Response bandwidth measuring device and method for a capacitance-based tip clearance measurement system based on varactor diodes

Abstract

The application discloses a response bandwidth measuring device and method of a capacitance type blade tip clearance measuring system based on a varactor, the capacitance type blade tip clearance measuring system is composed of a capacitance sensor, a measuring system host and an upper computer which are sequentially connected, the measuring system host comprises a signal demodulation module and an acquisition module, the capacitance sensor is composed of a sensor probe and a three coaxial cable which are connected with each other, the response bandwidth measuring device is connected with the three coaxial cable through an SMA joint after replacing the sensor probe, and a varactor is adopted to simulate the capacitance change caused by the blade tip sweeping through the capacitance sensor probe; the response bandwidth measuring device is composed of a varactor D, a resistor R1, a capacitor C1 and a capacitor C2; the two ends of the capacitor C2 connected in parallel with the varactor D are connected with the resistor R1 and the capacitor C1 in series respectively, the capacitor C1 is connected with the three coaxial cable, and the input end of the response bandwidth measuring device is connected with the resistor R1.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tip clearance measurement, in particular to a capacitive tip clearance measurement system bandwidth measurement device and design method. BACKGROUND

[0002] In rotating machinery such as aero-engines, gas turbines, steam turbines, etc., the small distance between the rotor blade tip and the inner wall of the casing is called tip clearance, which is one of the important parameters affecting the performance of rotating machinery. Tip clearance measurement technology is of great significance to improve the performance of rotating machinery and ensure the safe operation of rotating machinery. The capacitive tip clearance measurement method is widely used in engineering test of tip clearance due to its advantages of high temperature resistance, corrosion resistance, low intervention, non-contact, online, real-time, etc.

[0003] The capacitive tip clearance measurement system is composed of a capacitive sensor, a cable, a gap signal demodulation module, an acquisition and processing module, and a host computer software. Based on the parallel plate capacitor principle, the tip clearance is measured by measuring the capacitance between the sensor core and the rotor blade tip. In order to ensure the measurement accuracy and resolution of the blade rotating at the highest speed, the measurement system requires a high response bandwidth. Therefore, how to accurately measure the system response bandwidth becomes a key problem to be solved.

[0004] In order to measure the response bandwidth of the system, different frequency test signals are generally generated to simulate the system input, and the amplitude change of the system output signal is observed. However, the input signal of the capacitive tip clearance measurement system is the capacitance signal between the sensor core and the rotor blade, and the existing devices and methods cannot generate standard capacitance signals to simulate system input. If the voltage test signal is used as the input signal, the system capacitance-voltage conversion process will be ignored, resulting in low measurement accuracy of the system response bandwidth. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art, such as the inability to generate standard capacitance signals to simulate system input, and the direct use of standard voltage signals as input which ignores the influence of system capacitance-voltage conversion on response bandwidth, resulting in low measurement accuracy of response bandwidth. The present application provides a measurement device and method that can directly generate standard capacitance signals to achieve high-precision measurement of system response bandwidth.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] The application discloses a response bandwidth measuring device of a capacitance type blade tip clearance measuring system based on a varactor, and the capacitance type blade tip clearance measuring system is composed of a capacitance sensor, a measuring system host and an upper computer which are sequentially connected.

[0008] The signal demodulation module demodulates the blade tip clearance signal output by the capacitance sensor and converts the blade tip clearance signal into a voltage signal; the acquisition module collects and preliminarily processes the voltage signal and transmits data to the upper computer; the upper computer further processes the data to obtain a blade tip clearance value, and simultaneously performs data storage and numerical display.

[0009] The response bandwidth measuring device is used to replace the sensor probe and is connected to the long three-coaxial cable through an SMA joint, and a varactor is used to simulate the capacitance change caused by the blade tip sweeping the capacitance sensor probe; the response bandwidth measuring device is composed of a varactor D, a resistor R1, a first capacitor C1 and a second capacitor C2; the two ends of the second capacitor C2 in parallel connection with the varactor D are respectively connected with the resistor R1 and the first capacitor C1 in series connection, the first capacitor C1 is connected with the long three-coaxial cable, and the input end of the response bandwidth measuring device is connected with the resistor R1.

[0010] Further, the input voltage V of the response bandwidth measuring device is V=V0+V', wherein V0 is a direct current voltage, and V' is a sinusoidal alternating current voltage with a frequency of f, and the capacitance of the varactor D changes with the change of the voltage.

