Engine exhaust nozzle defect detection method and system based on self-adaptive stepping angle

Abstract

The invention relates to the technical field of solid engine defect detection, and discloses an engine exhaust nozzle defect detection method and system based on a self-adaptive stepping angle, a defect position is obtained through a low-resolution scanning mode, then the defect position is accurately scanned through a high-resolution scanning mode, and in addition, the defect detection accuracy is improved. The two scanning modes are combined with real-time echo data, and the stepping angle of the transducer array axial rotating motor is dynamically adjusted according to smooth control parameters by comparing the difference between an expected target echo signal and an actually measured echo signal in real time. According to the method, the optimization problem of the cost function is solved in each control period by using the gradient descent method, and the system can obtain the optimal stepping angle on the premise of meeting the real-time requirement, so that the scanning precision can be improved, and the scanning efficiency can be considered.

Description

Technical Field

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

[0002] Solid rocket engines have the advantages of simple structure, high mobility, high reliability, and easy maintenance, and are widely used in the aerospace field. The nozzle of the rocket engine accelerates and discharges the high-temperature and high-pressure gas in the combustion chamber, converting the thermal energy and pressure of the gas into kinetic energy. Its structural design and stability determine the efficiency of the engine thrust and play an important role in the engine. The nozzles of modern rocket engines are mainly made of composite materials such as carbon fiber, but defects such as bubbles and debonding are likely to occur during the production process. The existence of these defects is directly related to the performance and launch safety of the rocket engine. The high-temperature and high-pressure gas generated during propellant combustion may damage the nozzle, and in severe cases, it may even cause the engine to explode, threatening the safe operation of the rocket. Therefore, the defect detection of the engine nozzle is of crucial significance for the reliability and technological development of the rocket engine.

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

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

[0005] Aiming at the problems of low detection accuracy and poor reliability in the existing nozzle defect detection technology caused by difficulties in curved surface coupling, poor acoustic wave penetration, system control errors, etc., the present invention provides a method and system for defect detection of engine nozzles based on adaptive stepping angles to solve the problem that it is difficult to balance detection efficiency and accuracy.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for defect detection of engine nozzles based on adaptive stepping angles, the detection device used includes an ultrasonic transducer array, an axial rotation motor, and a plurality of electrically controlled telescopic components. Each ultrasonic transducer in the ultrasonic transducer array is respectively arranged on the rotating shaft of the axial rotation motor through 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 nozzle, and the axial rotation motor is used to drive the ultrasonic transducer array to rotate along the central axis of the nozzle, including the following steps: Step 1: Start the detection device; set the relevant parameters of the detection device and configure the detection device into a low-resolution preliminary scanning mode; Step 2: Control the ultrasonic transducer array to closely fit the inner wall of the nozzle and collect measurement signals to obtain the echo amplitude ; k represents the kth position, and i represents the ith frame echo at the current position; Step 3: Calculate the cost function J and the echo amplitude deviation according to the preset expected echo signal : ; ; Among them, 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 gain and calculate the stepping 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 kth position, represents the control gain of the k-1th position; represents 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 where abnormal echoes appear 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.

[0007] In step 1, the relevant parameters set include an initial low-resolution step angle, an initial high-resolution step angle and the number of transmitted pulses.

[0008] The specific steps of step 8 are: Determine the time T0 of the emission waveform, the time T1 of receiving the reflected wave from the outer wall of the tail nozzle, and remove 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 according to the wavelet basis decomposition results, and calculate the defect thickness according to the abnormal echo time , the calculation formula is: ; in, Represents the material sound velocity.

[0009] The engine tail nozzle defect detection method based on adaptive step angle further includes the following steps: Step 9: Unfold the three-dimensional image of the nozzle along the central axis into a sector, divide the sector image into grids according to the low-resolution stepping angle, and divide the grids at the defect locations according to the high-resolution stepping angle; Step 10: According to the defect detection results, correspondingly change the RGB color values of the grids where the defects are located, and characterize the depth difference of the defects through changes in brightness and saturation to achieve the visual display of the detection results.

