JP2005077320A - Ultrasonic probe, flaw detection device for turbine blade and its flaw detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic probe, a flaw detection device and its flaw detection method capable of measuring accurately in a short time the depth of a fine crack generated on a curved surface having a large curvature such as a turbine blade. <P>SOLUTION: A thin-film elastic member is used as a contact medium interposed between the ultrasonic probe 3 and the turbine blade surface 22 which is a measuring object. Hereby, an ultrasonic wave in a wide frequency band (1 MHz-15 MHz) is allowed to pass to the measuring object (turbine blade 2) side without being attenuated, to thereby enable to measure accurately the depth of a fine crack of 0.1 mm or more. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic probe for detecting a minute defect occurring in a turbine blade or the like, a flaw detection apparatus for flaw detection for a defect occurring in a turbine blade, and a flaw detection method therefor.

  A turbine blade of a gas turbine used in a power plant or plant is coated to prevent oxidation of the turbine blade. When the turbine is started, a large thermal stress is generated in the turbine blade, so that a crack is generated on the coating layer surface of the turbine blade. This crack propagates toward the inside of the turbine blade due to the fatigue of the turbine blade accompanying repeated start-up of the turbine. At this time, if the crack tip stays in the coating layer, the turbine blade can be reused by re-coating. However, when the crack tip crosses the coating layer and reaches the turbine blade substrate, it is no longer reused. Is impossible, and there is a risk that the turbine blade will be destroyed if it is used as it is. Therefore, it is necessary to predict the timing of recoating by measuring the crack depth for each period of use of the turbine blade.

Conventionally, as a method for detecting such a crack nondestructively, for example, an ultrasonic flaw detection method using an ultrasonic probe to measure the depth of the crack is disclosed in Japanese Patent Publication No. 63-21135 (patent) Reference 1). This method is similar to the time required for the ultrasonic wave incident on the object to be measured to be diffracted at the tip of the crack and reach the detection part, and when there is no crack in the object to be measured. The depth of the crack is estimated from the difference from the time required for the ultrasonic wave incident by the method to reach the detection unit.
Japanese Examined Patent Publication No. 63-21135 (2-3, Fig. 3)

  However, in this method, since it is necessary to bring the probe into contact with the object to be measured, it is difficult to accurately measure a turbine blade or the like having a large curvature and a complicated curved surface. In addition, even when a crack generated on a curved surface with a small curvature is detected using a conventional ultrasonic probe, the contact area between the probe and the object to be measured is required to ensure a constant incident energy. Need to be larger. However, when the contact area is increased, the ultrasonic beam diameter is increased, so that the resolution is lowered, and a minute crack (0.1 mm or more) generated in the coating layer of the turbine blade cannot be measured with high accuracy. In addition, since cracks generated in the coating layer are densely spaced at intervals of 1 mm or less, if the contact area is large, individual cracks cannot be accurately recognized and measured. Conversely, if the contact area is too small, the contact surface becomes the same size as the crack opening width, making measurement difficult.

As another means for detecting cracks, a flaw detection apparatus using eddy current is disclosed in Japanese Patent Laid-Open No. 11-101783 (see Patent Document 2). According to this flaw detection device, when an eddy current is induced in the object to be measured by the conductive circuit, the output of the conductive circuit changes due to the induced eddy current, but this output change is constant between the crack depths. Therefore, the crack depth can be predicted by measuring the change in output. However, since the conductivity of the turbine blade or its coating layer changes during use, and an insulator such as ceramic may be used for the coating layer, it is difficult to accurately measure the crack depth.
Japanese Patent Laid-Open No. 11-101783 (pages 4-5, FIG. 1)

  Further, the flaw detection apparatus described in Patent Document 2 detects only a crack generated at the front edge portion of the turbine blade and measures its dimension, and the measurement range is limited to a straight line on the front edge portion. Therefore, there arises a problem that a crack generated in a portion other than the front edge portion of the turbine blade (for example, the back portion) cannot be detected over a wide range.

  Therefore, an object of the present invention is to provide an ultrasonic probe and a flaw detection apparatus and a flaw detection method for solving the above-described problems.

  In order to achieve the above object, an ultrasonic probe according to the present invention includes a contact medium facing a measurement object, a transmission vibrator that transmits ultrasonic waves to the measurement object through the contact medium, and a transmission vibration. An ultrasonic probe having a receiving transducer for receiving, through the contact medium, ultrasonic waves that are adjacent to each other through an acoustic partition and that are reflected from the object to be measured, wherein the contact medium is a thin-film elastic member Thus, the ultrasonic wave having a wide frequency band of 1 MHz to 15 MHz transmitted from the transmission vibrator is passed through without being attenuated to the measured object side.