[0011] Further, the resistor R1 plays a role of protecting the power supply and prevents the power supply from being short-circuited to the ground when the varactor D is broken down, and the value range of the resistor R1 is 1-10kΩ.

[0012] Further, the first capacitor C1 and the second capacitor C2 are used as a voltage dividing capacitor, and the capacitance value of the whole response bandwidth measuring device is adjusted by changing the capacitance values of the first capacitor C1 and the second capacitor C2; the first capacitor C1 also has a direct current isolation function.

[0013] Further, under the input of the voltage V, the varactor D is equivalent to a capacitor C xand the capacitance AC x in parallel, where C x is determined by the DC voltage Vo, AC x varies with the sinusoidal AC voltage V', the variation frequency of AC x is the frequency f of the sinusoidal AC voltage V', and the capacitance of the varactor diode D varies linearly in the range [-Δ, Δ];

[0014] The capacitance value C TEST of the circuit in the response bandwidth measurement device is:

[0015]

[0016] Let the capacitance C0=C x +C2, then

[0017] Further, the selection of the first capacitance C1 and the second capacitance C2 includes:

[0018] 1) To realize long cable signal transmission, the measurement system host connects an AC voltage V1' with a frequency f1 between the core and the shell of the three coaxial cables, the frequency and amplitude of V1' are determined by the signal demodulation module and cannot be eliminated, to reduce the interference of the AC voltage V1' on the bandwidth measurement, the values of the first capacitance C1 and the second capacitance C2 are adjusted to make the effect of the AC voltage V1' less than 1 / 10 of the effect of the input voltage V, so the sum of the capacitance C0 and the variable capacitance AC x of the varactor diode is greater than 10 times the capacitance value of the first capacitance C1, that is:

[0019] C0+ΔC x >10C1

[0020] 2) Increase the variable capacitance AC x of the varactor diode D to increase the influence on C TEST , let AC x ∈[-Δ, Δ], Δ>0, and let then:

[0021]

[0022] If the change amount of C TEST takes the maximum value, the value of C needs to be increased, and the value of C also needs to be increased;

[0023] 3) The capacitance type tip clearance measurement system requires that the capacitance change amount before and after the simulated blade sweeps the sensor probe be 0pF TEST |C TEST =C TEST，max C TEST，min , then:

[0024]

[0025] Derivation C TEST The relationship with the change of C1 is:

[0026]

[0027] Since C0>>Delta, therefore That is, increase the value of C1;

[0028] Derivation C TEST The relationship with the change of C0 is:

[0029]

[0030] Therefore, reduce the value of C0;

[0031] Derivation C TEST The relationship with the change of Delta is:

[0032]

[0033] Therefore, increase the value of Delta;

[0034] Before carrying out the response bandwidth measurement experiment, the maximum value of the capacitance change in the process of the blade sweeping through the sensor probe is estimated, so as to select the values of C1 and C2.

[0035] The application also provides a measurement method based on the response bandwidth measurement device, comprising:

[0036] The response bandwidth measurement device is used to measure the bandwidth of the capacitive blade tip clearance measurement system, the response bandwidth measurement device generates a variable capacitance test signal with different frequencies, the signal is transmitted to the signal demodulation module through a long three coaxial cable to output a voltage signal, then the corresponding output voltage signal is collected and stored, finally the amplitudes of the output signals under different frequencies are compared, and the bandwidth of the blade tip clearance measurement system is obtained.

[0037] Further, the specific steps are as follows:

[0038] S1. Install and debug the experimental equipment to be measured;

[0039] S2. Select N different frequency points to be measured in the frequency band range to be measured set on the experimental equipment to be measured;

[0040] S3. Adjust the control signal frequency of the response bandwidth measurement device in turn to the frequencies of the N frequency points to be measured, record the output voltage of the signal demodulation module under different test frequencies, compare the output signal amplitude, when the output signal amplitude decreases to 0.707 times of the maximum amplitude, the upper limit value minus the lower limit value of the frequency obtained is the bandwidth of the tip clearance measurement system; if the signal amplitude output by the experimental equipment to be measured meets the requirements, the bandwidth of the experimental equipment to be measured is the selected working frequency band range, if the amplitude does not meet the requirements, the bandwidth of the experimental equipment to be measured is less than the working frequency band range, and the experimental equipment to be measured does not meet the requirements.