[0010] In addition, the present invention also provides an engine nozzle defect detection system based on an adaptive stepping angle, including: an ultrasonic C-scan industrial control computer and a nozzle defect automatic detection device; The nozzle defect automatic detection device includes a detection frame, on which an axial rotation motor, a vertical bearing seat and a nozzle positioning clamp are arranged. The rotation shaft of the axial rotation motor is arranged on the vertical bearing seat, and the end of the rotation shaft is fixedly connected to an ultrasonic transducer support rod. A plurality of electric control telescopic components are arranged on the ultrasonic transducer support rod along the extension direction of the rod. The end of the electric control telescopic component is provided with an ultrasonic transducer for driving the ultrasonic transducer to stretch and closely fit with the inner wall of the nozzle. The ultrasonic transducers at the ends of each electric control telescopic component form an ultrasonic transducer array; the axial rotation motor is used to drive the ultrasonic transducer array to rotate along the rotation shaft of the axial rotation motor to realize a 360° rotational scan of the inner wall of the nozzle; the nozzle positioning clamp is used to cooperate with the nozzle to realize the positioning of the nozzle defect automatic detection device; The ultrasonic C-scan industrial control computer is used to control the ultrasonic transducer array, the axial rotation motor and the electric control telescopic component to implement the method for detecting engine nozzle defects based on an adaptive stepping angle.

[0011] The electric control telescopic component includes a telescopic servo bracket, a servo, a connecting rod, a straight rod, a fixing block and a buffer spring. The telescopic servo bracket is fixedly connected to the ultrasonic transducer support rod. The servo and the fixing 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 fixing block and is connected to the buffer spring. The ultrasonic transducer is fixed at the end of the buffer spring. The fixing block is used to limit the straight rod so that it can stretch in a direction perpendicular to the rotation axis of the axial rotation motor.

[0012] A sliding rod in the vertical direction is also arranged on the detection frame. A slider that can slide in the vertical direction along the sliding rod is arranged on the sliding rod. An axial rotation motor bracket is arranged on the slider. The axial rotation motor is fixed on the slider through the axial rotation motor bracket. The vertical bearing seat and the nozzle positioning clamp are fixed on the slider.

[0013] A plurality of casters are provided at the bottom of the detection frame, and an electronic control module is also provided on the detection frame. The electronic 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 an ultrasonic C-scan industrial computer.

[0014] The ultrasonic C-scan industrial computer includes a function board and a main board. A nozzle ultrasonic C-scan defect detection software for controlling the detection process and data processing is set in the CPU inside the 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. The function board is used to send ultrasonic drive commands to the ultrasonic transducers under the control of the main board, and is used to receive the echo signals of the ultrasonic transducers and send them to the main board; the function board is also used to receive the control signals sent by the main board and transfer them to the electronic control module, and the control signals are used to control the rotation angle of the axial rotation motor and the telescopic length of the electric control telescopic assembly.

[0015] The function board includes a main FPGA, an ultrasonic drive and emission unit, a transceiver isolation circuit, and an impedance matching circuit. The main FPGA is connected to the ultrasonic transducer through the ultrasonic drive and emission unit, the transceiver isolation circuit, and the impedance matching circuit. A slave FPGA is set inside the electronic control module.

[0016] The present invention has the following beneficial effects compared with the prior art: 1. The present invention provides a method and system for detecting defects in an engine nozzle based on an adaptive stepping angle. The defect position is obtained through a low-resolution scanning mode, and then the defect position is accurately scanned through a high-resolution scanning mode. Moreover, both scanning modes combine real-time echo data. By comparing the difference between the expected target echo signal and the actually measured echo signal in real time, the stepping angle of the axial rotation motor of the transducer array is dynamically adjusted according to the smoothing control parameter. The present invention uses the gradient descent method to solve the optimization problem of this cost function in each control cycle. The system can obtain the optimal stepping angle on the premise of meeting the real-time requirement. Therefore, the present invention significantly improves the scanning accuracy on the premise of ensuring the scanning efficiency; 2. The present invention uses an automatic detection device for nozzle defects to realize 360° rotary scanning of the inner wall of the nozzle, which can improve the measurement accuracy; at the same time, the present invention reasonably sets the hardware structure of the ultrasonic C-scan industrial computer, which can improve the data processing efficiency of the system; 3. In addition, the present invention can also display in detail the position and size distribution of engine defects on the interface, providing important data support for the design and manufacture of the engine. Description of the Drawings

