CN212341109U - Guide wave detection device for edge defects of turbine blades - Google Patents
Guide wave detection device for edge defects of turbine blades Download PDFInfo
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- CN212341109U CN212341109U CN202021421552.7U CN202021421552U CN212341109U CN 212341109 U CN212341109 U CN 212341109U CN 202021421552 U CN202021421552 U CN 202021421552U CN 212341109 U CN212341109 U CN 212341109U
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Abstract
The utility model discloses a device that is used for turbine blade edge defect guided wave to detect. The two ultrasonic guided wave transducers are combined into one group, the two groups are provided, each group of guided wave transducers are respectively arranged at the edge of the turbine blade, each transducer is used for time-sharing detection, guided waves generated by excitation can be focused along the edge of the turbine blade and are transmitted along the edge, and when defects are met, guided wave echoes are received by the two groups of ultrasonic guided wave transducers to realize detection and positioning of the defects of the turbine blade. The utility model discloses can be used for having eliminated traditional guided wave and having detected the special-shaped structure and the protruding phenomenon that leads to the signal to mix of blade itself when detecting the turbine blade that the structure is complicated, improve the SNR and the reliability that the blade detected, can eliminate the detection blind area through two sets of transducer combinations moreover. And use the utility model discloses a magnetostrictive transducer device detects time measuring to turbine blade's edge, can realize the short-term test under the turbine does not dismantle the condition, and the suitability is strong and easy operation.
Description
Technical Field
The utility model relates to a turbine blade edge defect nondestructive test device, in particular to detection device based on turbine blade edge microminiature defect of supersound guided wave belongs to nondestructive test technical field.
Background
A turbine is a rotating machine commonly used in industrial production, and plays a very important role as a power plant. The blade is also a core component of the turbine and mainly plays a role in energy exchange, so that the blade bears complex impact load in the running process, the problems of fatigue damage, crack failure and the like are easy to occur, in the serious case, the crack propagation can cause the blade to break and fall off, the normal operation of the whole turbine is further damaged, serious production accidents are caused, and even the personal and property safety is endangered, meanwhile, the turbine blade is subjected to centrifugal force and stress concentration due to the edge of the blade, most of fatigue cracks or damage cracks are generated from the edge of the blade, and then in the subsequent rotating process of the turbine, the original micro cracks are easy to expand outwards to form large cracks to cause the occurrence of fracture. Therefore, the edges of the turbine blades are mainly required to be detected when the turbine blades are detected, the existing nondestructive detection mode mainly comprises ultrasonic detection and magnetic leakage detection, but the detection is point-to-point detection, and the blades cannot be rapidly and comprehensively detected. Meanwhile, the shell of most blades of the turbine is protected by the frame structure, so that a series of auxiliary processes of the shell and the frame are required when the traditional turbine blade edge defect detection device adopts an ultrasonic flaw detector to carry out point-by-point detection on a spiral welded pipe, and the installation structure of the turbine is likely to have a detection blind area, so that the efficiency is low, the cost is high, and the requirement of nondestructive detection of a large number of turbines which do not need to be disassembled at present is difficult to meet. Furthermore, conventional turbine blade inspection devices do not have the potential to perform online inspection.
The ultrasonic guided wave technology is a long-distance and large-range nondestructive testing technology, has the advantages of long testing distance, high testing efficiency, circumferential scanning and the like, and is widely applied to the field of nondestructive testing of various structures in recent years.
Since the piezoelectric transducer can excite pure Lamb guided waves, Lamb is widely applied in the previous guided wave detection research of the flat plate structure. However, according to the dispersion curve of the guided wave, the SH guided wave keeps constant in the wave velocity in the low frequency range, so that the dispersion phenomenon does not exist, the wave packet and the vibration mode of the echo signal are more complete, and the defect detection is facilitated. Simulation and experiment show that when Lamb and SH guided waves are excited at the edge of a blade, excited guided wave signals are focused on the edge to propagate forwards, and defect echoes generated after defects are encountered are also focused on the edge to propagate towards a transducer. Since a large amount of energy is concentrated at the edge and reflected back by the defect, the edge detection of the blade will result in a high signal-to-noise ratio and sensitivity. For turbine blades where manual mounting of the transducer is not possible, the test can also be carried out using a designed jig.
SUMMERY OF THE UTILITY MODEL
For solving the problem that exists among the background art, be difficult to realize quick effectual detection to the marginal microminiature defect of turbine blade to current detection mode and device, and the result of detecting can receive the influence of inherent structures such as step and arch on the blade, the utility model provides an use detection device of the marginal microminiature defect of supersound guided wave.
The utility model discloses an excitation out the supersound guided wave at the side edge of turbine blade, the energy of supersound guided wave will concentrate on the edge of blade to propagate forward along the edge of blade, overcome the structural change of itself on other routes of turbine blade and obtain disturbing to the guided wave detection, and because the concentrated phenomenon of energy, improved the relevance ratio and the SNR of turbine blade edge microminiature defect greatly. The detection device can reduce the peeling of the shell frame, and can realize detection only by a small installation space, so that the detection of the blade is more convenient and efficient; also, for turbine blades where manual mounting of the transducer is not possible, remote placement of the transducer and excitation and reception of the guided waves can be achieved using a designed fixture.