[0041] Compared with the prior art, the technical scheme of the present application has the beneficial effects that:

[0042] 1. Improve measurement accuracy: the present application directly generates a standard capacitance signal as input, avoiding errors in the capacitance-voltage conversion process in traditional methods, thereby significantly improving the accuracy of system response bandwidth measurement.

[0043] 2. Enhance adaptability: the device and method can be applied to various types of capacitive tip clearance measurement systems, widely applicable to tip clearance measurement in rotating machinery such as aero-engines, gas turbines, steam turbines, etc., improving the system's scope of application and practicality.

[0044] 3. Simplify the measurement process: the measurement method of the present application simplifies the process of response bandwidth measurement, eliminating the need for additional conversion devices or complex signal processing procedures, making the measurement process more intuitive and efficient.

[0045] 4. Real-time online measurement: the measurement device and method of the present application support real-time online measurement, enabling dynamic monitoring of tip clearance changes during rotating machinery operation, ensuring safe operation of the rotating machinery.

[0046] 5. Improve system stability: since the present application directly generates a standard capacitance signal to simulate system input, avoiding the system instability problem caused by conversion errors in traditional methods, the overall measurement system's stability and reliability are improved. The generated standard capacitance signal frequency is adjustable, and the amplitude is adjustable.

[0047] 6. Economical and efficient: the device of the present application is designed reasonably, with simple structure, easy miniaturization, convenient portability, which can effectively reduce the overall cost of the system, improve the measurement efficiency and the convenience of system maintenance. And can be designed according to user needs and application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 A schematic diagram of a capacitive tip clearance measurement system is shown.

[0049] Figure 2 A structure principle diagram of the response bandwidth measurement device in the present application is shown.

[0050] Figure 3 The equivalent circuit diagram of the response bandwidth measuring device in the application is shown.

[0051] Figure 4 The bandwidth measuring scheme diagram of the tip clearance measurement system in the application is shown.

[0052] Figure 5 The bandwidth measuring flowchart of the tip clearance measurement system in the application is shown.

[0053] The figure mark: 1-capacitance sensor, 11-sensor probe, 12-three coaxial cable, 13-SMA joint, 2-measuring system host, 21-signal demodulation module, 22-acquisition module, 3-upper computer, 4-response bandwidth measuring device DETAILED DESCRIPTION

[0054] The application will be further described in detail below in combination with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0055] The embodiment provides a response bandwidth measuring device of a capacitance type tip clearance measurement system based on a varactor, the capacitance type tip clearance measurement system is composed of a capacitance sensor 1, a measuring system host 2 and an upper computer 3 connected in sequence, as shown in Figure 1 The measuring system host 2 comprises a signal demodulation module 21 and an acquisition module 22; the capacitance sensor 1 is composed of a sensor probe 11 and a three coaxial cable 12 connected with each other, the three coaxial cable 12 comprises two sections of long and short, the short section of the three coaxial cable is fixed at the tail of the sensor probe 11 and is connected with the long section of the three coaxial cable through an SMA joint, so that the three coaxial cable can be applied to different sensor probes 11; the measurement is based on the flat plate capacitance principle, the core pole of the sensor probe 11 constitutes one pole plate of the variable capacitance, the rotating blade constitutes another pole plate of the variable capacitance, the tip clearance signal is obtained by measuring the capacitance change between the two pole plates, and the tip clearance signal obtained by the sensor probe 11 is transmitted to the measuring system host 2 through the three coaxial cable 12.

[0056] The signal demodulation module 21 in the measuring system host 2 demodulates the variable capacitance signal output by the capacitance sensor 1, converts the capacitance signal into a voltage signal; the acquisition module 22 collects and preliminarily processes the voltage signal and transmits the data to the upper computer 3; the upper computer 3 further processes the data, calculates the tip clearance value, and simultaneously stores and displays the data value.

