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EP0965055A1 - Constatation des degats - Google Patents

Constatation des degats

Info

Publication number
EP0965055A1
EP0965055A1 EP98909585A EP98909585A EP0965055A1 EP 0965055 A1 EP0965055 A1 EP 0965055A1 EP 98909585 A EP98909585 A EP 98909585A EP 98909585 A EP98909585 A EP 98909585A EP 0965055 A1 EP0965055 A1 EP 0965055A1
Authority
EP
European Patent Office
Prior art keywords
turbine
damage
record
signals
reflected
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98909585A
Other languages
German (de)
English (en)
Inventor
Peter Donald Fraser Tait
Adrian Peter Kyte
Peter James Steward
David John Shephard
Timothy Edward Ffrench
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems Electronics Ltd
Original Assignee
Marconi Electronic Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Marconi Electronic Systems Ltd filed Critical Marconi Electronic Systems Ltd
Publication of EP0965055A1 publication Critical patent/EP0965055A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G01S7/415—Identification of targets based on measurements of movement associated with the target
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications

Definitions

  • This invention relates to a method of assessing damage in a turbine such as a gas or a steam
  • blades includes compressor blades and turbine blades. Damage can be caused by impact of objects drawn into the turbine or failure of parts within the turbine, for example, failure of the blades themselves. If initial damage is not spotted quickly further damage can occur in the turbine.
  • the invention provides a method of checking for damage in a turbine
  • the record is a time domain data sequence.
  • the record may be analysed in the time domain.
  • the record or selected parts of it may be converted into the frequency domain for
  • the record which is analysed may have features caused by modulation of the transmitted signal
  • the record of the reflected signals is compared with a standard record.
  • the standard is a standard record.
  • the method uses radar signals.
  • the method uses coherent radar techniques.
  • amplitude and/or phase of reflected signals is used to determine a figure, value or
  • a figure, value or other damage discriminant may be generated by integrating a difference in
  • the method may use probes for generating a signal, receiving signals or both.
  • One or more J probes may be located within existing boroscope or inspection holes or apertures created
  • one or more probes may be mounted outside the rotor
  • a hybrid method may use
  • one or more probes for internal monitoring and one or more probes for external monitoring.
  • a continuous wave radar signal is used. This may be used in an application where
  • pulsed radar ranging techniques could be used. This may be used.
  • the method may be used in an application where ranging is required. If ranging is used, the method may be able
  • turbine may be monitored whilst the turbine is in operation. Continuous monitoring is possible.
  • the invention provides a system for assessing damage in a turbine
  • a transmitter which transmits a signal towards one or more rotating rotor stages, a
  • the record is in the time domain. It may be converted to the frequency domain for analysis purposes.
  • the processing means compares the record against a standard record.
  • record may be a measurement of an undamaged gas turbine or of the same turbine at an earlier
  • the standard record may be generated by calculation.
  • processing means may integrate differences in amplitude across the record and the standard record in order to determine a damage figure, value or other discriminant representative of damage of the particular turbine being measured.
  • the invention may be used to monitor turbines in a variety of applications including jet engines and turbines used in power generation.
  • Figure 1 shows a schematic representation of a damage monitoring system
  • Figure 2 shows a frequency spectrum returned by two undamaged rotor stages
  • Figure 3 shows a part of Figure 2 expanded
  • Figure 4 shows the frequency spectrum of Figure 3 after further processing and with an
  • Figure 5 shows a frequency spectrum returned by a single undamaged rotor stage
  • Figure 6 shows a frequency spectrum returned by a single rotor stage carrying a bent blade
  • Figure 7 shows a comparison of two frequency spectra each returned by a single undamaged
  • Figure 8 shows a comparison of processed versions of Figures 5 and 6;
  • Figure 9 shows a comparison of two frequency spectra each returned by three undamaged rotor
  • Figure 10 shows a comparison of two frequency spectra, one from an undamaged turbine and
  • Figure 11 shows another comparison of two frequency spectra, one from an undamaged turbine
  • Figure 12 shows a comparison of two frequency spectra returned by a set of seven rotor stages
  • Figure 13 shows a comparison between a frequency spectrum returned by an undamaged turbine
  • Figure 14 shows another comparison between a frequency spectrum returned by an undamaged turbine and a frequency spectrum returned by a damaged turbine
  • Figure 15 shows yet another comparison between a frequency spectrum returned by an
  • Figure 16 shows a visual representation of an algorithm used in the analysis of time domain data
  • FIGS 17, 18 and 19 show three measurements of damage against location for different levels
  • Figure 1 shows a damage monitoring system 10 for monitoring a gas turbine 12.
  • gas turbine 12 was represented by a single compressor section in order to
  • the system 10 comprises a radar system 14 for
  • the radar generates and receiving radar signals 16.
  • the radar generates a continuous wave signal at an
  • the radar system 14 is controlled by a computer 18.
  • the computer controls the radar operation and processing of received signals. Data generated
  • the computer 18 controls the transmitted
  • horns 22, 24 one for transmitting signals and the other for receiving signals.
  • the beamwidth available from small radiating elements at 10GHz is the beamwidth available from small radiating elements at 10GHz.
  • An alternative technique is a hybrid method using a combination of internal and external monitoring, which utilises a miniature radar probe mounted close to the wall of the air intake of the gas turbine and an internal probe.
