GB2322987A - Object detection in turbine influx or efflux - Google Patents

Object detection in turbine influx or efflux Download PDF

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Publication number
GB2322987A
GB2322987A GB9704634A GB9704634A GB2322987A GB 2322987 A GB2322987 A GB 2322987A GB 9704634 A GB9704634 A GB 9704634A GB 9704634 A GB9704634 A GB 9704634A GB 2322987 A GB2322987 A GB 2322987A
Authority
GB
United Kingdom
Prior art keywords
gas turbine
signal
radar
reflected
velocity
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Withdrawn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
GB9704634A
Other versions
GB9704634D0 (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
GEC Marconi Ltd
Marconi Co 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 GEC Marconi Ltd, Marconi Co Ltd filed Critical GEC Marconi Ltd
Priority to GB9704634A priority Critical patent/GB2322987A/en
Publication of GB9704634D0 publication Critical patent/GB9704634D0/en
Priority to PCT/GB1998/000711 priority patent/WO1998039671A1/en
Priority to AU65083/98A priority patent/AU6508398A/en
Publication of GB2322987A publication Critical patent/GB2322987A/en
Withdrawn legal-status Critical Current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
    • 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
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
    • G01S13/56—Discriminating between fixed and moving objects or between objects moving at different speeds for presence detection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
    • F02C7/04—Air intakes for gas-turbine plants or jet-propulsion plants
    • F02C7/05—Air intakes for gas-turbine plants or jet-propulsion plants having provisions for obviating the penetration of damaging objects or particles
    • 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
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/10—Systems for measuring distance only using transmission of interrupted, pulse modulated waves
    • G01S13/18—Systems for measuring distance only using transmission of interrupted, pulse modulated waves wherein range gates are used
    • 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
    • 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
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/04—Systems determining presence of a 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
    • 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
    • G01S7/411—Identification of targets based on measurements of radar reflectivity
    • G01S7/412—Identification of targets based on measurements of radar reflectivity based on a comparison between measured values and known or stored values

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

A detection system (10) detects if objects are drawn into the intake (12) of a gas turbine. The detection system (10) comprises a coherent radar system comprising a radar transmitter and a radar receiver (24, 26). A radar signal reflected by a moving object (20) entering the intake (12) is analysed by a processor (26) to determine velocity - versus time characteristics (fig 2) of the object (20) from Doppler shift in the signal relative to a transmitted signal. The processor (26) then classifies the object (20) as damaging or non-damaging.