[0057] The response bandwidth measuring device 4 of the capacitance type tip clearance measurement system in the application adopts a varactor to simulate the capacitance change caused by the rotating blade tip sweeping the capacitance sensor probe, and the device structure principle is as shown inFigure 2 As shown, the response bandwidth measuring device 4 mainly consists of a varactor diode D, a resistor R1, and capacitors C1 and C2. After replacing the sensor probe, the response bandwidth measuring device 4 is connected to a long section of three-coaxial cable via an SMA connector. The varactor diode simulates the capacitance change caused by the tip of a rotating blade sweeping across the capacitance sensor probe. The response bandwidth measuring device consists of a varactor diode D, a resistor R1, and capacitors C1 and C2. The two ends of capacitor C2, connected in parallel with the varactor diode D, are connected in series with resistor R1 and capacitor C1, respectively. Capacitor C1 is connected to the long section of three-coaxial cable. The input terminal of the response bandwidth measuring device is connected to resistor R1. V = V0 + V′ is the input voltage of the response bandwidth measuring device 4, where V0 is a DC voltage to ensure the varactor diode is in reverse bias; V′ is a sinusoidal AC voltage with frequency f, controlling the capacitance of the varactor diode D to change with the voltage. Resistor R1 protects the power supply, preventing short circuit to ground when the varactor diode D is damaged. A value of 1kΩ or 10kΩ can be selected.

[0058] Preferably, capacitors C1 and C2 are used as voltage divider capacitors, and the overall capacitance value of the response bandwidth measuring device is adjusted by changing the capacitance values ​​of C1 and C2. Capacitor C1 also has a DC blocking function.

[0059] When selecting a varactor diode D, a model with a larger linear operating region and stronger voltage withstand capability should be preferred. Under an input voltage V, the varactor diode D is equivalent to a capacitor C. x and changing capacitance ΔC x Parallel connection, such as Figure 3 As shown, the capacitor C x Determined by the DC voltage V0, ΔC x ΔC varies with the alternating current voltage V′. x The frequency of change is the frequency f of the AC voltage V′, and the linear range of the capacitance of the varactor diode is [-Δ, Δ].

[0060] Calculate along the direction of the arrow Figure 3 The capacitance value C of the response bandwidth measurement device TEST for:

[0061]

[0062] Let C0 = C x +C2, then

[0063] Specifically, the selection of capacitors C1 and C2 in a varactor diode-based response bandwidth measurement device needs to consider the following points:

[0064] 1) To achieve long cable signal transmission, the measurement system host connects an AC voltage V1′ with frequency f1 between the core and the outer shell of the triaxial cable. The frequency and amplitude of V1′ are determined by the signal demodulation module and cannot be eliminated. To reduce the interference of AC voltage V1′ on bandwidth measurement, the values ​​of capacitors C1 and C2 are adjusted so that the effect of AC voltage V1′ is less than 1 / 10 of the effect of input voltage V. Therefore, the capacitance C0 and the change in capacitance ΔC of the varactor diode are also affected. x The sum of these values ​​is greater than 10 times the capacitance value of the first capacitor C1, that is:

[0065] C0+ΔC x >10C1

[0066] 2) Change the capacitance ΔC of the varactor diode. x As large as possible, so that it can affect C TEST It has a significant impact. Let ΔC x ∈[-Δ, Δ], Δ>0, we can assume but:

[0067]

[0068] If C TEST If the change is taken to its maximum value, then it is necessary to Take as large a value as possible, and at the same time Take as large a value as possible.

[0069] 3) The capacitive tip clearance measurement system requires simulating the capacitance change before and after the blade sweeps across the capacitive sensor probe: 0 pF < |C TEST |<1pF, where C TEST =C TEST，max -C TEST，min ,,but:

[0070]

[0071] Derivation of C TEST Relationship with C1:

[0072]

[0073] Since C0 >> Δ, therefore That is, the value of C1 should be as large as possible.

[0074] Derivation of C TEST Relationship with C0:

[0075]

[0076] Therefore, the value of C0 should be as small as possible.

[0077] Derivation of C TEST Relationship with Δ:

[0078]

[0079] Therefore, the value of Δ should be as large as possible.

[0080] Before the response bandwidth measurement experiment is carried out, the maximum value of the capacitance change during the blade sweeping through the capacitance sensor probe is estimated, so as to select the values of C1 and C2.

[0081] When the gap value is 0.5 mm, the capacitance change C TEST In about 0.28 pF, the linear working region Δ of the selected variable capacitance diode is 20 pF, and C x = 60 pF. Based on the common capacitance standard value, C1 = 22 pF and C2 = 181 pF are selected, and C TEST = 0.2815 pF is calculated.

