal at a particular point in time represents the amount of reflection occurring at a specific range (R). Due to the differences in the propagation paths between a reflecting point P and each transducer element <NUM>, however, these echo signals will not occur simultaneously, and their amplitudes will not be equal. The function of receiver <NUM> is to amplify and demodulate these separate echo signals, impart the proper time delay and phase shift to each and sum them together to provide a single echo signal which accurately indicates the total ultrasonic energy reflected from point P located at range R along the ultrasonic beam oriented at the angle θ.

To simultaneously sum the electrical signals produced by the echoes from each transducer element <NUM>, time delays and phase shifts are introduced into each separate transducer element channel of receiver <NUM>. The beam time delays for reception are the same delays (Tk) as the transmission delays described above. However, in order to dynamically focus the receive beam, the time delay and phase shift of each receiver channel is continuously changing during reception of the echo to provide dynamic focusing of the received beam at the range R from which the echo signal emanates.

Under the direction of digital controller <NUM>, the receiver <NUM> provides delays during the scan such that the steering of receiver <NUM> tracks with the direction of the beam steered by transmitter <NUM> and it samples the echo signals at a succession of ranges and provides the proper delays and phase shifts to dynamically focus at points P along the beam. Thus, each emission, or firing, of an ultrasonic pulse waveform results in the acquisition of a series of data points which represent the amount (or magnitude) of reflected sound from a corresponding series of points P located along the ultrasonic beam. Display system <NUM> receives the series of data points produced by receiver <NUM> and converts the data to a form producing the desired image.

A wave normal direction <NUM> may extend generally perpendicularly to the face of the transducers <NUM>, which in <FIG> coincides or extends coaxially with the axial centerline <NUM>. Unlike isotropic media where group and phase velocities of an acoustic wave coincide with one another, ultrasonic wave propagation in an anisotropic media will not coincide with the wave normal direction <NUM> unless the propagation direction is along a symmetry axis. This phenomenon is known as energy flux deviation or beam skew. Acoustic energy does not necessarily propagate in the direction normal to the face of the transducers <NUM> (e.g., the wave normal direction <NUM>) as happens with isotropic media, but will rather be skewed at an oblique angle or anisotropic tilt angle <NUM> relative to the wave normal.

Particularly, in the anisotropic rotor blade <NUM>, the anisotropic tilt angle <NUM> may be generally known, but may vary within a range of between about <NUM>° and about <NUM>°, or such as between about <NUM>° and about <NUM>°. For example, the anisotropic tilt angle <NUM> may be within a range of between about <NUM>° and about <NUM>° from the axial centerline <NUM>, or such as between about <NUM>° and about <NUM>° from the axial centerline <NUM>.

As will be discussed in more detail below, the exemplary method for operating the phased array ultrasonic system <NUM> advantageously identifies and accounts for the anisotropic tilt angle <NUM> in the anisotropic rotor blade <NUM>, thereby allowing the anisotropic rotor blade <NUM> to be scanned for defects without error or ghost echoes (e.g., echoes that appear to indicate defects but are actually internal part geometry). Once the anisotropic tilt angle <NUM> is determined, the method may account for the angle by rotating the probe <NUM>, the anisotropic rotor blade <NUM>, or by adjusting the delay laws of the system <NUM> to steer the acoustic waves.

Still referring to <FIG>, the controller <NUM> is shown as a block diagram to illustrate the suitable components that may be included within the controller <NUM>. As shown, the controller <NUM> may include one or more processor(s) <NUM> and associated memory device(s) <NUM> configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and the like and storing relevant data as disclosed herein).

As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. Additionally, the memory device(s) <NUM> may generally comprise memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) <NUM> may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) <NUM>, configure the controller <NUM> to perform various functions and/or operations.

Additionally, in many embodiments, the probe <NUM> may be in wireless communication with the digital controller <NUM> (via any suitable wireless communication protocol). Int this way, the probe <NUM> may transmit the magnitude and/or time delay of the echo signals <NUM>, and the digital controller <NUM> may analyze these echo signals <NUM> and generate one or more adjustments to the delay laws of the probe <NUM>. The adjustments to the delay laws may be made wirelessly.