  The ultrasonic probe is used in contact with an object to be measured. Actually, a gap is generated between the probe and the object to be measured, so that the ultrasonic wave from the probe side is incident on the object to be measured without being attenuated. Fill with water or grease. However, if the crack depth to be measured is shallow, a measurement error may be caused by the liquid contact medium that has entered the crack. Therefore, as described above, the contact medium is a thin-film elastic member made of, for example, natural rubber, so that the ultrasonic wave having a wide frequency band of 1 MHz to 15 MHz transmitted from the transmission vibrator is measured. It was assumed to pass through without being attenuated to the side. Considering that the speed of the wave that passes through the substance is inherent to the substance and is equal to the product of the wavelength and the frequency, the wavelength of the ultrasonic wave having a high frequency region is shortened, so that the resolution can be improved. The depth of a minute crack can be measured with high accuracy. Further, by using a thin-film elastic member made of, for example, natural rubber instead of the liquid contact medium, measurement can be performed while maintaining a good contact state between the two even if the contact surface is other than horizontal. (Claims 1, 4, 10).

  Ensuring the energy of the incident ultrasonic wave even if the contact area between the transducer and the object to be measured is small by making the outer shape of the lower end of the probe into a truncated cone shape whose diameter is reduced downward Can do. Further, by adopting the above-described shape, the focal points of the transmission wave beam and the reception wave beam can be brought closer to the transducer side, so that a shallow crack can be measured with high accuracy. Furthermore, by setting the diameter of the lower end surface of the probe to 1 mm to 5 mm, it is possible to accurately measure without confusion of cracks that occur densely at intervals of 1 mm or less. 5, 11).

  In addition, a flaw detection apparatus for a turbine blade according to the present invention includes a flaw detection section for flaw detection of an opening crack on a turbine blade, a scanning section that holds the flaw detection section, and a scanning section that moves the scanning section along the longitudinal direction of the turbine blade surface. One moving mechanism, a second moving mechanism that moves the first moving mechanism along the arc direction of the turbine blade surface, and a fixing member that fixes the second moving mechanism to the turbine blade are provided. Thus, the surface of the turbine blade can be detected without removing the turbine blade from the rotor, and the turbine blade surface can be scanned without fail, so that the crack depth can be measured quickly and accurately.

  For the flaw detection part, not only an ultrasonic probe but also an eddy current probe can be used (claims 6 and 12).

  When scanning the turbine blade surface to detect a crack, as described above, either an ultrasonic probe or an eddy current probe is used. In either case, the lower end surface and the turbine blade surface (crack Need to be contacted. Therefore, by providing means (such as a spring) for biasing the ultrasonic probe or eddy current probe downward, the turbine blade surface having a complicated three-dimensional curved surface and the ultrasonic probe or eddy current are provided. The lower end surface of the probe can be reliably brought into contact with, and measurement with higher accuracy is possible (claims 7 and 13).

  The scanning unit includes a reflecting mirror that reflects the image of the scanning portion and a small camera that magnifies the image reflected by the reflecting mirror (claims 7 and 14), thereby confirming the exact position of the crack. As a result, only that portion can be measured, so that the flaw detection inspection can be speeded up (claims 8 and 14).

  As a method for flaw detection on a crack on the turbine blade surface using the ultrasonic flaw detection apparatus having the above-described configuration, the flaw detection is performed by first scanning the turbine blade surface with eddy current flaw detection means, and then the ultrasonic flaw detection means. By adopting a method for flaw detection where only cracks are found by the previous flaw detection operation (flaw detection by eddy current flaw detection means), the approximate position of cracks that occur relatively densely can be detected by eddy current flaw detection means. In addition, the flaw detection operation by the ultrasonic flaw detection means can be performed only at a location where the presence of a crack is recognized. By this operation procedure, the inspection time can be greatly shortened (claim 9).

  Next, the operation principle of the ultrasonic probe according to the present invention will be described by taking the following embodiment as an example.

