Engine tail nozzle defect detection method and system based on adaptive step angle

Abstract

The present invention relates to the technical field of solid rocket engine defect detection, and discloses a method and system for detecting engine tail nozzle defects based on adaptive step angles. The present invention obtains the defect position through a low-resolution scanning mode, and then accurately scans the defect position through a high-resolution scanning mode. Moreover, both scanning modes are combined with real-time echo data, and the step angle of the transducer array axial rotation motor is dynamically adjusted according to a smoothing control parameter by comparing the difference between the expected target echo signal and the actual measured echo signal in real time. The present invention utilizes a gradient descent method to solve the optimization problem of the cost function in each control cycle. The system can obtain the optimal step angle while meeting real-time requirements. Therefore, the present invention can not only improve scanning accuracy, but also take into account scanning efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solid rocket motor defect detection, and in particular to a method and system for detecting engine tail nozzle defects based on an adaptive step angle. The method and system implement ultrasonic C-scan defect detection of solid rocket motor tail nozzles based on an adaptive step angle iterative model predictive control algorithm (ASA-IMPC). Background Art

[0002] Solid rocket engines, with their advantages of simple structure, high performance, high reliability, and easy maintenance, have been widely used in the aerospace field. The rocket engine's tail nozzle accelerates and discharges the high-temperature, high-pressure gases within the combustion chamber, converting the heat and pressure of the gases into kinetic energy. Its structural design and stability determine the efficiency of the engine's thrust and play a vital role in the engine's overall performance. Modern rocket engine tail nozzles are primarily made of composite materials such as carbon fiber, but are prone to defects such as bubbles and debonding during the production process. These defects are directly related to the performance and launch safety of the rocket engine. The high-temperature, high-pressure gases generated by propellant combustion can damage the tail nozzle and, in severe cases, even cause the engine to explode, threatening the safe operation of the rocket. Therefore, defect detection in the engine tail nozzle is crucial to the reliability and technological development of rocket engines.

[0003] Ultrasonic non-destructive testing has been widely used in rocket engine defect detection due to its advantages such as good directionality, strong penetration and non-invasiveness. Ultrasonic C-scan testing, as an advanced ultrasonic scanning technology, can intuitively display defects inside the workpiece in the form of images. Compared with traditional A-scan testing, this method can not only perform more complex testing tasks, but also more accurately and reliably identify tiny defects such as bubbles and debonding inside the tail nozzle. Through C-scan testing, not only can the type, location and size of defects be quantitatively evaluated, but also comprehensive three-dimensional visualization results can be provided, greatly improving the efficiency and accuracy of testing, thereby effectively ensuring the performance and safety of rocket engines. In the production and maintenance of rocket engines, C-scan testing technology has become a key means, helping to improve the quality control and safety management level of the engine.

[0004] The application of ultrasonic C-scan technology in rocket engine tail nozzle defect detection has a long history, with significant progress in detection accuracy and reliability. Currently, C-scan technology can effectively identify internal defects in tail nozzles made of composite materials, such as bubbles, cracks, and debonding, and can visually present the internal defect structure of the workpiece in the form of images. However, with the increasing complexity of rocket engine tail nozzle materials and structures, existing ultrasonic C-scan technology has low signal quality due to insufficient coupling with complex surfaces, poor ultrasonic penetration in composite materials, or large control errors in the automatic detection system, affecting the accuracy and reliability of detection. Reducing the scan step value can increase the accuracy of defect detection to a certain extent, but it will affect the efficiency of defect detection. Summary of the Invention

[0005] In view of the problems of low detection accuracy and poor reliability caused by the difficulty of curved surface coupling, poor sound wave penetration, and system control errors in the existing tail nozzle defect detection technology, the present invention provides an engine tail nozzle defect detection method and system based on adaptive step angle to solve the problem of difficulty in balancing detection efficiency and accuracy.

[0006] To solve the above technical problems, the present invention adopts a technical solution: a method for detecting engine tail nozzle defects based on adaptive step angle, wherein the detection device used includes an ultrasonic transducer array, an axial rotary motor, and multiple electrically controlled telescopic components. Each ultrasonic transducer in the ultrasonic transducer array is respectively arranged on the rotating shaft of the axial rotary motor via an electrically controlled telescopic component. The electrically controlled telescopic component is used to drive the ultrasonic transducer array to closely fit the inner wall of the tail nozzle, and the axial rotary motor is used to drive the ultrasonic transducer array to rotate along the central axis of the tail nozzle. The method comprises the following steps:

[0007] Step 1: Start the detection device; set the relevant parameters of the detection device and configure the detection device to a low-resolution preliminary scanning mode;

[0008] Step 2: Control the ultrasonic transducer array to fit tightly against the inner wall of the tail nozzle, collect the measurement signal and obtain the echo amplitude ; k represents the kth position, i represents the i-th frame echo of the current position;