Referring now to <FIG> and <FIG>, a flow diagram two different embodiments of a method <NUM>, <NUM> for detecting defects in an anisotropic rotor blade using a phased array ultrasonic system are illustrated in accordance with aspects of the present subject matter. In general, the methods <NUM> and <NUM> will be described herein with reference to the phased array ultrasound system <NUM>, the gas turbine <NUM>, the anisotropic rotor blade <NUM>, and the rotor blade <NUM> described above with reference to <FIG>. However, it will be appreciated by those of ordinary skill in the art that the disclosed methods <NUM> and <NUM> may generally be utilized with any suitable phased array ultrasound system <NUM> and/or may be utilized in connection with a system having any other suitable system configuration. In addition, although <FIG> and <FIG> depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement unless otherwise specified in the claims. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure.

In exemplary implementations, the anisotropic rotor blade <NUM> for the turbine section <NUM>, which may have the same or a similar configuration as the rotor blade <NUM> described above with reference to <FIG>. In such embodiments, as shown in <FIG>, the anisotropic rotor blade <NUM> may extend along an axial centerline <NUM> and include a mounting portion <NUM> and an airfoil <NUM>. A cooling passage <NUM>, such as the cooling passage <NUM> shown and described above with reference to <FIG>, may be defined within the anisotropic rotor blade <NUM> at least partially along the axial centerline <NUM>. The cooling passage <NUM> may be at least partially defined by a ceiling <NUM>, which may form the radially outermost boundary of the cooling passage <NUM> (as shown in <FIG>).

Referring specifically to <FIG>, the method <NUM> may include at (<NUM>) positioning a probe <NUM> of the phased array ultrasound system <NUM> on the mounting portion <NUM> of the anisotropic rotor blade <NUM> at the axial centerline <NUM>. For example, the probe <NUM> may be positioned in contact with the mounting portion <NUM> of the anisotropic rotor blade <NUM>. Particularly, the mounting portion <NUM> may include a root face <NUM>. The root face <NUM> may be a generally planar (e.g., flat) surface. In such embodiments, the method <NUM> may include the probe <NUM> of a phased array ultrasound system <NUM> on the root face <NUM> of the anisotropic rotor blade <NUM> at the axial centerline <NUM>. Specifically, as shown in <FIG>, as an initial step of the method <NUM>, the transducer array <NUM>, including each transducer of the plurality of transducers <NUM>, may be positioned in contact with the root face <NUM> of the anisotropic rotor blade <NUM> at least partially along an axial centerline <NUM> of the anisotropic rotor blade (e.g., centered on the axial centerline in some embodiments).

The method <NUM> may further include at (<NUM>) scanning a sector <NUM> of the anisotropic rotor blade <NUM> along the axial centerline <NUM> with the probe <NUM> of the phased array ultrasound system <NUM>. Scanning the sector <NUM> (i.e., performing a sector scan with the system <NUM>) may include progressively changing the time delays Tk in successive excitations of the plurality of transducers <NUM>. The angle θ is thus changed in increments to steer the transmitted beam <NUM> in a succession of directions. When the direction of the beam is above central axis <NUM>, the timing of pulses <NUM> is reversed. In some embodiments, the sector scan may be at a fixed focal depth P. In other embodiments, the sector scan may include a multi-focal depth by successively targeting different depths and stitching together the resulting image with the display system <NUM>.

In many embodiments, scanning the sector at (<NUM>) may include transmitting, with the plurality of transducers <NUM> of the probe <NUM>, a plurality of ultrasonic beams <NUM> at varying angles θ (and varying focal depths) into the anisotropic rotor blade <NUM>. For example, scanning the sector at (<NUM>) may include transmitting, with the plurality of transducers <NUM> of the probe <NUM>, a plurality of ultrasonic beams <NUM> at varying depths into the anisotropic rotor blade <NUM>, the depths being defined by pre-set region of interest. Particularly, the depths may correspond with various span lengths of the airfoil <NUM> (such as between about <NUM>% and about <NUM>% span of the airfoil <NUM>). The regions of interest may be areas of the anisotropic rotor blade <NUM> that are prone to failures, such as one or more of the cooling channels or passages.