  First, an ultrasonic probe 3 according to the present invention includes a transmission piezoelectric element 31a, and a transmission wave transmission member 33a that transmits an ultrasonic wave (transmission wave) 32a transmitted from the transmission piezoelectric element 31a to a measurement object. A reception wave transmission member 33b facing the transmission wave transmission member 33a with the acoustic partition wall 34 interposed therebetween, and a reception piezoelectric wave receiving the diffracted wave (reception wave) 32b incident on the reception wave transmission member 33b from the measured object side It is comprised with the element 31b (refer Fig.4 (a)). Here, the ultrasonic probe 3 is a dry cup having a thickness of about 0.1 mm made of natural rubber or the like between a lower end surface thereof and a turbine blade surface 22 including an open crack 21 opposed to the lower end surface. Contact is made through a ring (corresponding to a thin-film elastic member) 35 (see FIG. 4B). The lower end of the probe has a frustoconical outer shape whose diameter is reduced downward, and the diameter of the lower end surface is about 3 mm.

  Here, the reason why the thickness of the dry coupling 35 is set to 0.1 mm is as follows. When dry coupling thicker than 0.1 mm is used, ultrasonic waves having a predetermined wide frequency band (frequency band centered on 10 MHz in this embodiment) are absorbed by the dry coupling, resulting in longer wavelengths and lower resolution. To do. Further, since the dry coupling is used in a state where it receives a downward load from the probe, if it is thinner than 0.1 mm, the durability against repeated use is poor and stable performance cannot be exhibited. Therefore, in this embodiment, the dry coupling 35 having a thickness of 0.1 mm is employed. Of course, the thickness of the dry coupling 35 is not limited to 0.1 mm, but allows the transmission wave 32a having a predetermined wide frequency band to pass through the device under test (in this example, the turbine blade 2) without being attenuated. If it is.

  When the opening crack 21 is present on the surface of the turbine blade 2, the ultrasonic wave is observed so that the acoustic partition wall 34 and the opening crack 21 in the ultrasonic probe 3 overlap each other when the ultrasonic probe 3 is viewed from above. The probe 3 is arranged (see FIG. 4A). First, a pulse signal (a spike pulse in this example) generated by a pulse generation circuit (not shown) excites vibration of the transmission piezoelectric element 31a, and a transmission wave 32a from the transmission piezoelectric element 31a is transmitted to a transmission wave transmitting member. 33a is transmitted, passes through the dry coupling 35, and enters the turbine blade 2. The wave (received wave) 32b diffracted by the crack tip 21a is received by the receiving piezoelectric element 31b again via the dry coupling 35 and the received wave transmitting member 33b.

  At this time, T is the time required until the transmission wave 32a transmitted from the transmission piezoelectric element 31a is transmitted to the reception piezoelectric element 31b as the reception wave 32b. On the other hand, when the open crack 21 does not exist on the turbine blade surface 22, the transmission wave 32 a transmitted from the transmission piezoelectric element 31 a does not enter the turbine blade but passes through the turbine blade surface 22 to receive piezoelectric. It is received by the element 31b. When the time required for this is Ta, the time difference T-Ta is proportional to the difference between the paths followed by the transmission wave 32a and the reception wave 32b. Therefore, if the proportionality constant is obtained in advance, the crack depth is determined as the transmission time. It can be easily obtained from the difference.

  At this time, by using the above-described dry coupling 35, broadband ultrasonic waves are transmitted into the object to be measured, and high resolution can be exhibited. For example, even if the opening crack 21 generated on the surface of the coating layer (thickness: about 200 μm) of the turbine blade 2 is very small (crack depth 100 μm to 200 μm), the depth can be measured accurately. .

  By making the contact medium interposed between the ultrasonic probe and the turbine blade surface, which is the object to be measured, a thin-film elastic member, ultrasonic waves in a wide frequency band (1 MHz to 15 MHz) can be obtained. It can be passed through without being attenuated to the (turbine blade) side, and a received wave with high resolution can be obtained. Therefore, it becomes possible to accurately measure the depth of a minute crack generated in the coating layer of the turbine blade.

According to the flaw detection apparatus for turbine blades according to the present invention, the surface of the turbine blade can be detected without removing the turbine blade from the rotor, and the turbine blade surface can be scanned without fail, so that the crack depth can be measured quickly and accurately.

  By using the eddy current flaw detection means that measures the crack occurrence position and depth and the ultrasonic flaw detection means that can measure the exact depth of the crack, the entire operation can be performed quickly and with high accuracy. The crack depth can be measured.

  Hereinafter, an embodiment of a flaw detection apparatus for turbine blades according to the present invention will be described with reference to FIGS. 1 to 3 and 5 to 7.

