High-temperature-resistant transparent shell type eddy current blade tip gap measuring device and method

Abstract

The invention belongs to the technical field of gap measurement, and particularly relates to a high-temperature-resistant transparent shell type eddy current tip gap measuring device and method, and the device comprises a sensor probe module, a signal conditioning module, a data collection module and a data processing module. The sensor probe module is mounted on the outer wall of the casing; the sensor probe module comprises a permanent magnet excitation source, a soft magnet magnetic core and a receiving coil; the signal conditioning module is electrically connected with the receiving coil and is used for amplifying, filtering and integrating the weak induction signal; the data acquisition module is electrically connected with the signal conditioning module and converts an analog signal into a digital signal; the data processing module is used for processing the acquired digital signals and extracting blade tip clearance information.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gap measurement, and particularly relates to a high-temperature-resistant shell-penetrating eddy current tip clearance measurement device and method. BACKGROUND

[0002] Tip clearance refers to the radial clearance between the top end of a rotating blade of a turbine of an aero-engine and the inner wall of a casing, and is a key parameter affecting the performance, efficiency and reliability of the engine. If the tip clearance is too large, air leakage occurs, reducing the efficiency and thrust of the engine; and if the tip clearance is too small, the blade and the casing may collide and rub, causing damage to the blade and even catastrophic failure. Research shows that if the tip clearance increases by 0.25 mm, the efficiency of the engine decreases by about 1%, and the fuel consumption increases by about 1.5%. Therefore, accurate measurement of the tip clearance is of great significance to the performance optimization, state monitoring and fault diagnosis of the engine.

[0003] In the prior art, tip clearance measurement methods mainly include: a capacitive measurement method, which measures the clearance by using the principle that the capacitance formed between the blade and the sensor changes with the clearance, needs to open a hole in the casing to install the sensor, destroys the structural integrity of the casing, and is greatly affected by temperature and oil pollution; a fiber-optic measurement method, which irradiates the blade with a light beam emitted by a fiber-optic probe, calculates the clearance according to the reflected light intensity or flight time, and the optical window is easily contaminated, and the reliability is poor in high-temperature, high-speed and vibration environments; a microwave / millimeter wave measurement method, which measures the clearance by using the principle of electromagnetic wave reflection, and the system is complex, the cost is high, and the spatial resolution is low; and a traditional eddy current measurement method, which directly measures the tip clearance by installing an eddy current sensor on the inner wall of the casing, and the service life of the eddy current sensor is short due to exposure to a harsh environment of high temperature and high pressure, and maintenance is difficult.

[0004] The common shortcomings of the above-mentioned prior art are that: all of them need to open a hole or a slot in the casing to install the sensor, destroying the structural integrity and aerodynamic sealing of the casing; increasing the installation difficulty and maintenance cost; and the sensor needs to face extreme working environments such as high temperature (600-1000℃), high pressure, high-speed airflow and strong vibration when installed inside the casing, making it difficult to guarantee the reliability and service life of the sensor. Therefore, there is an urgent need for a high-temperature-resistant shell-penetrating eddy current tip clearance measurement device and method to solve the technical problems of the need for opening a hole in the casing, a harsh working environment of the sensor and poor reliability. SUMMARY

[0005] The purpose of the present application is to provide a shell-penetrating eddy current tip clearance measurement device and method to solve the problems of the need for opening a hole in the casing, a harsh working environment of the sensor and poor reliability in the prior art, and to realize non-contact, shell-penetrating, high-precision and high-reliability tip clearance measurement.

[0006] The application aims to provide a high-temperature-resistant through-shell eddy current tip clearance measuring device, comprising a sensor probe module, a signal conditioning module, a data acquisition module and a data processing module.

[0007] The sensor probe module is installed on the outer wall of the casing; the casing is made of non-magnetic material; the sensor probe module comprises a permanent magnet excitation source, a soft magnetic core and a receiving coil; the permanent magnet excitation source generates a constant static magnetic field, and the magnetic lines of force pass through the casing wall to reach the rotating blade area; the soft magnetic core is arranged in the magnetic field radiation direction of the permanent magnet excitation source and is arranged separately from the permanent magnet excitation source, and is used for guiding the magnetic field and serving as the magnetic core of the receiving coil; the receiving coil is used for sensing the secondary magnetic field and generating an induced voltage.

[0008] The signal conditioning module is electrically connected with the receiving coil, amplifies, filters and integrates the weak induced signal; the data acquisition module is electrically connected with the signal conditioning module, converts the analog signal into a digital signal; the data processing module processes the collected digital signal and extracts the tip clearance information.

[0009] The permanent magnet excitation source adopts a samarium-cobalt permanent magnet or a neodymium-iron-boron permanent magnet, has a cylindrical shape, and has an axial magnetization direction; the magnetic induction intensity of the permanent magnet excitation source is 200-500 mT;

[0010] The soft magnetic core adopts a permalloy or a ferrite material, has a relative magnetic permeability of μr≥10,000 and a temperature resistance temperature of ≥350℃;

[0011] The receiving coil is wound on the soft magnetic core by using an enameled copper wire; the enameled copper wire has a wire diameter of 0.1-0.3 mm, a number of turns of 500-3000 turns, an inductance of 50-200 mH, and a direct current resistance of 200-800Ω.

[0012] The sensor probe module further comprises a cooling system and a shielding device;

[0013] The cooling system adopts an air path cooling mode, and the soft magnetic core and the receiving coil are cooled by compressed air; the shielding device comprises a stainless steel shell for packaging the sensor probe module and an electromagnetic shielding layer for reducing external electromagnetic interference; a twisted pair wire or a coaxial cable is used for signal output.

[0014] The signal conditioning module comprises a preamplifier, a band-pass filter and an integration circuit; the signal conditioning module is electrically connected with the receiving coil, amplifies, filters and integrates the weak induced signal;

[0015] The preamplifier adopts a high-performance instrument amplifier chip, amplifies the mV-level weak signal output by the receiving coil to a range of 0.1-5V;

[0016] The band-pass filter adopts a second-order Butterworth active filter, the passband range is 100Hz-300kHz, and the filter gain is 20dB.

[0017] The integration circuit adopts an RC active integrator.

[0018] The data acquisition module comprises a high-speed analog-to-digital converter and a data buffering and communication interface, and is electrically connected with the signal conditioning module to convert an analog signal into a digital signal.

[0019] The high-speed analog-to-digital converter adopts a continuous sampling mode to continuously collect the waveform data of the integrated Gaussian signal.

[0020] The data buffering and communication interface adopts an FPGA or a high-performance MCU to perform data buffering and preprocessing, and transmits the digital signal to an upper computer through an Ethernet interface.

[0021] The data packaging of the data acquisition module adopts a UDP protocol.

[0022] The data processing module comprises:

[0023] The Gaussian peak detection unit performs threshold judgment on the collected digital signal, identifies the peak position of the Gaussian waveform, and each peak corresponds to a blade passing event.

[0024] The Gaussian fitting unit extracts the waveform data segment around each detected peak, performs Gaussian function fitting, and extracts the amplitude parameter after fitting as the input of gap calculation.

[0025] The rotation speed calculation unit calculates the rotation speed according to the time interval of adjacent two blade passing events and the number of blades.

[0026] The gap calculation unit calculates the blade tip clearance through a pre-calibrated mapping relationship according to the amplitude obtained by Gaussian fitting and the rotation speed calculated by the rotation speed calculation unit; the gap calculation adopts a bilinear interpolation method to establish a rotation speed-amplitude-clearance three-dimensional calibration table.

[0027] The data output and display unit outputs the clearance value, rotation speed and timestamp of each blade in real time in the form of numerical value, waveform and trend curve, and records and stores the data.

[0028] Another object of the application is to improve a high-temperature-resistant shell-type eddy current blade tip clearance measurement method of a high-temperature-resistant shell-type eddy current blade tip clearance measurement device according to the application, comprising the following steps:

[0029] A calibration system of a casing and rotating blades is built, the Gaussian signal amplitude output by the sensor under different rotation speeds and different clearances is collected, and a mapping relationship of rotation speed-amplitude-clearance is established based on the Gaussian signal amplitude.