Description

OBJECT DETECTION SYSTEMS This invention relates to detection systems and is particularly, but not exclusively, related to a system for detecting objects being ingested into or ejected out of gas turbines.
The ingestion of objects such as nuts, rivets or stones into the compressor stages of a gas turbine often causes damage to the gas turbine which can result in expensive repairs. Furthermore, an operator of the turbine may be unaware that the ingestion of objects has occurred and that there may be darnage. Where the gas turbine is used to power an aircraft, the operation of a damaged gas turbine could be hazardous.
It is desirable to monitor the intake of gas turbines to detect ingestion of objects. Equally it is desirable to detect if an object is ejected out of a gas turbine. Both events indicate that damage may have occurred.
It is an object of the present invention to provide a system which is capable of detecting objects entering into a turbine.
According to a first aspect the invention provides a system for detecting an object travelling into or out of a gas turbine comprising a transmitter for transmitting electromagnetic radiation, a receiver for receiving electromagnetic radiation and processing means in which the transmitter transmits at least one signal the receiver detects at least one reflected signal reflected by the object and the processing means processes the or each reflected signal to determine the presence of the object.
Preferably the transmitter and receiver transmit and receive radar signals. Preferably they transmit and receive radar signals in the microwave band, that is above 1GHz. Alternatively, they may transmit and receive or other radiation.
Preferably the system is a coherent radar system. The system may operate in a continuous wave or a pulse mode. Motion of blades in the turbine can modulate the radar signal and create unwanted signals which can obscure signals reflected by the object. A coherent system enables these effects to be reduced in processing of reflected signals.
Preferably the system detects movement of the object in the intake of a gas turbine. This may be done by using Doppler shift in the reflected signal to discriminate the moving object from a large amount of stationary background clutter. If the Doppler shift is measured then the radial velocity (relative to the receiver) of the object may be determined and the object distinguished from other unwanted spectral signals. Changes in velocity of the object as it travels can give a measure of acceleration or deceleration. An impact with a side wall of the turbine or with a turbine blade may be detected by observing an abrupt change in velocity or a transient in the acceleration.
The system may be monostatic with the transmitter and receiver located substantially in the same location, for example in a single unit. The system may be bistatic with a separate transmitter and receiver in separate locations. The system may be multistatic with a plurality of separate transmitters and/or a plurality of separate receivers. A multistatic system could indicate the position of the object, either by using narrow beam sensors for the receivers, or by triangulation if high resolution range gating is used.
Preferably the system is used to measure objects passing through the intake of a gas turbine.
However, in this embodiment the transmitter and receiver do not necessarily have to be installed in the intake. At least one of the transmitter and/or receiver may be located outside the intake facing in or may be located inside the intake, perhaps even as far in as a compressor stage.
According to a second aspect the invention provides a method for detecting an object travelling into or out of a gas turbine comprising the steps of: transmitting at least one signal comprising electromagnetic radiation; detecting at least one signal reflected by the object; and processing the or each reflected signal to determine the presence of the object.
Although the system may be used in continuous wave mode this does not give information concerning the range of the object. High resolution radar techniques which can range gate the signal may be used.
Preferably processing of the or each reflected radar signal provides a characteristic of the object.
The characteristic may contain information related to the nature of the object. The characteristic of the object may be compared with reference characteristics of a plurality of objects already stored to enable the method or system to classify the nature of the object. The method or system may classify the object as damaging or non-damaging.
If it is known that an object has been ingested, the gas turbine can be inspected for damage. A system which can classify the nature of the object (which may also indicate if the object is of a damaging or a non-damaging type) enables decisions concerning inspection and repair of the gas turbine to be made. At present damage detection relies on regular routine inspections. In these "blind" inspections, the inspector has no advance knowledge of whether to expect damage, and can fail to detect minor damage. This invention reduces the need to carry out "blind" inspections and reduces the chance of blade damage going undetected, which can result in serious damage to the gas turbine.
Preferably the invention is used to detect objects travelling into or out of the gas turbine when it is used as to power an aircraft. This application is important because it is safety critical.
Alternatively it may detect an object travelling into or out of the compressor of a gas turbine used in, for example, power generation.
An example of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a schematic view of gas turbine incorporating a system according to the invention; and Figure 2 shows a schematic representation of velocity versus time characteristics expected for two different types of objects.
Figure 1 shows part of a gas turbine 10 comprising an intake 12 and a compressor 14. The compressor 14 comprises a number of stages 16 mounted on a shaft 18.
In operation of the gas turbine, foreign objects 20 may enter the intake and then be drawn into the compressor 14. Normally for small objects there would be no indication to an operator of the turbine that this has occurred. As a result damage could occur to the turbine and the operator could be unaware of this fact.
In this embodiment of the invention, the turbine 10 is provided with a coherent radar system 22 comprising an antenna 24 for transmitting and receiving radar signals and an electronics unit 26 containing a transmitter, a receiver and a processing system. Alternatively the system may use separate transmit and receive antennae, which may be probes or horns, either located adjacent to each other or separated in space. Radar signals transmitted from the antenna are reflected by objects passing through the air intake and are received by the antenna.
