JP5353517B2 - Turbine blade vibration measurement device - Google Patents

Description

The present invention relates to a vibration measuring device of a turbine blade Ru comprising an optical probe for measuring the vibration of the turbine blades during operation in a non-contact manner.

  Conventionally, in the performance evaluation of a turbine, the vibration of a turbine blade during operation has been measured. In Patent Document 1 below, the vibration of a turbine blade that is exposed to high-temperature working gas is caused to change characteristics by optically measuring the vibration of the turbine blade without attaching a strain gauge to the turbine blade. A vibration measurement device that performs measurement without loss is disclosed.

  In this vibration measuring device, an optical probe provided with a lens and a protective glass is passed through the end of an optical fiber disposed therein, and the tip of the optical probe is disposed opposite to the end face of the turbine blade. And it is the structure which detects the reflected light of the laser beam projected toward the turbine blade from the optical fiber for light projection via the optical fiber for light reception, and measures the vibration of a turbine blade.

Japanese Patent No. 2874310

  However, since the vibration measuring apparatus measures the vibration of the turbine blade locally, the vibration state (vibration mode) of the entire turbine blade is the primary vibration mode or the secondary vibration mode. There is a problem that it is difficult to determine whether or not.

Normally, the primary natural frequency n1 (Hz) and the secondary natural frequency n2 (Hz) have a relationship of n1 <n2, and can be measured by prior hammering or the like. If there is no obstacle on the upstream side of the turbine blade that obstructs the flow of the working gas, the rotational speed N1 (rps) at which the primary natural vibration mode appears and the rotational speed N2 (at which the secondary natural vibration mode appears) (rps) is expressed by the following formula (1).
N1 = n1 N2 = n2 (1)
Here, since n1 <n2, the primary natural vibration mode is observed when the rotational speed Nt (rps) of the turbine is N1, and the secondary natural vibration mode is observed when the turbine speed is N2. Therefore, if Nt is known, it is possible to determine the order of vibration mode by the conventional method.

However, when there are N parts arranged at equal intervals in the circumferential direction on the upstream side of the turbine blade, the primary natural vibration mode is the rotational speed Nt1 (rps) represented by the following equation (2). It will appear even if it exists.
Nt1 = n1 / N (2)
At this time, depending on the relationship between N and n1, n2, N1 and N2 may be the same. Therefore, the conventional method has a problem that it is difficult to determine the natural vibration mode from Nt.

  In order to improve the reliability of measurement data, it is often necessary to arrange a plurality of optical probes. As a generally conceivable method, the optical probes are arranged at equal intervals in the circumferential direction. However, when arranged at equal intervals, the measurement result of the vibration mode is affected by the installation of the optical probe due to the phenomenon shown in the above equation (2). This is a problem in terms of measurement reliability.

The present invention has been made in view of the above problems, and aims to provide a vibration measuring device capable of determining the vibration mode of a turbine blade, and further improve the measurement reliability of the vibration measuring device. It aims to plan.

In order to solve the above-described problems, the present invention includes an optical probe that projects laser light toward the end face of a turbine blade that rotates by receiving a working gas and receives the reflected laser light. A turbine blade vibration measuring device for measuring the vibration of the turbine blade based on the light reception result of the probe, wherein the end surface is located at a position corresponding to the antinode in the primary vibration mode and the secondary vibration mode. A first optical probe provided at a position corresponding to the antinode in the first position, and a position corresponding to the antinode in the first vibration mode and a position corresponding to the node in the second vibration mode on the end face. A configuration in which the second optical probe is provided is employed.
In this configuration, the blade vibration measurement conventionally performed by the first optical probe is performed, and the measurement for discrimination of the vibration mode is performed by the second optical probe newly installed according to the present invention.
That is, in the second optical probe, a large amplitude is measured because it is a portion corresponding to an antinode in the primary vibration mode, whereas an amplitude is hardly measured because it is a portion corresponding to a node in the secondary vibration mode. Therefore, when the first optical probe detects the antinode and the second optical probe detects the antinode, the primary vibration mode and the first optical probe detect the antinode and the second optical probe detects the node. It can be determined that the vibration mode is the secondary vibration mode.