The angles θ may be defined between the respective transmitted ultrasonic beam <NUM> and a wave normal direction <NUM> that is perpendicular to the plurality of transducers <NUM>. In exemplary implementations, the plurality of angles varying from between about -<NUM>° and about <NUM>°, or such as between about -<NUM>° and about <NUM>°. In this way, the sector <NUM> that is scanned may be defined between the two outermost angle values (e.g., -<NUM>° and <NUM>°). The focal depth (illustrated as "P" in <FIG>) of the sector scan may also vary, such that the sector scan includes a range of focal depths P (which may be stitched together in a single image by the display system <NUM>). The range of focal depths P may be between about <NUM>% and about <NUM>% of the length of the anisotropic rotor blade <NUM> (measured in a direction parallel to the axial centerline <NUM>). In other embodiments, the range of focal depths P may be between about <NUM>% and about <NUM>% of the length of the anisotropic rotor blade <NUM>.

In various implementations, the scanning the sector at (<NUM>) may include simultaneous multi-depth and multi-angle focusing of acoustic waves into the anisotropic blade. For example, multiple depths (e.g., the distance the beam <NUM> travels into the rotor blade <NUM>, which is illustrated in <FIG> as "P") and multiple angles θ of beams <NUM> (or acoustic waves) may be transmitted simultaneously by the probe <NUM> (e.g., via the plurality of transducers).

In many embodiments, a geometric fiducial marker <NUM> may be disposed at least partially within the sector <NUM>. The geometric fiducial marker <NUM> may be an identifiable or known (e.g., by the digital controller <NUM>) geometric feature of the anisotropic rotor blade <NUM>. For example, the geometric fiducial marker <NUM> may include an interior/exterior contour, a cooling hole, or other geometric feature of the anisotropic rotor blade <NUM>. In exemplary embodiments, the geometric fiducial marker <NUM> is the ceiling <NUM> of the cooling passage <NUM> defined within the airfoil <NUM> of the anisotropic rotor blade <NUM>. As shown in <FIG>, the cooling passage <NUM> may be at least partially disposed along the axial centerline <NUM>.

In exemplary implementations, the method <NUM> may include at (<NUM>) determining (e.g., with the digital controller) a magnitude and a time delay of the echo signals <NUM> corresponding with the geometric fiducial marker <NUM>. For example, the echo signals <NUM> may be the transmitted beams <NUM> that have reflected from the geometric fiducial marker <NUM>. The magnitude of the echo signals <NUM> may be based on the strength of the echo signal <NUM>. The time delay may be the time taken for the echo signal <NUM> to reach the transducer elements <NUM>. The magnitude and/or the time delay of the echo signals <NUM> may be compared to a predetermined maximum echo, and if the magnitude and/or the time delay of the echo signal falls outside of the predetermined maximum echo range, then a position of the anisotropic rotor blade <NUM> and/or the probe <NUM> may be adjusted to account for the anisotropic tilt angle <NUM>.