[0030] The sensor probe module is installed on the outer wall of the casing, and the Gaussian signal amplified, filtered and integrated is continuously obtained through the signal conditioning module; the data acquisition module acquires the waveform data of the integrated Gaussian signal to obtain a real-time digital signal stream;

[0031] The data processing module performs peak detection, Gaussian fitting and rotational speed calculation on the real-time digital signal stream, and calculates the tip clearance by using the mapping relationship of rotational speed-amplitude-clearance and outputs the measurement result.

[0032] The casing and rotating blade calibration system comprises a high-speed rotating table, a precision displacement table and an analog casing; the rotating table has a rotational speed range of 0-30,000 rpm and a rotational speed accuracy of ±0.1%; the precision displacement table has a stroke of ≥10 mm and a positioning accuracy of ≤5 μm; the analog casing is made of the same material as the actual casing and has a thickness of 3-8 mm;

[0033] The steps for building the casing and rotating blade calibration system comprise:

[0034] Selecting to install blade analog pieces on the high-speed rotating table, the number of blades being 6-12, and the material being titanium alloy or stainless steel;

[0035] Setting a plurality of rotational speed points, the rotational speed range covering the actual working range of 0-30,000 rpm;

[0036] Setting a plurality of clearance points, the clearance range covering the measurement range of 0.5-5 mm;

[0037] The Gaussian signal amplitude output by the sensor under different rotational speeds and different clearances comprises:

[0038] For each rotational speed-clearance combination, the following operations are performed:

[0039] Setting the rotational speed of the rotating table as ni and waiting for a first preset time length;

[0040] Moving the precision displacement table to the clearance position dj and waiting for a second preset time length;

[0041] Repeating the measurement for a first preset number of times, collecting a first preset number of blade passing events each time, and recording the corresponding Gaussian signal amplitude;

[0042] The mapping relationship of rotational speed-amplitude-clearance based on the Gaussian signal amplitude comprises:

[0043] Establishing a rotational speed-amplitude-clearance three-dimensional mapping relationship table to store all the calibration data points;

[0044] Calibration verification: selecting 5-10 intermediate points not participating in calibration, actually measuring and comparing with the theoretical value, and requiring an error;

[0045] The average amplitude and the standard deviation are calculated.

[0046] The sensor probe module is installed on the outer wall of the casing, and the Gaussian signal processed by amplification, filtering and integration is continuously obtained through the signal conditioning module; the waveform data of the integrated Gaussian signal is collected by the data acquisition module to obtain a real-time digital signal stream, including:

[0047] The sensor probe module is installed on the outer wall of the casing, and the Gaussian signal processed by amplification, filtering and integration is continuously obtained through the signal conditioning module; the waveform data of the integrated Gaussian signal is collected by the data acquisition module to obtain a real-time digital signal stream, including:

[0048] The signal conditioning module is started, and the ADC sampling rate is set to be greater than or equal to 1 MSPS, and the sampling mode is continuous sampling;

[0049] The signal conditioning module continuously collects the induction signal output by the receiving coil, and the signal is processed by a preamplifier, a band-pass filter and an integration circuit to obtain a Gaussian signal; the gain of the preamplifier is 40-60 dB; the frequency of the band-pass filter is 100 Hz-300 kHz; and the time constant of the integration circuit is 5-10 μs;

[0050] The waveform data of the integrated Gaussian signal is collected by the data acquisition module to obtain a real-time digital signal stream, which is transmitted to the data processing module after being buffered by the FPGA / MCU.

[0051] The data processing module performs peak detection, Gaussian fitting and speed calculation on the real-time digital signal stream, and calculates the tip clearance and outputs the measurement results by using the mapping relationship of speed-amplitude-clearance.

[0052] The data processing module receives the real-time digital signal stream and performs real-time processing; first, digital filtering is performed to remove high-frequency noise;

[0053] Threshold judgment is performed on the collected digital signal to detect the position of the Gaussian peak; the threshold setting adopts the 3σ criterion, and when the signal amplitude exceeds the threshold and meets the local maximum value condition, it is determined as an effective Gaussian peak, and the peak index and timestamp are recorded;

[0054] The single Gaussian waveform data segment corresponding to each peak is extracted, and a second threshold number of sampling points are collected.

[0055] The single Gaussian waveform is fitted with a Gaussian function: a nonlinear least squares method is used for fitting, and the amplitude parameter, peak center and width are extracted after fitting;

[0056] The goodness of fit R is calculated 2 ;

[0057] The speed is calculated according to the time interval of the adjacent two peaks and the number of blades.

[0058] Substitute the amplitude and rotating speed into the calibration relation, and solve the tip clearance: adopt the bilinear interpolation method, find the adjacent four points according to the calibration table, and calculate the tip clearance according to the interpolation formula;

[0059] Output the measurement results, including: blade number, tip clearance, rotating speed, time stamp, goodness of fit R 2 ;

[0060] Statistically analyze the clearance values of multiple blades per circle, calculate the mean value and standard deviation, and eliminate abnormal values exceeding the range of ±3σ;

[0061] Real-time display of measurement results, including: numerical display: current rotating speed, blade clearance value; waveform display: original signal waveform, integrated Gaussian signal waveform, fitting curve; trend curve: clearance change trend with time or rotating speed; alarm according to pre-set alarm rules;

[0062] Record and store all measurement data for subsequent fault diagnosis, life prediction and performance evaluation.

[0063] The beneficial effects of the present application are:

[0064] (1) Non-contact measurement through shell, maintaining the structural integrity of the casing

[0065] The sensor is installed on the outer wall of the casing, without the need for holes or slots on the casing, maintaining the structural integrity and aerodynamic sealing of the casing, avoiding the strength weakening and airflow leakage problems caused by the holes.

[0066] (2) Friendly working environment for the sensor, high reliability

[0067] The sensor is located on the outer wall of the casing and is not directly exposed to the harsh environment of high temperature (600-1000℃), high pressure and high speed airflow, with a relatively low working temperature (<200℃, with a cooling system, it can adapt to higher temperatures), greatly improving the reliability and service life of the sensor.

[0068] (3) Adopting permanent magnet excitation source, without excitation circuit

[0069] Adopting permanent magnet 1 as a static magnetic field source, without alternating excitation circuit, simplifying the system structure, reducing the power consumption and improving the reliability. The permanent magnet magnetic field is stable and is not affected by temperature and time (temperature coefficient of samarium-cobalt permanent magnet <0.04% / ℃).

[0070] (4) Soft magnetic core focuses the magnetic field, improving the sensitivity

[0071] The high magnetic permeability soft magnetic core (μr≥10,000) is adopted to effectively focus the magnetic field, improve the magnetic flux density and signal induction intensity, compensate for signal attenuation caused by the transparent shell measurement, and improve the measurement sensitivity and signal-to-noise ratio.

[0072] (5) Air cooling system, suitable for high temperature environment

[0073] An air cooling system is designed, which cools the soft magnetic core and the receiving coil by compressed air, so that the sensor can still maintain a reasonable working temperature in the 200℃ environment outside the engine case, and can adapt to a high temperature environment of 650℃ under the condition of air cooling, thereby expanding the application range.

[0074] (6) Gaussian fitting algorithm, improve measurement accuracy

[0075] The Gaussian curve fitting algorithm is adopted to extract the signal amplitude, and compared with simple peak detection, the fitting algorithm has the advantages of strong anti-noise ability and high precision. The data quality is evaluated by the goodness of fit (R2), and the abnormal data is automatically removed, thereby improving the measurement reliability.

[0076] (7) Rotational speed decoupling calibration to realize accurate measurement

[0077] By establishing the three-dimensional mapping relationship of rotational speed-amplitude-gap, the coupling problem that the induction signal is affected by rotational speed and gap at the same time is solved. The rotational speed is measured in real time, and the signal amplitude is combined to accurately calculate the tip clearance, thereby avoiding the influence of rotational speed change on the measurement result.

