Dynamic measurement method for blade tip clearance change during rotation of aero-engine

Abstract

The invention discloses a dynamic measurement method for blade tip clearance change during rotation of an aero-engine. A gradient magnetic field is generated through a magnetic excitation coil group arranged on a casing, and the resistance of the giant magnetoresistance sensor before and after the rotation of the engine, namely before and after the magnetic field intensity of the gradient magnetic field is changed, is obtained through voltage signals output by the giant magnetoresistance sensor arranged on the casing before and after the rotation of the engine; according to the method, temperature compensation is carried out on a voltage signal output by a giant magnetoresistance sensor after an engine rotates, and temperature compensation is carried out on the voltage signal output by the giant magnetoresistance sensor after the engine rotates; the relation between the gradient magnetic field intensity before and after the engine rotates and the resistance of the giant magnetoresistance sensor and the relation between the blade tip clearance under the engine rotating condition and the gradient magnetic field intensity before and after the engine rotates are established; and obtaining the blade tip clearance under the rotating condition of the engine. According to the invention, the dynamic measurement of the blade tip clearance under the rotating condition of the engine can be realized, and the accuracy is high.

Description

Technical Field

[0001] The present invention belongs to the field of aviation technology testing, and particularly relates to a dynamic measurement method for the change of tip clearance during the rotation of an aeroengine. Background Art

[0002] As the core power of an aircraft, the performance of an aeroengine is closely related to the tip clearance. An appropriate tip clearance can better achieve energy utilization efficiency. However, there are many limitations in the existing tip clearance measurement technologies. In the high-temperature, high-pressure, high-vibration, and strong electromagnetic interference environment inside the engine, the components of optical measurement are prone to performance degradation, optical path deviation, or signal distortion; capacitive measurement is affected by complex electromagnetic field interference, the measurement is unstable, and the sensor will have deviations at high temperatures; conventional electromagnetic measurement is based on a uniform magnetic field, with low sensitivity, and the magnetic field superposition interference is serious during the rotation of multiple blades, making signal processing difficult. Therefore, it is necessary to design a new measurement method that can dynamically measure the tip clearance of deformed blades at high speed to obtain more accurate data. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the existing technology and propose a dynamic measurement method for the change of tip clearance during the rotation of an aeroengine.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A dynamic measurement method for the change of tip clearance during the rotation of an aeroengine according to the present invention is as follows:

[0006] Step 1: Arrange a magnetic excitation coil group and a sensor group on the engine casing. The magnetic excitation coil group is composed of multiple coils arranged at axial intervals, and the sensor group is composed of giant magnetoresistive sensors, Hall sensors, and n temperature sensors arranged circumferentially along the coils, and n≥3;

[0007] Step 2: Pass alternating current through each coil. The magnetic fields generated by each coil are superimposed to form a gradually changing magnetic field. At the same time, a constant current I is passed through the giant magnetoresistive sensor; the resistance R0 of the giant magnetoresistive sensor under the gradually changing magnetic field when the engine is not rotating is obtained through the voltage output by the giant magnetoresistive sensor when the engine is not rotating.

[0008] Step 3: After the engine rotates at a preset speed for a preset time, through the voltage E i output by the giant magnetoresistive sensor when the engine is rotating, the resistance of the giant magnetoresistive sensor under the gradually changing magnetic field when the engine is rotating is obtained:

[0009] R i = E i / I (1)

[0010] The relationship between the resistance of the giant magnetoresistive sensor and the magnetic field strength of the gradually changing magnetic field is

[0011] R i = R0 + S*(B(d) - B0) (2)

[0012]

[0013] where S is the sensitivity of the giant magnetoresistive sensor, B(d) is the magnetic field strength of the gradually changing magnetic field when the tip clearance is d during engine rotation, B0 is the magnetic field strength of the gradually changing magnetic field when the engine is not rotating, B(d) and B0 are measured by the Hall sensor, R 原始 is the resistance of the giant magnetoresistive sensor in the absence of a magnetic field, B 饱和 is the magnetic field strength when the magneto - resistive effect of the giant magnetoresistive sensor reaches saturation, MR is the magnetoresistance ratio;

