US-12618808-B2 - Methods for detecting defects in an anisotropic rotor blade using a phased array ultrasound system

US12618808B2US 12618808 B2US12618808 B2US 12618808B2US-12618808-B2

Abstract

The method includes positioning a probe of the phased array ultrasound system on the mounting portion of the anisotropic rotor blade at the axial centerline. The method further includes scanning a sector of the anisotropic rotor blade along the axial centerline with the probe of the phased array ultrasound system. The method further includes determining a magnitude and a time delay of an echo signal corresponding with a geometric fiducial marker. The method further includes adjusting a position of one of the anisotropic rotor blade or the probe based on the magnitude and/or the time delay of the echo signal corresponding with the geometric fiducial marker. The method further includes repeating 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. The method further includes scanning the anisotropic rotor blade for defects.

Inventors

Manoj Kumar KM
Sivaramanivas Ramaswamy
Prasad Thapa
Thomas Earnest Moldenhauer

Assignees

GE VERNOVA INFRASTRUCTURE TECHNOLOGY LLC

Dates

Publication Date: 20260505
Application Date: 20230206

Claims (20)

1 . A method for detecting defects in an anisotropic rotor blade using a phased array ultrasound system, the anisotropic rotor blade extending along an axial centerline and comprising a mounting portion and an airfoil, the method comprising: positioning a probe of the phased array ultrasound system on the mounting portion of the anisotropic rotor blade at the axial centerline; scanning a sector of the anisotropic rotor blade along the axial centerline with the probe of the phased array ultrasound system, a geometric fiducial marker disposed at least partially within the sector of the anisotropic rotor blade; determining a magnitude and a time delay of an echo signal corresponding with the geometric fiducial marker; adjusting a position of one of the anisotropic rotor blade or the probe based on the magnitude of the echo signal corresponding with the geometric fiducial marker; and repeating 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.
2 . The method as in claim 1 , wherein scanning a sector of the anisotropic rotor blade comprises: transmitting, with a plurality of transducers, a plurality of ultrasonic beams into the anisotropic rotor blade along an inspection plane, whereby the ultrasonic beams deviate from the inspection plane while propagating through the anisotropic rotor blade at an anisotropic tilt angle associated with the anisotropic rotor blade; receiving, with the plurality of transducers, the echo signal corresponding with the geometric fiducial marker, the magnitude of the echo signal related to a magnitude of the anisotropic tilt angle.
3 . The method as in claim 2 , further comprising determining the anisotropic tilt angle by repeating the scanning, determining, and adjusting steps until the magnitude and time delay of the echo signal corresponding with the geometric fiducial marker is within a predetermined maximum echo range.
4 . The method as in claim 3 , wherein after the anisotropic tilt angle is determined, the method further comprises: adjusting the anisotropic rotor blade a final instance based on the anisotropic tilt angle; and scanning the anisotropic rotor blade for defects.
5 . The method as in claim 1 , wherein the geometric fiducial marker is a ceiling of a cooling passage defined within an airfoil of the anisotropic rotor blade.
6 . The method as in claim 1 , wherein scanning the sector comprises: transmitting, with a plurality of transducers of the probe, a plurality of ultrasonic beams at varying angles into the anisotropic rotor blade, the angles being defined between the respective ultrasonic beams and a wave normal direction that is perpendicular to the plurality of transducers, the angles varying from between about −5° and about 5°.
7 . The method as in claim 1 , wherein the anisotropic rotor blade is formed from a single crystal alloy.
8 . The method as in claim 1 , wherein the mounting portion of the anisotropic rotor blade includes a root face, and wherein the method comprises: positioning the probe of a phased array ultrasound system on the root face of the anisotropic rotor blade at the axial centerline.
9 . The method as in claim 1 , wherein, after scanning the anisotropic rotor blade for defects a first time, the method further comprises: translating the probe away from the axial centerline of the anisotropic rotor blade and along the mounting portion; and scanning the anisotropic rotor blade for defects a second time.
10 . The method as in claim 1 , wherein scanning the sector comprises: transmitting, with a plurality of transducers of the probe, a plurality of ultrasonic beams at varying depths into the anisotropic rotor blade, the depths being defined by pre-set region of interest.