[0078] (8) High bandwidth, high precision, wide measurement range

[0079] The system bandwidth is greater than 300kHz, which can adapt to the measurement requirements of high rotational speed (0-30,000rpm) and multiple blades (60-100 blades); the measurement range is 0.5-5mm, the precision is ±0.05mm or ±3%FS, and the actual requirements of the aero-engine tip clearance measurement are met.

[0080] (9) Real-time online monitoring, supporting full life cycle management

[0081] The system can realize real-time online continuous monitoring, obtain the gap data of each blade, support performance monitoring, fault diagnosis and life prediction of the engine in the whole life cycle, and provide key data support for engine health management. BRIEF DESCRIPTION OF DRAWINGS

[0082] Figure 1 It is a structure schematic view of a high-temperature-resistant transparent shell type eddy current tip clearance measurement device of the present application;

[0083] Figure 2 It is a principle schematic view of a high-temperature-resistant transparent shell type eddy current tip clearance measurement device of the embodiment of the present application;

[0084] Figure 3 The sensor probe module structure sectional view of the embodiment of the present application;

[0085] Figure 4 The casing and rotating blade calibration system structure schematic diagram of the embodiment of the present application;

[0086] Figure 5 The high-temperature-resistant transparent shell type eddy current tip clearance measurement method flowchart of the embodiment of the present application, wherein (a) is the original signal of the receiving coil - Gauss differential signal, (b) is the integrated signal - Gauss signal, and (c) is the multi-blade continuous measurement signal;

[0087] Figure 6 The high-temperature-resistant transparent shell type eddy current tip clearance measurement method flowchart of the embodiment of the present application;

[0088] Figure 7 The data processing module signal processing flowchart of the embodiment of the present application;

[0089] In the figure, 1 is a permanent magnet, 2 is a soft magnetic core, 3 is a receiving coil, 4 is a spiral cooling air duct, 5 is a shielding shell, 6 is a signal output, 7 is a casing wall, and 8 is a rotating blade. DETAILED DESCRIPTION

[0090] The present application provides a high-temperature-resistant transparent shell type eddy current tip clearance measurement device and method, which is further described in detail below in combination with the accompanying drawings.

[0091] The casing material of an aero-engine is generally non-magnetic material such as tungsten-nickel alloy, nickel-iron-based alloy, which provides the possibility for electromagnetic field to penetrate the casing. If the transparent shell type measurement can be realized, that is, the sensor is installed on the outer wall of the casing, and the gap measurement is performed through the casing wall 7, then the opening of the casing can be avoided, the structural integrity of the casing is maintained, the sensor works in a relatively mild environment, and the reliability and service life are greatly improved. The present application discloses a high-temperature-resistant transparent shell type eddy current tip clearance measurement device and method, which is particularly suitable for non-contact real-time measurement of the gap between the rotating blade 8 of the turbine of the aero-engine and the casing wall 7, and is especially suitable for high-temperature working environment (-55℃ to +650℃). In the specific implementation process, the following technical difficulties are faced:

[0092] 1) Sensor structure design: how to optimize the configuration of the permanent magnet and the receiving coil to realize high-sensitivity signal reception while ensuring the magnetic field strength;

[0093] 2) High-temperature adaptability: how to make the sensor work stably under the condition that the outer wall of the casing also faces high temperature above 200℃;

[0094] 3) Signal processing method: the shell measurement leads to weak signal, how to extract effective information through signal conditioning and digital processing technology;

[0095] 4) Rotational speed coupling problem: the induction signal amplitude is affected by the gap and the rotational speed, how to decouple the two parameters to realize accurate measurement;

[0096] 5) Calibration method: how to establish the accurate mapping relationship among the rotational speed, signal amplitude and gap.

[0097] In view of the above technical problems, the application provides a high-temperature-resistant shell-penetrating eddy current blade tip gap measuring device and method. Figure 1 As shown in the embodiment of the application, a high-temperature-resistant shell-penetrating eddy current blade tip gap measuring device is disclosed, comprising a sensor probe module, a signal conditioning module, a data acquisition module and a data processing module. Figure 1 In the embodiment, the first shell-penetrating sensor, the second shell-penetrating sensor and the nth shell-penetrating sensor show the installation positions of the n shell-penetrating sensors.

[0098] The sensor probe module is installed on the outer wall of the casing; the casing is made of non-magnetic material; the sensor probe module comprises a permanent magnet excitation source, a soft magnetic core and a receiving coil; the permanent magnet excitation source generates a constant static magnetic field, and the magnetic force line passes through the casing wall 7 to reach the rotating blade area; the soft magnetic core is arranged in the magnetic field radiation direction of the permanent magnet excitation source and is arranged separately from the permanent magnet excitation source, and is used for guiding the magnetic field and serving as the magnetic core of the receiving coil; the receiving coil is used for inducting the secondary magnetic field and generating an induced voltage;

[0099] The signal conditioning module is electrically connected with the receiving coil, and is used for amplifying, filtering and integrating the weak induction signal; the data acquisition module is electrically connected with the signal conditioning module, and is used for converting the analog signal into a digital signal; the data processing module is used for processing the collected digital signal and extracting the blade tip gap information.

[0100] The permanent magnet excitation source is a samarium-cobalt permanent magnet or a neodymium-iron-boron permanent magnet, has a cylindrical shape, and has an axial magnetization direction; the magnetic induction intensity of the permanent magnet excitation source is 200-500 mT;

[0101] The soft magnetic core is made of permalloy or ferrite material, has a relative magnetic permeability of μr≥10,000, and has a temperature resistance temperature of ≥350℃;

[0102] The receiving coil is made of enameled copper wire and is wound on the soft magnetic core; the enameled copper wire has a wire diameter of 0.1-0.3 mm, a number of turns of 500-3000 turns, an inductance of 50-200 mH, and a direct current resistance of 200-800Ω.

[0103] The principle of the high-temperature-resistant shell-penetrating eddy current blade tip gap measuring device of the embodiment is as shown inFigure 2 shown, Figure 2 The spatial position relationship of the sensor probe, the casing, the rotating blade 8, and the path of the magnetic field penetrating the casing are shown in Figure 2 The connection relationship of the permanent magnet 1, the soft magnetic core 2, and the receiving coil 3 is shown; the signal of the sensor probe is transmitted outward through the signal output 6; the static magnetic field penetrates the casing wall 7 to reach the rotating blade 8.

[0104] In a specific embodiment, the sensor probe module is installed on the outer wall of the casing, and a separate structure of a permanent magnet excitation source and a soft magnetic receiving coil is adopted, which specifically includes:

[0105] Permanent magnet excitation source: a samarium-cobalt (SmCo) or neodymium-iron-boron (NdFeB) permanent magnet is adopted, with a magnetic induction intensity of 200-500 mT (preferably 300 mT), and a cylindrical shape with an axial magnetization direction. The permanent magnet 1 generates a constant static magnetic field, and the magnetic lines penetrate the casing wall 7 to reach the rotating blade area.

[0106] In a preferred embodiment, the magnetic induction intensity of the permanent magnet excitation source is 300 mT.

[0107] Soft magnetic core: a permalloy or ferrite material is adopted, and the permalloy is a nickel-iron alloy; the relative permeability μr of the soft magnetic core is ≥10,000, and the temperature resistance temperature is ≥350℃. The soft magnetic core is arranged in the magnetic field radiation direction of the permanent magnet excitation source and is arranged separately from the permanent magnet excitation source (air gap 3-5 mm), which is used for focusing and guiding the magnetic field and simultaneously serving as the magnetic core of the receiving coil.

[0108] Receiving coil: enameled copper wire (wire diameter 0.1-0.3 mm) is wound on the soft magnetic core, with a number of turns of 500-3000 turns, an inductance of 50-200 mH, and a direct current resistance of 200-800 Ω. When the rotating blade 8 cuts the magnetic lines, eddy currents are formed on the surface of the blade, and the eddy currents generate a secondary magnetic field, which is inducted by the receiving coil through the casing to generate an induced voltage.

[0109] In a preferred embodiment, the number of turns of the enameled copper wire is 1000-2000 turns.