In the present invention, a plurality of the first optical probes and the second optical probes are provided, and each optical probe is provided at a different position in the circumferential direction around the rotation axis of the turbine blade. Is adopted.
By adopting this configuration, in the present invention, when a plurality of optical probes are provided as described above, it is difficult to secure an installation space in the axial direction, so the optical probes are arranged at positions shifted in the circumferential direction. .

In the present invention, a configuration is adopted in which a plurality of nozzle vanes for guiding the working gas are provided around the turbine blades at equal intervals, and the optical probes are provided at unequal intervals in the circumferential direction.
When a plurality of nozzle vanes are arranged at equal intervals around the turbine blade, if the optical probes are arranged at equal intervals in the circumferential direction, the optical probe itself vibrates the turbine blade as shown in the above equation (2). There is a risk of causing disturbance due to excitation (resonance). In the present invention, in order to avoid this resonance, the optical probes are arranged at unequal intervals in the circumferential direction.

In the present invention, a plurality of nozzle vanes for guiding the working gas are provided at equal intervals around the turbine blade, and the number of the optical probes and the number of the nozzle vanes are in a prime number relationship. adopt.
When a plurality of nozzle vanes are arranged at equal intervals around the turbine blade, if the number of optical probes and the number of nozzle vanes are arranged in multiples in the circumferential direction, the optical probe itself is connected to the turbine due to the natural frequency. There is a risk of causing disturbance due to excitation (resonance) of the blade vibration. In the present invention, in order to avoid this resonance, the number of optical probes and the number of nozzle vanes are in a prime number relationship.

  The present invention also includes an optical probe that projects laser light toward the end face of the turbine blade that rotates by receiving the working gas and receives the reflected laser light, and based on the light reception result of the optical probe. In the turbine blade vibration measuring method for measuring the vibration of the turbine blade, the step of obtaining the positions of the antinodes and nodes in the primary vibration mode and the secondary vibration mode in the end face in advance, Measuring the vibration of the turbine blade using a first optical probe provided at a position corresponding to the antinode in the primary vibration mode and at a position corresponding to the antinode in the secondary vibration mode; Using the second optical probe provided at a position corresponding to the antinode in the primary vibration mode and at a position corresponding to the node in the secondary vibration mode on the end face, the vibration of the turbine blade is To adopt the technique of having the step of measuring.

According to the present invention, the second optical probe provided at the position corresponding to the antinode in the primary vibration mode and at the position corresponding to the node in the secondary vibration mode is installed. The primary natural vibration mode and the secondary natural vibration mode at the same number of rotations, which were difficult with the method, can be distinguished. In addition, by adopting a method in which these optical probes are installed in the circumferential direction of unequal intervals and the number of nozzle vanes and the prime number, it is possible to perform measurement by installing optical probes as compared to the case where they are arranged at regular intervals. Reduce impact on results.
Therefore, according to the present invention, it is possible to obtain a vibration measuring apparatus that improves the reliability of measurement and can determine the vibration mode of the turbine blade.

