JPH05164602A - Method and apparatus for judging vibration mode of moving blade - Google Patents

Abstract

PURPOSE:To judge immediately the vibration mode of a moving blade in rotation. CONSTITUTION:Reflected lights 12 and 13 of laser lights, 6 and 7 from a plurality of places at the tip parts of a moving blade 2 are detected. The amplitude of each place of the tip part of the moving blade 2 are obtained with an estimated-pass-time operator 22, a first time measuring device 24, a second time measuring device 25, a first blade amplitude operator 26 and second blade- amplitude operator 27. The actually measured amplitude ratio, which is obtained by dividing the amplitude value of the other place by the amplitude value of the specified, place of the tip part of the moving blade, is obtained. Furthermore, assumed amplitude ratio data 34, which are obtained by dividing the amplitude value of the other place by the amplitude value of the specified place of the tip part of the moving blade 2 that is assumed when the moving blade 2 is vibrated in various kinds of vibrating modes, are compared with the actually- measured amplitude ratio signal 36 outputted from the amplitude-ratio operator 32 in vibrating-mode judging device 35. Thus the vibrating mode of the moving blade is judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor blade vibration mode determination method and a rotor blade vibration mode determination device.

[0002]

2. Description of the Related Art A rotor blade of a rotary machine such as an axial flow air compressor or a turbine engine reaches a resonance point where the rotation speed of a shaft to which the rotor blade is attached matches a natural frequency of the rotor blade. Vibrate.

When the stress of the bending moment or the like acting on the rotor blade is less than a certain value, the rotor blade of the rotating machine does not suffer damage such as cracks even if the stress is repeatedly applied.
When the stress acting on the blade exceeds a certain value and the number of stress repetitions exceeds a certain value, damage such as cracks occurs on the blade (such as high cycle fatigue, Called high cycle fatigue life).

Conventionally, in order to know the high cycle fatigue life of a rotor blade of a rotary machine, the amplitude of the rotor blade during rotation is measured, and the stress acting on the rotor blade is analyzed from the measured value.

The principle of conventional amplitude measurement of moving blades will be described below with reference to FIGS. 2 to 7.

2 to 4, 1 is a rotary shaft of a rotary machine, 2 is a moving blade attached to the rotary shaft 1, and 3 is a rotary reference position defined at a predetermined position on the outer peripheral surface of the rotary shaft 1. Rotation reference position mark, 18 is a rotation position detector, A
Indicates a displacement detection position whose position is fixed with respect to the center of rotation of the rotary shaft 1.

Although only one moving blade 2 is shown in the figure, a plurality of other moving blades having the same shape as the moving blade 2 are actually attached to the rotary shaft 1. ..

When the rotation reference signal is taken every time the rotation reference position indicator 3 passes through the rotation position detector 18 while the rotation shaft 1 is rotating in the direction of arrow D, the upper stage of each of FIGS. As shown in FIG. 5, the rotation reference signal has a waveform in which a pulse B is generated each time the rotation shaft 1 makes one rotation.
When the blade passing signal is taken every time the tip of the moving blade 2 and other moving blades pass the displacement detection position A as the rotor rotates, as shown in the lower stage of each of FIGS. The signal has almost the same number of pulses (the pulse C is a pulse generated when the moving blade 2 passes through the displacement detection position A) as the total number of the moving blade 2 and other moving blades each time the rotating shaft 1 makes one rotation. The waveform is generated at intervals.

2 and 5 assume that the rotating shaft 1 is rotating at the rotating speed N and the moving blades 2 are not vibrating, and FIGS. 3 and 6 are that the rotating shaft 1 is at the rotating speed N. It is assumed that the rotor 2 rotates and the rotor 2 vibrates and the tip of the rotor 2 is displaced in the rotation direction of the rotating shaft 1 (direction of arrow D).
When the tip of the rotor blade 2 is displaced in the direction of arrow D by vibration (see FIG. 3), the interval T ₂ between the pulse B and the pulse C (see FIG. 6) is not vibrating the rotor blade 2 (see FIG. 6). 2)) and the interval T ₁ between the pulse B and the pulse C (see FIG. 5).