[0014] The relationship between the tip clearance d and the magnetic field strength B(d) of the gradually changing magnetic field during engine rotation is designed as

[0015]

[0016] where K d is the attenuation coefficient;

[0017] Step 4. The voltage E output by the giant magnetoresistive sensor after temperature compensation during engine rotation is c as

[0018] E c = E i [1 + β(T)(T - T0)]

[0019]

[0020] where T is the temperature received by the giant magnetoresistive sensor, measured by the temperature sensor, T0 is the reference temperature, β(T) is the dynamic temperature coefficient, β0 and λ are the reference temperature coefficient and the attenuation index respectively, T i is the average value of m temperatures measured by the i - th temperature sensor, W i is the weight coefficient of T i , is the variance of m temperatures measured by the j - th temperature sensor, C ij is the correlation coefficient between the i - th temperature sensor and the j - th temperature sensor;

[0021] Using the voltage E after temperature compensation c to replace the uncompensated voltage E in Equation (1) i , the resistance R of the giant magnetoresistive sensor after temperature compensation during engine rotation is obtained c :

[0022] R c = E i [1 + β(T)(T - T0)] / I (4)

[0023] Step 5. Combine Equation (2), Equation (3) and Equation (4), and use the resistance R of the giant magnetoresistive sensor after temperature compensation c to replace the resistance R of the uncompensated giant magnetoresistive sensor in Equation (2) i to obtain the calculation formula for the tip clearance d during engine rotation.

[0024] Preferably, the number of turns of each coil decreases successively in the arrangement order; the sensor group is arranged on the engine casing near the magnetic excitation coil group and on the side of the coil with the least number of turns in the magnetic excitation coil group.

[0025] Preferably, the magnitude of the current passing through each coil decreases as the number of turns decreases.

[0026] Preferably, the attenuation coefficient K d The measurement process is as follows: When the engine is not rotating, change the tip clearance multiple times, and use a Hall sensor to measure the magnetic field strength of the gradually changing magnetic field each time the tip clearance is changed to obtain multiple data pairs (d x ,, B(d x ))), where d x and B(d x ) are the tip clearance and the magnetic field strength of the gradually changing magnetic field after the x-th change respectively. Take the natural logarithm of the formula for the magnetic field strength of the gradually changing magnetic field to obtain the linear relationship Convert each data pair (d x ,, B(d x )) into the form of (ln(B(d x ) / B0), d x ). Assume the linear model is y x = ad x , where y x = ln(B(d x ) / B0), a = -K d . Use the data pairs in the form of (ln(B(d x ) / B0), d x ) and substitute them into y x = ad x to calculate a by the least squares method:

[0027]

[0028] Furthermore, obtain the value of K d , where X is the number of data pairs,

[0029] Preferably, the process for measuring the reference temperature coefficient β0 and the attenuation index λ is as follows: In the absence of a magnetic field, the temperature is controlled to vary at intervals of 0.5 °C within the range of T0 to T0 + 10 °C, the voltage output by the giant magnetoresistive sensor at different temperatures is measured, the ratio of this voltage to the constant current I is calculated to obtain the resistance R(T). At this time, β(T) = β0 is taken, and by fitting the linear relationship the value of the reference temperature coefficient β0 is obtained, where is the resistance of the giant magnetoresistive sensor without a magnetic field and at the reference temperature; in the absence of a magnetic field, the temperature is controlled to vary at intervals of 5 °C within the range of T0 to T0 + 100 °C, the voltage output by the giant magnetoresistive sensor at different temperatures is measured to obtain the corresponding resistance R(T), and taking the natural logarithm gives Then substituting the expression of β(T) obtained from into a linear relationship is obtained. Based on the resistance R(T) of the giant magnetoresistive sensor at different temperatures and the corresponding temperature data, by fitting this linear relationship, the value of the attenuation index λ is obtained.