[0009] Step 3: Calculate the cost function J and the echo amplitude deviation based on the preset expected echo signal :

[0010] ;

[0011] ;

[0012] in, represents the expected echo signal, represents the control input, represents the weight coefficient; N represents the number of transmitted pulses;

[0013] Step 4: Update the control gains and calculate the step angle of the ultrasonic transducer array , the calculation formula is:

[0014] ;

[0015] ;

[0016] in, represents the learning rate, represents the cost function gradient, represents the updated control gain of the k-th position, represents the control gain of the k-1th position; Indicates the step angle of the k-1th position;

[0017] Step 5: Control the ultrasonic transducer array to separate from the inner wall of the tail nozzle, and then control the ultrasonic transducer array to rotate the step angle ;

[0018] Step 6: Return to step 2 and repeat steps 2-5 until the defect detection of the entire tail nozzle is completed and all defect locations with abnormal echoes are recorded;

[0019] Step 7: Configure the detection device to high-resolution precision scanning mode, control the ultrasonic transducer array to rotate to the first defect position in the low-resolution preliminary scanning mode, and repeat steps 2 to 5 until the high-resolution precision scanning of the current defect position is completed; then control the ultrasonic transducer array to rotate to the next defect position in the low-resolution preliminary scanning mode and repeat the high-resolution precision scanning until the high-resolution precision scanning of all defect positions is completed;

[0020] Step 8: Preprocess the abnormal echo signal during high-resolution precision scanning and calculate the defect thickness.

[0021] In step 1, the relevant parameters set include the initial low-resolution step angle, the initial high-resolution step angle and the number of transmitted pulses.

[0022] The specific steps of step 8 are:

[0023] Determine the time T0 of the transmitted waveform and the time T1 of the reflected wave received from the outer wall of the tail nozzle, and eliminate the data outside the T0-T1 interval in the abnormal echo signal during high-resolution precision scanning to complete data preprocessing;

[0024] Traverse the wavelet basis function, calculate the energy concentration factor C, and perform wavelet basis decomposition on the echo signal according to the wavelet basis with the largest energy concentration factor;

[0025] Identify the abnormal echo time t based on the wavelet basis decomposition results, and calculate the defect thickness based on the abnormal echo time , the calculation formula is:

[0026] ;

[0027] in, Represents the material sound velocity.

[0028] The engine tail nozzle defect detection method based on adaptive step angle further includes the following steps:

[0029] Step 9: Expand the tail nozzle 3D image into a sector along the central axis, divide the sector image into grids according to low-resolution step angles, and divide the defect area into grids according to high-resolution step angles;

[0030] Step 10: Based on the defect detection results, change the RGB color value of the grid where the defect is located, and characterize the difference in defect depth through changes in brightness and saturation to achieve a visual display of the detection results.

[0031] In addition, the present invention also provides an engine tail nozzle defect detection system based on adaptive step angle, comprising: an ultrasonic C-scan industrial control computer, a tail nozzle defect automatic detection device;

[0032] The automatic detection device for tail nozzle defects includes a detection frame, on which an axial rotating motor, a vertical bearing seat and a tail nozzle positioning card are provided. The rotating shaft of the axial rotating motor is provided on the vertical bearing seat, and its end is fixedly connected to the ultrasonic transducer support rod. The ultrasonic transducer support rod is provided with a plurality of electrically controlled telescopic components along the extension direction of the rod. The ends of the electrically controlled telescopic components are provided with ultrasonic transducers for driving the ultrasonic transducers to telescope and fit tightly with the inner wall of the tail nozzle. The ultrasonic transducers at the ends of the electrically controlled telescopic components form an ultrasonic transducer array; the axial rotating motor is used to drive the ultrasonic transducer array to rotate along the rotating shaft of the axial rotating motor to realize 360° rotational scanning of the inner wall of the tail nozzle; the tail nozzle positioning card is used to cooperate with the tail nozzle to realize the positioning of the automatic detection device for tail nozzle defects;

[0033] The ultrasonic C-scan industrial computer is used to control the ultrasonic transducer array, the axial rotation motor, and the electronically controlled telescopic assembly to implement the engine tail nozzle defect detection method based on adaptive step angle.

[0034] The electrically controlled telescopic assembly includes a telescopic servo bracket, a servo, a connecting rod, a straight rod, a fixed block, and a buffer spring. The telescopic servo bracket is fixedly connected to the ultrasonic transducer support rod. The servo and the fixed block are fixedly arranged on the telescopic servo bracket. One end of the connecting rod is hinged to the servo arm, and the other end is hinged to one end of the straight rod. The other end of the straight rod passes through the fixed block and is connected to the buffer spring. The ultrasonic transducer is fixed to the end of the buffer spring. The fixed block is used to limit the straight rod so that it can be extended and retracted in a direction perpendicular to the rotation axis of the axially rotating motor.