Further, FIGS. 4 and 7 show a state in which the rotary shaft 1 rotates at the number of revolutions N and the moving blade 2 vibrates so that the tip of the moving blade 2 is displaced in the direction opposite to the arrow D direction. When the tip of the moving blade 2 is displaced to the opposite side with respect to the direction of arrow D by vibration (see FIG. 4), the interval T ₃ between the pulse B and the pulse C (see FIG. 7). Is longer than the interval T ₁ between the pulse B and the pulse C when the moving blade 2 is not vibrating.

In the amplitude measurement of the rotor blade 2 which has been conventionally performed, attention is paid to the interval between the pulse B of the rotation reference signal and the pulse C of the blade passage signal, and the rotor blade is calculated by the following equations (1) and (2). The amplitude of 2 is calculated. a = 2πR · ΔT / Tu (1) ΔT = | Tb−Tv | (2) a: Amplitude value at the tip of the moving blade 2 Tu: Interval of pulse B of rotation reference signal (see FIG. 5) Tb: Regardless of whether or not the moving blade 2 is vibrating, the rotation reference position marker 3 passes through the rotation position detector 18 and then the moving blade 2 passes through the displacement detection position A based on the rotation speed N of the rotating shaft 1. Estimated passage time required to reach (corresponding to T ₁ in FIG. 5) Tv: From when the rotation reference position marker 3 passes the rotation position detector 18 to when the moving blade 2 passes the displacement detection position A Actual transit time required (T ₂ in FIG. 6, T ₃ in FIG. 7)
ΔT: Deviation of Tv from Tb R: Tip radius of rotor blade 2

[0012]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The vibration mode is not only a mode (vibration mode) in which the moving blade 2 is bent in the arrow D direction or the opposite direction (vibration mode), but the moving blade 2 is centered around the axis extending in the radial direction of the rotating shaft 1. There may be a vibration mode called a primary twist that is twisted or another vibration mode.

Therefore, it is not possible to analyze the stress acting when the moving blade 2 vibrates by simply obtaining the amplitude at one point of the tip of the moving blade 2.

On the other hand, the vibration mode of the moving blade 2 can be determined by means of photography such as laser holography. In laser holography, the vibration mode of the rotating blade 2 can be immediately determined. I can't.

[0015]

[Findings from research results] In order to solve such a problem, the inventors have made earnest studies by focusing on the relationship between the amplitude and the vibration mode at a plurality of locations at the tip of the rotor blade 2, and as a result, have found the following findings. I got it.

FIG. 8 is a graph obtained by numerical simulation of the amplitudes near the tip stacking axis and the tip trailing edge of the rotor blade 2 when the vibration mode is primary bending (1F). The vibration mode of 9 is the primary torsion (1
7 is a graph obtained by numerical simulation of the amplitude near the tip end stacking axis and near the tip end trailing edge of the moving blade 2 in the case of T).

In FIGS. 8 and 9, the point indicated by □ is that the stress acting on the rotor blade 2 is 28.0 mm / kg (the maximum stress for the high cycle life of the nickel-base alloy IN-100 forming the rotor blade 2). ) Is the amplitude of the tip of the rotor blade 2, and the point indicated by + is 23.8 mm / kg of stress acting on the rotor blade 2 (nickel-based alloy I
Maximum stress for high cycle life of N-100 is 0.8
It represents the amplitude of the tip of the rotor blade 2 when the value is 5 times the value).