[0110] In an optional embodiment, the sensor probe module further includes a cooling system and a shielding device.

[0111] The cooling system adopts an air cooling method, and the soft magnetic core and the receiving coil are cooled by compressed air; the shielding device includes a stainless steel shell for packaging the sensor probe module and an electromagnetic shielding layer for reducing external electromagnetic interference; a twisted pair or coaxial cable is used for signal output.

[0112] In the alternative embodiment, the cooling system adopts air cooling mode, and the soft magnetic core and the receiving coil are cooled by compressed air, so that the soft magnetic core and the receiving coil can still maintain a reasonable working temperature (< 150 DEG C) under the environment of 200 DEG C of the outer wall of the machine case, and can adapt to a high temperature environment of 650 DEG C under the air cooling condition.

[0113] The shielding device realizes shielding and packaging: the sensor probe is packaged with a stainless steel shell and is provided with an electromagnetic shielding layer to reduce external electromagnetic interference. The signal output adopts a shielded twisted pair or a coaxial cable to ensure signal transmission quality.

[0114] The sensor probe module structure profile of the embodiment of the application is shown in Figure 3 , and Figure 3 detailed structures of a permanent magnet 1, an air gap, a soft magnetic core 2, a receiving coil 3, a spiral cooling air duct 4 and a shielding shell 5 are shown.

[0115] The signal conditioning module comprises a preamplifier, a band-pass filter and an integration circuit; the signal conditioning module is electrically connected with the receiving coil 3 to amplify, filter and integrate the weak induction signal;

[0116] The preamplifier adopts a high-performance instrument amplifier chip to amplify the mV-level weak signal output by the receiving coil 3 to the range of 0.1-5V;

[0117] The band-pass filter adopts a second-order Butterworth active filter, the passband range is 100Hz-300kHz, and the filter gain is 20dB;

[0118] The integration circuit adopts an RC active integrator.

[0119] In a specific embodiment, the signal conditioning module is electrically connected with the receiving coil 3 to amplify, filter and integrate the weak induction signal, and specifically comprises:

[0120] 1) Preamplifier: a high-performance instrument amplifier chip is adopted, and the preamplifier amplifies the millivolt-level weak signal output by the receiving coil 3 to the range of 0.1-5V.

[0121] 2) Band-pass filter: a second-order Butterworth active filter is adopted, the passband range is 100Hz-300kHz. The lower limit cutoff frequency 100Hz is used to remove DC drift and low-frequency noise, and the upper limit cutoff frequency 300kHz is used for anti-aliasing filtering, which meets the Nyquist criterion of subsequent ADC sampling. The filter gain is 20dB, and the signal is further amplified.

[0122] 3) Integration circuit: RC active integrator is adopted, time constant τ = R × C, wherein R is resistance and C is capacitance. The integration circuit restores the Gauss differential signal (i.e. derivative of Gauss function) output by the receiving coil 3 to Gauss signal. The physical meaning of the Gauss differential signal is magnetic flux change rate dΦ / dt, and the integrated magnetic flux change ΔΦ corresponds to the waveform of Gauss shape.

[0123] The data acquisition module comprises a high-speed analog-to-digital converter and a data buffering and communication interface, and is electrically connected with the signal conditioning module to convert an analog signal into a digital signal.

[0124] The high-speed analog-to-digital converter adopts a continuous sampling mode to continuously collect Gauss signal waveform data after integration.

[0125] The data buffering and communication interface adopts an FPGA or a high-performance MCU to perform data buffering and preprocessing, and transmits the digital signal to an upper computer through an Ethernet interface.

[0126] The data acquisition module adopts a UDP protocol for data packaging.

[0127] In a specific embodiment, the data acquisition module is electrically connected with the signal conditioning module to convert an analog signal into a digital signal. The data acquisition module specifically comprises a high-speed analog-to-digital converter (ADC) which adopts a continuous sampling mode to continuously collect Gauss signal waveform data after integration. The data buffering and communication interface adopts an FPGA or a high-performance MCU to perform data buffering and preprocessing, and transmits the digital signal to an upper computer through an Ethernet interface (1 Gbps). The Ethernet interface has higher stability and anti-interference capability than a USB, and is suitable for industrial field applications. The data acquisition module adopts a UDP protocol for data packaging to realize low-delay real-time transmission.

[0128] The data processing module comprises:

[0129] A Gauss peak detection unit: performing threshold judgment on the collected digital signal to identify the peak position of the Gauss waveform, and each peak corresponds to a blade passing event;

[0130] A Gauss fitting unit: extracting a waveform data segment around each detected peak to perform Gauss function fitting, and extracting an amplitude parameter after fitting as an input for gap calculation;

[0131] A rotation speed calculation unit: calculating the rotation speed according to the time interval of adjacent two blade passing events and the number of blades.

[0132] The gap solving unit calculates the tip clearance (delta) by a mapping relationship pre-calibrated according to the amplitude (A) obtained by Gaussian fitting and (n) calculated by the rotating speed; the gap solving adopts a bilinear interpolation method, and a rotating speed-amplitude-clearance three-dimensional calibration table is established;

[0133] The data output and display unit outputs the clearance value, rotating speed and time stamp of each blade in real time in the form of numerical value, waveform and trend curve, and records and stores the data.

[0134] In a specific embodiment, the data processing module is realized by the upper computer software, processes the collected digital signals, and extracts the tip clearance information.

[0135] The data processing module specifically comprises:

[0136] The Gaussian peak detection unit performs threshold judgment on the collected digital signals, and identifies the peak position of the Gaussian waveform. Each peak corresponds to a blade passing event.

[0137] The Gaussian fitting unit extracts the waveform data segment (for example, 100 sampling points before and after the peak) around each detected peak, performs Gaussian function fitting, and extracts the amplitude parameter after fitting as the input of the gap solving.

[0138] The rotating speed calculation unit calculates the rotating speed according to the time interval of adjacent two blade passing events and the number of blades.

[0139] The gap solving unit calculates the tip clearance (delta) by a mapping relationship pre-calibrated according to the amplitude (A) obtained by Gaussian fitting and (n) calculated by the rotating speed; the gap solving adopts a bilinear interpolation method, and a rotating speed-amplitude-clearance three-dimensional calibration table is established.

[0140] The data output and display unit outputs the clearance value, rotating speed and time stamp of each blade in real time in the form of numerical value, waveform and trend curve, and records and stores the data.

[0141] Another embodiment of the present application discloses a high-temperature-resistant transparent shell type eddy current tip clearance measurement method of the high-temperature-resistant transparent shell type eddy current tip clearance measurement device.

[0142] A calibration system of a casing and rotating blades is built, the Gaussian signal amplitudes output by the sensor under different rotating speeds and different clearance conditions are collected, and a rotating speed-amplitude-clearance mapping relationship is established based on the Gaussian signal amplitudes;

[0143] The sensor probe module is installed on the outer wall of the casing. The signal conditioning module continuously acquires the Gaussian signal after amplification, filtering and integration. The data acquisition module acquires the integrated Gaussian signal waveform data to obtain a real-time digital signal stream.

[0144] The data processing module performs peak detection, Gaussian fitting, and rotational speed calculation on the real-time digital signal stream, and uses the rotational speed-amplitude-gap mapping relationship to solve the tip clearance and output the measurement results.

[0145] The specific process of the high-temperature resistant through-shell eddy current blade tip clearance measurement method of this invention is as follows: Figure 6 As shown. The flow chart of the high-temperature resistant through-shell eddy current blade tip clearance measurement method of this invention is as follows: Figure 5 As shown, (a) is the original signal from the receiving coil – the Gaussian differential signal. Eddy currents on the blade surface generate a secondary magnetic field, which passes through the casing and is induced by the receiving coil 3, generating an induced Gaussian differential signal. (b) is the integrated signal – the Gaussian signal. After being pre-amplified, the Gaussian differential signal is restored to a Gaussian signal by the integrating circuit. (c) is the continuous measurement signal from multiple blades. Each blade generates a Gaussian signal, and the multiple blades output a continuous Gaussian measurement signal.