The utility model discloses a realize through following technical scheme:
the device comprises four guided wave transducers, wherein the guided wave transducers are respectively arranged at the edges of two sides of the turbine blade, the two guided wave transducers on the same side are uniformly arranged at intervals along the edge direction, and the four guided wave transducers are connected with a guided wave detector through respective cables.
The guided wave detector comprises a power amplifier, a pulse signal generation module, a preamplifier and a signal acquisition module, wherein the input end of a guided wave transducer is connected with the pulse signal generation module through the power amplifier, and the output end of the guided wave transducer is connected with the signal acquisition module through the preamplifier.
Two guided wave transducers are arranged on the side face of the same side edge of the turbine blade, and the distance between every two adjacent guided wave transducers is larger than 4 times of the wavelength of a guided wave signal emitted by the guided wave transducers.
The turbine blade is a fan-shaped blade, the central angle of the fan shape is smaller than 15 degrees, and the cross section in the radial direction is of a structure with a thick middle part and thin two sides.
The guided wave transducer adopts a magnetostrictive transducer, one end of the magnetostrictive transducer is positioned at the edge of the turbine blade, and the coil size of the magnetostrictive transducer is smaller than the width of the turbine blade of 1/3.
The guided wave transducer is not limited to a magnetostrictive transducer and can send SH guided waves and Lamb waves for detection.
The guided wave transducer comprises two parts of an induction coil and a magnetostrictive strip, wherein the two parts are bonded together by using glue, the magnetostrictive strip is contacted with the edge surface of the turbine blade through a coupling agent on the other surface which is not connected with the induction coil, and the sound wave is coupled to the edge of the blade to realize the defect detection of the turbine blade.
The guide wave transducer is arranged on a turbine blade through a transducer device for detection, the transducer device comprises a movable end transducer clamp, a fixed end transducer clamp, a tensioning device, a steel cable and a spring, one end of the movable end transducer clamp is embedded in a sliding groove at one end of the fixed end transducer clamp through a rivet and moves along the sliding groove, the spring is connected between the end surfaces of the fixed end transducer clamp and the movable end transducer clamp, and the spring is compressed; the fixed end transducer clamp comprises a clamp part and a straight pipe part, the clamp part is fixedly connected with the straight pipe part, the tensioning device is fixed at the upper end of the straight pipe part of the fixed end transducer clamp and comprises a tensioning handle and a tensioning hand brake, the tensioning handle is sleeved on the straight pipe part of the fixed end transducer clamp, the tensioning hand brake is installed on the tensioning handle and is connected with one end of a steel cable, the other end of the steel cable is connected to a ribbed plate in the middle of the movable end transducer clamp, the tensioning hand brake is pressed down to pull the steel cable to move the movable end transducer clamp along the chute through the tensioning handle, so that the movable end transducer clamp is close to or far away from the clamp part of the fixed end transducer clamp to move, the movable end transducer clamp and the fixed end transducer clamp are adjusted and controlled to be mutually tightened, and the whole transducer clamp is fixed and tightened on; detecting edge defects of the turbine blade through a guided wave transducer fixed on a movable end transducer clamp and a fixed end transducer clamp;
the movable end transducer clamp and the fixed end transducer clamp are respectively provided with two respective transducer support branches on two sides of the edge of the turbine blade, and a conductive transducer is adhered to each transducer support branch by using a coupling agent.
The magnetostrictive transducer comprises a folded coil and a pre-magnetized magnetostrictive strip, one surface of each of 4 folded coils is fixed on the lower bottom surfaces of the 4 transducer fixing branches of the fixed end transducer clamp and the movable end transducer clamp respectively through a coupling agent, and the other surface of each of 4 coils is connected with the 4 magnetostrictive strip respectively through the coupling agent. And respective signal transmission cables of the 4 magnetostrictive transducers are led out from the round hole at the bottom end of the fixed end transducer clamp, penetrate through the welded round tube and are led out to be connected with the guided wave instrument.
The transducer anchor clamps before not pressing from both sides tightly, support 2 magnetostrictive transducer of 2 transducer fixed bolster installations of fixed end transducer anchor clamps one side on the edge of one side of blade now, then will remove end transducer anchor clamps and press on the blade surface, press down straining manual brake of straining device, realize that whole transducer anchor clamps are fixed on the blade, and 4 fixed branches of transducer on the transducer anchor clamps compress tightly the magnetostrictive transducer of coupling respectively on the edge of blade. The device can be used for turbine blades of different widths and thicknesses by means of the tensioning mechanism and the groove on the fixed end transducer clamp, and detection of defects on the edge of the turbine blade is achieved.
The utility model discloses when adopting SH guided wave and Lamb guided wave experiment, all found along the energy focusing phenomenon at edge, and then designed technical scheme and be used for the detection of the microminiature defect at turbine blade edge, concentrate the energy of guided wave at the blade edge of interest as far as possible, and then improve the detection efficiency to the marginal defect of turbine blade, realize the long distance detection of single-point, improve the sensitivity that detects.
The utility model discloses can realize the short-term test under the turbine condition of not dismantling, the suitability is strong and easy operation.