[0030] Preferably, the calculation process of the correlation coefficient C ij is as follows: Let the temperature data set measured by the i-th temperature sensor and the temperature data set measured by the j-th temperature sensor be x i = [x i1 , x i2 , x i3 , …, x im and x j = [x j1 , x j2 , x j3 …, x jm , both containing m temperature data; for each temperature data in the temperature data set x i measured by the i-th temperature sensor, sorting them from smallest to largest, the rank values corresponding to the temperature data in the temperature data set x i are obtained to form a rank sequence r i , for each temperature data in the temperature data set x j measured by the j-th temperature sensor, sorting them from smallest to largest, the rank values corresponding to the temperature data in the temperature data set x j are obtained to form a rank sequence r j , then

[0031]

[0032] In the formula, r ik is the rank value of the k-th temperature data in the temperature data set x i , r jkis the k-th rank value of the temperature data in the temperature data set x j

[0033] Preferably, the calculation formula for the tip clearance d when the engine rotates is

[0034]

[0035] The present invention has the following beneficial effects:

[0036] ​1. The present invention can achieve dynamic measurement of the tip clearance under the condition of engine rotation and has high precision. Specifically, the present invention designs a gradient magnetic field. By utilizing the non-linear variation characteristic that the magnetic field intensity of the gradient magnetic field decays exponentially with the tip clearance, the subtle changes in the tip clearance can be more significantly manifested through the change in the magnetic field intensity of the gradient magnetic field, thereby improving the measurement precision of the tip clearance. A giant magnetoresistive sensor is used to detect the change in the magnetic field intensity of the gradient magnetic field with the tip clearance. By utilizing the influence characteristic of the magnetic field on the resistance of the giant magnetoresistive sensor, the change in the magnetic field intensity of the gradient magnetic field is characterized by the change in the resistance of the giant magnetoresistive sensor. The giant magnetoresistive sensor is supplied with a constant current and outputs a voltage signal. Furthermore, the change in the magnetic field intensity of the gradient magnetic field is characterized by the change in the voltage signal output by the giant magnetoresistive sensor. Through the voltage signal values output by the giant magnetoresistive sensor before and after engine rotation (i.e., before and after the tip clearance rotation), the relationship between the resistance of the giant magnetoresistive sensor before and after engine rotation and the magnetic field intensity of the gradient magnetic field, and the relationship between the tip clearance after engine rotation and the magnetic field intensity of the gradient magnetic field, the tip clearance under the condition of engine rotation can be obtained, thereby realizing the dynamic measurement of the tip clearance under the condition of engine rotation. Further, the present invention considers the influence of the high temperature inside the engine on the giant magnetoresistive sensor, compensates the voltage signal value output by the giant magnetoresistive sensor under the condition of engine rotation for temperature, and introduces a dynamic temperature coefficient containing an exponential decay term during temperature compensation to capture the non-linear response under the combined action of the magnetic field and temperature, avoid over-compensation in a high-temperature environment, and improve the measurement precision of the tip clearance. At the same time, considering the influence of the position of the temperature sensor and the internal air flow of the engine on the detection result of the temperature sensor, multiple temperature sensors are used for measurement, and the detection results of each temperature sensor are weighted and integrated. The calculation of the weight coefficient introduces a correlation coefficient obtained by the Spearman rank correlation coefficient algorithm. At the same time, the measurement variance of each temperature sensor in the weight mechanism is updated in real time during the measurement. According to the trend analysis of the measurement variance, the degradation of the temperature sensor can be predicted in advance to achieve self-diagnosis, thereby realizing the effective integration of the detection data of each temperature sensor, avoiding the measurement error generated by the traditional single-point temperature measurement method in a high-temperature environment, and the measurement variance not conforming due to the aging of the temperature sensor or other factors, ensuring the accuracy of the measurement result, effectively compensating the measurement influence brought by the temperature factor to the giant magnetoresistive sensor, and further improving the measurement precision of the tip clearance.