Focusing on the amplitudes near the tip stacking axis and the tip trailing edge of the rotor blade 2 in each vibration mode shown in FIGS. 8 and 9, regardless of the magnitude of the stress acting on the rotor blade 2, The amplitude ratio obtained by dividing the amplitude value near the tip end stacking axis of the rotor blade 2 by the amplitude value near the tip end trailing edge is substantially constant for each vibration mode. The vibration mode of the rotor blade 2 can be specified by obtaining the ratio of the amplitude in the vicinity and the amplitude in the vicinity of the trailing edge of the tip.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to make it possible to immediately determine the vibration mode of a rotating blade.

[0020]

In the method for determining a vibration mode of a moving blade according to a first aspect of the present invention, the moving blade tip portion when the moving blade provided on the rotary shaft vibrates in various vibration modes. Amplitudes at multiple locations are assumed in advance by numerical simulation for each vibration mode, and the assumed amplitude ratio is obtained by dividing the assumed amplitude value at other locations by the assumed amplitude value at a predetermined location at the blade tip for each vibration mode. , Irradiating laser light to a plurality of corresponding rotating blade tip portions respectively, and detecting each laser light reflected by each portion of the moving blade tip portion, and setting it at a predetermined position on the outer peripheral surface of the rotating shaft. Obtain the expected passage time and the actual passage time required from the detection of the rotation reference position until the blade tip is irradiated with the laser beam, and based on the above-mentioned actual passage time and the estimated passage time, the rotating blade Tip The amplitude at a location is obtained, and the measured amplitude ratio obtained by dividing the measured amplitude value at another location by the measured amplitude value at a predetermined location of the blade tip is compared, and the assumed amplitude ratio and the measured amplitude ratio are compared to determine the Determine the vibration mode of the blade.

Further, in the vibration mode determination device for a moving blade according to a second aspect of the present invention, laser light output from the laser generator is applied to each of a plurality of positions on the tip of the moving blade provided on the rotating shaft. Obtaining a plurality of optical devices, an optical probe for detecting each laser beam reflected by each portion of the blade tip portion, and a reflected light detected by each optical probe provided for each optical device respectively blade passing signal A photoelectric converter for converting into a rotation position, a rotation position detector for detecting rotation of the rotation shaft, and a rotation speed calculator for calculating the rotation speed of the rotation shaft based on a rotation reference signal output by the rotation position detector, Based on the rotation speed detection signal output by the rotation speed calculation, it is expected to be required from the detection of the rotation reference position defined at the predetermined position on the outer peripheral surface of the rotary shaft to the irradiation of the blade tip with laser light. Passing An expected passage time calculator for calculating an idea time, and the rotor reference position is detected on the basis of the blade passage signal and the rotation reference signal provided for each of the photoelectric converters, and then the rotor blade tip portion becomes a laser beam. A time measuring device for calculating the actual passing time required until irradiation, and a predicted passing time signal output by the predicted passing time calculator provided for each time measuring device and a passing time signal output by the time measuring device. Based on the blade amplitude calculator that calculates the amplitude of each portion of the blade tip, and the blade amplitude signal output by each blade amplitude calculator, the amplitude value of the predetermined portion of the blade tip An amplitude ratio calculator that finds the measured amplitude ratio by dividing the amplitude value, and divides the amplitude values of other parts by the amplitude value of a predetermined part of the blade tip that is assumed when the blade vibrates in various vibration modes. The assumed amplitude ratio is Vibration mode determination that determines the vibration mode of the rotor blade by comparing the data storage device stored for each mode with the measured amplitude ratio signal output from the amplitude ratio calculator and the assumed amplitude ratio data stored in the data storage device And a display device that displays the vibration mode of the moving blade based on the vibration mode determination signal output by the vibration mode determination device.

[0022]

In any of the method for determining a vibration mode of a moving blade according to claim 1 of the present invention and the apparatus for determining a vibration mode of a moving blade according to claim 2 of the present invention, a laser beam is applied to a plurality of tip portions of the moving blade. Irradiation to a location, the reflected light reflected by the laser beam at a plurality of tip portions of the moving blade is detected, and a rotation reference position defined at a predetermined position on the outer peripheral surface of the rotating shaft is detected, and then the moving blade tip portion is detected. Calculate the expected transit time and actual transit time that are expected to be required for laser light irradiation.