To sum up, the utility model is used for turbine blade's guided wave detection device can be used for realizing the detection to the small defect in blade edge, not only can use the SH guided wave of magnetostrictive transducer excitation, also can use the Lamb guided wave of piezoelectric ultrasonic guided wave transducer and electromagnetic ultrasonic transducer excitation to detect the marginal defect of blade, to the blade that can't touch with the hand, the utility model discloses transducer fixture device can realize the defect monitoring to the blade edge of unable manual installation transducer position.
The utility model has the advantages that:
the utility model discloses the marginal microminiature defect of example turbine blade indicates the crack that receives the shock vibration and lead to or because the crack that mechanical fatigue leads to, and this defect mainly appears at the edge of blade, for slim and long type defect, because its cross section loss is less, so the echo signal energy less results in lou examining the phenomenon often appearing. The utility model discloses can realize the supersound guided wave along blade edge propagation because the physical effect of its energy concentration, can carry out the detection of marginal microminiature defect to all blades under the condition that need not to dismantle, and echo SNR is higher, easy operation is quick.
The utility model provides an ultrasonic guided wave, the ultrasonic guided wave after the surface excitation of turbine blade goes out suitable frequency, the ultrasonic guided wave that propagates forward is because the gathering phenomenon of energy, most energy can concentrate on the edge of blade completely, energy after concentrating runs into the microminiature crack defect at edge after, there is some guided wave energy to take place the reflection, because the guided wave energy of the guided wave itself of propagating to come is just bigger, consequently the guided wave echo signal energy after the reflection also can be bigger than the energy after not energy gathering. Therefore, through the utility model discloses the device detects the marginal defect effect of blade obvious, and the relevance ratio is high.
Meanwhile, the surface of the turbine blade is not necessarily completely smooth, and because a plurality of convex structures or step-shaped structures are machined on the surface of the turbine blade in different working types and working occasions, if the traditional whole-end excited guided wave detection is used, a plurality of echo signals caused by the structures exist in received echoes, and the amplitude of the echo caused by the micro-crack defect is low, so that the echo signal of the defect is easily submerged in the echo signals generated by other structures, and the defect cannot be detected. Meanwhile, in order to eliminate the blind area existing in the transducer detection process, the structure that two transducers are arranged on one side of the blade at the same time according to the moving detection is adopted, and the detection of the blind area around the transducers can be realized.
To sum up, the utility model is used for the detection device of the small defect detection in turbine blade edge can realize the location and the detection to the small defect in edge of turbine blade under the condition that need not to dismantle turbine and blade, the device is through outside one magnetostrictive transducer, piezoelectric transducer, EMAT electromagnetic ultrasonic transducer, the edge of the one end of blade is arranged in the installation, through the transducer device of disconnect-type and used repeatedly's couplant, can be applicable to the blade of different structures and material, and detection distance is far away, can improve the suitability and the practicality of device greatly. Simultaneously to the condition of unable manual installation under the not dismantlement condition, the utility model discloses used a transducer anchor clamps to realize arranging of remote magnetostrictive transducer and the defect detection of this position department blade edge.
Drawings
FIG. 1 is a schematic view of the structural arrangement of the device of the present invention;
FIG. 2 is a schematic simulation diagram of guided wave propagation along the edge of a blade according to an embodiment of the present invention;
fig. 3 is an echo diagram of the results of microminiature defect detection using magnetostrictive transducers according to an embodiment of the present invention;
fig. 4(a) is an echo diagram of the result of detecting an edge crack defect by using an electromagnetic ultrasonic transducer according to an embodiment of the present invention;
fig. 4(b) is an echo diagram of the result of detecting the irregular protrusion at the non-end position of the blade by using the electromagnetic ultrasonic transducer according to the embodiment of the present invention;
FIG. 5 is a schematic diagram of the operation of a magnetostrictive transducer clamp for turbine blade edge defect detection in accordance with an embodiment of the present invention;
FIG. 6 is a diagram of a magnetostrictive transducer fixture design for turbine blade edge defect detection in accordance with an embodiment of the present invention;
fig. 7 is a close-up view of the lower end of a magnetostrictive transducer clamp for turbine blade edge defect detection in accordance with the teachings of the present invention.
In the figure: turbine blades 1, guided wave transducers 2; a fixed end transducer clamp (3), a movable end transducer clamp (4), a tensioning device (5), a steel cable (6) and a spring (7).
Detailed Description
The present invention will be described in further detail with reference to the following embodiments and accompanying drawings, which are, by way of illustration and not limitation, examples of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
As shown in fig. 1, the device includes four guided wave transducers 2, the guided wave transducers 2 are respectively arranged at the edges of two sides of the turbine blade 1, two guided wave transducers 2 at the same side are uniformly arranged at intervals along the edge direction, the two guided wave transducers 2 at the same side form a group, the two guided wave transducers are two groups in total, and the four guided wave transducers 2 are connected with a guided wave detector through respective cables.
The guided wave detector comprises a power amplifier, a pulse signal generation module, a preamplifier and a signal acquisition module, wherein the input end of the guided wave transducer 2 is connected with the pulse signal generation module through the power amplifier, and the output end of the guided wave transducer 2 is connected with the signal acquisition module through the preamplifier.
The guided wave transducer 2 is a magnetostrictive transducer, a piezoelectric transducer or an electromagnetic ultrasonic transducer. The magnetostrictive transducer and the piezoelectric transducer need to coat a couplant on the surface of the turbine blade for detection, and the electromagnetic ultrasonic transducer can be adsorbed on the blade for detection without the couplant. When the magnetostrictive transducer is used for detection, the turbine blade which cannot be manually installed with the transducer is detected through the designed transducer clamp.