[0037] 2. In the present invention, a magnetic excitation coil group composed of a plurality of coils arranged at a coaxial interval is arranged on the engine casing, and the number of turns of each coil and the magnitude of the current passing through it both decrease along the arrangement direction, so that the magnetic fields generated by each energized coil are superimposed to form a gradually changing magnetic field. Among them, each coil is excited by high-frequency alternating current, which reduces the penetration depth of the magnetic field in the radial direction, reduces the coupling of external electromagnetic noise, and the high-frequency magnetic field formed by the excitation of high-frequency alternating current decays faster in space, which can reduce the interference to other electronic systems of the engine, and makes it difficult for external low-frequency noise to mix into the signal. At the same time, the gradually changing magnetic field forms a directional characteristic in space, that is, the magnetic field direction is mainly perpendicular to the direction of the blade rotation plane, so that the stray magnetic field parallel to the blade rotation plane direction is suppressed, improving the measurement accuracy of the giant magnetoresistive sensor, and further improving the measurement accuracy of the tip clearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 FIG. is a schematic layout diagram of the excitation coil group and the sensor group on a plane perpendicular to the blade rotation plane;

[0039] Figure 2 FIG. is a schematic layout diagram of the excitation coil group and the sensor group on a plane parallel to the blade rotation plane. DETAILED DESCRIPTION OF THE INVENTION

[0040] The present invention will be further described below with reference to the drawings.

[0041] A dynamic measurement method for the tip clearance change during the rotation of an aeroengine according to the present invention is as follows:

[0042] Step 1. As shown in FIGS. Figure 1 and Figure 2 , a magnetic excitation coil group is arranged on the engine casing. The magnetic excitation coil group is composed of a plurality of coils arranged at an axial interval, and the number of turns of each coil decreases in sequence according to the arrangement order; a sensor group 401 is arranged on the engine casing near the magnetic excitation coil group. The sensor group 401 is located on the side of the coil with the least number of turns in the magnetic excitation coil group. The sensor group 401 is composed of giant magnetoresistive sensors, Hall sensors and three temperature sensors arranged circumferentially along the coil; in this embodiment, the magnetic excitation coil group includes coil one 101, coil two 201 and coil three 301. The number of turns N1 of coil one 101 is 100, the number of turns N2 of coil two 201 is 60, the number of turns N3 of coil three 301 is 30. The distance between coil one 101 and coil two 201 is 3 mm, the distance between coil two 201 and coil three 301 is 2 mm. The distance between the circular trajectory lines where the giant magnetoresistive sensor, Hall sensor and three temperature sensors in the sensor group 401 are located and coil three 301 is 0.8 mm.

[0043] ​​​​Step 2: Pass high-frequency alternating current (with a frequency greater than 100 Hz. In this embodiment, 50 kHz high-frequency alternating current is used) through each coil, and the magnitude of the current passed through each coil decreases as the number of turns decreases. The magnetic fields generated by each coil are superimposed to form a gradually changing magnetic field. At the same time, a constant current I is passed through the giant magnetoresistive sensor. In this embodiment, 5 A alternating current is passed through coil 101, 3 A alternating current is passed through coil 201, and 1.5 A alternating current is passed through coil 301; according to the voltage E output by the giant magnetoresistive sensor when the engine is not rotating, the resistance R0 of the giant magnetoresistive sensor under the gradually changing magnetic field when the engine is not rotating is obtained according to Ohm's law:

[0044] R0 = E / I

[0045] Step 3: Make the engine rotate at a preset speed. When the engine rotates at the preset speed for a preset time, it is considered that the tip clearance and the temperature inside the engine tend to be stable at this time. Since the blade deforms when the engine rotates, the tip clearance changes, and then the magnetic field strength of the gradually changing magnetic field changes. Affected by the changed gradually changing magnetic field, the resistance of the giant magnetoresistive sensor changes, so that the voltage signal output by the giant magnetoresistive sensor changes. According to the voltage E output by the giant magnetoresistive sensor when the engine is rotating i , the resistance R of the giant magnetoresistive sensor under the gradually changing magnetic field when the engine is rotating is obtained according to Ohm's law i :

[0046] R i = E i / I (1)