Next, based on the above-mentioned actual passing time and expected passing time, the amplitude at each position of the tip of the rotating blade is found, and the amplitude value of the other part is determined by the amplitude value of the predetermined part of the blade tip. Calculate the divided actual amplitude ratio.

Further, the assumed amplitude ratio obtained by dividing the amplitude value of the other part by the amplitude value of the predetermined part of the blade tip, which is assumed when the blade vibrates in various vibration modes, and the actually measured amplitude ratio. To determine the vibration mode of the moving blade.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a vibration mode determination device for a moving blade according to the present invention, in which 1 is a rotating shaft of a rotating machine, 2 is a rotating blade attached to the rotating shaft and whose amplitude is to be measured (monitor). Wings).

Although only one moving blade 2 is shown in the figure, a plurality of other moving blades having the same shape as the moving blade 2 are actually attached to the rotary shaft 1.

A rotation reference position mark 3 is attached to a rotation reference position defined at a predetermined position on the outer peripheral surface of the rotary shaft 1.

Further, the rotating shaft 1 and the moving blades 2 are arranged in a casing (not shown) such as an engine outer shell, and the stationary blades, struts and the like are provided in the casing.

Numerals 4 and 5 are laser generators for outputting laser beams 6 and 7, 8 is a first optical device such as a lens capable of irradiating the laser beam 6 near the tip end stacking axis of the rotor blade 2, 9 Is a second optical device such as a lens capable of irradiating the laser beam 7 to the vicinity of the trailing edge of the tip of the moving blade 2, and the first optical device 8 and the second optical device.
The optical device 9 is attached to the casing.

Reference numeral 10 denotes a first optical probe for detecting the reflected light 12 of the laser beam 6 reflected by the vicinity of the tip end stacking axis of the moving blade 2, and 11 reflects by the vicinity of the trailing edge of the leading end of the moving blade 2. A second optical probe for detecting the reflected light 13 of the laser light 7, a first photoelectric converter 14 for converting the reflected light 12 detected by the first optical probe 10 into a blade passing signal 16,
Reference numeral 15 is a second photoelectric converter that converts the reflected light 13 detected by the second optical probe 11 into a blade passing signal 17,
The optical probe 10 and the second optical probe 11 are attached to the casing.

Reference numeral 18 denotes a rotational position detector attached to the casing. The rotational position detector 18 rotates when the rotational reference position marker 3 passes a position where the rotational position detector 18 is installed. The reference signal 19 is output.

Reference numeral 20 is an amplifier for amplifying the rotation reference signal 19, and 21 is one of the rotary shafts 1 based on the rotation reference signal 19.
A rotational speed calculator for calculating the number of revolutions per minute, 22 is a rotor 2 after the rotational reference position indicator 3 is detected by the rotational position detector 18 based on the rotational speed detection signal 23 output from the rotational speed calculator 21. It is an estimated passage time calculator that calculates an estimated passage time Tb expected to be required until the tip portion is irradiated with the laser beams 6 and 7.

Reference numeral 24 denotes a laser beam 6 near the tip end stacking axis of the moving blade 2 after the rotation reference position marker 3 is detected by the rotation position detector 18 based on the blade passing signal 16 and the rotation reference signal 19. The first time measuring device 25 for measuring the actual passing time Tv ₁ required until
Based on the rotation reference signal 19, the actual passing time Tv ₂ required from the detection of the rotation reference position marker 3 by the rotation position detector 18 to the irradiation of the laser beam 7 near the trailing edge of the tip of the moving blade 2 is calculated. It is a second time measuring device for measuring.