[0035] The detection frame is also provided with a sliding rod along the vertical direction, the sliding rod is provided with a slider that can slide along the sliding rod in the vertical direction, the slider is provided with an axial rotating motor bracket, the axial rotating motor is fixed to the slider through the axial rotating motor bracket, and the vertical bearing seat and the tail nozzle positioning card are fixed to the slider.

[0036] A plurality of Forma wheels are provided at the bottom of the detection frame, and an electric control module is also provided on the detection frame. The electric control module is used to control the rotation angle of the axial rotation motor and the telescopic length of the electric control telescopic assembly under the control of the ultrasonic C-scan industrial computer.

[0037] The ultrasonic C-scan industrial computer includes a function board and a main board. The CPU in the main board is equipped with tail nozzle ultrasonic C-scan defect detection software that controls the detection process and data processing; the function board is connected to each ultrasonic transducer through an SMA interface; the main board is connected to the function board through a PCIE interface; the function board is connected to the electronic control module through an SPI interface. The function board is used to send ultrasonic drive commands to the ultrasonic transducer under the control of the main board, and to receive the echo signal of the ultrasonic transducer and send it to the main board; the function board is also used to receive the control signal sent by the main board and transfer it to the electronic control module. The control signal is used to control the rotation angle of the axial rotation motor and the telescopic length of the electronically controlled telescopic assembly.

[0038] The function board includes a main FPGA, an ultrasonic drive transmitting unit, a transceiver isolation circuit, and an impedance matching circuit. The main FPGA is connected to the ultrasonic transducer through the ultrasonic drive transmitting unit, the transceiver isolation circuit, and the impedance matching circuit. A slave FPGA is provided in the electronic control module.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The present invention provides an engine tail nozzle defect detection method and system based on adaptive step angle. The defect location is obtained through a low-resolution scanning mode, and then the defect location is accurately scanned through a high-resolution scanning mode. Moreover, both scanning modes are combined with real-time echo data. By comparing the difference between the expected target echo signal and the actual measured echo signal in real time, the step angle of the transducer array axial rotation motor is dynamically adjusted according to the smoothing control parameter. The present invention uses the gradient descent method to solve the optimization problem of the cost function in each control cycle. The system can obtain the optimal step angle while meeting the real-time requirements. Therefore, the present invention significantly improves the scanning accuracy while ensuring the scanning efficiency.

[0041] 2. The present invention utilizes the tail nozzle defect automatic detection device to achieve 360° rotational scanning of the tail nozzle inner wall, which can improve measurement accuracy. At the same time, the present invention rationally sets the hardware structure of the ultrasonic C-scan industrial control computer, which can improve the data processing efficiency of the system.

[0042] 3. In addition, the present invention can also display the location and size distribution of engine defects in detail on the interface, providing important data support for engine design and manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the structure of the detection device used in the embodiment of the present invention;

[0044] Figure 2 A flowchart of an engine tail nozzle defect detection method based on adaptive step angle provided in the first embodiment of the present invention; a flowchart of parameter configuration of a solid fuel engine tail nozzle defect detection system;

[0045] Figure 3 This is a flow chart of a step angle control algorithm for an axial rotation motor of an ultrasonic transducer array according to an embodiment of the present invention;

[0046] Figure 4 A schematic structural diagram of an engine tail nozzle defect detection system provided in a second embodiment of the present invention;

[0047] Figure 5 Schematic diagram of the structure of the electric-controlled telescopic assembly in the second embodiment of the present invention;

[0048] Figure 6 A parameter configuration workflow diagram of an engine tail nozzle defect detection system provided in the second embodiment of the present invention;

[0049] Figure 7 This is a workflow diagram of an engine tail nozzle defect detection system provided in the second embodiment of the present invention;

[0050] In the figure: 1-detection frame, 2-slide rod, 3-slider, 4-axial rotation motor, 5-axial rotation motor bracket, 7-tail nozzle positioning card, 8-vertical bearing seat, 9-ultrasonic transducer support rod, 10-electrically controlled telescopic component, 11-electric control module, 12-Foma wheel, 14-telescopic servo bracket, 15-servo, 16-servo arm, 17-connecting rod, 18-connecting block, 19-straight rod, 20-fixed block, 21-buffer spring. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0052] Example 1