It is a whole lineblock diagram showing the variable capacity type turbocharger provided with the optical probe of the vibration measuring device in the embodiment of the present invention. It is arrow K figure in FIG. FIG. 3 is a cross-sectional view taken along line X1 and line X2 in FIG. 2. It is sectional drawing in the line view Y1 and line view Y2 in FIG. It is a figure which shows the vibration mode of the turbine impeller in embodiment of this invention. It is a figure which shows the measurement result of the vibration measuring device in embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall configuration diagram showing a variable capacity turbocharger provided with an optical probe of a vibration measuring apparatus according to an embodiment of the present invention. FIG. 2 is an arrow K diagram in FIG. 3 is a cross-sectional view taken along line X1 and line X2 in FIG. 4 is a cross-sectional view taken along line Y1 and line Y2 in FIG. FIG. 5 is a diagram illustrating vibration modes of the turbine impeller in the embodiment of the present invention. FIG. 6 is a diagram illustrating a measurement result of the vibration measuring device according to the embodiment of the present invention.
As shown in the figure, the specimen provided with the optical probe 50 of the vibration measuring apparatus 100 in the present embodiment is a variable capacity turbocharger T.

The variable displacement turbocharger T includes a housing 1 including a bearing housing 1a, a turbine housing 1b, and a compressor housing 1c.
A turbine shaft 2 extending in the horizontal direction in FIG. 1 is rotatably supported in the bearing housing 1a via a bearing (not shown). A turbine impeller (turbine blade) 3 is integrally connected to one end side (left end side in the illustrated example) of the turbine shaft 2, and a compressor impeller 4 is connected to the other end side (right end side in the illustrated example). They are connected together. The turbine impeller 3 is arranged in the turbine housing 1b, and the compressor impeller 4 is arranged in the compressor housing 1c.

 The turbine housing 1b has a turbine scroll passage 5 provided on the radially outer side of the turbine impeller 3 and exhausts working gas that opens in the axial direction of the turbine shaft 2 and on the opposite side of the turbine shaft 2. It has a turbine housing outlet 6 which is a mouth. A variable nozzle unit N having a substantially annular shape is installed on the radially outer side of the turbine impeller 3 in the turbine housing 1b.

 The turbine scroll passage 5 is formed in a substantially annular shape surrounding the turbine impeller 3, and the turbine scroll passage 5 is communicated with a gas inlet 5 </ b> A for introducing working gas. Further, a space (flow path) formed between the turbine scroll flow path 5 and the turbine housing outlet 6 is configured such that a nozzle vane 12 described later of the variable nozzle unit N is disposed.

The compressor housing 1 c is formed with an intake port 7 that opens in the axial direction of the turbine shaft 2 and on the opposite side of the turbine shaft 2. Further, between the bearing housing 1 a and the compressor housing 1 c, a diffuser flow path 8 that compresses and pressurizes air is formed in a substantially annular shape on the radially outer side of the compressor impeller 4. The diffuser flow path 8 communicates with the intake port 7 through the installation location of the compressor impeller 4.
Further, the compressor housing 1 c is formed with a compressor scroll passage 9 formed in a substantially annular shape on the outer side in the radial direction of the compressor impeller 4, and the compressor scroll passage 9 is communicated with the diffuser passage 8. Yes. The compressor scroll passage 9 communicates with an intake port of an internal combustion engine (not shown).

  The variable nozzle unit N is provided in a space (flow path) formed between the turbine scroll flow path 5 and the turbine housing outlet 6 at a predetermined equal interval around the shroud ring 10 and the nozzle ring 11. A plurality of nozzle vanes 12 are rotatably provided via a support shaft 13. The support shafts 13 of the nozzle vanes 12 are connected to synchronization transmission links 14, respectively. The synchronization transmission links 14 are connected to a drive ring 15 that is rotatably provided.

  The drive ring 15 is connected to a drive transmission link 17 connected to one end side of the drive shaft 16. The drive shaft 16 is pivotally supported through a bearing 18 provided in the bearing housing 1a. The other end of the drive shaft 16 is connected to the actuator A located outside the bearing housing 1 a via a drive lever 19.

  In the variable capacity turbocharger T, the working gas discharged from the exhaust port of the internal combustion engine (not shown) is introduced into the turbine scroll flow path 5. Then, the introduced working gas flows between the shroud ring 10 and the nozzle ring 11, rotates the turbine impeller 3, and is discharged from the turbine housing outlet 6. When the turbine impeller 3 is rotationally driven, the compressor impeller connected by the turbine shaft 2 is rotationally driven to generate compressed air.