The embodied turbine blade 1 has two guided wave transducers 2 arranged laterally on the same side edge, and the distance between adjacent guided wave transducers 2 is more than 4 times of the wavelength of the guided wave signal emitted by the guided wave transducers 2. The turbine blade 1 is a blade with a fan-shaped structure, the central angle of the fan shape is less than 15 degrees, and the cross section in the radial direction is of a structure with a thick middle part and thin two sides.
The guided wave transducer 2 is a magnetostrictive transducer, one end of the magnetostrictive transducer is positioned at the edge of the turbine blade 1, and the coil size of the magnetostrictive transducer is smaller than 1/3 of the width of the turbine blade 1.
The guided wave transducer 2 emits SH guided waves and Lamb waves for detection. The magnetostrictive transducer excites SH guided waves, the piezoelectric transducer and the electromagnetic ultrasonic transducer excite Lamb waves, and the guided waves of the two modes detect the edge defects of the blade.
The pulse signal generating module generates periodic pulse signals, the periodic pulse signals are loaded into the magnetostrictive transducer wires after being amplified by the power amplifying module to generate current with periodically changed magnitude and direction, a dynamic magnetic field is generated, and SH guided waves are formed and coupled to the turbine blades together with a static magnetic field generated by a strip mounted on the edge surface of each blade; the guided wave echo meeting the defect is received by the magnetostrictive transducer in an induction way, is conditioned and amplified by the preamplification module, and is converted into a digital signal by the signal acquisition module for analysis and processing.
Meanwhile, the EMAT can also be used for detecting tiny defects on the edge of the turbine blade, the EMAT can excite a periodically vibrating Lamb signal of A0 on the blade by utilizing the self magnetic adsorption effect without a coupling agent, and meanwhile, the scanning of the edge of the blade can also be realized by the EMAT detection trolley.
The guided wave transducer 2 comprises two parts of an induction coil and a magnetostrictive strip, the two parts are bonded together by using glue, the magnetostrictive strip is contacted with the edge surface of the turbine blade 1 through a coupling agent on the other surface which is not connected with the induction coil, and the sound wave is coupled to the edge of the blade to realize the defect detection of the turbine blade 1.
The utility model discloses a detection principle process is:
the method comprises the steps of controlling a plurality of guided wave transducers 2 on the edge of the side face of the same side of a turbine blade 1 to work in a polling mode, exciting each guided wave transducer 2 to the edge of the turbine blade 1 by a pulse signal generation module and sending out pulse guided waves, wherein the propagation direction of the pulse guided waves also propagates along the edge of the blade, when the pulse guided waves encounter defects (cracks, collision injuries and the like) on the edge of the turbine blade 1, defect echoes propagate along the reverse direction of the propagation direction, the same guided wave transducer 2 receives the defect echoes and then converts the defect echoes into electric signals, the vibration signals of the guided waves are converted into the electric signals, the electric signals are sent into a guided wave detector for filtering amplification, signal acquisition, signal normalization and other processing, and the guided wave detector performs comprehensive analysis processing after receiving the electric signals of different guided wave transducers 2 to obtain, signals received by the transducers on the same side are compared to eliminate the detection blind area. And specifically, obtaining the location of the defect position according to the analysis and the processing of the dispersion curve.
The utility model discloses such guided wave transducer 2 arranges at 1 border position of blade, and the propagation direction of the guided wave that the arrangement mode arouses is roughly parallel with blade edge line, and the scope of the guided wave signal that arouses is in 50kHz ~ 200 kHz.
The guided wave detector carries out comprehensive analysis and processing after receiving the electric signal of different guided wave transducers 2 and obtains the complete condition of turbine blade 1 and the position information of defect, and the signal that same side transducer received compares and eliminates the detection blind area, specifically is:
according to the distance between the two guided wave transducers, the distance value of the two guided wave transducers receiving the two groups of signals is compensated, so that the signal end faces of the two groups of signals corresponding to the turbine blades are aligned, and then the two groups of signals are superposed to reconstruct a group of signals, so that the dead zones of the excitation positions and the surrounding positions of the guided wave transducers are eliminated.
The turbine blade 1 belongs to a spiral variable cross-section waveguide, when a blade dispersion curve is calculated, a flat plate model with curvature and thickness equal to the average thickness of the turbine blade 1 is established, the material mechanics parameters are consistent with the blades, and the flat plate model is analyzed and calculated by a semi-analytic finite element method to obtain the wave velocity of the impulse guided wave of SH or Lamb at the excitation frequency;
establishing a blade model of a turbine blade 1 with curvature through finite element analysis, determining the optimal excitation length by changing the size of the length of an excitation region along the vertical propagation direction, controlling the excitation length to excite a guided pulse wave transducer 2 to generate a guided pulse wave propagating along the edge of the blade, coupling the elastic strain of the guided pulse wave to the turbine blade, and reflecting the guided pulse wave after encountering a defect when the guided pulse wave propagates along the edge of the blade, wherein the echo of the guided pulse wave is received by the position of the excitation transducer;
and determining the position of the blade edge defect according to the defect wave packet in the electric signal of the defect echo to obtain the distance L between the position of the defect and the guided wave transducer 2.