11 . The method as in claim 1 , wherein scanning the sector comprises simultaneous multi-depth and multi-angle focusing of the acoustic waves into the anisotropic blade.
12 . A method for detecting defects in an anisotropic rotor blade using a phased array ultrasound system, the anisotropic rotor blade extending along an axial centerline and comprising a mounting portion and an airfoil, the method comprising: positioning a probe of the phased array ultrasound system on the mounting portion of the anisotropic rotor blade at the axial centerline; scanning a sector of the anisotropic rotor blade along the axial centerline with the probe of the phased array ultrasound system, a geometric fiducial marker disposed at least partially within the sector of the anisotropic rotor blade; determining a magnitude and a time delay of an echo signal corresponding with the geometric fiducial marker; adjusting delay laws of the probe based on the magnitude of the echo signal corresponding with the geometric fiducial marker; repeating 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.
13 . The method as in claim 12 , wherein scanning a sector of the anisotropic rotor blade comprises: transmitting, with a plurality of transducers, a plurality of ultrasonic signals into the anisotropic rotor blade along an inspection plane, whereby the ultrasonic signals deviate from the inspection plane while propagating through the anisotropic rotor blade at an anisotropic tilt angle associated with the anisotropic rotor blade; receiving, with the plurality of transducers, the echo signal corresponding with the geometric fiducial marker, the magnitude and the time delay of the echo signal related to a magnitude of the anisotropic tilt angle.
14 . The method as in claim 13 , further comprising determining the anisotropic tilt angle by repeating 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.
15 . The method as in claim 14 , wherein after the anisotropic tilt angle is determined, the method further comprises: adjusting the delay laws of the probe a final instance based on the anisotropic tilt angle; and scanning the anisotropic rotor blade for defects.
16 . The method as in claim 12 , wherein the geometric fiducial marker is a ceiling of a cooling passage defined within an airfoil of the anisotropic rotor blade.
17 . The method as in claim 12 , wherein scanning the sector comprises: transmitting, with a plurality of transducers of the probe, a plurality of ultrasonic beams at varying angles into the anisotropic rotor blade, the angles being defined between the respective ultrasonic beam and an axis normal to the plurality of transducers, the angles varying from between about −5° and about 5°.
18 . The method as in claim 12 , wherein the anisotropic rotor blade is formed from a single crystal alloy.
19 . The method as in claim 12 , wherein the mounting portion of the anisotropic rotor blade includes a root face, and wherein the method comprises: positioning the probe of a phased array ultrasound system on the root face of the anisotropic rotor blade at the axial centerline.
20 . The method as in claim 12 , wherein, after scanning the anisotropic rotor blade for defects a first time, the method further comprises: translating the probe away from the axial centerline of the anisotropic rotor blade and along the mounting portion; and scanning the anisotropic rotor blade for defects a second time.

Description

FIELD The present disclosure relates generally to methods for detecting defects in an anisotropic rotor blade using a phased array ultrasound system. Particularly, the present disclosure is directed to calibrating a phased array ultrasound system based on geometric fiducial markers within the anisotropic rotor blade. BACKGROUND 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. 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. 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. BRIEF DESCRIPTION Aspects and advantages of the methods in accordance with the present disclosure 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. In accordance with one embodiment, a method for detecting defects in an anisotropic rotor blade using a phased array ultrasound system is provided. The anisotropic rotor blade extends along an axial centerline and includes a mounting portion and an airfoil. The method includes positioning a probe of the phased array ultrasound system on the mounting portion of the anisotropic rotor blade at the axial centerline. The method further includes scanning a sector of the anisotropic rotor blade along the axial centerline with the probe of the phased array ultrasound system. A geometric fiducial marker is disposed at least partially within the sector of the anisotropic rotor blade. The method further includes determining a magn