[0017] Figure 1Schematic diagram of the detection device adopted in the embodiment of the present invention; Figure 2 Flow chart of a method for detecting defects in an engine nozzle based on an adaptive step angle provided in Embodiment 1 of the present invention; Flow chart of parameter configuration for a solid rocket motor nozzle defect detection system; Figure 3 Flow chart of an axial rotation motor step angle control algorithm for an ultrasonic transducer array in an embodiment of the present invention; Figure 4 Schematic diagram of a system for detecting defects in an engine nozzle provided in Embodiment 2 of the present invention; Figure 5 Schematic diagram of the electro-controlled telescopic assembly in Embodiment 2 of the present invention; Figure 6 Flow chart of parameter configuration for a system for detecting defects in an engine nozzle provided in Embodiment 2 of the present invention; Figure 7 Flow chart of the operation of a system for detecting defects in an engine nozzle provided in Embodiment 2 of the present invention; In the figure: 1 - detection frame, 2 - slide bar, 3 - slider, 4 - axial rotation motor, 5 - axial rotation motor bracket, 7 - nozzle positioning clamp, 8 - vertical bearing block, 9 - ultrasonic transducer support rod, 10 - electro-controlled telescopic assembly, 11 - electronic control module, 12 - Fuma wheel, 14 - telescopic servo bracket, 15 - servo, 16 - servo arm, 17 - connecting rod, 18 - connecting block, 19 - straight rod, 20 - fixing block, 21 - buffer spring. Detailed implementation manners

[0018] To make the objectives, 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. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Embodiment 1 Embodiment 1 of the present invention provides a method for detecting defects in an engine nozzle based on an adaptive step angle, and ultrasonic C-scan defect detection of a solid rocket motor nozzle based on an adaptive step angle iterative model predictive control algorithm (ASA-IMPC). As Figure 1As shown in the figure, the detection device adopted includes an ultrasonic transducer array, an axial rotation motor 4, and a plurality of electro-controlled telescopic components 10. Each ultrasonic transducer in the ultrasonic transducer array is respectively arranged on the rotating shaft of the axial rotation motor 4 through an electro-controlled telescopic component 10. The electro-controlled telescopic component 10 is used to drive the ultrasonic transducer array to be closely attached to the inner wall of the tail nozzle. The axial rotation motor 4 is used to drive the ultrasonic transducer array to rotate along the central axis of the tail nozzle. The measurement principle of the embodiment of the present invention is as follows: Since there are differences in the acoustic characteristics between the defective part and the normal material, when the pulsed wave emitted by the ultrasonic transducer encounters a defect in the tail nozzle, reflection will occur. Therefore, in the echo signal of each frame, there is an abnormal echo signal in addition to the end face echo. By identifying the position of the abnormal echo, the defect depth of the measured item can be obtained. Among them, the axial rotation motor 4 and the electro-controlled telescopic component 10 control the ultrasonic transducer array to perform circular motion and closely adhere to the inner wall of the tail nozzle, so as to realize the defect detection of the entire tail nozzle.

[0020] Specifically, as Figure 2 shown, the detection method of this embodiment specifically includes the following steps: Step 1: Start the detection device; set the relevant parameters of the detection device, and configure the detection device into a low-resolution preliminary scanning mode. In the low-resolution preliminary scanning mode, the initial stepping angle is the initial low-resolution stepping angle.

[0021] In the above step 1, the initialized relevant parameters include the initial low-resolution stepping angle, the initial high-resolution stepping angle, and the number of emitted pulses.

[0022] Step 2: Control the ultrasonic transducer array to be closely attached to the inner wall of the tail nozzle, and collect the measurement signal to obtain the echo amplitude ; k represents the kth position, and i represents the ith frame echo at the current position.

[0023] Step 3: Calculate the cost function J and the echo amplitude deviation according to the preset expected echo signal : ; (1) ; (2) Among them, represents the expected echo signal, represents the control input, that is, the change amount of the previous stepping angle, represents the weight coefficient, which is used to balance the signal tracking error and the change of the control input; N represents the number of emitted pulses.