When transducers are arranged at the side edges of the turbine blades to excite guided waves, due to physical factors of energy accumulation of the edges of the blades, the excited guided waves can gradually gather towards the edges of the blades in the forward propagation process, the gathered guided waves continue to propagate along the edges of the blades, when micro-defects exist on the edges, the gathered guided waves generate defect echoes at the positions, the defect echoes can still gather at the edges and return along the original path to be received by the transducers on the edges, and most of the excited guided wave energy is focused at the edges, so that the propagation distance of the edge guided waves is far, and the energy value of echo signals generated when the defects are met is far greater than that of echo signals detected by conventional guided wave detection; meanwhile, as the guided wave signals are concentrated and converged at the edge position, the inherent structure of the rest part of the blade can not influence the detection of the defects, as shown in fig. 1, due to different working requirements of the turbine, the surface of the blade can be cast with some special-shaped bulges and step structures, and most of the guided waves are transmitted along the edge of the blade in the radial direction at the moment, so that the special-shaped bulges and step structures can not cause obvious echo signals. In conclusion, use the utility model discloses to the microminiature defect detection at blade edge, the echo defect that the signal to noise ratio that will obtain is higher, and the echo signal amplitude and the energy of microminiature defect are great, and are more obvious in signal analysis.
As shown in FIG. 1, the utility model discloses the implementation includes 2 transducer devices and 1 guided wave detector, and the transducer device can use the magnetostrictive device to produce the SH guided wave, also can use piezoelectric transducer, electromagnetic acoustic device (EMAT) to produce Lamb guided wave and detect the marginal microminiature defect of turbine blade. The magnetostrictive transducer and the piezoelectric transducer are arranged on the surface of the turbine blade by using a coupling agent and connected with the guided wave detector through a cable, the electromagnetic ultrasonic transducer is adsorbed on the turbine blade through the magnetism of the electromagnetic ultrasonic transducer without the coupling agent, and the other end of the electromagnetic ultrasonic transducer is connected with the guided wave detector through the cable. The installation of the transducer can be realized only by a certain installation space, so that the diagnosis and the positioning of the tiny defects of the turbine blade under the condition of no disassembly can be realized.
Detailed description when the mounting position of turbine can't realize the manual installation transducer, can use magnetostrictive transducer anchor clamps to detect the small defect on the turbine blade, it is right to combine embodiment and attached drawing below the utility model provides a magnetostrictive transducer anchor clamps further detailed description.
As shown in fig. 5-7, the guided wave transducer 2 is mounted on the turbine blade 1 for detection through a transducer device, the transducer device comprises a moving end transducer clamp 4, a fixed end transducer clamp 3, a tension device 5, a steel cable 6 and a spring 7, one end of the moving end transducer clamp 4 is embedded in a sliding groove at one end of the fixed end transducer clamp 3 through a rivet and moves along the sliding groove, the sliding groove is parallel to the radial direction of the blade, the spring 7 is connected between the end surfaces of the fixed end transducer clamp 3 and the moving end transducer clamp 4, and the spring 7 is compressed; stiff end transducer anchor clamps 3 include anchor clamps portion and straight tube portion, fixed connection between anchor clamps portion and the straight tube portion, tensioning device 5 is fixed in the straight tube portion upper end of stiff end transducer anchor clamps 3, tensioning device 5 is fixed on the pipe structure 32 of stiff end transducer 3 through the round hole cover of tensioning handle 51 lower extreme, be used for the fixed of whole tensioning device 5, tensioning device 5 includes tensioning handle 51 and taut manual brake 52, tensioning handle 51 suit is in the straight tube portion of stiff end transducer anchor clamps 3, taut manual brake 52 is installed on tensioning handle 51 and is connected with 6 one end of steel cable, taut manual brake 52 links together through rotatable pivot with taut fixed block 51, realize the fixed of whole tensioning device 5 on stiff end transducer anchor clamps 3 and the taut action of manual brake. The other end of the steel cable 6 extends along the straight pipe part of the fixed end transducer clamp 3 and then is connected to the ribbed plate 43 in the middle of the movable end transducer clamp 4, the tensioning hand brake 52 is pressed down, the steel cable 6 is pulled through the tensioning handle 51 to move the movable end transducer clamp 4 along the sliding groove, so that the movable end transducer clamp 4 is close to or far away from the clamp part of the fixed end transducer clamp 3 to move, the movable end transducer clamp 4 and the fixed end transducer clamp 3 are adjusted and controlled to be clamped mutually, and the whole transducer clamp is fixed and clamped on the turbine blade 1; the turbine blade 1 is inspected for edge defects by moving the end transducer holder 4 and the guided wave transducer 2 fixed on the fixed end transducer holder 3.
The movable end transducer clamp 4 and the fixed end transducer clamp 3 are respectively provided with two respective transducer support branches 31 and 41 on two sides of the edge of the turbine blade 1, a conductive transducer 2 is adhered to each transducer support branch 31 and 41 by using a coupling agent, and the conductive transducer 2 is adhered to the transducer support branches by using an induction coil and a magnetostrictive strip material in sequence by using the coupling agent. The two transducer support branches 31, 41 on the same transducer clamp on the same side of the turbine blade 1 are fixedly connected at intervals by a central beam.