 On the other hand, in the operation of the actuator A, the drive shaft 16 is rotated via the drive lever 19 and the drive ring 15 is rotationally driven via the drive transmission link 17 provided at the end of the drive shaft 16. When the drive ring 15 is driven to rotate, the angle of each nozzle vane 12 is tilted (variable) in synchronization with each other via each synchronization transmission link 14, and the opening area (opening) between the shroud ring 10 and the nozzle ring 11. Is changed. The flow rate of the working gas supplied to the turbine impeller 3 is adjusted by changing the opening area.

  The optical probe 50 measures the vibration of the turbine impeller 3 by detecting the reflected light of the laser light projected toward the turbine impeller 3 that is rotationally driven in response to the working gas. The optical fiber cable 51 guides the laser light. Is provided. The optical fiber cable 51 includes a light projecting optical fiber (light projecting unit) that projects laser light and a light receiving optical fiber (light receiving unit) that receives reflected light. The light projecting optical fiber and the light receiving optical fiber are exposed at the tip 51 a facing the end surface 3 a of the turbine impeller 3. The optical probe 50 extends linearly in the radial direction (radial direction) of the turbine impeller 3, passes through the turbine housing 1 b, crosses the turbine scroll flow path 5, and extends to the vicinity of the end surface 3 a of the turbine impeller 3. Yes.

  The light projecting optical fiber is connected to a laser oscillator (not shown), and the laser light transmitted from the laser oscillator is projected toward the end surface 3 a of the turbine impeller 3. And the laser beam reflected by the end surface 3a of the turbine impeller 3 is received and transmitted by the optical fiber for receiving light. The reflected light transmitted through the optical fiber for receiving light is converted into an electrical signal by a photoelectric converter and analyzed by a PC (Personal Computer) of the vibration measuring device 100. When the turbine impeller 3 vibrates, a slight deviation occurs in the light reception timing of the pulsed laser beam reflected by the deformation of the end surface 3a of the turbine impeller 3, and therefore, by measuring the amount of change, the turbine impeller 3 Vibration level (amplitude) measurement is possible. Moreover, it is possible to measure the stress acting on the turbine impeller 3 by numerically analyzing the vibration level using FEM (Finite Element Method).

Here, before describing the characteristic configuration of the present embodiment, the vibration mode of the turbine impeller 3 will be described with reference to FIG. In FIG. 5, a region (antinode) where the vibration is large is shown in a light color tone, and a region (node) where the vibration is small is shown in a dark color tone.
As shown in FIG. 5, in the primary vibration mode, one antinode appears on the end face 3a, and the number of antinodes increases as the order increases. Here, paying attention to the difference between the primary vibration mode and the secondary vibration mode, it can be seen that nodes appear in the secondary vibration mode in the region where the antinodes appear in the primary vibration mode.

  Therefore, the vibration measuring apparatus 100 of the present embodiment is provided on the end surface 3a at a position corresponding to the antinode in the primary vibration mode and at a position corresponding to the antinode in the secondary vibration mode. The optical probes 50A1 and 50A2 (see FIG. 3) and the end surface 3a are provided at positions corresponding to the antinodes in the primary vibration mode and positions corresponding to the nodes in the secondary vibration mode. Using a total of four optical probes 50, optical probes 50B1 and 50B2 (see FIG. 4), the vibration mode of the turbine impeller 3 is detected by detecting the difference between the positions where the vibration antinodes and nodes appear, and the vibration of the turbine impeller 3 is primary. It is determined whether the vibration mode is a secondary vibration mode or a secondary vibration mode.