  1, 2, and 3 are a front view, a plan view, and a right side view of a flaw detection apparatus for a turbine blade attached to the turbine blade, respectively. This turbine blade flaw detector 1 includes an eddy current probe 4 for flaw detection on a crack on the turbine blade 2, a probe holder (corresponding to a scanning unit) 5 that holds the eddy current probe 4, and the probe holder 5 as a turbine blade. A first moving mechanism 7 that moves along the surface longitudinal direction (the direction of arrow A in FIG. 1), and a first moving mechanism 7 that moves the first moving mechanism 7 along the turbine blade surface arc direction (the direction of arrow B in FIG. 3). A two moving mechanism 8 and a clamp portion (corresponding to a fixing member) 9 for fixing the second moving mechanism 8 to the turbine blade 2 are configured as main components. The above configuration is a configuration example in the case of performing flaw detection inspection using eddy current flaw detection means. When flaw detection is performed by ultrasonic flaw detection means instead of eddy current flaw detection means, ultrasonic flaw detection is performed instead of eddy current probe 4. The probe holder 60 can be used for the probe 3 instead of the probe holder 5. Further, the turbine blade flaw detector 1 is attached so that the contact surface 6 of the turbine blade flaw detector 1 faces the flat end surface of the turbine blade 2.

  Here, as shown in FIG. 1 or FIG. 2, the first moving mechanism 7 is coupled to the probe holder 5 and slides in the longitudinal direction of the turbine blade surface when driven by a first drive circuit 71 such as a stepping motor. And a slide rail sliding portion 73a interlocked with the slider 72, a slide rail supporting portion 73b that slidably supports the slide rail sliding portion 73a, and the slide rail supporting portion 73b and the first drive circuit 71 are coupled. The first connecting member 74 is used. At this time, if the slidable width of the slider 72 is set to the length in the longitudinal direction of the effective portion of the turbine blade 2 that is not implanted in the turbine rotor, the flaw detection can be performed without slipping in the longitudinal direction of the turbine blade surface.

As shown in FIG. 1, the second moving mechanism 8 includes an interlocking member 81 that interlocks with the connecting member 74, and a second drive circuit 83 such as a stepping motor that rotates the interlocking member 81 via a gear 82. Is done. The first drive circuit 71 and the second drive circuit 83 are controlled by a control circuit (not shown).

  As shown in FIG. 6, the eddy current probe 4 is attached to a probe outer frame 40, a probe coil 41 supported by the probe outer frame 40 so as to be slidable in the vertical direction, and a peripheral edge of the lower end portion of the probe coil 41. The ceramic guide 42 is constituted by a second spring 44 whose upper end is locked to the spring holder 43 and whose lower end is connected to the probe coil 41 and urges the probe coil 41 downward. At this time, the diameter of the lower end surface of the eddy current probe 4 facing the turbine blade surface 22 is about 5 mm. Note that the change in the output voltage of the probe coil due to the eddy current induced in the turbine blade 2 is measured by an output measuring device (not shown) via the cord 45.

  The probe holder 5 that holds the eddy current probe 4 includes a probe holder body 51 and four pairs of high-density resin rollers 52 that are rotatably attached to the probe holder body 51. The probe holder body 51 includes: The slider 72 is connected via the second connecting member 53 (see FIG. 1). The probe holder body 51 is provided with a through hole 54 for mounting the eddy current probe 4 (see FIG. 2).

  Further, the above-described ultrasonic probe 3 is held by a probe holder 60 as shown in FIG. Here, the probe holder 60 includes a holder main body 60a, an ultrasonic probe 3 supported by the holder main body 60a so as to be slidable in the vertical direction, and a guide shaft connected to the ultrasonic probe 3. 61, a first spring 63 that is coupled to the guide shaft 61 via a spring holder 62 and biases the ultrasonic probe 3 downward, and an image of the turbine blade surface 22 that faces the probe. Is composed of a reflecting mirror 64 that reflects the image upward, a CCD camera 65 that captures an image reflected upward by the reflecting mirror 64, and a plurality of casters 66 installed at the lower end of the holder body 60a. A wave received by the receiving piezoelectric element is amplified by a pulsar receiver (not shown) via a transmission cable 67 in the figure and taken into a digital oscilloscope (not shown).