  • a waveform generator in the radar system 14 produces an output which is up-converted to a continuous wave signal at I band, for example around 10 GHz.
  • the signal is transmitted
  • the gas turbine was rotated at approximately 1545 rpm which corresponds to a spool rate of approximately 25.75Hz, that is the number of revolutions of the shaft per second.
  • Each compressor stage has a number of blades (between 24 and 51) which generate a chopping rate which is the product of the
  • Standard radar down-conversion techniques are used to convert the reflected signal to baseband
  • I In-phase (I) and Quadrature (Q) channels.
  • the baseband signal is digitised using a two channel analogue to digital converter.
  • digitisation rate is 500kHz per channel.
  • the data are then down-loaded to the computer 18 for
  • the raw data file contains baseband data
  • Each block of data first has the offset carrier frequency removed by digitally shifting the
  • the data size has to be
  • This redundant data is removed by using a time domain low pass filter with a cut-off frequency
  • final spectrum has a bandwidth of ⁇ 25kHz and a resolution of about 1/12th Hz.
  • Figures 2 to 15 and 17 to 19 show results obtained by the system 10 in which a single
  • Figure 2 shows a frequency spectrum returned by two undamaged stages of rotors present in a
  • each frequency bin in the FFT represents about one twelfth of a hertz.
  • Figure 3 shows a section taken from Figure 2 expanded to show the reduced frequency range
  • Figure 4 shows the corrected spool rate harmonic response calculated to take account
  • Figures 5 to 8 show results obtained using a single rotor stage in the gas turbine.
  • the single rotor stage has 25 blades. This gives rise to a
  • Figure 5 shows a spectrum of the returned signal for
  • the DC component shows the strength of the
  • stage of rotors has 25 blades, the radar return from the gas turbine should repeat every time the
  • Figure 6 shows a spectrum returned by a single rotor stage having a bent blade.
  • Figure 7 shows the difference between the spool rate harmonic responses of two undamaged
  • the resulting mean value is taken as the damage meter reading when a damaged turbine
  • the consistency of damage meter reading can be used to provide a measure of the repeatability between measurements.
  • Figure 8 shows the ratio of the spool rate harmonic response for the result in Figure 6 over the spool rate harmonic response of the result shown in Figure 5 and gives a comparison between
  • Figures 9 to 11 show frequency spectra returned by three rotor stages present in the gas turbine.
  • the first stage has 25 blades which gives a chop rate of approximately 645Hz as above.
  • the second rotor stage has 37 blades which gives a chop rate of approximately 955Hz.
  • the third rotor stage has 51 blades which gives a chop rate of approximately 1315Hz.
  • Figure 9 shows the ratio of spool rate harmonics comparing two frequency spectra returned by the gas turbine having three undamaged rotor stages.
  • Figure 10 shows a comparison of a spectrum recorded with three undamaged rotor stages being
  • Figure 11 shows a comparison of a spectrum, recorded with three undamaged rotor stages being
  • Figures 12 to 15 are difference plots for:
  • Figure 13 is 1.04, for Figure 14 is 1.64 and for Figure 15 is 1.72.
  • the radar system 14 is used with internal probes instead of the horns 22 and 24.
  • the probes are fitted in inspection or boroscope holes in the turbine so that the
  • reflected signals received come predominantly from one rotor stage. Multiple probes may be
  • processing the data record in the time domain This is carried out by isolating an individual
  • the damaged blade to be identified within an engine cycle-period.
  • Disruption of the radar beam by moving blades produces a fluctuation in the received signal.
  • the fluctuation caused by a normal blade has a characteristic shape.
  • a damaged blade produces
  • the correlation coefficient By correlating a section of data obtained from the turbine in a damaged state with a section of reference data, the correlation coefficient can be calculated. This value becomes lower as the
  • the correlation coefficient can also be used as an indicator of position within the turbine cycle.
  • the reference and recorded cycles (30, 32) are roughly aligned. This is done by correlating the
  • the alignment is sufficiently good to allow refinement of alignment.
  • a small section 34 of the reference cycle 30 is selected and sought in a corresponding section
  • the search sections in the recorded cycle 32 are larger than the sections in
  • the difference 40 will reflect the size of the blade damage, and the position of the damage
  • Readings on the output dial will also be due to factors other than damage to a turbine blade.
  • One cause of variation in the output reading is the variation in the amplitude of the data
  • thermal noise is not negligible. Since thermal noise is uncorrelated, a small-scale
  • variation of speed in the time-domain data obtained from the turbine is one of regular
  • the correlation coefficient is calculated. As the size of its sample is reduced, the correlation
  • the time-domain processing algorithm incorporates two further operations, subtraction and integration.
  • the output dial readings for the unwanted variations can be subtracted from those which were obtained by comparing a reference with a recorded data series. This results in rejection of the unwanted variations and allows variations due to blade damage to remain.
  • blade damage can be detected by the time-domain algorithm.
  • a peak is evident at 38° although
  • probes may be passive antenna elements connected to a transmitter or receiver via a microwave
  • the active microwave circuitry and signal processing components are located in a less
  • centimetres which is typical of the spacing between rotor stages.
  • fluttering blades may have characteristic Doppler
  • the technique can be used to detect damaged or missing blades, and detect flutter of blades.
  • the technique may be used to monitor gas turbines in jet engines for aircraft, in centrifugal