  The positions of the antinodes and nodes of the turbine impeller 3 can be obtained in advance by, for example, FEM analysis. Note that these positions may not exactly match due to minute differences between the drawing values at the time of analysis and the actual dimensions. However, when determining the primary vibration mode and the secondary vibration mode, even if the position of the belly or the position of the node is slightly shifted, the tendency of these vibrations is caused by the optical probe 50 provided at that position. If it is possible to measure the vibration mode, the vibration mode can be determined even if the positions of the abdomen and the nodes do not exactly match.

As shown in FIG. 3, the first optical probe 50 </ b> A <b> 1 (50 </ b> A <b> 2) is attached toward the end surface 3 a at a position corresponding to the outlet side corner of the turbine impeller 3.
On the other hand, as shown in FIG. 4, the second optical probe 50B1 (50B2) is attached on the end surface 3a at a position shifted in the axial direction from the position where the first optical probes 50A1 and 50A2 are attached to the compressor side. .
In addition, when the variable capacity turbocharger T is small as in the present embodiment, if a plurality of optical probes 50 are provided, it is difficult to secure an installation space in the axial direction. Optical probes 50 (50A1, 50A2, 50B1, 50B2) are arranged at positions shifted from each other in the circumferential direction around the rotation axis of the turbine impeller 3.

  When a plurality (14 in this embodiment) of nozzle vanes 12 are arranged at equal intervals around the turbine impeller 3 as in this embodiment, the optical probes 50 are arranged at equal intervals (90-degree pitch) in the circumferential direction. Then, the optical probe 50 itself may cause the vibration of the turbine impeller 3 to be excited (resonated). That is, when the turbine impeller 3 rotates once, one blade is opposed to each of the 14 nozzle vanes 12, and 14 vibrations are applied per cycle. Further, when the turbine impeller 3 makes one revolution, one blade faces the four optical probes 50, and vibration is applied four times per cycle. When these vibrations have a multiple relationship with the natural frequency, the turbine impeller 3 resonates and a disturbance occurs.

  For this reason, in this embodiment, the optical probes 50 (50A1, 50A2, 50B1, and 50B2) are arranged at unequal pitches (unequal intervals) in the circumferential direction. In the optical probe 50, the pitch between the optical probe 50A1 and the optical probe A2 is an angle θ1, the pitch between the optical probe 50A1 and the optical probe B1 is an angle θ2, and the pitch between the optical probe 50B1 and the optical probe B2 is an angle. Arranged at θ3. In the present embodiment, the angle θ1 and the angle θ3 are set to an angle of 30 degrees, and the angle θ2 is set to an angle of 40 degrees.

  Next, an example of a vibration measurement result of the turbine impeller 3 obtained using the vibration measuring apparatus 100 having the above configuration will be described with reference to FIG. In FIG. 6, the vertical axis represents the blade amplitude, and the horizontal axis represents the rotational speed of the turbine impeller 3. In FIG. 6, the thin solid line shows the measurement result of the optical probe 50A1, the thin dotted line shows the measurement result of the optical probe 50A2, the thick solid line shows the measurement result of the optical probe 50B1, and the thick dotted line shows the measurement result of the optical probe 50B2. .

As shown in FIG. 6, when the rotation speed is increased, the amplitude output from each optical probe 50 is substantially constant up to the line L1. The vibration mode at this time can be determined to be a secondary vibration mode because the amplitude values at the optical probes A1 and A2 are high and the amplitude values at the optical probes B1 and B2 are low. .
However, between the line L1 and the line L2, the amplitude values at the optical probe A1 and the optical probe A2 remain high, and the amplitude values at the optical probe B1 and the optical probe B2 increase and are high. The value is shown. That is, it can be determined that the vibration mode of the turbine impeller 3 is changing to the first order in the range from the line L1 to the line L2.

