JP2002098583A - Method and device for measuring moving-blade oscillation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily measure accurate blade oscillation which is not an apparent oscillation phenomenon dependent on rotation numbers by accurately measuring such blade oscillation as resonates with a rotation frequency. SOLUTION: An optical measuring probe 1 so provided as to face a rotational moving blade 3 (advanced blade) comprises an irradiating part which projects light and a light receiving part which receives light. A local part of the rotational moving blade 3 is formed as an optical reflection region 4. The irradiating part irradiates light wider than the optical reflection region 4 and the positional fluctuation of the optical reflection region 4 is continuously measured. Since measurement is continuously performed for every rotation instead of fixed-point measurement for each rotation frequency, an oscillation dependent fluctuation amount is measured while a fixed-point region 4 transits once before the probe 1. The measurement like this is realized by allowing an irradiation region to be a region which is so wide as to comprise the fixed-point region. An optical system of the means like that is simple while its measurement system is presented at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving blade vibration measuring device and a measuring method therefor, and more particularly to a moving blade vibration measuring device for optically measuring vibration during operation of a moving blade of a gas turbine engine, and a measuring device therefor. Related to measurement method.

[0002]

2. Description of the Related Art The blades of an engine such as a gas turbine vibrate during operation of the engine. Such vibrations need to be measured. As shown in FIG. 3, the optical measurement probe 1 fixed to an engine case (not shown)
The laser beam 102 at the time of incidence, which is emitted as a thin beam from 01, is reflected by the moving blade 103, and the reflected laser beam 104 by the moving blade 103 is
Return to 01. The optical measurement probe 101 has both transmitting and receiving functions. The optical measurement probe 101 continuously measures the time (time) at which the tip of the rotating blade 103 crosses in front of the optical measurement probe 101.

[0003] Since the number of revolutions of the engine and the number of moving blades are known, if the aforementioned measurement is performed by the optical measurement probe 101, the vibration phenomenon of the moving blade 103 can be grasped by calculation. However, in such a measurement method, when the frequency of the rotor blade vibration and the frequency of the engine speed are an integer multiple, since each rotating blade deforms the same at a position crossing the front of the probe, Apparently, the amount of deformation of the moving blade is zero, and it is not possible to capture accurate fluctuations of the moving blade. Such a measurement method is effective for grasping a vibration phenomenon such as flutter, but it is difficult and inappropriate to measure a blade vibration resonating with the rotation frequency.

A method of measuring the vibration of a rotating body from a stationary field is structurally easier than measuring the frequency of the rotating body from a rotating field and the measuring device is inexpensive. A method of measuring the vibration of a rotating body from a field has been adopted.

[0005] On the premise of measurement in a stationary field, it is desired to accurately measure blade vibration resonating with the rotation frequency.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to accurately measure a blade vibration that resonates with a rotation frequency and easily measure an accurate blade vibration that is not an apparent vibration phenomenon that depends on the rotation speed. It is an object of the present invention to provide a moving blade vibration measuring device and a measuring method thereof.

[0007]

Means for solving the problem are described as follows. The technical items appearing in the expression are appended with numbers, symbols, and the like in parentheses (). The numbers, symbols, and the like refer to technical items that constitute at least one embodiment or a plurality of embodiments of the embodiments or embodiments of the present invention, particularly, the embodiments or the embodiments. Corresponds to the reference numbers, reference symbols, and the like assigned to the technical matters expressed in the drawings corresponding to. Such reference numbers and reference symbols clarify the correspondence and bridging between the technical matters described in the claims and the technical matters of the embodiments or examples. Such correspondence / bridge does not mean that the technical matters described in the claims are interpreted as being limited to the technical matters of the embodiments or the examples.

[0008] A moving blade vibration measuring apparatus according to the present invention comprises an optical measuring probe (1) provided to face a rotating blade (2), and the optical measuring probe (1) irradiates light. Section and a light receiving section for receiving light, the rotating blade (2
Or 3) the local portion is formed as an optical reflection region (4), and the irradiation portion irradiates light over a wider area than the optical reflection region (4), and the position of the optical reflection region (4) Fluctuations are measured continuously over time.

As described above, the distance measurement is continuously performed temporally for each rotation without relying on the fixed point measurement for each rotation cycle, so that the fixed point area (4) is located only once before the probe (1). During the passage, the vibration-dependent variation is measured. Such measurement is realized by means for setting the irradiation area to a wide area including the fixed point area. The optical system of such means is simple and its measurement system can be provided at low cost.

A lens (6) is used for optimizing the irradiation range. The lens (6) is also used for focusing. The lens (6) expands the light beam irradiated from the irradiation unit to a wide angle and irradiates light over a wider area than the optical reflection area.

In the method for measuring blade vibration according to the present invention, a part of a rotating blade (3, advanced blade) is formed as a reflection area (4), and light is irradiated to a wider area than the reflection area (4). Receiving light reflected from the reflection area (4);
It consists of measuring the position variation of the reflection area (4) continuously in time. It is preferable that the reflectivity of the reflection area (4) be positively higher than that of the other areas. However, since the original reflection surface of the rotor blade (3) is not uniform, a part of the reflection area is used as the reflection area (4). It is possible to use. The position change is
This is a change in the optical path length (D "), and the optical path length (D") is measured. As the distance measuring means, an appropriate means is selected from a plurality of conventional means.