[0053] The first embodiment of the present invention provides an engine tail nozzle defect detection method based on adaptive step angle, and a solid engine tail nozzle ultrasonic C-scan defect detection method based on adaptive step angle iterative model predictive control algorithm (ASA-IMPC). Figure 1 As shown, the detection device used includes an ultrasonic transducer array, an axially rotating motor 4, and multiple electrically controlled telescopic assemblies 10. Each ultrasonic transducer in the ultrasonic transducer array is mounted on the rotating shaft of the axially rotating motor 4 via an electrically controlled telescopic assembly 10. The electrically controlled telescopic assembly 10 is used to drive the ultrasonic transducer array to closely adhere to the inner wall of the tail nozzle, while the axially rotating motor 4 is used to drive the ultrasonic transducer array to rotate along the central axis of the tail nozzle. The measurement principle of this embodiment of the present invention is that due to the difference in acoustic properties between the defect and the normal material, the pulse wave emitted by the ultrasonic transducer will be reflected when encountering the defect in the tail nozzle. As a result, in each frame of the echo signal, there will be an abnormal echo signal in addition to the end face echo. By identifying the location of the abnormal echo, the defect depth of the tested object can be determined. The axially rotating motor 4 and the electrically controlled telescopic assembly 10 control the ultrasonic transducer array to perform circular motion and closely adhere to the inner wall of the tail nozzle, achieving defect detection for the entire tail nozzle.

[0054] Specifically, if Figure 2 As shown, the detection method of this embodiment specifically includes the following steps:

[0055] Step 1: Start the detection device; set the relevant parameters of the detection device and configure the detection device to a low-resolution preliminary scanning mode. In the low-resolution preliminary scanning mode, the initial step angle is the initial low-resolution step angle.

[0056] In step 1, the initialization-related parameters include an initial low-resolution step angle, an initial high-resolution step angle, and the number of transmitted pulses.

[0057] Step 2: Control the ultrasonic transducer array to fit tightly against the inner wall of the tail nozzle, collect the measurement signal and obtain the echo amplitude ; k represents the kth position, and i represents the i-th frame echo of the current position.

[0058] Step 3: Calculate the cost function J and the echo amplitude deviation based on the preset expected echo signal :

[0059] ; (1)

[0060] ; (2)

[0061] in, represents the expected echo signal, Represents the control input, that is, the change in the last step angle, Represents the weight coefficient, which is used to balance the signal tracking error and the control input change; N represents the number of transmitted pulses.

[0062] Step 4: Update the control gain based on the gradient descent method and calculate the step angle of the ultrasonic transducer array , the calculation formula is:

[0063] ; (3)

[0064] ; (4)

[0065] in is the learning rate, is the cost function gradient, represents the updated control gain of the k-th position, represents the control gain of the k-1th position; Indicates the step angle of the k-1th position. When k=1, Indicates the preset initial step angle.

[0066] Step 5: Control the ultrasonic transducer array to separate from the inner wall of the tail nozzle, according to the calculated step angle Controls the rotation of the ultrasound transducer array.

[0067] Step 6: Return to step 2 and repeat steps 2-5 until the defect detection of the entire tail nozzle is completed; at the same time, according to the echo amplitude deviation at each position The size of the echo is used to determine whether there is a defect at the current position, and the defect position where the abnormal echo appears is recorded.

[0068] In addition, the above steps 3 to 6 are the adaptive step angle iterative model predictive control algorithm (ASA-IMPC) used in the embodiment of the present invention. It uses the preset expected echo information to calculate the weight coefficient of the balance signal tracking error and the control input change, initializes the gradient descent model to achieve the update of the step angle, and can realize the real-time change of the scanning accuracy according to the defect of the tail nozzle, improve the detection efficiency without losing the detection accuracy. Specifically, the common methods in the field can be used to determine whether there is a defect. For example, a threshold is set. If the echo amplitude deviation If it is greater than this threshold, it means that this is an abnormal echo, and the position k at this time is the defect position.

[0069] Step 7: Configure the inspection device to high-resolution precision scanning mode, control the ultrasonic transducer array to rotate to the first defect location during the low-resolution preliminary scan, and repeat steps 2 to 5 multiple times until the high-resolution precision scan of the current defect location is completed. Then control the ultrasonic transducer array to rotate to the next defect location during the low-resolution preliminary scan and repeat the high-resolution precision scan until all defect locations are scanned with high resolution precision.

[0070] Specifically, in the high-resolution precision scanning mode, the initial step angle is the initial high-resolution step angle. In the high-resolution precision scanning mode, the preset initial high-resolution step angle is smaller than the initial low-resolution step angle.

[0071] In this embodiment, the defect position is initially located using a low-resolution scanning mode, and then the defect position is further finely scanned using a high-resolution scanning mode, thereby improving the detection accuracy of the defect position. Moreover, ASA-IMPC dynamically adjusts the step angle of the transducer array axial rotation motor according to the smoothing control parameters based on the real-time comparison between the expected target echo signal and the actual measured echo signal, which can greatly improve detection efficiency and reduce detection time.

[0072] Step 8: Preprocess the abnormal echo signal during high-resolution precision scanning and calculate the defect thickness. In this embodiment, it is necessary to perform adaptive wavelet basis function decomposition on the preprocessed echo data, and then calculate the defect thickness based on the decomposition result.