[0047] The relationship between the resistance of the giant magnetoresistive sensor and the change in the magnetic field strength of the gradually changing magnetic field is

[0048] R i = R0 + S * (B(d) - B0) (2)

[0049]

[0050] In the formula, S is the sensitivity of the giant magnetoresistive sensor, B(d) is the magnetic field strength of the gradually changing magnetic field when the tip clearance is d under the condition that the engine is rotating, B0 is the magnetic field strength of the gradually changing magnetic field when the engine is not rotating, which can be directly measured by the Hall sensor when the engine is not rotating, B(d) can also be measured in real time by the Hall sensor, R 原始 is the resistance of the giant magnetoresistive sensor in the absence of a magnetic field, B 饱和 is the magnetic field strength when the magneto - resistive effect of the giant magnetoresistive sensor reaches saturation, which is related to the material, MR is the magnetoresistance ratio, an index used to measure the ability of a magnetic material or device to change resistance under an applied magnetic field, which is related to the material, R 原始 , B 饱和Both the resistance and the magnetoresistance ratio can be obtained by referring to relevant materials. In this embodiment, the giant magnetoresistance sensor adopts a CoFe / Cu multi-layer film and an IrMn pinning layer structure, and the resistance R 原始 is 1000 Ω, the magnetoresistance MR is 0.18, and the magnetic induction intensity B 饱和 is 20 mT. Through calculation, S = 9 is obtained;

[0051] Under the gradient magnetic field, the magnetic field intensity changes non-linearly with the tip clearance. When there is a slight change in the tip clearance, the magnetic field intensity of the gradient magnetic field will mutate, thereby achieving the effect of amplifying microscopic quantities. The relationship between the tip clearance d and the magnetic field intensity B(d) of the gradient magnetic field when the engine rotates is designed as

[0052]

[0053] In the formula, K d is the attenuation coefficient, which is determined through a calibration experiment. The process of determining the attenuation coefficient K d is as follows: When the engine is not rotating, the tip clearance is changed multiple times (simulating deformation through mechanical fine-tuning), and the magnetic field intensity of the gradient magnetic field is measured using a Hall sensor each time the tip clearance is changed, obtaining multiple data pairs (d x , B(d x ))). d x and B(d x ) are the tip clearance and the magnetic field intensity of the gradient magnetic field after the x-th change respectively. Taking the natural logarithm of the gradient magnetic field intensity formula results in a linear relationship Converting the data pair into the form of (ln(B(d x ) / B0), d x ), assuming the linear model is y x = ad x , where y x = ln(B(d x ) / B0), a = -K d . Using each data pair in the form of (ln(B(d x ) / B0), d x ), substituting them into y x = ad x , and calculating a through the least squares method:

[0054]

[0055] Furthermore, the value of K d is obtained, where X is the number of data pairs,

[0056] Step 4. Since the internal temperature is relatively high during engine rotation, the sensitivity of the giant magnetoresistive sensor will be interfered by temperature factors, and the voltage signal value output by the giant magnetoresistive sensor according to its original fixed sensitivity S will be inaccurate. Therefore, it is necessary to perform temperature compensation on the voltage E output by the giant magnetoresistive sensor during engine rotation to obtain the voltage E output by the giant magnetoresistive sensor after temperature compensation during engine rotation. i The temperature compensation is performed to obtain the voltage E output by the giant magnetoresistive sensor after temperature compensation during engine rotation. c It is

[0057] E c = E i [1 + β(T)(T - T0)]

[0058] In the formula, T is the temperature inside the engine, that is, the temperature received by the giant magnetoresistive sensor, which is measured by a temperature sensor. T0 is the reference temperature, and T0 = 25°C is taken. β(T) is the dynamic temperature coefficient.