26 is a predicted passage time signal 39 output from the predicted passage time calculator 22 and the first time measuring device 2
4 and the passage time signal 28 output from
A first blade amplitude calculator for calculating the amplitude value a ₁ at the tip end stacking axis of the moving blade 2, 27 is the predicted passage time signal 39 and the passage time signal output by the second time measuring device 25. 29, a _second blade amplitude calculator for calculating the amplitude a ₂ value at the trailing edge of the tip end of the moving blade 2 based on the equations 1 and 2, and 32 is output by the first blade amplitude calculator 26. It is an amplitude ratio calculator that obtains a measured amplitude ratio a ₁ / a ₂ by dividing the amplitude value a ₁ by the amplitude value a _{2 based on the} blade amplitude signal 30 and the blade amplitude signal 31 output from the second blade amplitude calculator 27. ..

Numeral 33 indicates the vicinity of the stacking axis of the blade tip by the amplitude value near the trailing edge of the tip of the blade 2 when the vibration mode of the blade 2 previously obtained by numerical simulation is primary bending and primary torsion. A data storage unit that stores an assumed amplitude ratio obtained by dividing the amplitude value of 1 as assumed amplitude ratio data 34, and 35 compares the measured amplitude ratio signal 36 output from the amplitude ratio calculator 32 with the assumed amplitude ratio data 34. A vibration mode determiner that determines the vibration mode of the moving blade 2 is a display device that displays the vibration mode determination result of the moving blade 2 based on the vibration mode determination signal 38 output from the vibration mode determiner 35.

The operation of the apparatus having the above-mentioned structure will be described below.

When determining the vibration mode of the rotor blade 2 while the rotary shaft 1 is rotating, the laser beams 6 and 7 are output from the laser generators 4 and 5, and the rotary shaft 1 rotates. Accordingly, when the moving blade 2 passes through the displacement detection position,
The first optical device 8 irradiates the laser light 6 to the vicinity of the tip end stacking axis of the moving blade 2, the laser light 6 is reflected by the vicinity of the tip end stacking axis of the moving blade 2, and the second The optical device 9 irradiates the laser light 7 near the trailing edge of the tip of the moving blade 2, and the laser light 7 is reflected by the vicinity of the trailing edge of the tip of the moving blade 2.

The reflected light 12 of the laser beam 6 reflected near the tip end stacking axis of the moving blade 2 is detected by the first optical probe 10 and is reflected near the tip end trailing edge of the moving blade 2. The reflected light 13 of the light 7 is reflected by the second optical probe 11
Detected by.

The reflected lights 12 and 13 detected by the optical probes 10 and 11 are the first photoelectric converter 14 and the second photoelectric converter 14, respectively.
Is converted into blade passing signals 16 and 17 by the photoelectric converter 15 of FIG.
4, input to the second time measuring device 25.

On the other hand, the rotation reference signal 19 is output from the rotation position detector 18 with the rotation of the rotary shaft 1, and the rotation reference signal 19 is amplified by the amplifier 20 to output the rotation reference signal 19 to the rotation speed calculator. 21, first time measuring device 2
4, input to the second time measuring device 25.

The first time measuring device 24 uses the rotation reference signal 1
9 and the wing passage signal 16 based on the rotation reference position marker 3
Is detected by the rotational position detector 18 until the laser beam 6 is irradiated to the vicinity of the tip end stacking axis of the moving blade 2, the actual passing time Tv ₁ is measured, and the second time measuring device 25 Based on the rotation reference signal 19 and the blade passage signal 17, the passage required from when the rotation reference position marker 3 is detected by the rotation position detector 18 to when the laser light 7 is irradiated to the vicinity of the trailing edge of the tip of the moving blade 2. The actual time Tv ₂ is measured.

The rotation speed calculator 21 calculates the rotation speed of the rotary shaft 1 per minute based on the rotation reference signal 19, and the rotation speed calculator 21 calculates the expected passage time calculator 22.
The rotation speed detection signal 23 is input to.