[0082] The response bandwidth measurement device 4 of the embodiment is used to measure the bandwidth of the capacitive blade tip gap measurement system, and a system bandwidth measurement scheme is shown in Figure 4 The response bandwidth measurement device 4 based on the variable capacitance diode can generate variable capacitance test signals of different frequencies, which are transmitted to the signal demodulation module 21 through the three coaxial cables 12 to output voltage signals. The output voltage signals are collected and stored, the amplitudes of the output signals at different frequencies are compared, and the bandwidth of the blade tip gap measurement system is obtained.

[0083] Specifically, the bandwidth measurement experiment process of the capacitive blade tip gap measurement system is shown in Figure 5 The experimental equipment to be measured is installed and debugged. It is assumed that there are 13 frequency points to be measured, 5 Hz and 230 kHz are selected as the frequency test points, and 11 other test points are selected as 100 Hz, 1 kHz, 10 kHz, 30 kHz, 50 kHz, 70 kHz, 101 kHz, 121 kHz, 151 kHz, 181 kHz and 202 kHz. The control signal frequency of the response bandwidth measurement device 4 based on the variable capacitance diode is adjusted, the output voltage of the signal demodulation module 21 at the above different test frequencies is recorded, the amplitudes of the output signals are compared, and the bandwidth of the blade tip gap measurement system is obtained. If the amplitude of the signal output by the experimental equipment to be measured meets the requirements, the bandwidth of the experimental equipment to be measured is the selected working frequency band range, if the amplitude does not meet the requirements, the bandwidth of the experimental equipment to be measured is less than the working frequency band range, and the experimental equipment to be measured does not meet the requirements.

[0084] The present application is not limited to the above-described embodiments. The above description of the specific embodiments is intended to describe and illustrate the technical solutions of the present application, and the specific embodiments described above are merely illustrative and are not restrictive. Without departing from the purpose of the present application and the scope protected by the claims, those of ordinary skill in the art can make many forms of specific changes under the inspiration of the present application, and these all belong to the protection scope of the present application.

Claims

1. A response bandwidth measurement device for a variable capacitance diode-based capacitive tip clearance measurement system, the capacitive tip clearance measurement system being composed of a capacitive sensor, a measurement system host and an upper computer connected in sequence, the measurement system host comprising a signal demodulation module and an acquisition module, the capacitive sensor being composed of a sensor probe and a triaxial cable connected to each other, the triaxial cable comprising a long section and a short section, the triaxial cable of the short section being fixed to the tail of the sensor probe and connected to the triaxial cable of the long section through an SMA joint, so as to apply the triaxial cable to different capacitive sensor probes; the measurement is based on the principle of flat plate capacitance, the core of the sensor probe constitutes one plate of the variable capacitor, the rotating blade constitutes the other plate of the variable capacitor, the tip clearance signal is obtained by measuring the capacitance change between the two plates, and the tip clearance signal obtained by the sensor probe is transmitted to the measurement system host through the triaxial cable; the signal demodulation module demodulates the tip clearance signal output by the capacitive sensor, and converts the tip clearance signal into a voltage signal; the acquisition module acquires and preliminarily processes the voltage signal, and transmits the data to the upper computer; the upper computer further processes the data to obtain the tip clearance value, and simultaneously stores and displays the data; characterized in that, the response bandwidth measurement device is used to replace the sensor probe and is connected to the triaxial cable of the long section through the SMA joint, and a variable capacitance diode is used to simulate the capacitance change caused by the rotating blade tip sweeping the capacitive sensor probe; the response bandwidth measurement device is composed of a variable capacitance diode D, a resistor R1, a first capacitor C1 and a second capacitor C2; the two ends of the second capacitor C2 in parallel connection with the variable capacitance diode D are respectively connected in series with the resistor R1 and the first capacitor C1, the first capacitor C1 is connected to the triaxial cable of the long section, and the input end of the response bandwidth measurement device is connected to the resistor R1.

2. The response bandwidth measuring device for a varactor-diode-based capacitive tip-turbine-blade-clearance measuring system according to claim 1, characterized in that The input voltage V of the response bandwidth measurement device is V=V0+V', wherein V0 is a direct current voltage, which ensures that the variable capacitance diode D is in a reverse bias state; V' is a sinusoidal alternating current voltage, the frequency of which is f, and the capacitance of the variable capacitance diode D changes with the change of the voltage.

3. The response bandwidth measuring device for a varactor-diode-based capacitive tip-turbine-blade-clearance measuring system according to claim 1, characterized in that The resistor R1 plays a role in protecting the power supply, preventing the power supply from being short-circuited to the ground when the variable capacitance diode D is broken down, and the value range is 1-10 kΩ.