For example, the method <NUM> may further include at (<NUM>) adjusting a position of one of the anisotropic rotor blade <NUM> or the probe based on the magnitude (and/or the time delay) of the echo signal <NUM> corresponding with the geometric fiducial marker <NUM>. Particularly, the magnitude of the echo signal <NUM> may be compared (e.g., by the digital controller <NUM>) to the predetermined maximum echo range, and based on the extent that the magnitude of the echo signal falls outside of the predetermined maximum echo range, the position of one of the anisotropic rotor blade <NUM> or the probe <NUM> is modified. Similarly, the time delay of the echo signal <NUM> (e.g., the time it takes for the echo signal <NUM> to be received by the transducer element) may be compared to a predetermined maximum echo range, and based on the extent that the time delay of the echo signal falls outside the predetermined maximum range, the position of the anisotropic rotor blade <NUM> and/or the probe <NUM> may be modified. The predetermined maximum echo range may include a predetermined range for both magnitude and time delay. As a non-limiting example, if the magnitude (and/or the time delay) of the echo signal <NUM> is <NUM>% outside of the predetermined maximum echo range, then the probe <NUM> and/or the anisotropic rotor blade <NUM> may be rotated and/or translated by <NUM>%. Alternatively, or additionally, the magnitude (and/or the time delay) of the echo signal <NUM> may correspond with a rotation and/or translation adjustment in a look up table stored within the memory <NUM> of the controller <NUM>. For example, based on the magnitude (and/or the time delay) of the echo signal <NUM>, the controller <NUM> may consult the look up table and suggest a rotation and/or translation of the probe <NUM> and/or the rotor blade <NUM>. Adjusting a position of the probe <NUM> and/or the rotor blade <NUM> may include rotating and/or translating the probe <NUM> and/or the rotor blade <NUM> (e.g., along or about any of the axial direction A, the radial direction R, or the circumferential direction C).

The scanning, determining, and adjusting steps shown in (<NUM>), (<NUM>), and (<NUM>) shown in <FIG> and described above may be iterative. Such that the steps may be repeated to iteratively increase the magnitude and/or the time delay of the echo signal <NUM> until the magnitude of the echo signal and its time delay is within the predetermined maximum echo range, thereby indicating that the anisotropic tilt angle <NUM> has been accounted for. For example, the predetermined maximum echo range may be the range of echo magnitudes and/or time delays that occur when the anisotropic tilt is accounted for, or when the anisotropic tilt is <NUM>°, such that the maximum amount of beams <NUM> are reflecting off of the geometric fiducial marker <NUM>. As such, when the magnitude and/or the time delay of the echo signal is within the predetermined maximum echo range, this indicates that the anisotropic tilt angle <NUM> has been accounted for (e.g., by physically rotating/translating the rotor blade <NUM> and/or the probe <NUM>). For example, the method <NUM> may include at (<NUM>) repeating the scanning, determining, and adjusting steps (e.g., steps <NUM>, <NUM>, and <NUM>) until the magnitude and/or the time delay of the echo signals <NUM> corresponding with the geometric fiducial marker <NUM> are within the predetermined maximum echo range (e.g., the echo magnitude and its time delay does not exceed or fall below the range).

Finally, once the rotor blade <NUM> and/or the probe <NUM> has been physically adjusted, such that scanning the rotor blade accounts for the anisotropic tilt angle <NUM>, the method <NUM> may include at (<NUM>) scanning the anisotropic rotor blade for defects. The defects that may be detected by the present phased array ultrasonic system <NUM> and method are cracks, corrosion, voids, pin-holes, air pockets, and others.

In many embodiments, scanning the sector <NUM> at (<NUM>) may include transmitting, with the plurality of transducers, a plurality of ultrasonic beams <NUM> into the anisotropic rotor blade <NUM> along an inspection plane (e.g., the plane of the page in <FIG> or another two dimensional plane). In such embodiments, the probe <NUM> may include a linear array (e.g., a single row) of transducers <NUM>, such that the sector <NUM> is within a two dimensional inspection plane. As a result of the anisotropic media of the rotor blade, the ultrasonic beams <NUM> may deviate from the inspection plane at the anisotropic tilt angle <NUM> while propagating through the anisotropic rotor blade <NUM>. The anisotropic tilt angle <NUM> may be associated with the anisotropic rotor blade <NUM>. The anisotropic tilt angle <NUM> may be generally known, but may vary within a range of between about <NUM>° and about <NUM>°, or such as between about <NUM>° and about <NUM>° from blade to blade. As such, the anisotropic tilt angle <NUM> must be determined and accounted for to increase the accuracy and effectiveness of the phased array ultrasonic system <NUM>. In such embodiments, the method may include receiving, with the plurality of transducers <NUM>, the echo signal corresponding with the geometric fiducial marker <NUM>. The magnitude of the echo signal and its time delay received by the plurality of transducers <NUM> is related to a magnitude of the anisotropic tilt angle. For example, the magnitude and time delay of the echo signal may be related based on historical data (which may be stored in the memory of the controller <NUM>), or based on a look up table, or based on another correlation.