In the expected passage time calculator 22, the rotation reference position indicator 3 indicates the rotation position detector 1 based on the rotation speed detection signal 23.
Estimated transit time Tb expected to be required from the detection by 8 to the irradiation of the laser beams 6 and 7 on the tip of the moving blade 2.
Is calculated.

Further, the first blade amplitude calculator 26 uses the passage time signal 28 output from the first time counter 24 and the estimated passage time signal 39 output from the estimated passage time calculator 22 to calculate the above. The amplitude value a _{1 in the} vicinity of the tip end stacking axis of the moving blade 2 is calculated based on Expressions 1 and 2, and the second blade amplitude calculator 27 outputs the passage time output from the second time measuring device 25. From the signal 29 and the estimated passage time signal 39 output from the estimated passage time calculator 22, the amplitude value a _{2 in the} vicinity of the trailing edge of the tip portion of the moving blade ₂ is calculated based on the equations 1 and 2.

The above-mentioned blade amplitude calculators 26 and 27 make the amplitude a ₁ near the tip end stacking axis of the rotor blade 2 and near the tip trailing edge a ₁ ,
When a ₂ is obtained, the amplitude ratio calculator 32 uses the amplitude value a ₂ near the trailing edge of the tip of the moving blade 2 based on the blade amplitude signals 30 and 31 input from the blade amplitude calculators 26 and 27. The amplitude ratio calculator 3 calculates the measured amplitude ratio a ₁ / a ₂ by dividing the amplitude value a ₁ near the tip end stacking axis of the rotor blade 2.
The actual measurement amplitude ratio signal 36 is output from 2 to the vibration mode determiner 35.

The vibration mode determiner 35 compares the measured amplitude ratio signal 36 with the assumed amplitude ratio data 34 stored in the data memory 33 to determine the vibration mode of the moving blade 2, and the vibration mode determiner 35. The vibration mode of the moving blade 2 is displayed on the display device 37 based on the vibration mode determination signal 38 output from the display device 37.

As described above, according to the vibration mode determining apparatus for a moving blade of the present embodiment, the vibration mode of the moving blade 2 can be immediately determined, so that the stress acting on the moving blade 2 can be accurately determined in a short period of time. It will be possible to analyze.

The method for determining the vibration mode of the moving blade and the apparatus for determining the vibration mode of the moving blade according to the present invention are not limited to the above-described embodiment, and the number of amplitude measurement points at the tip of the moving blade is appropriately increased. Needless to say, various kinds of vibration modes stored in the data storage device can be increased, and various changes can be made without departing from the scope of the present invention.

[0050]

As described above, according to the rotor blade vibration mode determination method and rotor blade vibration mode determination apparatus of the present invention, the rotor blade vibration mode can be immediately determined. Therefore, it is possible to obtain an excellent effect that the stress acting on the moving blade can be accurately analyzed in a short period of time.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a vibration mode determination device for a moving blade of the present invention.

FIG. 2 is a conceptual diagram showing the principle of amplitude measurement of a moving blade.

FIG. 3 is a conceptual diagram showing the principle of measuring the amplitude of a moving blade.

FIG. 4 is a conceptual diagram showing the principle of measuring the amplitude of a moving blade.

FIG. 5 is a graph showing the principle of amplitude measurement of a moving blade.

FIG. 6 is a graph showing the principle of amplitude measurement of a moving blade.

FIG. 7 is a graph showing the principle of amplitude measurement of a moving blade.

FIG. 8 is a graph obtained by numerical simulation of the amplitude near the tip stacking axis and near the tip trailing edge of the blade when the vibration mode of the blade is first bending.