[0073] The specific steps of step 8 are:

[0074] 1. Determine the time T0 when the waveform is transmitted and the time T1 when the reflected wave is received from the outer wall of the tail nozzle. Remove the data outside the T0-T1 interval in the abnormal echo signal during high-resolution precision scanning to complete data preprocessing to reduce the amount of computational data.

[0075] 2. Traverse the wavelet basis function set ,in Respectively represent the 1st, 2nd... …, n wavelet bases, calculate the energy concentration factor C corresponding to each wavelet basis function, and perform wavelet basis decomposition on the echo signal according to the wavelet basis with the largest energy concentration factor; the energy concentration factor C calculation formula is:

[0076] ; (5)

[0077] in, represents the square of the maximum amplitude of the i-th wavelet basis, and E represents the total energy of the wavelet basis. Specifically,

[0078] ; (6)

[0079] Among them, the value range of C is 0~1. The closer it is to 1, the higher the energy concentration is and the better the wavelet basis is selected.

[0080] 3. Identify the abnormal echo time t based on the wavelet basis decomposition results, and calculate the defect thickness based on the abnormal echo time , the calculation formula is:

[0081] ; (7)

[0082] in, Represents the material sound velocity.

[0083] like Figure 3 As shown, in this embodiment, all signals are analyzed and processed by the defect location algorithm until all abnormal echo signals are analyzed, and the defect information at all positions of the tail nozzle can be obtained.

[0084] Furthermore, the engine tail nozzle defect detection method based on adaptive step angle of this embodiment further includes the following steps:

[0085] Step 9: Expand the tail nozzle 3D image into a sector along the central axis. Divide the sector image into a grid according to the real-time step angle in low-resolution mode. Divide the defect area into a grid according to the real-time step angle in high-resolution mode.

[0086] Step 10: Based on the defect detection results, change the RGB color value of the grid where the defect is located, and characterize the difference in defect depth through changes in brightness and saturation to achieve a visual display of the detection results.

[0087] Specifically, in this embodiment, green is used to indicate that the current grid area has no defects, red is used to indicate that there are defects in the grid, and the difference in defect depth is represented by the changes in the brightness and saturation of red.

[0088] Example 2

[0089] The second embodiment of the present invention provides an engine tail nozzle defect detection system, such as Figure 4 As shown, the system comprises an ultrasonic C-scan industrial computer and an automatic nozzle defect detection device. The ultrasonic C-scan industrial computer is used to control the ultrasonic transducer array, the axial rotation motor 4, and the electronically controlled telescopic assembly 10 to implement the engine nozzle defect detection method based on adaptive step angle described in Example 1.

[0090] Among them, the ultrasonic C-scan industrial computer includes a function board and a main board, the function board is connected to each ultrasonic transducer through an SMA interface; the main board is connected to the function board through a PCIE interface; the function board is connected to the electronic control module through an SPI interface, and the function board is used to send ultrasonic drive commands to the ultrasonic transducer under the control of the main board, and receive the echo signal of the ultrasonic transducer and send it to the main board; the main board is used to send control signals to the axial rotation motor 4 and the electric control telescopic assembly 10 through the function board and the electronic control module 11 to control the rotation angle of the axial rotation motor 4 and the telescopic length of the electric control telescopic assembly 10.

[0091] Specifically, if Figure 1 As shown, in this embodiment, the tail nozzle defect automatic detection device includes a detection frame 1, on which an axial rotary motor 4, a vertical bearing seat 8 and a tail nozzle positioning card 7 are provided. The rotating shaft of the axial rotary motor 4 is provided on the vertical bearing seat 8, and its end is fixedly connected to the ultrasonic transducer support rod 9. The ultrasonic transducer support rod 9 is provided with a plurality of electrically controlled telescopic components 10 along the extension direction of the rod. The end of the electrically controlled telescopic component 10 is provided with an ultrasonic transducer. The electrically controlled telescopic component 10 is used to drive the ultrasonic transducer to extend and contract and fit closely with the inner wall of the tail nozzle. The ultrasonic transducers at the ends of each electrically controlled telescopic component 10 form an ultrasonic transducer array; the axial rotary motor 4 is used to drive the ultrasonic transducer array to rotate along the rotating axis of the axial rotary motor 4 to realize 360° rotational scanning of the inner wall of the tail nozzle; the tail nozzle positioning card 7 is used to cooperate with the tail nozzle to realize the positioning of the tail nozzle defect automatic detection device;

[0092] Furthermore, if Figure 5As shown, the electrically controlled telescopic assembly 10 includes a telescopic servo bracket 14, a servo 15, a connecting rod 17, a straight rod 19, a fixed block 20, and a buffer spring 21. The telescopic servo bracket 14 is fixedly connected to the ultrasonic transducer support rod 9. The servo 15 and the fixed block 20 are fixedly arranged on the telescopic servo bracket 14. One end of the connecting rod 17 is hinged to the servo arm 16, and the other end is hinged to one end of the straight rod 19. The other end of the straight rod 19 passes through the fixed block 20 and is connected to the buffer spring 21. The ultrasonic transducer is fixed to the end of the buffer spring 21. The fixed block 20 is used to limit the straight rod 19 so that it can be extended and retracted in a direction perpendicular to the rotation axis of the axial rotation motor 4. In addition, a connecting block 18 is provided at one end of the straight rod 19 near the connecting rod 17. One end of the connecting block 18 is hinged to the connecting rod 17, and the other end is fixedly connected to the straight rod 19.