[0146] In one specific embodiment, the high-temperature resistant through-shell eddy current blade tip clearance measurement method is divided into: calibration stage, measurement stage, and signal processing stage.

[0147] I. Calibration Phase

[0148] The casing and rotating blade calibration system includes: a high-speed rotary table, a precision displacement stage, and a simulated casing; the high-speed rotary table has a rotational speed range of 0-30,000 rpm and a rotational speed accuracy of ±0.1%; the precision displacement stage has a stroke ≥10 mm and a positioning accuracy ≤5 μm; the simulated casing is made of the same material as the actual casing, with a thickness of 3-8 mm.

[0149] The structure of the casing and rotating blade calibration system in this embodiment of the invention is as follows: Figure 4 As shown, Figure 4 The exhibition showcases the layout of the high-speed rotary table, precision displacement stage, analog housing, sensor probe, and measurement system.

[0150] The steps for assembling the casing and rotating blade calibration system include:

[0151] Select blade simulation components to be installed on a high-speed rotating table, with 6-12 blades, and the material is titanium alloy or stainless steel;

[0152] Multiple speed points can be set, covering the actual working range of 0-30,000 rpm;

[0153] Set multiple gap points, gap range covers the measurement range 0.5-5mm;

[0154] The Gaussian signal amplitude of the sensor output under different rotating speeds and different gap conditions includes:

[0155] For each rotating speed-gap combination, the following operations are performed:

[0156] Set the rotating table rotating speed to ni, and wait for a first preset time length;

[0157] The precision displacement table moves to the gap position dj, and waits for a second preset time length;

[0158] Repeat the measurement for a first preset number of times, collect a first preset number of blade passing events each time, and record the corresponding Gaussian signal amplitude;

[0159] The Gaussian signal amplitude is based on the Gaussian signal amplitude to establish a rotating speed-amplitude-gap mapping relationship, which includes:

[0160] A rotating speed-amplitude-gap three-dimensional mapping relationship table is established, and all calibration data points are stored;

[0161] Calibration verification: select 5-10 intermediate points not involved in calibration, and actually measure and compare with theoretical values, and require error;

[0162] Obtain the calculation average amplitude and standard deviation.

[0163] In one specific embodiment, the calibration stage specifically includes:

[0164] Build a calibration system, including: a high-speed rotating table (rotating speed range 0-30,000 rpm, rotating speed accuracy ±0.1%), a precision displacement table (stroke≥10mm, positioning accuracy≤5μm) and a simulation case (material and actual case are the same, thickness 3-8mm).

[0165] Install the blade simulation piece (blade number 6-12, material titanium alloy or stainless steel) on the rotating table;

[0166] Set multiple rotating speed points, and the rotating speed range covers the actual working range 0-30,000 rpm.

[0167] Set multiple gap points, gap range covers the measurement range 0.5-5mm.

[0168] For each rotating speed-gap combination, the following operations are performed:

[0169] - Set the rotating table rotating speed to ni, and wait for the rotating speed to be stable (10 seconds);

[0170] - The precision displacement table moves to the gap position dj, and waits for the position to be stable (5 seconds);

[0171] - Repeat the measurement 5-10 times, each time collecting 1000 leaf blade passage events, and record the corresponding Gaussian signal amplitude;

[0172] - Calculate the average amplitude and standard deviation.

[0173] Establish a three-dimensional mapping relationship table of speed-amplitude-gap, and store all calibration data points.

[0174] Calibration verification: select 5-10 intermediate points not involved in calibration, actually measure and compare with theoretical values, and require error.

[0175] In this embodiment, a casing and rotating blade calibration system is constructed: by obtaining reference data for tip clearance measurement under controllable and repeatable experimental conditions, and establishing a "speed-amplitude-gap" correspondence relationship, the device can accurately calculate the tip clearance in actual measurement, especially for solving the measurement error problem caused by the coupling of speed and clearance.

[0176] (1) Collect standard Gaussian signal data under controllable speed and clearance conditions;

[0177] (2) Use Gaussian fitting and statistical processing to obtain stable amplitude data;

[0178] (3) Establish a three-dimensional calibration relationship of speed-amplitude-gap to solve the coupling problem of signal amplitude changing with speed;

[0179] (4) Verify the reliability and accuracy of the calibration relationship;

[0180] (5) Provide a unique and usable clearance calculation basis for the actual measurement stage, and achieve high-precision measurement.

[0181] II. Measurement stage

[0182] The sensor probe module is installed on the outer wall of the casing, and the Gaussian signal after amplification, filtering and integration processing is continuously obtained through the signal conditioning module; the data acquisition module collects the integrated Gaussian signal waveform data to obtain real-time digital signal flow, including:

[0183] The sensor probe module is installed on the outer wall of the casing, ensuring that the front end of the probe is tightly attached to the casing wall 7, and the probe axis is perpendicular to the casing wall 7, aligned with the blade swept area;

[0184] Start the signal conditioning module, set the ADC sampling rate ≥ 1 MSPS, and the sampling mode is continuous sampling;

[0185] The signal conditioning module continuously collects the induction signal output by the receiving coil 3, and the signal is processed by a preamplifier, a band-pass filter and an integration circuit to obtain a Gaussian signal; the gain of the preamplifier is 40-60 dB; the frequency of the band-pass filter is 100 Hz-300 kHz; and the time constant of the integration circuit is 5-10 μs.

[0186] The data acquisition module collects the Gaussian signal waveform data after integration to obtain a real-time digital signal stream, which is transmitted to the data processing module after being buffered by an FPGA / MCU.

[0187] In one specific embodiment, the measurement phase includes:

[0188] The sensor probe is installed on the outer wall of the casing, ensuring that the front end of the probe is tightly attached to the casing wall 7, and the probe axis is perpendicular to the casing wall 7 and aligned with the blade passing area.

[0189] Start the cooling system, set the cooling airflow flow rate, monitor the sensor temperature, and ensure that the working temperature is within the allowable range (<150℃ for natural cooling and <350℃ for air cooling).

[0190] Start the data acquisition system, set the ADC sampling rate to be greater than or equal to 1 MSPS, and set the sampling mode to be continuous sampling.

[0191] The induction signal output by the receiving coil 3 is continuously collected, and the signal is processed by a preamplifier (gain 40-60 dB), a band-pass filter (100 Hz-300 kHz) and an integration circuit (time constant 5-10 μs) to obtain a Gaussian signal.

[0192] The ADC collects the Gaussian signal waveform data after integration, and the data is transmitted to the host computer after being buffered by an FPGA / MCU.

[0193] III. Signal processing phase

[0194] The data processing module performs peak detection, Gaussian fitting and speed calculation on the real-time digital signal stream, and uses the mapping relationship of speed-amplitude-gap to calculate the tip clearance and output the measurement results, including:

[0195] The data processing module receives the real-time digital signal stream and performs real-time processing; first, digital filtering is performed to remove high-frequency noise;

[0196] Threshold judgment is performed on the collected digital signal to detect the position of the Gaussian peak; the threshold setting uses the 3σ criterion, and when the signal amplitude exceeds the threshold and meets the local maximum value condition, it is determined as an effective Gaussian peak, and the peak index and timestamp are recorded;

[0197] Extract the single Gaussian waveform data segment corresponding to each peak, and collect a pre-set second threshold number of sampling points.

[0198] Gaussian function fitting for single Gaussian waveform: fitting with nonlinear least squares method, extracting amplitude parameter (A), peak center (mu), width (sigma) after fitting;

[0199] Calculate the goodness of fit R 2 ;

[0200] Calculate the speed according to the time interval of the adjacent two peaks and the number of blades;

[0201] Substitute amplitude (A) and speed (n) into the calibration relationship to solve the tip clearance (d): use bilinear interpolation method, find the adjacent four points according to the calibration table, and calculate (d) according to the interpolation formula;

[0202] Output the measurement results, including: blade number, tip clearance (d), speed (n), timestamp (t), goodness of fit (R 2 );

[0203] Statistical analysis of the clearance values of multiple blades per revolution, calculate the mean and standard deviation, and eliminate abnormal values beyond ±3σ range;

[0204] Real-time display of measurement results, including: numerical display: current speed, blade clearance value; waveform display: original signal waveform, integrated Gaussian signal waveform, fitting curve; trend curve: clearance change trend with time or speed; alarm according to pre-set alarm rules;

[0205] Record and store all measurement data for subsequent fault diagnosis, life prediction and performance evaluation.