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
  • Control Of Turbines (AREA)

Abstract

La présente invention concerne un système (10) destiné à détecter les dégats affectant la turbine à gaz (12) d'un turboréacteur. Ce système comprend un émetteur radar (14, 22) et un récepteur radar (14, 24). Les signaux radar (16) émis vers la turbine (12) sont réfléchis. Les signaux réfléchis sont ensuite analysés dans un dispositif de traitement du signal (18). On constate les dégats de la turbine en comparant à une séquence de données normalisée des signaux déjà mesurés une séquence de données des signaux mesurés.
EP98909585A 1997-03-06 1998-03-05 Constatation des degats Withdrawn EP0965055A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB9704637 1997-03-06
GB9704637A GB2322988A (en) 1997-03-06 1997-03-06 Damage assessment using radar
PCT/GB1998/000698 WO1998039670A1 (fr) 1997-03-06 1998-03-05 Constatation des degats

Publications (1)

Publication Number Publication Date
EP0965055A1 true EP0965055A1 (fr) 1999-12-22

Family

ID=10808790

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98909585A Withdrawn EP0965055A1 (fr) 1997-03-06 1998-03-05 Constatation des degats

Country Status (5)

Country Link
EP (1) EP0965055A1 (fr)
AU (1) AU6407798A (fr)
CA (1) CA2282291A1 (fr)
GB (1) GB2322988A (fr)
WO (1) WO1998039670A1 (fr)

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DE10359930A1 (de) * 2003-01-23 2004-08-05 Siemens Ag Verfahren zum Ermitteln der Beanspruchung von Schaufeln einer Strömungsmaschine während des Betriebs sowie entsprechende Vorrichtung zur Durchführung des Verfahrens
US7095221B2 (en) * 2004-05-27 2006-08-22 Siemens Aktiengesellschaft Doppler radar sensing system for monitoring turbine generator components
DE102009047761B3 (de) * 2009-12-09 2011-06-16 Areva Np Gmbh Überwachungssystem für einen Innenraum einer Maschine
GB201611894D0 (en) * 2016-07-08 2016-08-24 Imp Innovations Ltd An apparatus and method for generating a motional signature indicative of motion of moving parts of a target machine
DE102016216412A1 (de) * 2016-08-31 2018-03-01 Siemens Aktiengesellschaft Verfahren und Anordnung zur Überwachung eines Heißgasbereichs einer Gasturbine
US10705198B2 (en) * 2018-03-27 2020-07-07 Infineon Technologies Ag System and method of monitoring an air flow using a millimeter-wave radar sensor

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US3419820A (en) * 1965-12-06 1968-12-31 Curtiss Wright Corp Electronic frequency ratio generator
GB1143339A (en) * 1968-02-05 1969-02-19 Ts I Aviat Motorostroenia Im P Apparatus for indicating the vibration of turboengine rotor blades
US4194400A (en) * 1977-12-21 1980-03-25 General Electric Company Ultrasonic inspection method
GB2055269B (en) * 1979-08-04 1983-10-05 Emi Ltd Checking the location of moving parts in a machine
DE3044242A1 (de) * 1979-12-11 1981-09-03 Smiths Industries Ltd., London Anzeigesystem zur anzeige des abstandes der blaetter einer turbine zu einem bezugspunkt
DE3050608A1 (de) * 1980-10-10 1982-11-04 Franklin Institute Method and apparatus for detecting and identifying excessively vibrating blades of a turbomachine
US4380172A (en) * 1981-02-19 1983-04-19 General Electric Company On-line rotor crack detection
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Title
See references of WO9839670A1 *

Also Published As

Publication number Publication date
CA2282291A1 (fr) 1998-09-11
WO1998039670A1 (fr) 1998-09-11
GB2322988A (en) 1998-09-09
GB9704637D0 (en) 1997-04-23
AU6407798A (en) 1998-09-22

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