[0024] Step 4: Update the control gain based on the gradient descent method, and calculate the stepping angle of the ultrasonic transducer array , and the calculation formula is: ; (3) ; (4) where is the learning rate, is the gradient of the cost function, represents the control gain at the updated k-th position, represents the control gain at the (k - 1)-th position; represents the stepping angle at the (k - 1)-th position. When k = 1, represents the preset initial stepping angle.

[0025] Step 5: Control the separation of the ultrasonic transducer array from the inner wall of the nozzle, and control the rotation of the ultrasonic transducer array according to the calculated stepping angle Step 6: Return to Step 2 and repeat Steps 2 - 5 until the defect detection of the entire nozzle is completed; meanwhile, judge whether there is a defect at the current position according to the echo amplitude deviation

[0026] at each position, and record the defect position where abnormal echoes appear.

[0027] In addition, Steps 3 - 6 above are the adaptive stepping angle iterative model predictive control algorithm (ASA - IMPC) adopted in the embodiments of the present invention. By presetting the desired echo information, calculating the weight coefficients of the balance signal tracking error and the control input change, and initializing the gradient descent model to update the stepping angle, it can realize real - time change of the scanning accuracy according to the defect situation of the nozzle, improve the detection efficiency and without loss of detection accuracy. Specifically, the common methods in the art can be used to judge whether there is a defect. For example, set a threshold. If the echo amplitude deviation is greater than this threshold, it indicates an abnormal echo, and the position k at this time is the defect position.

[0028] Step 7: Configure the detection device to the high - resolution precision scanning mode, control the ultrasonic transducer array to rotate to the first defect position during the low - resolution preliminary scanning, and repeat Steps 2 - 5 multiple times 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 during the low - resolution preliminary scanning and repeat the high - resolution precision scanning until the high - resolution precision scanning of all defect positions is completed; Specifically, in the high - resolution precision scanning mode, the initial stepping angle is the initial high - resolution stepping angle. In the high - resolution precision scanning mode, the preset initial high - resolution stepping angle is less than the initial low - resolution stepping angle.

[0029] In this embodiment, the defect position is preliminarily located by a low-resolution scanning mode, and the defect position is further finely scanned by a high-resolution scanning mode, so that the detection accuracy of the defect position can be improved. Moreover, ASA-IMPC dynamically adjusts the stepping 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 actually measured echo signal, which can greatly improve the detection efficiency and reduce the detection time.

[0030] 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.

[0031] The specific steps of step 8 are: 1. Determine the time T0 of the emission waveform and the time T1 of receiving the reflected wave 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, and complete data preprocessing to reduce the amount of computational data; 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 base with the largest energy concentration factor; the energy concentration factor C calculation formula is: ; (5) in, represents the square of the maximum amplitude of the ith wavelet basis, and E represents the total energy of the wavelet basis. Specifically, we have: ; (6) 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.

[0032] 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: ; (7) in, Represents the material sound velocity.

[0033] like Figure 3 As shown, in this embodiment, all signals are analyzed and processed by a defect location algorithm until all abnormal echo signals are analyzed, and then defect information at all positions of the tail nozzle can be obtained.

[0034] Further, a method for detecting defects in an engine tail nozzle based on an adaptive step angle in this embodiment further includes the following steps: Step 9: Unfold the three-dimensional image of the tail nozzle along the central axis into a sector, divide the sector image into grids according to the real-time step angle in the low-resolution mode, and divide the grids at the defect locations according to the real-time step angle in the high-resolution mode; Step 10: According to the defect detection results, correspondingly change the RGB color values of the grids where the defects are located, and characterize the depth difference of the defects through changes in brightness and saturation to achieve a visual display of the detection results.

[0035] Specifically, in this embodiment, green is used to indicate that there are no defects in the current grid area, and red is used to identify that there are defects in the grid. The depth difference of the defects is characterized by changes in the brightness and saturation of the red color.

[0036] Embodiment 2 Embodiment 2 of the present invention provides an engine tail nozzle defect detection system, as Figure 4 shown, including: an ultrasonic C-scan industrial control computer and a tail nozzle defect automatic detection device. The ultrasonic C-scan industrial control computer is used to control the ultrasonic transducer array, the axial rotation motor 4, and the electro-hydraulic telescopic assembly 10 to implement the method for detecting defects in an engine tail nozzle based on an adaptive step angle described in Embodiment 1.