In many embodiments, the method <NUM> may include determining the anisotropic tilt angle <NUM> by repeating the scanning, determining, and adjusting steps (e.g., steps <NUM>, <NUM>, and <NUM>) until the magnitude and/or the time delay of the echo signal <NUM> corresponding with the geometric fiducial marker <NUM> is within the predetermined maximum echo range. For example, the predetermined maximum echo range may be the range of echo magnitudes and/or time delays that occur when the anisotropic tilt is accounted for, or when the anisotropic tilt is <NUM>°, such that the maximum amount of beams <NUM> are reflecting off of the geometric fiducial marker <NUM>. As such, when the magnitude and/or the time delay of the echo signal is within the predetermined maximum echo range, this indicates that the anisotropic tilt angle <NUM> has been accounted for (e.g., by physically rotating/translating the rotor blade <NUM> and/or the probe <NUM>). Once the anisotropic tilt angle <NUM> is accounted for, it may be determined by the controller <NUM> (e.g., based on the movements/adjustments made to the rotor blade <NUM> and/or the probe <NUM>, or based on the adjustments made to the delay profile). In such embodiments, after the anisotropic tilt angle is determined, the method may further include adjusting a position of anisotropic rotor blade <NUM> and/or the probe <NUM> a final instance based on the determined anisotropic tilt angle <NUM> and scanning the anisotropic rotor blade <NUM> for defects.

In many embodiments, after scanning the part for defects a first time, the method may include translating the probe <NUM> away from the axial centerline <NUM> of the rotor blade and along the mounting portion <NUM>. Subsequently, the method may include scanning the anisotropic rotor blade for defects a second time with the phased array ultrasound system <NUM>. For example, once the anisotropic tilt angle <NUM> is identified and accounted for, the probe <NUM> may be translated along the root face <NUM> for scanning multiple portions of the anisotropic rotor blade <NUM> for defects.

In many embodiments, scanning the sector at (<NUM>) may include transmitting, with the plurality of transducer elements <NUM> of the probe <NUM>, a plurality of ultrasonic beams <NUM> at varying angles θ (and varying depths) into the anisotropic rotor blade <NUM>. The angles θ may be defined between the respective transmitted ultrasonic beam <NUM> and a wave normal direction <NUM> that is perpendicular to the plurality of transducer elements <NUM>. In exemplary implementations, the plurality of angles varying from between about -<NUM>° and about <NUM>°, or such as between about -<NUM>° and about <NUM>°. In this way, the sector <NUM> that is scanned may be defined between the two outermost angle values (e.g., -<NUM>° and <NUM>°). The focal depth (illustrated as "P" in <FIG>) of the sector scan may also vary, such that the sector scan includes a range of focal depths P (which may be stitched together in a single image by the display system <NUM>). The range of focal depths P may be between about <NUM>% and about <NUM>% of the length of the anisotropic rotor blade <NUM> (measured in a direction parallel to the axial centerline <NUM>). In other embodiments, the range of focal depths P may be between about <NUM>% and about <NUM>% of the length of the anisotropic rotor blade <NUM>.

