Response bandwidth measuring device and method for capacitive tip clearance measurement system based on bipolar plate rotating structure

Abstract

This invention discloses a response bandwidth measurement device and method for a capacitive blade tip clearance measurement system based on a bipolar plate rotating structure. The blade tip clearance measurement system consists of a capacitive sensor, a measurement system host, and a host computer connected in sequence. The measurement system host includes a signal demodulation module and a data acquisition module. The response bandwidth measurement device includes a sensitive plate, a receiving plate, a rotating stage, a displacement stage, and a DC blocking capacitor. The rotating stage includes a rotating shaft, a mounting base, and a controller. The controller controls the rotational speed of the rotating shaft and displays the speed in real time. A displacement stage is sleeved on a support rod on the mounting base. The rotating shaft is rotatably mounted on the mounting base. The sensitive plate is fixed on the rotating shaft as a rotating component. The receiving plate is mounted and fixed on the displacement stage and located above the sensitive plate. The distance between the receiving plate and the sensitive plate is changed by adjusting the height of the displacement stage. The receiving plate is connected in sequence to the DC blocking capacitor and the core of a triaxial cable.

Description

Technical Field

[0001] This invention relates to the field of blade tip clearance measurement, and more particularly to a bandwidth measurement device and design method for a capacitive blade tip clearance measurement system based on a bipolar plate rotating structure. Background Technology

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

[0003] The capacitive blade tip clearance measurement system consists of a capacitive sensor, cable, clearance signal demodulation module, acquisition and processing module, and host computer software. Based on the principle of parallel plate capacitors, it measures the blade tip clearance by measuring the capacitance between the sensor core and the rotor blade tip. Since the capacitive blade tip clearance measurement system is an online measurement, a high response bandwidth is required to ensure measurement accuracy and resolution when the blade rotates to its maximum speed. Therefore, accurately measuring the system's response bandwidth is a critical problem that urgently needs to be solved.

[0004] To measure the system response bandwidth, test signals of different frequencies are typically generated to simulate the system input, while the amplitude changes of the system output signal are observed. However, the input signal of a capacitive blade tip clearance measurement system is the changing capacitance signal between the sensor core and the rotor blade. Existing devices and methods cannot generate a standard capacitance signal to simulate the system input. If a voltage test signal is used as the input signal, the capacitance-voltage conversion process of the system will be ignored, resulting in low accuracy in measuring the system response bandwidth. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing devices and methods, such as the inability to generate standard capacitance signals to simulate system inputs, and the neglect of the influence of system capacitance-voltage conversion on response bandwidth when using standard voltage signals as inputs, resulting in low measurement accuracy of response bandwidth. This invention provides a measurement device and method that can directly generate standard capacitance signals and achieve high-precision measurement of system response bandwidth.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A response bandwidth measurement device for a capacitive blade tip clearance measurement system based on a bipolar rotating structure is disclosed. The capacitive blade tip clearance measurement system consists of a capacitive sensor, a measurement system host, and a host computer connected in sequence. The measurement system host includes a signal demodulation module and a data acquisition module. The capacitive sensor consists of interconnected sensor probes and a three-coaxial cable. The three-coaxial cable includes two sections, one long and one short. The short section of the three-coaxial cable is fixed to the tail of the sensor probe and connected to the long section of the three-coaxial cable via an SMA connector, so that the three-coaxial cable can be applied to different capacitive sensor probes. The measurement is based on the principle of a parallel plate capacitor. The core of the sensor probe forms one plate of a variable capacitor, and the rotating blade forms the other plate of the variable capacitor. The blade tip clearance signal is obtained by measuring the capacitance change between the two plates. The blade tip clearance signal obtained by the sensor probe is transmitted to the measurement system host via the three-coaxial cable.

[0008] The signal demodulation module demodulates the blade tip gap signal output by the capacitive sensor, converting it into a voltage signal; the acquisition module acquires and performs preliminary processing on the voltage signal, and transmits the data to the host computer; the host computer further processes the data to obtain the blade tip gap value, and simultaneously stores and displays the value.

[0009] Replace the sensor probe with a response bandwidth measuring device and connect it to a long section of triaxial cable via an SMA connector;

[0010] The response bandwidth measuring device consists of a sensitive electrode, a receiving electrode, a rotating stage, a displacement stage, and a DC blocking capacitor.

[0011] The rotary table includes a rotating shaft, a mounting base, and a controller. The controller controls the rotational speed of the rotating shaft and displays the current rotational speed in real time. A support rod is provided on the mounting base, and the displacement table is movably sleeved on the support rod. The rotating shaft is rotatably located in the middle of the mounting base.

[0012] The sensitive electrode plate, as a rotating component, is fixed on the rotating shaft and is constructed from a PCB board.

[0013] The receiving electrode plate is mounted and fixed on the displacement stage and located above the sensitive electrode plate. It is made of PCB board. The distance between the receiving electrode plate and the sensitive electrode plate can be changed by adjusting the height of the displacement stage.

[0014] The surfaces of the receiving electrode and the sensitive electrode opposite each other are covered with a copper conductive layer, which respectively constitutes the receiving electrode and the sensitive electrode. The rest is an insulating layer. The sensitive electrode is grounded, and the receiving electrode is connected in sequence to the core of the DC blocking capacitor and the long section of the triaxial cable.

[0015] The sensitive electrode forms one pole of the variable capacitor, and the receiving electrode forms the other pole. During the rotation of the sensitive plate, the area between the two electrodes changes, causing a change in the capacitance of the response bandwidth measuring device. The shapes of the sensitive electrode and the receiving electrode are designed so that the change in capacitance between the plates is a standard sinusoidal signal.