[0059] Using the voltage E after temperature compensation c to replace the uncompensated voltage E in formula (1), the resistance R of the giant magnetoresistive sensor after temperature compensation during engine rotation can be obtained: i c :

[0060] R c = E i [1 + β(T)(T - T0)] / I (4)

[0061] Among them, since the change in magnetic field intensity will change the electron transport characteristics of the giant magnetoresistive sensor material, resulting in the temperature dependence of the giant magnetoresistive sensor resistance deviating from the ideal linear model, an exponential decay term is introduced to capture the non-linear response under the combined action of magnetic field and temperature and avoid overcompensation in high-temperature environments. The dynamic temperature coefficient β(T) is defined as

[0062]

[0063] In the formula, β0 and λ are the reference temperature coefficient and the decay exponent respectively, both of which are determined by calibration experiments. The determination process of the reference temperature coefficient β0 and the decay exponent λ is as follows: In the absence of a magnetic field, the temperature is controlled to change at intervals of 0.5°C in the range of T0 to T0 + 10°C, the voltage output by the giant magnetoresistive sensor at different temperatures is measured, and the ratio of this voltage to the constant current I is calculated to obtain the resistance R(T). At this time, the exponential decay term model degenerates into a linear form, β(T) ≈ β0, and the exponential decay term has no effect. Then, the value of the reference temperature coefficient β0 can be obtained by fitting the linear relationship , where $R_0$ is the resistance of the giant magnetoresistive sensor without a magnetic field and at the reference temperature, which can be obtained by the ratio of the voltage output by the giant magnetoresistive sensor without a magnetic field and at the reference temperature to the constant current $I$. Since the voltage output by the giant magnetoresistive sensor under constant current conditions is linearly related to the resistance, so $E$ c $= E$ i $[1 + \beta(T)(T - T_0)]$ holds also applies; in this embodiment, $\beta_0 = -0.08\% / ^{\circ}C$ (the negative sign indicates that the resistance decreases as the temperature increases); in the absence of a magnetic field, the temperature is controlled to vary at intervals of $5^{\circ}C$ in the range of $T_0$ to $T_0 + 100^{\circ}C$, and the voltage output by the giant magnetoresistive sensor at different temperatures is measured to obtain the corresponding resistance $R(T)$. At this time, the exponential decay term comes into play. For taking the natural logarithm gives and then substituting the expression of $\beta(T)$ obtained from into to obtain a linear relationship. Based on the resistance $R(T)$ of the giant magnetoresistive sensor at different temperatures and the corresponding temperature data, by fitting this linear relationship, the value of the attenuation exponent $\lambda$ is obtained. In this embodiment, $\lambda = 0.01$.

[0064] Furthermore, since the temperature sensor will produce measurement deviations in high-temperature environments and due to position problems, $n$ temperature sensors ($n = 3$ in this embodiment) are set to measure the temperature $T$ received by the giant magnetoresistive sensor. Then

[0065]

[0066] where $T$ i is the average value of the $m$ temperatures measured by the $i$-th temperature sensor, $W$ i is the weight coefficient of $T$ i , and

[0067]

[0068] is the variance of the $m$ temperatures measured by the $j$-th temperature sensor, $C$ ij is the correlation coefficient between the $i$-th temperature sensor and the $j$-th temperature sensor, which is used to reflect the monotonic correlation between the temperature measured by the $i$-th temperature sensor and the temperature measured by the $j$-th temperature sensor, and $0\leq C$ ij $\leq 1$. If $C$ ij is close to 1, it means that the temperature measured by the $i$-th temperature sensor and the temperature measured by the $j$-th temperature sensor are approaching consistency and the credibility is high. If $C$ ij is close to 0, it indicates that there may be a fault in the $i$-th temperature sensor or the $j$-th temperature sensor, and the credibility of the temperature measured by the $i$-th temperature sensor is low;

[0069] Among them, the correlation coefficient C ij is obtained by using the Spearman rank correlation coefficient algorithm. The calculation process of the correlation coefficient C ij is as follows: Let the temperature data sets measured by the i-th temperature sensor and the j-th temperature sensor be x i and x j respectively, both of which contain m temperature data, that is, x i = [x i1 , x i2 , x i3 , …, x im , x j = [x j1 , x j2 , x j3 …, x jm . Sort the temperature data in the temperature data set x i measured by the i-th temperature sensor from small to large to obtain the rank values corresponding to the temperature data in the temperature data set x i , and form a rank sequence r i , such as r i = [2, 1, 4, 3…]. Sort the temperature data in the temperature data set x j measured by the j-th temperature sensor from small to large to obtain the rank values corresponding to the temperature data in the temperature data set x j , and form a rank sequence r j . Then

[0070]

[0071] In the formula, r ik is the rank value of the k-th temperature data in the temperature data set x i , and r jk is the rank value of the k-th temperature data in the temperature data set x j .