In exemplary implementations, the method <NUM> may include at (<NUM>) determining (e.g., with the digital controller) a magnitude and a time delay of echo signals <NUM> corresponding with the geometric fiducial marker <NUM>. For example, the echo signals <NUM> may be the transmitted beams <NUM> that have reflected from the geometric fiducial marker <NUM>. The magnitude of the echo signals <NUM> may be based on the strength of the echo signal <NUM>. The time delay may be the time taken for the echo signal <NUM> to reach the transducer elements <NUM>. The magnitude of the echo signals <NUM> and/or the time delay of the echo signals <NUM> may be compared to a predetermined maximum echo range, and if the magnitude and/ time delay of the echo signal falls outside of the predetermined maximum echo range, then delay laws of the probe <NUM> may be adjusted to steer the beams <NUM> and account for the anisotropic tilt angle <NUM>. Similarly, the time delay of the echo signal <NUM> (e.g., the time it takes for the echo signal <NUM> to be received by the transducer element) may be compared to a predetermined maximum echo range, and based on the extent that the time delay of the echo signal falls outside the predetermined maximum range, then delay laws of the probe <NUM> may be adjusted to steer the beams <NUM> and account for the anisotropic tilt angle <NUM>.

For example, the method <NUM> may further include at (<NUM>) adjusting delay laws of the probe <NUM> based on the magnitude and/or the time delay of the echo signal <NUM> corresponding with the geometric fiducial marker <NUM>. The delays (Tk) between each of the pulses <NUM> may be referred to as the "delay laws. " The delays (Tk) between each pulse <NUM> may be independently adjusted or manipulated to steer or direct the beam <NUM> along a desired path. Accordingly, adjusting the delay laws makes an adjustment to the path along which the beam <NUM> travels, such that the anisotropic tilt angle <NUM> may be accounted for once identified.

Particularly, the magnitude and/or the time delay of the echo signal <NUM> may be compared (e.g., by the digital controller <NUM>) to the predetermined maximum echo range, and based on the extent that the magnitude and delay of the echo signal <NUM> falls outside of the predetermined maximum echo range, the delay laws may be adjusted. As a non-limiting example, if the magnitude (and/or the time delay) of the echo signal <NUM> is <NUM>% outside of the predetermined maximum echo range, then the delay laws may be adjusted (e.g., increased or decreased) by <NUM>%. Alternatively, or additionally, the magnitude (and/or time delay) of the echo signal <NUM> may correspond with a delay law adjustment in a look up table stored within the memory <NUM> of the controller <NUM>. For example, based on the magnitude (and/or time delay) of the echo signal <NUM>, the controller <NUM> may consult the look up table and suggest a delay law adjustment to the probe <NUM> and/or the rotor blade <NUM>.

The scanning, determining, and adjusting steps shown in (<NUM>), (<NUM>), and (<NUM>) shown in <FIG> and described above may be iterative and optimized algorithmically. Such that the steps may be repeated to iteratively increase the magnitude (and/or the time delay) of the echo signal <NUM> until the magnitude (and/or the time delay) of the echo signal is within the predetermined maximum echo range, thereby indicating that the anisotropic tilt angle <NUM> has been accounted for. For example, the predetermined maximum echo range may be the range of echo magnitudes that occur when the anisotropic tilt is accounted for, or when the anisotropic tilt is <NUM>°, such that the maximum amount of beams <NUM> are reflecting off of the geometric fiducial marker <NUM>. As such, when the magnitude (and/or the time delay) of the echo signal is within the predetermined maximum echo range, this indicates that the anisotropic tilt angle <NUM> has been accounted for (e.g., by the adjustments made to the delay laws). For example, the method <NUM> may include at (<NUM>) repeating the scanning, determining, and adjusting steps (e.g., steps <NUM>, <NUM>, and <NUM>) until the magnitude and delay of the echo signals <NUM> corresponding with the geometric fiducial marker <NUM> are within the predetermined maximum echo range (e.g., the magnitude and/or time delay does not exceed or fall below the range).

Finally, once the delay laws have been adjusted, such that scanning the rotor blade accounts for the anisotropic tilt angle <NUM>, the method <NUM> may include at (<NUM>) scanning the anisotropic rotor blade for defects. The defects that may be detected by the present phased array ultrasonic system <NUM> and method are cracks, corrosion, voids, pin-holes, air pockets, and others.