[0037] Among them, the ultrasonic C-scan industrial control 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. The function board is used to send ultrasonic drive commands to the ultrasonic transducers under the control of the main board, and receive the echo signals of the ultrasonic transducers and send them to the main board; the main board is used to send control signals to the axial rotation motor 4 and the electro-hydraulic 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 electro-hydraulic telescopic assembly 10.

[0038] Specifically, as Figure 1As shown in the figure, in this embodiment, the automatic tailpipe defect detection device includes a detection frame 1. An axial rotation motor 4, a vertical bearing block 8, and a tailpipe positioning clamp 7 are arranged on the detection frame 1. The rotation shaft of the axial rotation motor 4 is arranged on the vertical bearing block 8, and an ultrasonic transducer support rod 9 is fixedly connected to its end. A plurality of electric control telescopic components 10 are arranged on the ultrasonic transducer support rod 9 along the extending direction of the rod. Ultrasonic transducers are arranged at the ends of the electric control telescopic components 10. The electric control telescopic components 10 are used to drive the ultrasonic transducers to expand and contract and closely fit with the inner wall of the tailpipe. The ultrasonic transducers at the ends of the respective electric control telescopic components 10 form an ultrasonic transducer array. The axial rotation motor 4 is used to drive the ultrasonic transducer array to rotate along the rotation shaft of the axial rotation motor 4 to realize a 360° rotational scan of the inner wall of the tailpipe. The tailpipe positioning clamp 7 is used to cooperate with the tailpipe to realize the positioning of the automatic tailpipe defect detection device. Further, as Figure 5 shown, the electric control telescopic component 10 includes a telescopic servo bracket 14, a servo motor 15, a connecting rod 17, a straight rod 19, a fixing block 20, and a buffer spring 21. The telescopic servo bracket 14 is fixedly connected to the ultrasonic transducer support rod 9. The servo motor 15 and the fixing 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 fixing block 20 and is connected to the buffer spring 21. The ultrasonic transducer is fixed to the end of the buffer spring 21. The fixing block 20 is used to limit the straight rod 19 so that it expands and contracts in a direction perpendicular to the rotation shaft of the axial rotation motor 4. In addition, a connecting block 18 is arranged at one end of the straight rod 19 close to 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.

[0039] Further, as Figure 1 shown, a sliding rod 2 in the vertical direction is further arranged on the detection frame 1. A slider 3 that can slide in the vertical direction along the sliding rod 2 is arranged on the sliding rod 2. An axial rotation motor bracket 5 is arranged on the slider 3. The axial rotation motor 4 is fixed on the slider 3 through the axial rotation motor bracket 5. The vertical bearing block 8 and the tailpipe positioning clamp 7 are fixed on the slider 3. By arranging the slider 3 and the sliding rod 2, the height of the rotation shaft of the axial rotation motor 4 can be adjusted to enable the automatic tailpipe defect detection device to adapt to the real-time height of the tailpipe. A locking mechanism can also be arranged on the slider 3. When sliding to a suitable height in the vertical direction along the sliding rod 2, it can be locked through the locking mechanism so that it is fixed on the sliding rod 2. The locking mechanism can be a bolt arranged on the slider 3. When the slider 3 slides to a suitable position on the sliding rod 2, by screwing the bolt to press against the sliding rod 2, the sliding can be locked. In addition, the locking mechanism can also be other structures.

[0040] Further, as Figure 1As shown, a plurality of casters 12 are provided at the bottom of the detection frame 1 to enable the movement of the detection frame 1. An electronic control module 11 is also provided on the detection frame 1. The electronic 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 control computer.

[0041] Further, as Figure 4 shown, the function board includes a main FPGA, an ultrasonic driving and transmitting unit, a transceiver isolation circuit, and an impedance matching circuit. The main FPGA is connected to the ultrasonic transducer through the ultrasonic driving and transmitting unit, the transceiver isolation circuit, and the impedance matching circuit. Specifically, a slave FPGA is provided in the electronic control module 11. The main FPGA is connected to the main board through PCIE, and the main FPGA is connected to the slave FPGA in the electronic control module through SPI communication. The main chip of the main FPGA is XC7K325T, and the main chip of the slave FPGA is XC7A35T.