Therefore, according to the present embodiment, by providing the first optical probes 50A1 and 50A2 and the first optical probes 50B1 and 50B2, the vibration mode of the turbine impeller 3 is detected by detecting the difference in position where the vibration antinode and the node appear. Can be judged. That is, there is a region corresponding to an antinode with a large vibration between nodes having low vibration, and in the secondary vibration mode, a node appears in an area corresponding to the antinode in the primary vibration mode. Therefore, when the first optical probes 50A1 and 50A2 detect the antinodes and the second optical probes 50B1 and 50B2 detect the antinodes, the primary vibration mode and the first optical probes 50A1 and 50A2 detect the antinodes. When the second optical probes 50B1 and 50B2 detect a node, it can be determined that the vibration mode is a secondary vibration mode.
Therefore, the present embodiment provides a vibration measuring apparatus 100 that can discriminate between the primary natural vibration mode and the secondary natural vibration mode at the same rotational speed, which is difficult with the conventional method.

  Moreover, in this embodiment, installation space can be ensured by providing each optical probe 50 in a mutually different position in the circumferential direction around the rotating shaft of the turbine impeller 3. Further, when a plurality of nozzle vanes 12 are arranged at equal intervals around the turbine impeller 3, if the optical probes 50 are arranged at equal intervals in the circumferential direction, the optical probe 50 itself excites vibrations of the turbine impeller 3 (resonance). In this embodiment, the optical probes 50 are arranged at unequal intervals in the circumferential direction to avoid disturbance due to resonance. Therefore, the vibration of the turbine impeller 3 can be accurately measured.

  In order to avoid resonance, a configuration in which the number of nozzle vanes 12 arranged at equal intervals and the number of optical probes 50 are in a prime relationship may be employed. According to this configuration, since these vibrations do not have a multiple relationship with the natural frequency, the optical probes 50 can be arranged at equal intervals in the circumferential direction. For example, when 13 nozzle vanes 12 are provided, a configuration in which two optical probes 50 are provided can be employed.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  2 ... turbine shaft (rotary shaft), 3 ... turbine impeller (turbine blade), 3a ... end face, 12 ... nozzle vane, 50 ... optical probe, 50A1, 50A2 ... first optical probe, 50B1, 50B2 ... second optical probe, 100 ... Vibration measuring device

Claims (3)

An optical probe that projects laser light toward the end face of the turbine blade that rotates by receiving the working gas and receives the reflected laser light, and vibrates the turbine blade based on the light reception result of the optical probe. A turbine blade vibration measuring device for measuring,
Around the turbine blade, a plurality of nozzle vanes for guiding the working gas are provided at equal intervals,
A first optical probe provided on the end face at a position corresponding to the antinode in the primary vibration mode and at a position corresponding to the antinode in the secondary vibration mode;
A plurality of second optical probes provided at positions corresponding to the antinodes in the primary vibration mode and positions corresponding to the nodes in the secondary vibration mode on the end face ;
The turbine blade vibration measuring device , wherein the optical probes are provided at different positions in the circumferential direction around the rotation axis of the turbine blade and at unequal intervals in the circumferential direction . Vibration device of the turbine blade according to claim 1, characterized in that has a prime relationship with the number of the the number of the optical probe nozzle vanes. An optical probe that projects laser light toward the end face of the turbine blade that rotates by receiving the working gas and receives the reflected laser light, and vibrates the turbine blade based on the light reception result of the optical probe. A turbine blade vibration measuring device for measuring,
Around the turbine blade, a plurality of nozzle vanes for guiding the working gas are provided at equal intervals,
A first optical probe provided on the end face at a position corresponding to the antinode in the primary vibration mode and at a position corresponding to the antinode in the secondary vibration mode;
A plurality of second optical probes provided at positions corresponding to the antinodes in the primary vibration mode and positions corresponding to the nodes in the secondary vibration mode on the end face;
Each optical probe is provided at a position different from each other in the circumferential direction around the rotation axis of the turbine blade,
The turbine blade vibration measuring apparatus according to claim 1, wherein the number of the optical probes and the number of the nozzle vanes are in a prime number relationship.

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