[0206] In a specific embodiment, the signal processing stage includes:

[0207] The host computer software receives the digital signal data stream and performs real-time processing. First, digital filtering (such as FIR low-pass filtering) is performed to remove high-frequency noise.

[0208] Threshold judgment is performed on the collected digital signal to detect the position of the Gaussian peak. The threshold is set using the 3σ criterion. When the signal amplitude exceeds the threshold and meets the local maximum value condition, it is determined to be an effective Gaussian peak, and the peak index and timestamp are recorded.

[0209] Extract the single Gaussian waveform data segment corresponding to each peak, for example, 100 sampling points before and after the peak, a total of 200 points.

[0210] Gaussian function fitting for single Gaussian waveform: fitting with nonlinear least squares method (Levenberg-Marquardt algorithm), extracting amplitude parameter (A), peak center \(mu\), width (sigma) after fitting.

[0211] The goodness of fit (R 2 ) is calculated.

[0212] The rotation speed is calculated according to the time interval of the adjacent two peaks and the number of blades.

[0213] The amplitude (A) and the rotation speed (n) are substituted into the calibration relationship to solve the tip clearance (d). A bilinear interpolation method is used to find the adjacent four points according to the calibration table, and the tip clearance (d) is calculated according to the interpolation formula.

[0214] The measurement results are output, including the blade number (obtained by taking the modulus of the blade number with the peak number), the tip clearance (d), the rotation speed (n), the timestamp (t), the goodness of fit (R 2 ), etc.

[0215] The clearance values of multiple blades per revolution are statistically analyzed to calculate the mean value and the standard deviation, and the abnormal values exceeding the range of ±3σ are removed.

[0216] The measurement results are displayed in real time, including: numerical display: current rotation speed, blade clearance value; waveform display: original signal waveform, integrated Gaussian signal waveform, fitting curve; trend curve: clearance change trend with time or rotation speed; alarm function: when the clearance is less than 0.3mm, a rub-against warning is issued, and when the clearance is greater than 5.5mm, an efficiency decline warning is issued.

[0217] All measurement data are recorded and stored for subsequent fault diagnosis, life prediction and performance evaluation.

[0218] The signal processing flow of the data processing module of the embodiment is shown in Figure 7 .

[0219] The high-temperature-resistant transparent shell type eddy current tip clearance measurement device and method disclosed by the application can obtain the following technical effects:

[0220] I. Realize transparent shell non-contact measurement technology

[0221] Traditional eddy current / capacitance / optical fiber sensors all need to be opened on the casing. The application realizes true transparent shell measurement for the first time without the need for casing opening. The sensor is installed on the outer wall of the casing without the need for casing opening or slotting; the magnetic field penetrates the non-magnetic casing wall (tungsten-nickel alloy / nickel-iron-based alloy, thickness 3-8mm) for measurement; the casing structure integrity and aerodynamic sealing are maintained. Avoiding the strength weakening caused by casing opening, without damaging the casing aerodynamic seal, easy installation and maintenance, online sensor replacement, and low sensor working environment temperature (casing outer wall vs. inner wall).

[0222] II. Realize permanent magnet excitation source + soft magnet core receiving discrete structure

[0223] Traditional eddy current sensors use AC excitation coils (high frequency 10-50MHz); permanent magnet solutions eliminate the need for high-frequency excitation circuits, simplifying the system and reducing power consumption; existing technologies do not disclose the focusing technology related to soft magnetic cores. This invention uses a permanent magnet 1 (300mT samarium cobalt) as the static magnetic field excitation source, eliminating the need for AC excitation circuits; the soft magnetic core (permalloy, μr≥10,000) is separately set from the permanent magnet 1 (air gap 3-5mm); the receiving coil 3 is wound on the soft magnetic core to focus the induced magnetic field and improve sensitivity. Permanent magnet excitation source: zero power consumption, high stability, long lifespan; Soft magnetic core focusing: increases magnetic flux density and compensates for through-shell losses; Discrete structure allows for optimized magnetic field configuration and improved signal-to-noise ratio.

[0224] III. Design an air-cooling system to improve high-temperature adaptability.

[0225] Existing through-shell sensors lack high-temperature adaptability design. This invention achieves 650℃ temperature resistance through material selection and active cooling, creatively applying air-path cooling in the field of blade tip clearance measurement. Permalloy is selected to achieve a soft magnetic core temperature resistance of 350℃; an integrated air-path cooling system (compressed air 0.5MPa, 10L / min) is used; a spiral air passage design uniformly cools the coil; combined with cooling, it can adapt to high-temperature environments up to 650℃. It also adapts to the high-temperature environment (200-300℃) of the casing outer wall; ensures the operating temperature of the soft magnetic core and coil is <150℃; and expands the application range to high-temperature regions (turbine section).

[0226] IV. System Integration Innovation

[0227] Design a complete system integrating sensor probe, signal conditioning, data acquisition, and host computer processing; design a targeted analog front-end (preamplifier, bandpass filter, and integrator); directly acquire the integrated signal using a high-speed ADC (≥5MSPS, 16bit); and implement real-time Gaussian fitting and gap calculation using host computer software. Systematic design achieves synergistic optimization of each module; achieves high bandwidth (>300kHz) to adapt to high-speed multi-blade operation; and enables real-time processing with a processing time of <1ms per blade.

[0228] To verify the effectiveness of the high-temperature resistant through-shell eddy current blade tip clearance measuring device and method disclosed in this invention, the following verification embodiments are disclosed to describe the implementation process of a complete through-shell eddy current blade tip clearance measuring system, including sensor fabrication, signal processing, calibration, and practical application.

[0229] (1) Sensor probe fabrication

[0230] The sensor probe adopts a separate structure of a permanent magnet excitation source and a soft magnet receiving coil 3. A samarium-cobalt permanent magnet (SmCo) is selected as the excitation source, which is cylindrical and axially magnetized. The soft magnet core is made of permalloy material and is cylindrical. The receiving coil 3 is wound on the soft magnet core using high-temperature resistant enameled copper wire.

[0231] During sensor assembly, the permanent magnet 1 is fixed at the bottom of the stainless steel shell, and the soft magnet core and receiving coil assembly are installed above it at a distance of 3-5 mm, keeping the air gap uniform. A spiral air cooling channel is provided around the soft magnet core to cool the coil by compressed air. The outside of the receiving coil 3 is wrapped with an electromagnetic shielding layer to reduce external interference. Shielded twisted pair wires are used for lead-out, and a temperature sensor is installed inside to monitor the operating temperature. The whole is filled with high-temperature resistant epoxy resin to form an integrated probe.

[0232] Sensor testing includes normal temperature performance testing, high temperature performance testing, and long-term stability testing. The output characteristics of the sensor are verified under different gaps (0.5-5 mm) and different rotation speeds by testing the outer wall of a simulated case (thickness 5 mm). The high temperature test verifies that the sensor can work stably at 200°C in cooperation with the air cooling system. The long-term stability test shows that the sensor has a zero drift of less than 1% FS and a sensitivity drift of less than 2% after continuous operation for 100 hours.

[0233] (2) Signal conditioning circuit implementation

[0234] The signal conditioning circuit includes three cascaded modules: a preamplifier, a bandpass filter, and an integration circuit.

[0235] The preamplifier uses an instrument amplifier chip to amplify the millivolt-level weak signal output by the receiving coil 3 to the range of 0.1-5V. A protection circuit is provided at the input end, including a series resistor, a parallel capacitor, and a TVS tube, to prevent overvoltage damage.