The movable end transducer clamp 4 and the fixed end transducer clamp 3 slide in a groove structure on the fixed end transducer clamp 3 through a rivet structure on the movable end transducer clamp 4, so that the clamp can clamp and release two sides of the blade 1. Taut manual brake 52 pushes down and drives steel cable 6 to 5 directions removal of straining device, drives whole removal end transducer anchor clamps 4 and removes to stiff end transducer 3, and the guide effect that removes end transducer anchor clamps 4 removal is realized to the recess of stiff end transducer anchor clamps 3 and the rivet mechanism of removing end transducer anchor clamps 4.
The tensioning device 5 pulls the movable end transducer clamp 4 to move towards the fixed end transducer clamp 3 through a steel cable 6 to realize tensioning, and the clamped transducer clamp presses the magnetostrictive transducers 21 coupled on the transducer fixing branches 31 and 41 on the edge of the blade to excite and receive SH guided waves. After the detection is finished, the hand brake 52 is loosened and tensioned, and the spring 7 rebounds to return the movable end transducer clamp 4 to the initial loosening position.
As shown in fig. 6, the moving end transducer clamp 4 is installed with 4 rivet mechanisms 42, each 4 rivet mechanisms 42 are grouped in pairs, and pass through 2 groove positions 33 of the fixed end transducer clamp 3 to be fixed on the bottom surface of the moving end transducer, and the boss of the rivet 42 is pressed on the surface of the fixed end transducer clamp 3, so that the movable connection between the moving end transducer clamp 4 and the fixed end transducer clamp 3 is realized.
The signal transmission cables 21 of the guided wave transducers 2 arranged on the 4 transducer clamp branches 31 and 41 are led out from the round mouth positions of the round tube welding parts of the fixed end transducer clamp 3, and the led-out cable cables 21 penetrate through the middle of the round tube and are connected to the guided wave transducers 3.
As shown in fig. 6, the magnetostrictive transducer 21 includes a folded coil, one side of which is mounted on the transducer fixing branches 31 and 41 of the fixed end transducer holder 3 and the moving end transducer holder 4 via a couplant, and a pre-magnetized magnetostrictive strip, which is mounted on the other side of the folded coil via the couplant. The signal transmission cables 22 of the 4 magnetostrictive transducers 21 jointly pass through the opening at the bottom of the fixed end transducer clamp 3, and are led out from the whole magnetostrictive transducer clamp under the guidance of the circular tube structure 32 to be connected with the wave guide instrument 3 so as to realize the excitation and the reception of SH guided waves. The 4 magnetostrictive transducers 2 are independent of each other, and the guided wave signals are excited and received in a polling mode.
When a certain magnetostrictive transducer 21 is used for operation, the guided wave signal channel 22 is switched. But the same transducer 21 must be used for both transmission and reception during each test.
As shown in fig. 1, a magnetostrictive transducer, a piezoelectric transducer and an electromagnetic ultrasonic transducer are mounted on the edge surface of a turbine blade 1 in different coupling modes, the arrangement of the transducer 2 should be as close as possible to the edge of the blade 1, there is no special requirement for the length of the transducer, but the required length cannot exceed 1/3 of the width of the blade, the transducer 2 is connected with a guided wave detector through a signal transmission cable, the guided wave detector comprises a pulse signal generation module, a power amplification module and a pre-amplification module, the pulse signal generation module is connected with the transducer through the power amplification module, and the transducer is connected with a signal acquisition module through the pre-amplification module; the pulse signal generating module generates a detection pulse signal, the detection pulse signal is loaded to the energy converter 2 after being amplified by the power amplifying module, and SH guided waves or Lamb are formed and coupled to the blades 1; the echo of the guided wave signal transmitted at the edge of the blade 1 is received by the transducer 2 in a sensing way, is conditioned and amplified by the preamplification module, and is converted into a digital signal by the signal acquisition module for analysis and processing.
As long as the outer shell of the turbine blade 1 is provided with a small space for installing the transducer, the defect detection can be carried out on all blades of the turbine, the transducer can be installed on each blade by rotating the turbine, and the installed transducer can test the defect detection of the blade.
In the specific implementation, SH guided waves and Lamb waves are used for detection, and the transduction principle comprises but is not limited to piezoelectric type, magnetostriction type and electromagnetic ultrasound. The SH wave can be excited by adopting a guided wave transducer based on the magnetostrictive principle, and the guided wave is coupled to the turbine blade through a paste coupling agent. The Lamb wave can be excited by adopting a piezoelectric or electromagnetic guided wave transducer, and the piezoelectric guided wave transducer can couple the guided wave to the turbine blade through a liquid coupling agent.
The utility model discloses arrange guided wave transducer 2 at 1 edge of turbine blade, lead to the microminiature crackle because impact and fatigue, this crack defect cross section loss is less, and because the focusing effect at the marginal at the guided wave of terminal surface excitation, will propagate forward along the edge of blade, run into the defect after, energy after the focus will take place the interact with the defect to produce the echo of high SNR, this echo is gathered equally and is propagated and received by the transducer along the blade edge at the edge.