[0093] Furthermore, if Figure 1 As shown, the detection frame 1 is also provided with a vertically extending slide bar 2. The slide bar 2 is provided with a slider 3 that can slide vertically along the slide bar 2. The slider 3 is provided with an axially rotating motor bracket 5. The axially rotating motor 4 is fixed to the slider 3 via the axially rotating motor bracket 5. The vertical bearing seat 8 and the tail nozzle positioning clamp 7 are fixed to the slider 3. By providing the slider 3 and the slide bar 2, the height of the rotating axis of the axially rotating motor 4 can be adjusted, so that the tail nozzle defect automatic detection device can adapt to the real-time height of the tail nozzle. The slider 3 can also be provided with a locking mechanism. When it slides along the slide bar 2 to the appropriate height in the numerical direction, it can be locked by the locking mechanism and fixed to the slide bar 2. The locking mechanism can be a bolt provided on the slider 3. When the slider 3 slides to the appropriate position on the slide bar 2, the bolt is tightened to support the slide bar 2, thereby achieving sliding locking. In addition, the locking mechanism can also be other structures.

[0094] Furthermore, if Figure 1 As shown, a plurality of Forma wheels 12 are provided at the bottom of the detection frame 1 to realize the movement of the detection frame 1. An electric control module 11 is also provided on the detection frame 1. The electric control module 11 is used to control the rotation angle of the axial rotation motor 4 and the telescopic length of the electric control telescopic assembly 10 under the control of the ultrasonic C-scan industrial computer.

[0095] Furthermore, if Figure 4As shown, the function board includes a master FPGA, an ultrasonic drive and transmitter unit, a transceiver isolation circuit, and an impedance matching circuit. The master FPGA is connected to the ultrasonic transducer via the ultrasonic drive and transmitter unit, the transceiver isolation circuit, and the impedance matching circuit. Specifically, a slave FPGA is provided within the electronic control module 11. The master FPGA is connected to the mainboard via PCIE and is connected to the slave FPGA within the electronic control module via SPI communication. The master FPGA uses an XC7K325T as its main chip, while the slave FPGA uses an XC7A35T as its main chip.

[0096] Furthermore, in this embodiment, the ultrasonic C-scan industrial control computer also includes a power supply, an industrial control chassis, and peripherals. Within the function board, the ultrasonic drive and transmission unit's main chip is the HV7321. Furthermore, the function board includes a multi-stage tunable filter unit using the AD9271 as its main chip, an adaptive gain adjustment module using the AD7801 as its main chip, and other components such as an SMA interface. The CPU within the main board contains the tailpipe ultrasonic C-scan defect detection software that controls the inspection process and data processing. Furthermore, the tailpipe ultrasonic C-scan defect detection software is also responsible for data acquisition and result display. The function board's main FPGA communicates with the tailpipe ultrasonic C-scan defect detection software (i.e., the host computer software) via the PCIE protocol. During the data processing phase, the ultrasonic C-scan defect detection software utilizes the adaptive step angle iterative model predictive control algorithm (ASA-IMPC) to optimize the step angle in real time and transmit it to the electronic control module 11. Simultaneously, the scanning path is dynamically adjusted based on the ultrasonic echo signal fed back by the function board to improve defect location accuracy.

[0097] The working process of an engine tail nozzle defect detection system of this embodiment is as follows:

[0098] (1) Connect the tail nozzle defect automatic detection device to the engine tail nozzle: point the large end of the tail nozzle toward the ultrasonic transducer array, move the tail nozzle positioning card 7 of the tail nozzle defect automatic detection device to the end surface position of the large end of the tail nozzle, and adjust the detection frame 1 or the slider 3 so that the tail nozzle positioning card 7 is aligned with the tail nozzle.

[0099] (2) Before the test, a self-check procedure is performed to ensure the normal operation of electronic components such as the axial rotation motor 4 and the servo 15, and to verify the connection stability of structural parts such as the vertical bearing seat 8, the ultrasonic transducer support rod 9 and the buffer spring 21.

[0100] (3) Configure the high-voltage pulse wave parameters and echo recording time through the ultrasonic C-scan defect detection software, verify the PCIE connection, and transmit the test pulse wave to ensure the normal operation of the ultrasonic C-scan industrial computer.