[0236] The bandpass filter uses a second-order active filter based on the Sallen-Key topology. The lower cutoff frequency is 100Hz, removing DC drift and low-frequency noise; the upper cutoff frequency is 300kHz, achieving anti-aliasing filtering. The filter gain is 10 times (20dB), further amplifying the signal. Butterworth response design is used, with a flat passband and linear phase.

[0237] The integration circuit uses an RC active integrator with a time constant of about 5μs to restore the Gaussian differential signal output by the receiving coil 3 to a Gaussian signal. To prevent integrator saturation, a large parallel resistor is used for long-time constant reset. High-precision thin-film capacitors are used for the integration capacitor, and metal film resistors are used for the resistors to ensure circuit stability.

[0238] During circuit debugging, a function generator is used to input standard signals to test the frequency response and noise performance. After connecting the sensor probe, simulate the blade passing events, adjust the gain and time constant to make the output waveform clear and undistorted.

[0239] (3) Data acquisition and processing system

[0240] The data acquisition system uses a 16-bit high-speed ADC with a sampling rate of 5 MSPS, connected to the main control chip through SPI or parallel interface. The main control chip is configured to work in circular buffer mode to achieve continuous sampling and data transmission. The collected data is transmitted to the host computer through the Ethernet interface (100 Mbps) and packaged using the UDP protocol to ensure real-time performance.

[0241] The host computer software is developed using C++ language and based on Qt5 graphical interface library. The software includes five main modules: data reception, signal processing, calibration management, display, and data recording.

[0242] The signal processing algorithm includes four core steps:

[0243] Step 1) Gaussian peak detection: adaptive threshold method (3σ criterion) is used to detect Gaussian peaks. Calculate the mean and standard deviation of the signal, set the threshold to the mean plus 3 times the standard deviation. Traverse the signal data, when a point amplitude exceeds the threshold and is a local maximum, it is determined as a valid peak.

[0244] Step 2) Gaussian curve fitting: nonlinear least squares method (Levenberg-Marquardt algorithm) is used for Gaussian function fitting to extract the amplitude parameter A. Calculate the goodness of fit R², require R²>0.95, otherwise reject the data point.

[0245] Step 3) Speed calculation: calculate the speed according to the time interval of adjacent two peaks and the number of blades. Use multi-cycle averaging method to improve accuracy, set the speed change rate threshold to remove abnormal data.

[0246] Step 4) Gap calculation: based on the pre-established speed-amplitude-gap three-dimensional calibration table, use bilinear interpolation method or empirical formula method to calculate the gap value.

[0247] The graphical interface includes the main window (real-time numerical display), waveform window (original signal and fitted curve), trend window (gap change over time), calibration window (calibration data management), and setting window (parameter configuration).

[0248] (4) Calibration experiment

[0249] The calibration system comprises a high-speed rotating table (rotation speed range 0-30,000 rpm, precision ±0.1%), a precision displacement table (positioning precision ±1 μm), an analog case (GH4169 alloy, thickness 5 mm) and a blade analog piece (TC4 titanium alloy, 8 pieces).

[0250] The calibration adopts a grid method, 9 rotation speed points (1000 to 30000 rpm) and 10 gap points (0.5 to 5.0 mm) are set, and a total of 90 calibration points are set. The operation process of each calibration point is as follows: set the rotation speed and wait for stabilization, move the displacement table to the target gap, collect 1000 blade passing events, perform Gaussian fitting to extract the amplitude, calculate the average value and standard deviation, and repeat 5 times to take the average value.

[0251] The calibration result shows that the signal amplitude A is proportional to the rotation speed n and inversely proportional to the gap δ.

[0252] Through the above verification examples, the whole process of the transparent shell type eddy current tip clearance measurement system from design, production, calibration to simulation application is fully demonstrated. The examples verify the following key technical effects:

[0253] (1) Sensor structure design: the permanent magnet excitation source and the soft magnet receiving coil are in a separate structure, which cooperates with the air cooling system, and can stably work in the high temperature environment (650 DEG C) of the outer wall of the case, and the temperature of the sensor body is controlled below 350 DEG C.

[0254] (2) Signal processing technology: three-stage signal conditioning circuit (pre-amplification, band-pass filtering, integral processing) effectively extracts the transparent shell weak signal, restores the Gaussian differential signal to clear Gaussian waveform, and provides a high-quality signal source for subsequent digital processing.

[0255] (3) Intelligent algorithm application: the Gaussian fitting algorithm combined with the rotation speed decoupling technology accurately calculates the tip clearance through the calibration mapping relationship, and the measurement precision reaches ±1% FS.

[0256] (4) System reliability verification: the simulation bench test shows that the comparison error between the system measurement result and the laser measurement is less than ±0.03 mm, the long-term stability test (200 hours) deviation is within ±0.02 mm, and the system meets the needs of the whole life cycle monitoring of the aero-engine.

[0257] The present application realizes the truly transparent shell type non-contact measurement, does not need to open a hole in the case, maintains the integrity and aerodynamic sealing of the case structure, the sensor working environment is friendly, the reliability is high, and the present application has important engineering application value and broad market prospect. The present application can be applied to the following fields:

[0258] Aero-engine: turbine, compressor tip clearance measurement, used for performance optimization, state monitoring and fault diagnosis.

[0259] Gas turbine: tip clearance monitoring of gas turbine for power generation, gas turbine for ship.

[0260] Steam turbine: tip clearance measurement of steam turbine for power plant, improving efficiency.

[0261] Turbocharger: tip clearance online monitoring of turbocharger for automobile, turbocharger for ship.

[0262] Compressor: tip clearance measurement of centrifugal compressor, axial flow compressor.

[0263] Compared with the traditional method, the transparent shell type measurement technology disclosed by the application has obvious advantages, and has important significance for the safety and economy of the aero-engine: improving safety: monitoring the tip clearance in real time, discovering the rubbing risk in time, avoiding blade damage and engine failure; improving efficiency: optimizing the tip clearance design, reducing air leakage, improving engine efficiency, and saving fuel; prolonging life: accurately grasping the change trend of the tip clearance, implementing predictive maintenance, and prolonging the engine overhaul interval.

[0264] Another embodiment of the application provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program stored in the memory, the processor executes the high-temperature-resistant transparent shell type eddy current tip clearance measurement method according to the application.

[0265] Another embodiment of the application provides a computer readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the processor executes the high-temperature-resistant transparent shell type eddy current tip clearance measurement method according to the application.

Claims

1. A high temperature resistant, through shell, eddy current tip clearance measurement device, characterized by, The sensor probe module, the signal conditioning module, the data acquisition module, and the data processing module are included. The sensor probe module is installed on the outer wall of the casing. The casing is made of non-magnetic material. The sensor probe module includes a permanent magnet excitation source, a soft magnetic core, and a receiving coil. The permanent magnet excitation source generates a constant static magnetic field, and the magnetic lines of force pass through the casing wall to reach the rotating blade area.

2. The high temperature resistant, through shell, eddy current tip clearance measurement device of claim 1, wherein, The soft magnetic core is arranged in the magnetic field radiation direction of the permanent magnet excitation source and is separately arranged with the permanent magnet excitation source to guide the magnetic field and serve as the magnetic core of the receiving coil. The receiving coil is used to induce a secondary magnetic field and generate an induced voltage. The signal conditioning module is electrically connected with the receiving coil to amplify, filter, and integrate the weak induced signal.

3. The high temperature resistant, through shell, eddy current tip clearance measurement device of claim 1, wherein, The data acquisition module is electrically connected with the signal conditioning module to convert the analog signal into a digital signal. The data processing module processes the collected digital signal to extract the blade tip clearance information.

4. The high temperature resistant, through shell, eddy current tip clearance measurement device of claim 1, wherein, The permanent magnet excitation source is a samarium-cobalt permanent magnet or a neodymium-iron-boron permanent magnet, which is cylindrical in shape and has an axial magnetization direction. The magnetic induction intensity of the permanent magnet excitation source is 200-500 mT. The soft magnetic core is made of permalloy or ferrite material, with a relative magnetic permeability of μr≥10,000 and a temperature resistance of ≥350℃. The receiving coil is made of enameled copper wire wound on the soft magnetic core.