The technical scheme of the utility model under, guided wave transducer 2 is when the guided wave that the edge arouses propagates on the blade, the edge of blade can be focused on gradually to the energy of guided wave, guided wave after the focus can propagate forward along the edge of blade, reflect out the defect echo when meetting defective position, the defect echo also can be received by the transducer along the edge of blade, so to marginal defect, guided wave signal also can produce great echo signal, obtain the echo signal-to-noise ratio higher echo signal, can realize the detection to the crackle of the microminiature on turbine blade edge or corrosion defect.
Because the guided wave excited by the transducer can be immediately focused to the edge and is transmitted forwards along the edge in the transmission process, the guided wave transmitted on the edge is hardly influenced by some inherent bulges and step structures on the blade, and the echo received by the transducer can only be the echo caused by the defect, so that the received defect echo has higher signal-to-noise ratio and is positioned accurately.
In the specific implementation, to some turbine blades that can't manually install the transducer, use the utility model discloses a transducer anchor clamps mentioned carry out defect detection to this blade, at first use the couplant with the one side of back-folding type coil to install on this transducer anchor clamps, then use couplant and magnetostrictive strip coupling together with the other one side of back-folding type coil, paint the transducer with the magnetostrictive strip surface after the pre-magnetization, then utilize this anchor clamps to compress tightly whole magnetostrictive transducer and realize the excitation and the receipt of SH guided wave on turbine blade surface. Meanwhile, the fixture can also realize defect detection on the back edge of the turbine blade.
The utility model discloses a concrete implementation working process and condition as follows:
as shown in fig. 1, a guided wave transducer 2 is coupled and installed at the edge of the outer wall of a turbine blade 1, the other end of the transducer device 2 is connected with a guided wave detector 3 through a signal transmission cable, the guided wave detector 3 excites guided waves on the surface of the blade 1 through the excitation transducer device 2, after the guided waves propagating along the edge meet micro defects, defect echoes are generated and return along the original path, the defect echoes are received by the transducer 2, and the received signals are transmitted to the guided wave detector through the cable to analyze the signals. Whereby diagnosis and localization of defects on the blade 1 is achieved.
As shown in fig. 3, the excited guided wave will mostly propagate forward along the edge of the blade 1, but since the simulation uses a linear excitation, a vertically oriented wave will be generated, similar to a point source. This phenomenon can be eliminated by using a comb array transducer.
Fig. 3 shows an experimental result of detecting a defect on a turbine blade 1 using a guided wave detector and a magnetostrictive transducer 2, from the obtained signal, although the cross-sectional loss of the defect at the edge of the blade is relatively small, and the defect is relatively difficult to detect using conventional guided wave detection, from the obtained signal result, the positions of the defect and the end face can be clearly judged from the echo signal, and the signal-to-noise ratio is high and is not affected by a convex structure on the surface.
Fig. 4 shows that, in order to obtain an experimental result of monitoring defects on a turbine blade 1 by using a guided wave detector and an electromagnetic ultrasonic transducer 2, an obtained echo result is not affected by a convex structure on the surface of the blade 1, and meanwhile, when the position of the transducer 2 is not arranged on the edge of the blade but is arranged and coupled on a path of a special-shaped convex, the echo of the convex component appears once in the echo at the moment.
Fig. 5 shows a transducer clamp device designed for a blade 1 where manual mounting of the transducer is not possible. When the transducer clamp is used, the transducer clamp can be arranged at the edge position of the blade. Firstly, the zigzag coil and the pre-magnetized magnetostrictive strip are sequentially coupled on the transducer fixing branches 31 and 41 by using the coupling agent, and after the magnetostrictive transducer 21 is mounted on a transducer clamp, the clamp can be used for detecting the blade which is difficult to mount the transducer.
The transducer fixing branch 31 of the fixed end transducer clamp 3 and the 2 magnetostrictive transducers 21 are first applied to one side of the blade 1, and then the moving end transducer clamp 4 is also applied against the other side edge of the blade 1 without pressing down the tightening handbrake 52.
When the magnetostrictive transducers 21 on the two sides are attached to the edge surface of the blade 1, the hand brake 52 is tightened by pressing down, at the moment, the hand brake 52 is tightened to drive the steel cable 6 to move towards the direction of tightening the hand brake 52, the other end of the steel cable 6 is connected with the rib plate 43 of the movable end transducer clamp 4, the movable steel cable 6 pulls the movable end transducer clamp 4 to move towards the fixed end transducer clamp 3, and the rivet mechanism 42 on the lower end surface of the movable end transducer clamp 4 moves in the groove mechanism 33 of the fixed end transducer clamp 3, so that the sliding of the movable end transducer clamp 4 is guided and limited.
After tensioning, the entire transducer clamp presses the 4 magnetostrictive transducers 21 against the surface of the blade 1 edge. At the moment, the wave guide instrument is sequentially connected with cables 22 of 4 transducers to realize that any one magnetostrictive transducer 21 excites and receives SH guided wave signals, obtained echo signals are stored, distance compensation is carried out on the echo signals received by the transducers on the same side to eliminate detection blind areas around the transducers, and then two groups of echo signals are combined to finish defect detection and defect positioning.
After the detection is finished, the tightening hand brake is loosened, the resilience force of the spring mechanism per se moves the end transducer clamp to the direction far away from the fixed end transducer clamp, and therefore resetting of the movable end transducer and loosening of the whole transducer clamp are achieved.