[0042] Further, in this embodiment, the ultrasonic C-scan industrial control computer further includes a power supply, an industrial control computer chassis housing, and peripherals. In the function board, the main chip of the ultrasonic driving and transmitting unit is HV7321; in addition, the function board further includes a multi-stage configuration adjustable filtering unit with the main chip of AD9271, an adaptive gain adjustment module with the main chip of AD7801, and devices such as an SMA interface; the CPU in the main board is provided with a tail pipe ultrasonic C-scan defect detection software for controlling the detection process and data processing. In addition, the tail pipe ultrasonic C-scan defect detection software is also used for data acquisition and result display, etc. The main FPGA of the function board communicates with the tail pipe ultrasonic C-scan defect detection software, i.e., the upper computer software, through the PCIE protocol. In the data processing stage, the ultrasonic C-scan defect detection software combines the adaptive step angle iterative model predictive control algorithm (ASA-IMPC) to optimize the step angle in real time and send it to the electronic control module 11. At the same time, it also dynamically adjusts the scanning path according to the ultrasonic echo signal fed back by the function board to improve the accuracy of defect positioning.

[0043] The working process of an engine tail pipe defect detection system in this embodiment is as follows: (1) Docking the tail pipe defect automatic detection device with the engine tail pipe: Orient the large end of the tail pipe towards the ultrasonic transducer array, move the tail pipe positioning card 7 of the tail pipe defect automatic detection device to the end face position of the large end of the tail pipe, and align the tail pipe positioning card 7 with the tail pipe exactly by adjusting the detection frame 1 or the slider 3.

[0044] (2) Before testing, execute a self-check program to ensure the normal operation of electronic components such as the axial rotation motor 4 and the servo 15, and verify the connection stability of structural components such as the vertical bearing seat 8, the ultrasonic transducer support rod 9, and the buffer spring 21.

[0045] (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 control computer.

[0046] (4) Configure the relevant parameters of the tail pipe 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 servo, etc. As Figure 6 shown, in this embodiment, the parameter configuration work flow of the ultrasonic C-scan defect detection software for the tail pipe is as follows.

[0047] As Figure 7 shown, the overall work flow of an engine tail pipe defect detection system in this embodiment is as follows. After the parameters of the ultrasonic C-scan industrial control computer are configured, they are sent to the slave FPGA in the electronic control module 11 through the main FPGA in the function board. After the slave FPGA configures the parameters, it controls the electronic control telescopic component 10 to extend so that the ultrasonic transducer array is in close contact with the inner wall of the tail pipe. Then, it sends a ready-to-measure signal to the ultrasonic C-scan defect detection software through the main FPGA. The ultrasonic C-scan defect detection software controls the main 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 main FPGA. At the same time, after controlling the electronic control telescopic component 10 to retract, it controls the axial rotation motor 4 to rotate the step angle. After the rotation is completed, it enters the next measurement cycle.

[0048] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting defects in an engine tail nozzle based on an adaptive stepping angle, characterized in that The detection device used comprises an ultrasonic transducer array, an axially rotating motor (4) and a plurality of electrically controlled telescopic components (10), wherein each ultrasonic transducer in the ultrasonic transducer array is arranged on a rotating shaft of the axially rotating motor (4) via an electrically controlled telescopic component (10), the electrically controlled telescopic component (10) is used to drive the ultrasonic transducer array to closely fit the inner wall of the tail nozzle, and the axially 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 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 closely fit the inner wall of the nozzle, and collect measurement signals to obtain echo amplitudes ; k represents the k-th position, and i represents the i-th frame echo at the current position; Step 3: Calculate the cost function J and the echo amplitude deviation according to the preset expected echo signal : ； ； Among them, 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 gain and calculate the step angle of the ultrasonic transducer array , and the calculation formula is as follows: ； ； Among them, represents the learning rate, represents the cost function gradient, represents the control gain at the k-th position obtained by update, represents the control gain at the (k - 1)-th position; represents the step angle at the (k - 1)-th position; Step 5: Control the separation of the ultrasonic transducer array from the inner wall of the nozzle, and then control the ultrasonic transducer array to rotate by a 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 where abnormal echoes appear 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 method for defect detection of an engine nozzle based on an adaptive step angle according to claim 1, wherein In step 1, the relevant parameters set include an initial low-resolution step angle, an initial high-resolution step angle and the number of transmitted pulses.