4. The response bandwidth measuring device for a varactor-diode-based capacitive tip-turbine-shroud-clearance measuring system according to claim 1, characterized in that The first capacitor C1 and the second capacitor C2 are used as a voltage dividing capacitor, and the capacitance value of the whole response bandwidth measurement device is adjusted by changing the capacitance values of the first capacitor C1 and the second capacitor C2; the first capacitor C1 also has a direct current blocking function.

5. The response bandwidth measuring device for a varactor-diode-based capacitive tip-turbine-blade-clearance measuring system according to claim 1, characterized in that Under the input of voltage V, the varactor D is equivalent to a capacitor C x in parallel with a capacitor ΔC x , where C x is determined by a direct current voltage V0, and ΔC x varies with the change of a sinusoidal alternating voltage V', and the change frequency of ΔC x is the frequency f of the sinusoidal alternating voltage V', and the linear change range of the capacitor of the varactor D is [-Δ, Δ]. The capacitance value C of the circuit in the response bandwidth measuring device TEST is: Let the capacitance Co = C x + C2, then 6. The response bandwidth measuring device for a varactor-diode-based capacitive tip-turbine-blade-clearance measuring system according to claim 5, characterized in that The selection of the first capacitor C1 and the second capacitor C2 includes: 1) To achieve long cable signal transmission, the measurement system host connects an AC voltage V1′ with frequency f1 between the core and the outer shell of the triaxial cable. The frequency and amplitude of V1′ are determined by the signal demodulation module and cannot be eliminated. To reduce the interference of AC voltage V′1 on bandwidth measurement, the values ​​of the first capacitor C1 and the second capacitor C2 are adjusted so that the effect of AC voltage V′1 is less than 1 / 10 of the effect of input voltage V. Therefore, the capacitance C0 and the change in capacitance ΔC of the varactor diode are also affected. x The sum of these values ​​is greater than 10 times the capacitance value of the first capacitor C1, that is: C0 + ΔC x >10 C1 2) the varying capacitance AC of the varicap D x is increased, increasing the influence on C TEST ; AC is x ∈ [-Δ, Δ], Δ > 0, let then: If the change amount of C TEST takes the maximum value, the value of C needs to be increased, and the value of C needs to be increased simultaneously. 3) Capacitive tip clearance measurement systems require a change in capacitance of 0 pF < |C TEST |<1 pF, where C TEST = C TTEST，max - C TEST，min Then: Derivation C TEST Relationship with changes in C1: Since Co » Δ, therefore That is, increase the value of Ci; Derivation C TEST Relationship with changes in C0: Therefore, the value of C0 is reduced; Derivation C TEST With respect to the change in Δ: Therefore, the value of Δ is increased; Before carrying out the response bandwidth measurement experiment, the maximum value of the capacitance change in the process of the blade sweeping the sensor probe is estimated, so as to select the values of C1 and C2.

7. A measuring method based on the response bandwidth measuring apparatus according to any one of claims 1 to 6, characterized by, including: The bandwidth of the capacitive tip clearance measurement system is measured by a response bandwidth measurement device, the response bandwidth measurement device generates a variable capacitance test signal of different frequencies, the signal is transmitted to a signal demodulation module through a long three coaxial cable to output a voltage signal, then the corresponding output voltage signal is collected and stored, finally the amplitudes of the output signals at different frequencies are compared to obtain the bandwidth of the tip clearance measurement system.

8. The measurement method of the response bandwidth measurement apparatus according to claim 7, wherein The specific steps are as follows: S1. Install and debug the experimental equipment to be tested; S2. Select N different frequency points in the frequency band range to be tested on the experimental equipment to be tested; S3. Adjust the control signal frequency of the response bandwidth measurement device to the frequency of the N frequency points to be tested in turn, record the output voltage of the signal demodulation module at different test frequencies, compare the output signal amplitude, when the output signal amplitude is reduced to 0.707 times of the maximum amplitude, the upper limit value minus the lower limit value is the bandwidth of the tip clearance measurement system; if the signal amplitude output by the experimental equipment to be tested meets the requirements, the bandwidth of the experimental equipment to be tested is the selected working frequency band range, if the amplitude does not meet the requirements, the bandwidth of the experimental equipment to be tested is less than the working frequency band range, and the experimental equipment to be tested does not meet the requirements.

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