[0101] (4) Configure the relevant parameters of the tail nozzle defect automatic detection device, including the scanning initial step angle, scanning speed, interval time of the axial rotation motor 4, the deflection angle and deflection time of the steering gear, etc. Figure 6 FIG. 1 shows the parameter configuration workflow of the tail nozzle ultrasonic C-scan defect detection software in this embodiment.

[0102] like Figure 7 As shown, the overall workflow of an engine tail nozzle defect detection system in this embodiment is shown. After the ultrasonic C-scan industrial control computer parameter configuration is completed, it is sent to the slave FPGA in the electronic control module 11 through the master FPGA in the function board. After the slave FPGA configures the parameters, it controls the electronically controlled telescopic assembly 10 to extend so that the ultrasonic transducer array is tightly fitted with the inner wall of the tail nozzle. Then, the master FPGA sends a preparation measurement signal to the ultrasonic C-scan defect detection software. The ultrasonic C-scan defect detection software controls the master FPGA to send and receive ultrasonic waves. After the reception is completed, the ultrasonic C-scan defect detection software updates the step angle according to the received signal and transmits the step angle to the slave FPGA through the master FPGA. At the same time, after controlling the electronically controlled telescopic assembly 10 to retract, the axial rotation motor 4 is controlled to rotate by the step angle. After the rotation is completed, the next measurement cycle begins.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting engine tail nozzle defects based on adaptive step angle, characterized in that: The detection device used includes an ultrasonic transducer array, an axial rotating motor (4) and a plurality of electrically controlled telescopic components (10), wherein each ultrasonic transducer in the ultrasonic transducer array is respectively arranged on the rotating shaft of the axial rotating motor (4) through an electrically controlled telescopic component (10), the electrically controlled telescopic component (10) is used to drive the ultrasonic transducer array to be closely attached to the inner wall of the tail nozzle, and the axial rotating motor (4) is used to drive the ultrasonic transducer array to rotate along the central axis of the tail nozzle, comprising the following steps: Step 1: Start the detection device; set the relevant parameters of the detection device and configure the detection device to a low-resolution preliminary scanning mode; Step 2: Control the ultrasonic transducer array to fit tightly against the inner wall of the tail nozzle, collect the measurement signal and obtain the echo amplitude ; k represents the kth position, i represents the i-th frame echo of the current position; Step 3: Calculate the cost function J and the echo amplitude deviation based on the preset expected echo signal : ； ； in, represents the expected echo signal, represents the control input, represents the weight coefficient; N represents the number of transmitted pulses; Step 4: Update the control gains and calculate the step angle of the ultrasonic transducer array , the calculation formula is: ； ； in, represents the learning rate, represents the cost function gradient, represents the updated control gain of the k-th position, represents the control gain of the k-1th position; Indicates the step angle of the k-1th position; Step 5: Control the ultrasonic transducer array to separate from the inner wall of the tail nozzle, and then control the ultrasonic transducer array to rotate the step angle ; Step 6: Return to step 2 and repeat steps 2-5 until the defect detection of the entire tail nozzle is completed and all defect locations with abnormal echoes are recorded; Step 7: Configure the detection device to high-resolution precision scanning mode, control the ultrasonic transducer array to rotate to the first defect position in the low-resolution preliminary scanning mode, and repeat steps 2 to 5 until the high-resolution precision scanning of the current defect position is completed; then control the ultrasonic transducer array to rotate to the next defect position in the low-resolution preliminary scanning mode and repeat the high-resolution precision scanning until the high-resolution precision scanning of all defect positions is completed; Step 8: Preprocess the abnormal echo signal during high-resolution precision scanning and calculate the defect thickness.

2. The engine tail nozzle defect detection method based on adaptive step angle according to claim 1, characterized in that: In step 1, the relevant parameters set include the initial low-resolution step angle, the initial high-resolution step angle and the number of transmitted pulses.

3. The engine tail nozzle defect detection method based on adaptive step angle according to claim 1, characterized in that: The specific steps of step 8 are: Determine the time T0 of the transmitted waveform and the time T1 of the reflected wave received from the outer wall of the tail nozzle, and eliminate the data outside the T0-T1 interval in the abnormal echo signal during high-resolution precision scanning to complete data preprocessing; Traverse the wavelet basis function, calculate the energy concentration factor C, and perform wavelet basis decomposition on the echo signal according to the wavelet basis with the largest energy concentration factor; Identify the abnormal echo time t based on the wavelet basis decomposition results, and calculate the defect thickness based on the abnormal echo time , the calculation formula is: ； in, Represents the material sound velocity.