3. A method for detecting defects in an engine nozzle based on an adaptive step angle according to claim 1, characterized in that The specific steps of step 8 are: Determine the time T0 of the emission waveform, the time T1 of receiving the reflected wave from the outer wall of the tail nozzle, and remove 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 result, and calculate the defect thickness according to the abnormal echo time , and the calculation formula is: ； Among them, represents the sound velocity of the material.

4. A method for detecting defects in an engine nozzle based on an adaptive step angle according to claim 1, characterized in that The following steps are also included: Step 9: Expand the three-dimensional image of the tail nozzle into a sector along the central axis, divide the sector image into grids according to the low-resolution step angle, and divide the defect into grids according to the high-resolution step angle; Step 10: According to the defect detection results, the RGB color value of the grid where the defect is located is changed accordingly, and the difference in defect depth is represented by changes in brightness and saturation to achieve a visual display of the detection results.

5. An engine tail nozzle defect detection system based on an adaptive stepping angle, characterized in that include: Ultrasonic C-scan industrial computer and tail nozzle defect automatic detection device; The automatic detection device for the tail nozzle defects includes a detection frame (1). An axial rotation motor (4), a vertical bearing seat (8) and a tail nozzle positioning clamp (7) are arranged on the detection frame (1). The rotation shaft of the axial rotation motor (4) is arranged on the vertical bearing seat (8), and the end of the rotation shaft is fixedly connected with an ultrasonic transducer support rod (9). A plurality of electric control telescopic components (10) are arranged on the ultrasonic transducer support rod (9) along the extending direction of the rod. Ultrasonic transducers are arranged at the ends of the electric control telescopic components (10) for driving the ultrasonic transducers to telescopically fit tightly with the inner wall of the tail nozzle. The ultrasonic transducers at the ends of the electric control telescopic components (10) form an ultrasonic transducer array. The axial rotation motor (4) is used for driving the ultrasonic transducer array to rotate along the rotation shaft of the axial rotation motor (4) to realize 360° rotational scanning of the inner wall of the tail nozzle. The tail nozzle positioning clamp (7) is used for cooperating with the tail nozzle to realize the positioning of the automatic detection device for the tail nozzle defects. The ultrasonic C-scan industrial control computer is used for controlling the ultrasonic transducer array, the axial rotation motor (4) and the electric control telescopic component (10) to realize a method for detecting defects of an engine tail nozzle based on an adaptive stepping angle according to any one of claims 1 to 4.

6. The defect detection system for an engine nozzle based on an adaptive step angle according to claim 5, wherein The electric control telescopic component (10) includes a telescopic servo support (14), a servo motor (15), a connecting rod (17), a straight rod (19), a fixing block (20) and a buffer spring (21). The telescopic servo support (14) is fixedly connected with the ultrasonic transducer support rod (9). The servo motor (15) and the fixing 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 fixing block (20) and is connected with the buffer spring (21). The ultrasonic transducer is fixed at the end of the buffer spring (21). The fixing block (20) is used for limiting the straight rod (19) to telescopically move along the direction perpendicular to the rotation shaft of the axial rotation motor (4).

7. An engine tail nozzle defect detection system based on an adaptive stepping angle according to claim 5, characterized in that, A slide rod (2) in the vertical direction is further arranged on the detection frame (1). A slider (3) that can slide in the vertical direction along the slide rod (2) is arranged on the slide rod (2). An axial rotation motor support (5) is arranged on the slider (3). The axial rotation motor (4) is fixed on the slider (3) through the axial rotation motor support (5). The vertical bearing seat (8) and the tail nozzle positioning clamp (7) are fixed on the slider (3).

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

9. An engine tail nozzle defect detection system based on an 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. A nozzle ultrasonic C-scan defect detection software for controlling the detection process and data processing is set in the CPU within the 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 electric control module (11) through an SPI interface. The function board is used to send ultrasonic drive commands to the ultrasonic transducers under the control of the main board, and is used to receive the echo signals of the ultrasonic transducers and send them to the main board. The function board is also used to receive the control signals sent by the main board and transfer them to the electric control module (11). The control signals are used to control the rotation angle of the axial rotation motor (4) and the telescopic length of the electric control telescopic component (10).

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

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