In many embodiments, scanning the sector <NUM> at (<NUM>) may include transmitting, with the plurality of transducers, a plurality of ultrasonic beams <NUM> into the anisotropic rotor blade <NUM> along an inspection plane (e.g., the plane of the page in <FIG> or another two dimensional plane). In such embodiments, the probe <NUM> may include a linear array (e.g., a single row) of transducers <NUM>, such that the sector <NUM> is within a two dimensional inspection plane. As a result of the anisotropic media of the rotor blade, the ultrasonic beams <NUM> may deviate from the inspection plane at the anisotropic tilt angle <NUM> while propagating through the anisotropic rotor blade <NUM>. The anisotropic tilt angle <NUM> may be associated with the anisotropic rotor blade <NUM>. The anisotropic tilt angle <NUM> may be generally known, but may vary within a range of between about <NUM>° and about <NUM>°, or such as between about <NUM>° and about <NUM>° from blade to blade. As such, the anisotropic tilt angle <NUM> must be determined and accounted for to increase the accuracy and effectiveness of the phased array ultrasonic system <NUM>. In such embodiments, the method may include receiving, with the plurality of transducers <NUM>, the echo signal <NUM> corresponding with the geometric fiducial marker <NUM>. The magnitude and delay of the echo signal <NUM> received by the plurality of transducers <NUM> is related to a magnitude of the anisotropic tilt angle. For example, the magnitude and time delay of the echo signal may be related based on historical data (which may be stored in the memory of the controller <NUM>), or based on a look up table, or based on another correlation.

In many embodiments, the method <NUM> may include determining the anisotropic tilt angle <NUM> by repeating the scanning, determining, and adjusting steps (e.g., steps <NUM>, <NUM>, and <NUM>) until the magnitude and delay of the echo signal <NUM> corresponding with the geometric fiducial marker <NUM> is within the predetermined maximum echo range. For example, the predetermined maximum echo range may be the range of echo magnitudes and/or time delays that occur when the anisotropic tilt is accounted for, or when the anisotropic tilt is <NUM>°, such that the maximum amount of beams <NUM> are reflecting off of the geometric fiducial marker <NUM>. As such, when the magnitude and/or the time delay of the echo signal is within the predetermined maximum echo range, this indicates that the anisotropic tilt angle <NUM> has been accounted (e.g., by altering or adjusting the delay laws). Once the anisotropic tilt angle <NUM> is accounted for, it may be determined by the controller <NUM> (e.g., based on the adjustments made to the delay laws). In such embodiments, after the anisotropic tilt angle is determined, the method may further include adjusting the delay laws a final instance based on the determined anisotropic tilt angle <NUM> and scanning the anisotropic rotor blade <NUM> for defects.

Claim 1:
A method for detecting defects in an anisotropic rotor blade (<NUM>, <NUM>) using a phased array ultrasound system (<NUM>), the anisotropic rotor blade extending along an axial centerline (<NUM>) and comprising a mounting portion (<NUM>) and an airfoil (<NUM>), the method comprising:
positioning (<NUM>, <NUM>) a probe (<NUM>) of the phased array ultrasound system (<NUM>) on the mounting portion of the anisotropic rotor blade at the axial centerline;
scanning (<NUM>, <NUM>) a sector (<NUM>) of the anisotropic rotor blade (<NUM>, <NUM>) along the axial centerline with the probe of the phased array ultrasound system, a geometric fiducial marker (<NUM>) disposed at least partially within the sector of the anisotropic rotor blade;
determining (<NUM>, <NUM>) a magnitude and a time delay of an echo signal (<NUM>) corresponding with the geometric fiducial marker;
adjusting (<NUM>, <NUM>) a position of one of the anisotropic rotor blade (<NUM>, <NUM>) or the probe (<NUM>) based on the magnitude of the echo signal corresponding with the geometric fiducial marker; and
repeating (<NUM>, <NUM>) the scanning, determining, and adjusting steps until the magnitude and the time delay of the echo signal corresponding with the geometric fiducial marker is within a predetermined maximum echo range; and
scanning the anisotropic rotor blade for defects.