Therefore, the utility model discloses can be used for eliminating traditional guided wave when detecting and detecting the special-shaped structure and the protruding mixed phenomenon that leads to the signal of blade itself when detecting the turbine blade that the structure is complicated, improve the SNR and the reliability that the blade detected, eliminate the detection blind area through two sets of transducer combinations moreover. And use the utility model discloses a magnetostrictive transducer device detects time measuring to turbine blade's edge, can realize the short-term test under the turbine does not dismantle the condition, and the suitability is strong and easy operation.
Claims (6)
1. An apparatus for guided wave detection of edge defects of a turbine blade, comprising: the wind turbine blade guiding device comprises four guiding wave transducers (2), wherein the guiding wave transducers (2) are respectively arranged at the edges of two sides of a turbine blade (1), the two guiding wave transducers (2) on the same side are uniformly arranged at intervals along the edge direction, and the four guiding wave transducers (2) are connected with a guiding wave detector through respective cables;
the guide wave transducer (2) is mounted on a turbine blade (1) through a transducer device for detection, the transducer device comprises a movable end transducer clamp (4), a fixed end transducer clamp (3), a tensioning device (5), a steel cable (6) and a spring (7), one end of the movable end transducer clamp (4) is embedded in a sliding groove in one end of the fixed end transducer clamp (3) through a rivet and moves along the sliding groove, the spring (7) is connected between the end faces of the fixed end transducer clamp (3) and the movable end transducer clamp (4), and the spring (7) is compressed; the fixed end transducer clamp (3) comprises a clamp part and a straight pipe part, the clamp part is fixedly connected with the straight pipe part, the tensioning device (5) is fixed at the upper end of the straight pipe part of the fixed end transducer clamp (3), the tensioning device (5) comprises a tensioning handle (51) and a tensioning hand brake (52), the tensioning handle (51) is sleeved on the straight pipe part of the fixed end transducer clamp (3), the tensioning hand brake (52) is installed on the tensioning handle (51) and connected with one end of a steel cable (6), the other end of the steel cable (6) is connected on a ribbed plate (43) in the middle of the movable end transducer clamp (4), the tensioning hand brake (52) is pressed down to pull the steel cable (6) through the tensioning handle (51) to move the movable end transducer clamp (4) along a sliding groove, so that the movable end transducer clamp (4) is close to or far away from the clamp part of the fixed end transducer clamp (3) to move, adjusting and controlling a movable end transducer clamp (4) and a fixed end transducer clamp (3) to be clamped mutually, so that the whole transducer clamp is fixedly clamped on the turbine blade (1); detecting edge defects of the turbine blade (1) by a guided wave transducer (2) fixed on a movable end transducer clamp (4) and a fixed end transducer clamp (3); the two sides of the edge of the turbine blade (1) are respectively provided with two respective transducer support branches (31, 41) by the movable end transducer clamp (4) and the fixed end transducer clamp (3), and each transducer support branch (31, 41) is adhered with a conductive transducer (2) by using a coupling agent.
2. The apparatus of claim 1, wherein the guided wave detection device comprises: the guided wave detector comprises a power amplifier, a pulse signal generation module, a preamplifier and a signal acquisition module, wherein the input end of the guided wave transducer (2) is connected with the pulse signal generation module through the power amplifier, and the output end of the guided wave transducer (2) is connected with the signal acquisition module through the preamplifier.
3. The apparatus of claim 1, wherein the guided wave detection device comprises: two guided wave transducers (2) are arranged on the side face of the same side edge of the turbine blade (1), and the distance between every two adjacent guided wave transducers is larger than 4 times of the wavelength of a guided wave signal emitted by the guided wave transducers (2).
4. The apparatus of claim 1, wherein the guided wave detection device comprises: the turbine blade (1) is a blade with a fan-shaped structure, the central angle of the fan shape is smaller than 15 degrees, and the cross section in the radial direction is of a structure with a thicker middle part and thinner two sides.
5. The apparatus of claim 1, wherein the guided wave detection device comprises: the guided wave transducer (2) adopts a magnetostrictive transducer, one end of the magnetostrictive transducer is positioned at the edge of the turbine blade (1), and the coil size of the magnetostrictive transducer is smaller than the width of the turbine blade (1) of 1/3.
6. The apparatus of claim 1, wherein the guided wave detection device comprises: the guided wave transducer (2) comprises an induction coil and a magnetostrictive strip, the induction coil and the magnetostrictive strip are bonded together by glue, the magnetostrictive strip is in contact with the edge surface of the turbine blade (1) through a coupling agent on the other surface which is not connected with the induction coil, and the acoustic wave is coupled to the edge of the blade to realize the defect detection of the turbine blade (1).
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| CN202021421552.7U CN212341109U (en) | 2020-07-17 | 2020-07-17 | Guide wave detection device for edge defects of turbine blades |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114216960A (en) * | 2021-11-15 | 2022-03-22 | 江苏方天电力技术有限公司 | Nondestructive testing device for cracks of turbine blades |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114216960A (en) * | 2021-11-15 | 2022-03-22 | 江苏方天电力技术有限公司 | Nondestructive testing device for cracks of turbine blades |
| CN114216960B (en) * | 2021-11-15 | 2024-03-08 | 江苏方天电力技术有限公司 | Turbine blade crack nondestructive test device |
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