  The ultrasonic probe 3 and the eddy current probe 4 are provided with means for biasing the ultrasonic probe 3 main body and the probe coil 41 in contact with the turbine blade surface 22 downward (in this example, a spring 44, 63) together, it is possible to obtain a stable contact state between the ultrasonic probe 3, the probe coil 41 and the turbine blade surface 22.

  In the turbine blade flaw detector 1 having the above-described configuration, first, the probe holder 5 provided in the turbine blade flaw detector 1 is, as shown in FIG. 2, the end surface side (see FIG. 7) of the back 22 b (see FIG. 7) of the turbine blade surface 22. It is arranged on the flaw detector mounting side). Initially, the eddy current probe 4 is attached to the probe holder 5. When the first drive circuit 71 in the first moving mechanism 7 is driven, the probe holder 5 is linked to the slider 72 from the above position along the turbine blade surface longitudinal direction toward the turbine blade surface implantation portion 2 ′ at a constant speed. Move with. Along with this, the eddy current probe 4 in contact with the turbine blade surface 22 performs a flaw detection inspection. When the probe holder 5 and the eddy current probe 4 move to a position close to the turbine blade surface implantation portion 2 ′ (scanning locus A0-A1 in FIG. 2), the second moving mechanism 8 is maintained while maintaining its position in the longitudinal direction. The entire first moving mechanism 7 including the probe holder 5 is rotated by a predetermined angle in the direction of the front edge of the turbine blade 2 (in the direction of arrow B in FIG. 3) via the interlocking member 81 by the second drive circuit 83 in the inside (FIG. 3). 2 scan trajectory A1-A2). Next, the first drive circuit 71 in the first moving mechanism 7 is driven while maintaining the position in the arcuate direction of the turbine blade surface, and the eddy current probe 4 and the probe holder 5 are again moved in the longitudinal direction of the turbine blade surface. The flaw detection is performed while sliding (scanning locus A2-A3 in FIG. 2).

  As described above, the eddy current probe 4 performs flaw detection scanning up to a certain scanning range (for example, up to the lower end line of the scanning locus in FIG. 2) along the scanning locus shown in FIG. Thereby, the position and crack depth of the open crack 21 existing within a certain range on the turbine blade surface 22 can be obtained. At this time, a position where a crack having a certain depth (for example, 0.2 mm or more) is detected is detected by a potentiometer (not shown) and recorded.

  Next, flaw detection scanning of the turbine blade surface 22 is performed using the ultrasonic probe 3. A probe holder 60 is installed in place of the probe holder 5, and the ultrasonic probe 3 is mounted on the probe holder 60, and these are arranged at the initial position A0. Next, the probe holder 60 and the ultrasonic probe 3 are moved along the above-described scanning locus. At this time, flaw detection scanning is performed only at the position of a crack having a certain depth recorded by the recording apparatus, and a more accurate crack depth is measured. At this time, the accurate position of the crack is confirmed with the image projected on the monitor (not shown) by the reflecting mirror 64 and the CCD camera 65 provided in the probe holder 60, and the position is accurately measured. Can do.

  In the above embodiment, scanning was performed along the scanning locus (A0-A4) shown in FIG. 2 with the back 22b of the turbine blade surface as the inspection start point, but of course the embodiment is not limited to this. Instead, the initial position and scanning trajectory of the probe holder 5 (or probe holder 60) may be set according to the required scanning range.

1 is a front view of a turbine blade flaw detector 1 attached to a turbine blade 2. FIG. It is a top view of the said flaw detector 1 for turbine blades. It is a right view of the said turbine blade flaw detector 1. FIG. 2 is a basic configuration diagram of an ultrasonic probe 3 and an enlarged cross-sectional view in the vicinity of a contact surface for explaining the principle of the ultrasonic probe 3. FIG. 4 is a cross-sectional view and a right side view of a probe holder 60 that includes an ultrasonic probe 3. 3 is a cross-sectional view of the eddy current probe 4. FIG. 2 is a perspective view of a turbine blade 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbine blade flaw detector 2 Turbine blade 3 Ultrasonic probe 4 Eddy current probe 5 Probe holder 7 First moving mechanism 8 Second moving mechanism 9 Clamp part 21 Opening crack 22b Turbine blade back 31a Transmitting vibrator 31b Receiving vibrator 32a Transmitted wave 32b Received wave 35 Dry coupling 41 Probe coil 64 Reflector 65 CCD camera 71 First drive circuit 73a Slide rail sliding part 73b Slide rail supporting part 83 Second drive circuit

Claims (14)