5. The high temperature resistant, through shell, eddy current tip clearance measurement device of claim 1, wherein, The wire diameter of the enameled copper wire is 0.1-0.3 mm, the number of turns is 500-3000 turns, the inductance is 50-200 mH, and the direct current resistance is 200-800 Ω. The sensor probe module further includes a cooling system and a shielding device. The cooling system uses an air cooling method to cool the soft magnetic core and the receiving coil with compressed air. The shielding device includes a stainless steel shell to encapsulate the sensor probe module and an electromagnetic shielding layer to reduce external electromagnetic interference.

6. The high temperature resistant, through shell, eddy current tip clearance measurement device of claim 1, wherein, The signal output is achieved through twisted pair or coaxial cable. The signal conditioning module includes a preamplifier, a band-pass filter, and an integration circuit. The preamplifier is a high-performance instrument amplifier chip that amplifies the mV-level weak signal output by the receiving coil to 0.1-5 V. The band-pass filter is a second-order Butterworth active filter with a passband range of 100 Hz-300 kHz and a filter gain of 20 dB. The integration circuit is an RC active integrator. The data acquisition module includes a high-speed analog-to-digital converter and a data buffering and communication interface. The high-speed analog-to-digital converter uses a continuous sampling mode to continuously collect Gaussian signal waveform data after integration. The data buffering and communication interface uses FPGA or high-performance MCU for data buffering and preprocessing, and transmits the digital signal to the host computer through an Ethernet interface. The data packaging of the data acquisition module uses UDP protocol. The data processing module includes a Gaussian peak detection unit. The Gaussian peak detection unit performs threshold judgment on the collected digital signal to identify the peak position of the Gaussian waveform, and each peak corresponds to a blade passing event. Gaussian fitting unit: extract the waveform data segment around each detected peak, perform Gaussian function fitting, and extract the amplitude parameter after fitting as the input of gap calculation; Rotational speed calculation unit: calculate the rotational speed according to the time interval of adjacent two blade passing events and the number of blades; Gap calculation unit: calculate the tip clearance through the mapping relationship of pre-calibration according to the amplitude obtained by Gaussian fitting and the rotational speed calculated by rotational speed calculation unit; the gap calculation adopts bilinear interpolation method to establish a rotational speed-amplitude-clearance three-dimensional calibration table; Data output and display unit: output the clearance value, rotational speed and time stamp of each blade in real time, display in the form of numerical value, waveform and trend curve, and record and store the data.

7. A high-temperature-resistant transparent shell eddy current tip clearance measurement method of a high-temperature-resistant transparent shell eddy current tip clearance measurement device according to any one of claims 1 to 6, characterized by, The method comprises the following steps: a casing and rotating blade calibration system is built, Gaussian signal amplitudes output by sensors under different rotational speeds and different clearance conditions are collected, and a rotational speed-amplitude-clearance mapping relationship is established based on the Gaussian signal amplitudes; a sensor probe module is installed on the outer wall of the casing, and a signal conditioning module is used to continuously acquire Gaussian signals processed by amplification, filtering and integration; a data acquisition module acquires the waveform data of the integrated Gaussian signals to obtain a real-time digital signal stream; a data processing module performs peak detection, Gaussian fitting and rotational speed calculation on the real-time digital signal stream, calculates the tip clearance by using the rotational speed-amplitude-clearance mapping relationship, and outputs the measurement result.

8. The high temperature resistant transparent shell eddy current tip clearance measurement method of claim 7, wherein, The casing and rotating blade calibration system comprises a high-speed rotating table, a precision displacement table and an analog casing; the high-speed rotating table has a rotational speed range of 0-30,000 rpm and a rotational speed accuracy of ±0.1%; the precision displacement table has a stroke of ≥10 mm and a positioning accuracy of ≤5 μm; the analog casing is made of the same material as the actual casing and has a thickness of 3-8 mm; The building steps of the casing and rotating blade calibration system comprise: a blade simulation part is selected and installed on the high-speed rotating table, the number of blades is 6-12, and the material is titanium alloy or stainless steel; a plurality of rotational speed points are set, and the rotational speed range covers the actual working range of 0-30,000 rpm; a plurality of clearance points are set, and the clearance range covers the measurement range of 0.5-5 mm; The collection of Gaussian signal amplitudes output by sensors under different rotational speeds and different clearance conditions comprises: for each rotational speed-clearance combination, the following operations are performed: the rotational speed of the rotating table is set to ni, and a first preset time duration is waited; the precision displacement table is moved to the clearance position dj, and a second preset time duration is waited; a first preset number of measurements is repeated, a first preset number of blade passing events are collected each time, and the corresponding Gaussian signal amplitudes are recorded; The establishment of a rotational speed-amplitude-clearance mapping relationship based on the Gaussian signal amplitudes comprises: a rotational speed-amplitude-clearance three-dimensional mapping relationship table is established, and all calibration data points are stored; calibration verification: 5-10 intermediate points not involved in calibration are selected, actual measurement is performed, and the error is compared with the theoretical value; the average amplitude and the standard deviation are obtained.

9. The high temperature resistant transparent shell ECT tip clearance measurement method according to claim 7, wherein, The sensor probe module is installed on the outer wall of the casing, and the signal conditioning module is used to continuously acquire Gaussian signals processed by amplification, filtering and integration; The acquisition of waveform data of the integrated Gaussian signals by the data acquisition module to obtain a real-time digital signal stream comprises: The sensor probe module is installed on the outer wall of the casing, ensuring that the front end of the probe is tightly attached to the casing wall, and the probe axis is perpendicular to the casing wall and aligned with the blade swept area; The start signal conditioning module is started, the ADC sampling rate is set to be greater than or equal to 1 MSPS, and the sampling mode is continuous sampling; The signal conditioning module continuously collects the induction signals output by the receiving coil, and the signals are processed by a preamplifier, a band-pass filter and an integration circuit to obtain a Gaussian signal; the gain of the preamplifier is 40-60 dB; the frequency of the band-pass filter is 100 Hz-300 kHz; and the time constant of the integration circuit is 5-10 μs; The data acquisition module acquires the Gaussian signal waveform data after integration to obtain a real-time digital signal stream, which is transmitted to the data processing module after being buffered by the FPGA / MCU.

10. The high temperature resistant transparent shell eddy current tip clearance measurement method of claim 7, wherein, The data processing module performs peak detection, Gaussian fitting and speed calculation on the real-time digital signal stream, and calculates the tip clearance using the mapping relationship of speed-amplitude-clearance and outputs the measurement results, including: The data processing module receives the real-time digital signal stream and performs real-time processing; first, digital filtering is performed to remove high-frequency noise; Threshold judgment is performed on the collected digital signals to detect the position of the Gaussian peak; the threshold is set using the 3σ criterion, and when the signal amplitude exceeds the threshold and meets the local maximum value condition, it is determined as an effective Gaussian peak, and the peak index and timestamp are recorded; The single Gaussian waveform data segment corresponding to each peak is extracted, and a second threshold number of sampling points are collected; The single Gaussian waveform is fitted with a Gaussian function: a nonlinear least squares method is used for fitting, and the amplitude parameter, peak center and width are extracted after fitting; Computing the goodness of fit R 2 ; The speed is calculated according to the time interval of the adjacent two peaks and the number of blades; The amplitude and speed are substituted into the calibration relationship to calculate the tip clearance: a bilinear interpolation method is used to find the adjacent four points according to the calibration table, and the tip clearance is calculated according to the interpolation formula; Output measurement results, including: blade number, blade tip clearance, rotational speed, time stamp, goodness of fit R 2 ; The clearance values of multiple blades per revolution are statistically analyzed to calculate the mean value and standard deviation, and the abnormal values exceeding ±3σ are removed; The measurement results are displayed in real time, including: numerical display: current speed, blade clearance value; waveform display: original signal waveform, integrated Gaussian signal waveform, fitting curve; trend curve: clearance change trend with time or speed; alarm according to pre-set alarm rules; All measurement data are recorded and stored for subsequent fault diagnosis, life prediction and performance evaluation.

Images