[0072] Step Five: Combine Equation (2), Equation (3) and Equation (4), and use the resistance R c of the giant magnetoresistive sensor after temperature compensation to replace the resistance R i of the uncompensated giant magnetoresistive sensor in Equation (2), to obtain the calculation formula for the tip clearance d during engine rotation. Then, according to the calculated temperature T received by the giant magnetoresistive sensor, the value of the tip clearance d during engine rotation can be calculated; among them, the calculation formula for the tip clearance d during engine rotation is

[0073]

Claims

1. A dynamic measurement method for the change of tip clearance during the rotation of an aeroengine, characterized in that: The details are as follows: Step 1: Arrange a magnetic excitation coil group and a sensor group on the engine casing. The magnetic excitation coil group is composed of multiple coils arranged at axial intervals, and the sensor group is composed of a giant magnetoresistive sensor, a Hall sensor, and n temperature sensors arranged circumferentially around the coils, where n≥3; Step 2: Pass alternating current through each coil. The magnetic fields generated by each coil are superimposed to form a gradually changing magnetic field. At the same time, pass a constant current I through the giant magnetoresistive sensor; obtain the resistance R0 of the giant magnetoresistive sensor under the gradually changing magnetic field when the engine is not rotating through the voltage output by the giant magnetoresistive sensor when the engine is not rotating; Step 3: After the engine rotates at a preset speed for a preset time, obtain the resistance of the giant magnetoresistive sensor under the gradually changing magnetic field during the rotation of the engine through the voltage E output by the giant magnetoresistive sensor when the engine rotates i , and obtain the resistance of the giant magnetoresistive sensor under the gradually changing magnetic field during the rotation of the engine R i = E i / I (1) The relationship between the resistance of the giant magnetoresistive sensor and the magnetic field strength of the gradually changing magnetic field is R i = R0 + S * (B(d) - B0) (2) Wherein, S is the sensitivity of the giant magnetoresistive sensor, B(d) is the magnetic field intensity of the gradually changing magnetic field when the tip clearance is d during the rotation of the engine, B0 is the magnetic field intensity of the gradually changing magnetic field when the engine is not rotating, B(d) and B0 are measured by the Hall sensor, and R 原始 is the resistance of the giant magnetoresistive sensor in the absence of a magnetic field, and B 饱和 is the magnetic field intensity when the magneto - effect of the giant magnetoresistive sensor reaches saturation, and MR is the magnetoresistance ratio; Design the relationship between the tip clearance d and the magnetic field strength B(d) of the gradually changing magnetic field when the engine is rotating as where K d is the attenuation coefficient; Step 4: The voltage E output by the giant magnetoresistive sensor after temperature compensation when the engine rotates c is E c = E i [1 + β(T)(T - T0)] Wherein, T is the temperature received by the giant magnetoresistive sensor, measured by the temperature sensor, T0 is the reference temperature, β(T) is the dynamic temperature coefficient, β0 and λ are the reference temperature coefficient and the attenuation index respectively, T i is the average value of m temperatures measured by the i-th temperature sensor, W i is the weight coefficient of T i , is the variance of m temperatures measured by the j-th temperature sensor, C ij is the correlation coefficient between the i-th temperature sensor and the j-th temperature sensor; Use the temperature-compensated voltage E c to replace the uncompensated voltage E in Equation (1) i , and obtain the resistance R of the giant magnetoresistive sensor after temperature compensation during engine rotation c : R c = E i [1 + β(T)(T - T0)] / I (4) Step 5: Combine equations (2), (3) and (4), and use the resistance R of the giant magnetoresistive sensor after temperature compensation c to replace the resistance R of the uncompensated giant magnetoresistive sensor in equation (2) i to obtain the calculation formula for the tip clearance d during engine rotation.