A contact medium facing the object to be measured, a transmitting vibrator for transmitting ultrasonic waves to the object to be measured through the contact medium, and an ultrasonic wave reflected from the object to be measured adjacent to the transmitting vibrator via an acoustic partition. An ultrasonic probe having a receiving transducer for receiving through the contact medium,
By using the contact medium as a thin-film elastic member, ultrasonic waves having a wide frequency band of 1 MHz to 15 MHz transmitted from the transmission vibrator are allowed to pass through without being attenuated to the object to be measured. Characteristic ultrasonic probe. 2. The ultrasonic probe according to claim 1, wherein the outer shape of the ultrasonic probe has a truncated conical shape whose lower end is reduced in diameter, and the diameter of the lower end surface is 1 mm to 5 mm. Sonic probe. A flaw detection portion for flaw detection of a turbine blade, a scanning portion for holding the flaw detection portion, a first moving mechanism for moving the scanning portion along the longitudinal direction of the turbine blade surface, and a first moving mechanism in the arc direction of the turbine blade surface A turbine blade flaw detection apparatus comprising: a second moving mechanism that moves along the second moving mechanism; and a fixing member that fixes the second moving mechanism to the turbine blade. The flaw detection unit includes a contact medium facing the object to be measured, a transmitting vibrator that transmits ultrasonic waves to the object to be measured through the contact medium, and a transmitter vibrator and an acoustic partition that are adjacent to each other from the object to be measured. An ultrasonic probe having a receiving transducer for receiving reflected ultrasonic waves through the contact medium,
By making the contact medium a thin-film elastic member, the ultrasonic wave having a wide frequency band of 1 MHz to 15 MHz transmitted from the transmission vibrator is allowed to pass through without being attenuated to the measured object side. The flaw detection apparatus for turbine blades according to claim 3, wherein the flaw detection apparatus is provided. 5. The turbine according to claim 4, wherein the ultrasonic probe has a frustoconical shape whose lower end portion is reduced in diameter at a lower end thereof, and a diameter of the lower end surface thereof is 1 mm to 5 mm. Blade flaw detector. 4. The turbine blade flaw detector according to claim 3, wherein the flaw detector is an eddy current probe. The flaw detection apparatus for a turbine blade according to any one of claims 3 to 6, further comprising a mechanism for urging the scanning unit downward on the turbine blade surface to bring the scanning unit into contact with the turbine blade. The turbine blade according to any one of claims 3 to 7, wherein the scanning unit includes a reflecting mirror that reflects an image of a scanning portion and a small camera that captures an image reflected by the reflecting mirror. Flaw detection equipment. A scanning unit provided with a flaw detection unit for flaw detection of the turbine blade is moved along the longitudinal direction of the turbine blade surface by the first moving mechanism to perform flaw detection, and the second movement mechanism includes the flaw detection unit. A method for flaw detection by moving the mechanism along the arc direction of the turbine blade surface,
A turbine blade flaw detection method characterized in that the flaw detection is performed by eddy current flaw detection means, and then the ultrasonic flaw detection means performs only a portion where a crack can be detected by the previous eddy current flaw detection means. The ultrasonic flaw detection means includes a contact medium facing the object to be measured, a transmitting vibrator for transmitting ultrasonic waves to the object to be measured through the contact medium, and a measuring element adjacent to the transmitting vibrator via an acoustic partition. An ultrasonic probe having a receiving transducer for receiving ultrasonic waves reflected from an object through the contact medium;
By using the contact medium as a thin-film elastic member, ultrasonic waves having a wide frequency band of 1 MHz to 15 MHz transmitted from the transmission vibrator are allowed to pass through without being attenuated to the object to be measured. The method for flaw detection for a turbine blade according to claim 9, wherein: 11. The turbine according to claim 10, wherein the ultrasonic probe has a frustoconical shape whose lower end portion is reduced in diameter at a lower end thereof, and a diameter of the lower end surface thereof is 1 mm to 5 mm. A flaw detection method for blades. The turbine blade flaw detection method according to claim 9, wherein the eddy current flaw detection means performs flaw detection using an eddy current probe. The flaw detection method for a turbine blade according to any one of claims 9 to 12, further comprising a mechanism for urging the scanning unit downward on the surface of the turbine blade to bring the scanning unit into contact with the turbine blade. The turbine blade according to any one of claims 9 to 13, wherein the scanning unit includes a reflecting mirror that reflects an image of a scanning portion and a small camera that captures an image reflected by the reflecting mirror. Flaw detection method.