Radar signals reflected from the moving blades of the gas turbine 10 create unwanted spectral signals which may obscure signals reflected from foreign objects. The unwanted signals can be reduced by coherent processing techniques or by directing the radar beam away from the moving blades. If further rejection of signals reflected from the blades is required a range gating technique may be used.
The radar system 22 uses a continuous wave signal operating in I band, for example a frequency of 9.7 GHz and a wavelength of approximately 3cm. A suitable power level is 200pW.
The antenna 24 may be in any suitable form such as a loop or flat plates. Although in Figure 1 the antenna 24 is shown at the outer region of the intake, it may be located elsewhere. For example, it may be located outside the intake or deeper into the intake than shown. Signals detected by the antenna 24 are analysed by an electronics unit 26.
Since the foreign objects 20 generally have a size which is smaller than the wavelength of the transmitted radar signals, they are reflected in a mode which is known as Rayleigh Scattering.
In this mode, the size of the reflected radar signal is closely related to the physical size and the dielectric constant of the foreign object. The dielectric constant can be broadly related to density.
For a large object made of a dense material such as metal, a relatively large reflected signal would be expected. For a small object made of something less dense such as an organic material, a lower reflected signal would be expected. A small dense object may give a similar reflected signal to a larger, less dense object. However, less dense objects show different velocity/time characteristics to more dense objects. Therefore the size of the reflected radar signals, used in conjunction with a measure of the object's velocity/time characteristic, give an indication of the size and material composition of the object.
Hard, dense and structurally strong objects are most likely to produce damage in a gas turbine.
Less dense and structurally weak objects are usually themselves broken or deformed without causing damage to the gas turbine.
Figure 2 shows a schematic representation of velocity/time characteristics which are expected for objects entrained in the air flow into a gas turbine and accelerating towards terminal velocity.
The graph has time as an x-axis and velocity as a y-axis. The unbroken line 30 represents a less dense object which accelerates rapidly and approaches the terminal velocity relatively quickly.
The broken line 32 represents a dense object which accelerates relatively slowly and takes a longer time to reach the terminal velocity. The vertical broken lines 34, 36 define a region in which it is practical for the object to be detected and measured by the radar system 22. It can be seen that the different objects have different, distinguishable, characteristics in this region.
This provides a way of differentiating between potentially damaging and non-damaging objects by using the radar system 22 to measure the change in velocity of an object passing through the air intake.
Radar can measure the velocity of an object moving radially with respect to the antenna by measuring the frequency shift on the reflected radar signals due to the Doppler effect. The resolution with which the frequency (and hence the velocity) can be measured is inversely proportional to the time over which the signal is observed. Therefore the greater the time, the more precise is the velocity measurement. However, for an accelerating or decelerating target, the velocity will vary within the measurement period, which may serve to degrade the velocity resolution. If the velocity and acceleration characteristics expected for objects passing into a gas turbine are known, then a good compromise for the measurement period can be selected.
In one embodiment of the invention, velocity is measured by first recording the reflected radar signal in the time domain. A Fourier Transform is then performed on a period of the data around the point of interest. The Doppler shift can then be read off from the frequency of the largest signal in the frequency domain and the velocity is calculated from the relationship between velocity, Doppler shift and radar wavelength. If the objects have a velocity in the region of 40 m/sec and the period of the Fourier Transform was selected to be 10 ms, giving a frequency resolution of 100 Hz, this corresponds to a velocity resolution of 1.5 m/sec. In many practical situations the object's velocity will be higher than 40 m/sec and a shorter measurement period would be appropriate. Successive, overlapping regions of data are transformed into the frequency domain and the resultant spectra are plotted side by side to show the gradual change in the velocity of the object. The overlap of the regions is such that the time series data sets are spaced from each other by 2 ms. Oversampling in this way provides a greater number of results and better illustrates the change in velocity with time.
In this embodiment a system is described in which objects are accelerating. This is only one example of the motion of the object, for example an object could be thrown up by the undercarriage of an aircraft and be travelling at high speed or decelerating as it enters the air intake. In this case different velocity/time characteristics would be analysed.
The electronics unit 26 may be provided with a series of look-up tables to compare the reflected radar signals measured from an object passing through the air intake with standard reference signals which are stored in the electronics unit 26. The electronics unit 26 may indicate to an operator of the turbine that an object has been detected entering the turbine and provide an indication of whether the object is considered to be damaging or non-damaging.
Reflections of the radar signals from the side walls of the air intake and from the turbine at the end of the air intake may give rise to interference effects which cause variation in the signal strength with the position of the object in the air intake. Optimisation of the sensor and overall system design can reduce this variation and any remaining variation can be allowed for in subsequent signal processing.
Although radar is associated with detecting large objects at large distances, it is being used in a very different way, that is to detect much smaller objects at short range.
The invention provides a system for detecting foreign objects in the air intake or other parts of a gas turbine. The system can also monitor the progress of an object into or out of a gas turbine, and provide information on the velocity and acceleration of the object and, if range gating is included, on the range of the object. As a result it may be possible to classify the nature of the object, for example its size, density or the material from which it is made. Accordingly, the system can provide an assessment of the likelihood of the object causing damage in the gas turbine. It may also be possible to detect impacts of the object against parts of the engine by measuring sudden changes in the velocity of the object.
The invention is particularly suitable for detecting objects entering the intake of a gas turbine used to power an aircraft.