2. The dynamic measurement method for the change of tip clearance during the rotation of an aero-engine according to claim 1, wherein: The number of turns of each coil decreases sequentially according to the arrangement order; the sensor group is arranged on the engine casing near the magnetic excitation coil group and on the side of the coil with the fewest turns in the magnetic excitation coil group.

3. A dynamic measurement method for the change of tip clearance during the rotation of an aero-engine according to claim 2, characterized in that: The magnitude of the current passed through each coil decreases as the number of turns decreases.

4. A dynamic measurement method for the change in tip clearance during the rotation of an aero-engine according to claim 1, characterized in that: The attenuation coefficient K d The measurement process is as follows: When the engine is not rotating, the tip clearance is changed multiple times, and a Hall sensor is used to measure the magnetic field strength of the gradually changing magnetic field each time the tip clearance is changed, obtaining multiple data pairs (d x ,, B(d x ))), where d x and B(d x ) are the tip clearance and the magnetic field strength of the gradually changing magnetic field after the x-th change respectively. Taking the natural logarithm of the formula for the magnetic field strength of the gradually changing magnetic field , a linear relationship is obtained. Convert each data pair (d x ,, B(d x )) into the form of (ln(B(d x ) / B0), d x ). Let the linear model be y x =ad x , where y x =ln(B(d x ) / B0), a=-K d . Substitute each data pair in the form of (ln(B(d x ) / B0), d x ) into y x =ad x , and calculate a by the least squares method: and then obtain the value of K d where X is the number of data pairs 5. A dynamic measurement method for the tip clearance change during the rotation of an aero-engine according to claim 1, characterized in that: The measurement process of the reference temperature coefficient β0 and the attenuation exponent λ is as follows: In the absence of a magnetic field, the temperature is controlled to vary at intervals of 0.5 °C in the range of T0 to T0 + 10 °C, the voltage output by the giant magnetoresistive sensor at different temperatures is measured, and the ratio of this voltage to the constant current I is calculated to obtain the resistance R(T). At this time, β(T) = β0 is taken, and the reference temperature coefficient β0 is obtained by fitting the linear relationship , where is the resistance of the giant magnetoresistive sensor without a magnetic field and at the reference temperature; in the absence of a magnetic field, the temperature is controlled to vary at intervals of 5 °C in the range of T0 to T0 + 100 °C, the voltage output by the giant magnetoresistive sensor at different temperatures is measured to obtain the corresponding resistance R(T), and is taken the natural logarithm to obtain Then, the expression of β(T) obtained from is substituted into to obtain a linear relationship. Based on the resistance R(T) of the giant magnetoresistive sensor at different temperatures and the corresponding temperature data, the value of the attenuation exponent λ is obtained by fitting this linear relationship.

6. The dynamic measurement method for the change of tip clearance during the rotation of an aero-engine according to claim 1, wherein: The correlation coefficient C ij is calculated as follows: Assume that the temperature data sets measured by the i-th temperature sensor and the j-th temperature sensor are x i =[x i1 , x i2 , x i3 , …, x im and x j =[x j1 , x j2 , x j3 …, x jm , both containing m temperature data; sort the temperature data in the temperature data set x i measured by the i-th temperature sensor from smallest to largest, and obtain the rank values corresponding to the temperature data in the temperature data set x i to form a rank sequence r i ; sort the temperature data in the temperature data set x j measured by the j-th temperature sensor from smallest to largest, and obtain the rank values corresponding to the temperature data in the temperature data set x j to form a rank sequence r j , then where r ik is the rank value of the k-th temperature data in the temperature data set x i , and r jk is the rank value of the k-th temperature data in the temperature data set x j .

7. A dynamic measurement method for the change in tip clearance during the rotation of an aeroengine according to claim 1, characterized in that: The calculation formula for the tip clearance d when the engine is rotating is

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