FIG. 9 is a graph obtained by numerical simulation for the amplitude near the tip stacking axis and near the tip trailing edge of the moving blade when the vibration mode of the moving blade is the first-order torsion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft 2 moving blade 3 rotation reference position mark (rotation reference position) 4,5 laser generator 6,7 laser light 8 first optical equipment 9 second optical equipment 10 first optical probe 11 second light Probes 12 and 13 Reflected light (laser light) 14 First photoelectric converter 15 Second photoelectric converter 16 and 17 Blade passage signal 18 Rotation position detector 19 Rotation reference signal 21 Rotation speed calculator 22 Expected passage time calculator 23 rotation speed detection signal 24 first time measuring device 25 second time measuring device 26 first blade amplitude calculator 27 second blade amplitude calculator 28, 29 passing time signal 30, 31 blade amplitude signal 32 amplitude ratio Calculator 33 Data storage 34 Assumed amplitude ratio data 35 Vibration mode determiner 36 Measured amplitude ratio signal 37 Display device 38 Vibration mode determination signal 39 Expected transit time signal

Claims (2)

[Claims] 1. When the rotor blade provided on the rotary shaft vibrates in various vibration modes, the amplitudes at a plurality of portions of the rotor blade tip are assumed in advance by numerical simulation for each vibration mode, and each vibration mode is estimated. Calculate the assumed amplitude ratio by dividing the assumed amplitude value of the other part by the assumed amplitude value of the predetermined part of the blade tip, and irradiate the laser beam to each of the corresponding multiple parts of the rotating blade tip, The passage required from detecting each laser beam reflected by each part of the tip to detecting the rotation reference position set at a predetermined position on the outer peripheral surface of the rotary shaft until the blade tip is irradiated with the laser beam. Obtain the expected time and the actual passage time, and based on the above-mentioned actual passage time and expected passage time, obtain the amplitude at each point of the rotating blade tip, and then use the measured amplitude value at the prescribed point of the blade to determine the amplitude. The fruit of A method for determining a vibration mode of a moving blade, characterized in that a measured amplitude ratio is obtained by dividing a measured amplitude value, and the vibration mode of the rotating blade is judged by comparing the assumed amplitude ratio and the measured amplitude ratio. 2. A plurality of optical devices capable of irradiating laser light output from a laser generator to a plurality of portions of a rotor blade tip portion provided on a rotating shaft, and reflecting by each portion of the rotor blade tip portion. An optical probe that detects each laser beam, a photoelectric converter that is provided for each optical device and converts the reflected light detected by each optical probe into a blade passing signal, and a rotation position that detects the rotation of the rotation shaft. A detector,
A rotation speed calculator for calculating the rotation speed of the rotation shaft based on the rotation reference signal output by the rotation position detector, and a predetermined position on the outer peripheral surface of the rotation shaft based on the rotation speed detection signal output by the rotation speed calculation. An estimated passage time calculator that calculates an estimated passage time that is expected to be required from the detection of the rotation reference position defined in to until the blade tip is irradiated with the laser beam, and each photoelectric converter is provided. Based on the blade passage signal and the rotation reference signal, a time measuring device for calculating the actual passage time required from the detection of the rotation reference position until the moving blade tip is irradiated with the laser beam, and each time. Based on the expected passage time signal output by the expected passage time calculator provided for each measuring instrument and the passage time signal output by the time measuring instrument, a blade amplitude calculator that calculates the amplitude of each portion of the blade tip portion, Amplitude performance of each wing Based on the blade amplitude signal output from the detector, the amplitude ratio calculator that finds the measured amplitude ratio by dividing the amplitude value of the other part by the amplitude value of the predetermined part of the blade tip, and the rotor blade vibrates in various vibration modes. The amplitude ratio calculator calculates and outputs a data memory that stores an assumed amplitude ratio for each vibration mode, which is obtained by dividing the amplitude value at another position by the amplitude value at a predetermined position of the blade tip. A vibration mode determiner that determines the vibration mode of the moving blade by comparing the measured amplitude ratio signal and the assumed amplitude ratio data stored in the data storage, and a motion based on the vibration mode determination signal output by the vibration mode determiner. A vibration mode determination device for a moving blade, comprising: a display device that displays a vibration mode of the blade.