Claims (20)

1. A system for detecting an object travelling into or out of a gas turbine comprising a transmitter for transmitting electromagnetic radiation, a receiver for receiving electromagnetic radiation and processing means in which the transmitter transmits at least one signal the receiver detects at least one reflected signal reflected by the object and the processing means processes the or each reflected signal to determine the presence of the object.
2. A system according to claim 1 which detects movement of the object in the intake of the gas turbine.
3. A system according to claim 1 or claim 2 in which the object is detected by using Doppler shift in the reflected signal to discriminate the object from an amount of stationary background clutter.
4. A system according to any preceding claim in which changes in velocity of the object as it travels are analysed to indicate acceleration or deceleration.
5. A system according to claim 4 in which an abrupt change in velocity or a transient in the acceleration of the object is used to detect an impact between the object and a part of the gas turbine.
6. A system according to any preceding claim which measures a characteristic of the object which is related to the nature of the object and then compares the characteristic with at least one reference characteristic to enable the method or system to classify the nature of the object.
7. A system according to claim 6 which classifies the object as damaging or non-damaging.
8. A system according to any preceding claim in which the transmitter transmits radar signals and the receiver receives radar signals.
9. A system according to claim 8 which is a coherent radar system.
10. A system according to claim 8 or claim 9 in which high resolution radar techniques are used to range gate the signal.
11. A system according to any of claims 8 tolO in which radar signals transmitted and received are in the microwave band.
12. A system according to any preceding claim in which the gas turbine is used to power an aircraft.
13. A system substantially as described herein with reference to the figures of the accompanying drawings.
14. A method for detecting an object travelling into or out of a gas turbine comprising the steps of: transmitting at least one signal comprising electromagnetic radiation; detecting at least one signal reflected by the object; and processing the or each reflected signal to determine the presence of the object.
15. A method according to claim 14 in which radar signals are transmitted and received.
16. A method according to claim 14 in which microwave or other radiation is transmitted and received.
17. A method according to any of claims 14 to 16 in which the gas turbine is used to power an aircraft.
18. A method substantially as described herein with reference to the figures of the accompanying drawings.
19. A gas turbine using a system or a method in accordance with any preceding claim.
20. A gas turbine substantially as described herein with reference to the figures of the accompanying drawings.
GB9704634A 1997-03-06 1997-03-06 Object detection in turbine influx or efflux Withdrawn GB2322987A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB9704634A GB2322987A (en) 1997-03-06 1997-03-06 Object detection in turbine influx or efflux
PCT/GB1998/000711 WO1998039671A1 (en) 1997-03-06 1998-03-05 Object detection systems
AU65083/98A AU6508398A (en) 1997-03-06 1998-03-05 Object detection systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9704634A GB2322987A (en) 1997-03-06 1997-03-06 Object detection in turbine influx or efflux

Publications (2)

Publication Number Publication Date
GB9704634D0 GB9704634D0 (en) 1997-04-23
GB2322987A true GB2322987A (en) 1998-09-09

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GB9704634A Withdrawn GB2322987A (en) 1997-03-06 1997-03-06 Object detection in turbine influx or efflux

Country Status (3)

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AU (1) AU6508398A (en)
GB (1) GB2322987A (en)
WO (1) WO1998039671A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102576070A (en) * 2009-12-09 2012-07-11 阿利发Np有限公司 Monitoring system for an inner chamber of a machine
WO2014023420A1 (en) * 2012-08-09 2014-02-13 Linde Aktiengesellschaft Method and device for detecting moving objects in a gas stream during cryogenic gas separation
WO2016016633A1 (en) * 2014-08-01 2016-02-04 Bae Systems Plc Foreign object debris detection system and method
US9995167B2 (en) 2014-08-01 2018-06-12 Bae Systems Plc Turbine blade monitoring
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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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8459103B2 (en) 2011-06-24 2013-06-11 United Technologies Corporation IDMS signal processing to distinguish inlet particulates
CN105022046B (en) * 2015-07-31 2017-06-23 中国电子科技集团公司第二十八研究所 A kind of radar weak target detection method based on characteristics of image
CN115047443A (en) * 2021-03-09 2022-09-13 深圳市万普拉斯科技有限公司 Target detection method and device of millimeter wave radar and handheld terminal