4. The engine tail nozzle defect detection method based on adaptive step angle according to claim 1, characterized in that: The following steps are also included: Step 9: Expand the tail nozzle 3D image into a sector along the central axis, divide the sector image into grids according to low-resolution step angles, and divide the defect area into grids according to high-resolution step angles; Step 10: Based on the defect detection results, change the RGB color value of the grid where the defect is located, and characterize the difference in defect depth through changes in brightness and saturation to achieve a visual display of the detection results.

5. An engine tail nozzle defect detection system based on adaptive step angle, characterized in that: include: Ultrasonic C-scan industrial computer and tail nozzle defect automatic detection device; The tail nozzle defect automatic detection device comprises a detection frame (1), the detection frame (1) is provided with an axial rotation motor (4), a vertical bearing seat (8) and a tail nozzle positioning card (7), the rotation axis of the axial rotation motor (4) is provided on the vertical bearing seat (8), and the end thereof is fixedly connected to the ultrasonic transducer support rod (9), and a plurality of electric control telescopic components (10) are provided on the ultrasonic transducer support rod (9) along the extension direction of the rod, and the end of the electric control telescopic component (10) is provided with an ultrasonic transducer for driving the ultrasonic transducer to telescope and fit closely with the inner wall of the tail nozzle, and the ultrasonic transducers at the end of each electric control telescopic component (10) form an ultrasonic transducer array; the axial rotation motor (4) is used to drive the ultrasonic transducer array to rotate along the rotation axis of the axial rotation motor (4) to realize 360° rotation scanning of the inner wall of the tail nozzle; the tail nozzle positioning card (7) is used to cooperate with the tail nozzle to realize the positioning of the tail nozzle defect automatic detection device; The ultrasonic C-scan industrial computer is used to control the ultrasonic transducer array, the axial rotation motor (4), and the electrically controlled telescopic assembly (10) to implement the engine tail nozzle defect detection method based on adaptive step angle according to any one of claims 1 to 4.

6. The engine tail nozzle defect detection system based on adaptive step angle according to claim 5, characterized in that: The electrically controlled telescopic assembly (10) comprises a telescopic servo support (14), a servo (15), a connecting rod (17), a straight rod (19), a fixed block (20), and a buffer spring (21). The telescopic servo support (14) is fixedly connected to the ultrasonic transducer support rod (9). The servo (15) and the fixed block (20) are fixedly arranged on the telescopic servo support (14). One end of the connecting rod (17) is hinged to the servo arm (16), and the other end is hinged to one end of the straight rod (19). The other end of the straight rod (19) passes through the fixed block (20) and is connected to the buffer spring (21). The ultrasonic transducer is fixed to the end of the buffer spring (21). The fixed block (20) is used to limit the straight rod (19) so that it can be telescoped in a direction perpendicular to the rotation axis of the axial rotating motor (4).

7. The engine tail nozzle defect detection system based on adaptive step angle according to claim 5, characterized in that: The detection frame (1) is further provided with a slide bar (2) in a vertical direction, the slide bar (2) is provided with a slider (3) that can slide along the slide bar (2) in a vertical direction, the slider (3) is provided with an axial rotation motor bracket (5), the axial rotation motor (4) is fixed to the slider (3) through the axial rotation motor bracket (5), and the vertical bearing seat (8) and the tail nozzle positioning card (7) are fixed to the slider (3).

8. The engine tail nozzle defect detection system based on adaptive step angle according to claim 5, characterized in that: A plurality of Forma wheels (12) are provided at the bottom of the detection frame (1), and an electric control module (11) is also provided on the detection frame (1). The electric control module (11) is used to control the rotation angle of the axial rotation motor (4) and the telescopic length of the electric control telescopic assembly (10) under the control of an ultrasonic C-scan industrial computer.

9. The engine tail nozzle defect detection system based on adaptive step angle according to claim 5, characterized in that: The ultrasonic C-scan industrial control computer includes a function board and a main board, wherein the CPU in the main board is provided with tail nozzle ultrasonic C-scan defect detection software for controlling the detection process and data processing; the function board is connected to each ultrasonic transducer via an SMA interface; the main board is connected to the function board via a PCIE interface; the function board is connected to an electric control module (11) via an SPI interface, and the function board is used to send an ultrasonic drive command to the ultrasonic transducer under the control of the main board, and to receive an echo signal of the ultrasonic transducer and send it to the main board; the function board is also used to receive a control signal sent by the main board and transfer it to the electric control module (11), and the control signal is used to control the rotation angle of the axial rotation motor (4) and the telescopic length of the electric control telescopic component (10).

10. The engine tail nozzle defect detection system based on adaptive step angle according to claim 9, characterized in that: The function board comprises a main FPGA, an ultrasonic drive transmitting unit, a transceiver isolation circuit, and an impedance matching circuit. The main FPGA is connected to the ultrasonic transducer via the ultrasonic drive transmitting unit, the transceiver isolation circuit, and the impedance matching circuit. A slave FPGA is provided in the electric control module (11).

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