In the method for measuring rotor blade vibration according to the present invention, a portion to be measured of the rotating blade (2 or 3) is irradiated by irradiating a part of the rotating blade (2 or 3) with a distance measuring laser at a wide angle. 4) Continuously measuring the vibration width in time.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Corresponding to the drawings, in a moving blade vibration measuring apparatus according to the present invention, an optical measuring probe is provided to face a rotating blade of a gas turbine engine. As shown in FIG. 1, the optical measurement probe 1 is fixed to an engine case (not shown). The rotating blade is formed from the advanced blade 2. A reflection portion 4 is provided locally at one fluctuation measurement target position of a partial advanced wing 3 which is a portion of the advanced wing 2. The reflection portion 4 has a sufficiently higher reflectance than the other region portions.

The optical measurement probe 1 emits a laser,
It is a conventional probe that can receive a laser. The laser beam 5 emitted from the optical measurement probe 1 is expanded into a beam diameter by a lens 6 or is diffused and widened to be changed to a radiation beam 7.

A part of the reflected light 8 reflected by the reflecting portion 4 follows the same course as the incident path, and
Then, the light returns to the same course in the opposite direction and enters the photoelectric conversion unit of the optical measurement probe 1. The radiation beam 7 having a wide angle has a low density, and the amount of light returning to the optical measurement probe 1 can be considered to be only the amount of light reflected by the reflection portion 4.

The distance between the optical measurement probe 1 and the reflection part 4 changes with time. By subtracting the amount corresponding to the amount of rotation from the amount of change over time, the amount of variation (positional variation) of the reflecting portion 4 due to actual vibration can be obtained by calculation. Since such a measuring method measures the amount of light reflected from the reflecting portion 4 which is a local moving point, it is possible to capture a change in the motion of the vibration of the reflecting portion 4 regardless of the rotation speed of the advanced wing 2. .

As shown in FIG. 2, any one of the advanced wings
A static distance D between a point, in particular, a point P representing the reflection portion 4 and a representative point A of the optical measurement probe 1 as a measurement base point is D
(Θ). The static distance is a distance between APs when the advanced wing is not vibrating. The actual distance between the point P and the point A that fluctuates due to the change in the rotational vibration and θ is represented by D ′ (θ). In a static field without vibration, its actual distance is D (θ), as shown in the figure. The fluctuation value of the geometric static distance due to rotation is represented by D (0) -D (θ). The displacement D ″ due to only vibration when there is vibration is D ″ (θ) = D ′ (θ) − (D (0) −D (θ)).

The vibration-dependent distance fluctuation amount ΔD ″ of the point P that fluctuates only depending on the vibration is ΔD ″ = D ″ (θ2) −D ″ (θ1) = D ′ for the angular position θ1 and the angular position θ2. (Θ2) −D ′ (θ1) − (D (θ1) −D (θ
2)). Here, θ is a function of time t, and substantially θ = k
t. k is a constant that depends on the rotation speed in the measurement time range. For laser ranging, an optical interferometer for ranging and other conventional techniques are used. If the reference point is θ1, the reference point θ
By measuring the position D ″ of the real point P rotating and moving from 1 continuously and temporally, the actual displacement due to the radial vibration of the real point P can be obtained while passing only once before the probe. Here, continuous means that the number of laser pulses while the point P passes through the irradiation area is sufficiently large,
In addition, it means that distance measurement is performed for each pulse.

[0019]

The measuring apparatus and the measuring method of the blade vibration according to the present invention are simple devices and can accurately capture the actual fluctuation even at the time of the resonance of the rotational frequency response.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a moving blade vibration measuring apparatus according to the present invention.

FIG. 2 is a geometric diagram illustrating a calculation method of an actual variation amount;

FIG. 3 is a front view showing a known distance measuring method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... (Optical measurement) probe 2 ... Rotating moving blade 3 ... Rotating moving blade (advanced wing) 4 ... Optical reflection area 5 ... Laser (light) 6 ... Lens D "... Optical path length

Claims (6)

[Claims] An optical measurement probe is provided to face a rotating blade, the optical measuring probe includes an irradiating unit for irradiating light and a light receiving unit for receiving light, The local part is formed as an optical reflection area, and the irradiating unit irradiates the light over a wider area than the optical reflection area, and the position fluctuation of the optical reflection area is continuously measured in time. Measurement device for rotor blade vibration. 2. The moving blade according to claim 1, further comprising a lens, wherein the lens expands the light beam irradiated from the irradiation unit to a wide angle and irradiates the light over a wider area than the optical reflection area. Vibration measuring device. 3. The moving blade vibration measuring device according to claim 1, wherein the reflectance of the optical reflection region is positively set higher than the reflectance of other regions. 4. Forming a part of the rotating blade as a reflection area; irradiating light over a wider area than the reflection area; receiving light reflected from the reflection area; A method of measuring blade vibrations, which comprises measuring time-continuously. 5. The method according to claim 4, wherein the position fluctuation is a fluctuation of a moving blade which is a fluctuation of an optical path length. 6. A rotating blade vibration measurement method comprising: irradiating a part of a rotating blade with a distance measuring laser at a wide angle to continuously and temporally measure a vibration width of a measurement target portion of the rotating blade. Method.