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1463758A (en) * 1973-06-11 1977-02-09 Control Data Canada Nozzle area measurement
GB2011752A (en) * 1977-12-20 1979-07-11 Saskatchewan Power Corp Method and apparatus for contactless rotational speed measurement
US4413519A (en) * 1981-07-29 1983-11-08 Westinghouse Electric Corp. Turbine blade vibration detection apparatus
US5424824A (en) * 1993-05-12 1995-06-13 The Boeing Company Method and apparatus for normal shock sensing within the focal region of a laser beam
GB2295670A (en) * 1994-12-03 1996-06-05 Deutsche Forsch Luft Raumfahrt Measuring flow vectors in gas flows

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4049349A (en) * 1976-06-30 1977-09-20 Wennerstrom Arthur J Device for measuring rotor tip clearance in operating turbomachinery
IT1116443B (en) * 1977-05-10 1986-02-10 Adele Advanced Electronic S R LOW CONSUMPTION PULSE OPERATION DOPPLER INTRUSION SENSOR
US4346383A (en) * 1979-08-04 1982-08-24 Emi Limited Checking the location of moving parts in a machine
US4286260A (en) * 1979-09-11 1981-08-25 E-Systems, Inc. Ranging quadrature doppler microwave intrusion alarm system
DE3044242A1 (en) * 1979-12-11 1981-09-03 Smiths Industries Ltd., London DISPLAY SYSTEM FOR DISPLAYING THE DISTANCE OF THE BLADES OF A TURBINE TO A REFERENCE POINT
EP0213558A1 (en) * 1985-08-23 1987-03-11 C & K Systems, Inc. A method and an apparatus for detecting an intruder
US5287111A (en) * 1992-08-24 1994-02-15 Shmuel Hershkovitz Doppler shift motion detector with variable power

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1463758A (en) * 1973-06-11 1977-02-09 Control Data Canada Nozzle area measurement
GB2011752A (en) * 1977-12-20 1979-07-11 Saskatchewan Power Corp Method and apparatus for contactless rotational speed measurement
US4413519A (en) * 1981-07-29 1983-11-08 Westinghouse Electric Corp. Turbine blade vibration detection apparatus
US5424824A (en) * 1993-05-12 1995-06-13 The Boeing Company Method and apparatus for normal shock sensing within the focal region of a laser beam
GB2295670A (en) * 1994-12-03 1996-06-05 Deutsche Forsch Luft Raumfahrt Measuring flow vectors in gas flows

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102576070A (en) * 2009-12-09 2012-07-11 阿利发Np有限公司 Monitoring system for an inner chamber of a machine
WO2014023420A1 (en) * 2012-08-09 2014-02-13 Linde Aktiengesellschaft Method and device for detecting moving objects in a gas stream during cryogenic gas separation
CN104520730A (en) * 2012-08-09 2015-04-15 林德股份公司 Method and device for detecting moving objects in a gas stream during cryogenic gas separation
CN104520730B (en) * 2012-08-09 2017-09-19 林德股份公司 Method and apparatus for the mobile object in gas stream during detecting cryogenic gas separation
WO2016016633A1 (en) * 2014-08-01 2016-02-04 Bae Systems Plc Foreign object debris detection system and method
GB2528880A (en) * 2014-08-01 2016-02-10 Bae Systems Plc Foreign object debris detection system and method
US9784827B2 (en) 2014-08-01 2017-10-10 Bae Systems Plc Foreign object debris detection system and method
US9995167B2 (en) 2014-08-01 2018-06-12 Bae Systems Plc Turbine blade monitoring
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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Publication number Publication date
AU6508398A (en) 1998-09-22
WO1998039671A1 (en) 1998-09-11
GB9704634D0 (en) 1997-04-23

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