[0016] Furthermore, an even number of sensitive electrodes are provided on the conductive layer of the sensitive electrode plate, and the inner diameter of the sensitive electrode plate is R. si The outer diameter is R so R1 and R2 are the edges of the sensitive electrodes, and the portion between R1 and R2 is the sensitive electrode itself, forming an even number of petal-shaped structures. The remaining portion is an insulating layer. R1 and R2 can be represented by polar coordinate equations as follows:

[0017] R1 = R + τ[sin(Nφ) + 1]

[0018] R² = R - τ[sin(Nφ) + 1

[0019] Where R is the radius of the reference circle that can separate the two sine waves formed by R1 and R2; N is the number of petal-shaped structures of the sensitive electrode; τ is the amplitude of the sine signal superimposed on the reference circle; φ represents the rotation angle of the rotor relative to the stator, φ=ωt, ω is the rotational angular velocity of the rotor;

[0020] To ensure the integrity of the sensitive electrode plate, the inner diameter R of the sensitive electrode plate... si >R+2τ, outer diameter R of the sensitive electrode so >R+2τ.

[0021] Furthermore, an even number of receiving electrodes are provided on the conductive layer of the receiving plate, and the inner diameter of the receiving plate is R. ri The outer diameter is R ro The receiving electrode is shaped like a fan ring, with an inner diameter of R3, an outer diameter of R4, and a central angle of λ.

[0022] To ensure the integrity of the receiving electrode, the inner diameter R of the receiving electrode plate... ri <R3, outer diameter R of the receiving electrode ri >R4.

[0023] Furthermore, mechanical vibration and rotor tilt can cause a change in the distance d between the sensitive electrode and the receiving electrode, Δd. An even number of receiving electrodes are uniformly distributed on the conductive layer of the receiving electrode, with each pair of receiving electrodes facing each other along the diameter. Let the area of ​​a single receiving electrode be S, then the capacitance C between each pair of receiving electrodes and the sensitive electrode is:

[0024]

[0025] Ignore (Δd) 2By utilizing the averaging effect of several receiving electrodes, the error introduced by the change in the distance d between the sensitive electrode and the receiving electrode is reduced.

[0026] Furthermore, to ensure that the signals received by the multiple receiving electrodes are in phase, the number of receiving electrodes M is an approximation of the number of sensitive electrodes N.

[0027] Furthermore, the central angle of the sector ring of each receiving electrode Calculate the overlap area between the receiving electrode and the sensing electrode. The formula for the sector area in polar coordinates is given. Where r(θ) is the radius of the sector and θ is the central angle, then the overlapping area is:

[0028]

[0029] The overlapping area S between the plates rs The capacitance C between the receiving electrode and the sensing electrode is calculated as follows:

[0030]

[0031] Where d is the distance between the sensitive electrode and the receiving electrode; φ represents the rotation angle of the rotor relative to the stator, φ=ωt, ω is the rotational angular velocity of the rotor; N is the number of petal-shaped structures of the sensitive electrode; R1 and R2 are the edges of the sensitive electrode; M is the number of receiving electrodes; τ is the amplitude of the sinusoidal signal superimposed on the reference circumference.

[0032] Once the shapes of the receiving and sensing electrodes are determined, the DC component is isolated by the DC blocking capacitor C1, leaving a sinusoidal signal with an amplitude of [value missing]. Frequency is

[0033] Before conducting the response bandwidth measurement experiment, the number of sensitive electrodes N and the rotational angular velocity ω need to be determined based on the frequency band range of the object being measured.

[0034] Furthermore, a level is provided on the upper surface of the displacement stage, and the support rods include support rod A and support rod B. To ensure that the displacement stage remains level, two methods are used:

[0035] Firstly, support rings are movably installed on both support rod A and support rod B, allowing them to move up and down. The displacement platform is sleeved on support rod A and support rod B, and the displacement platform is kept horizontal by adjusting the position of the support rings and observing the level.

[0036] Another method is to have a support ring that can be moved up and down on the support rod B, and a support plate installed on the support ring. One end of the displacement stage is sleeved on the support rod A, and the other end is placed on the support plate. The displacement stage is kept horizontal by adjusting the position of the support ring and observing the level.

[0037] The present invention also provides a measurement method based on the aforementioned response bandwidth measurement device, comprising:

[0038] The bandwidth of the capacitive blade tip clearance measurement system is measured using a response bandwidth measuring device. The response bandwidth measuring device generates variable capacitance test signals at different frequencies, which are transmitted to the signal demodulation module via a three-coaxial cable to output voltage signals. The corresponding output voltage signals are then acquired and stored. Finally, the amplitude of the output signals at different frequencies is compared to obtain the bandwidth of the blade tip clearance measurement system.

[0039] Furthermore, the specific steps are as follows:

[0040] S1. Install and debug the experimental equipment to be tested;

[0041] S2. Select N different frequency points within the frequency band to be tested set on the experimental equipment under test;

[0042] S3. Sequentially adjust the control signal frequency of the response bandwidth measuring device to the frequencies of N test frequency points, record the output voltage of the signal demodulation module at different test frequencies, compare the output signal amplitude, and when the output signal amplitude decreases to 0.707 times the maximum amplitude, the upper limit value minus the lower limit value of the obtained frequency is the bandwidth of the blade tip clearance measurement system; if the signal amplitude output by the test equipment meets the requirements, the bandwidth of the test equipment is the selected working frequency band range; if the amplitude does not meet the requirements, the bandwidth of the test equipment is less than the working frequency band range, and the test equipment does not meet the requirements.

[0043] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0044] 1. Improved measurement accuracy: By designing a device capable of generating a standard capacitance signal, a capacitance signal with a sinusoidal trend can be generated to simulate the input of the capacitive blade tip clearance measurement system; this avoids the error caused by ignoring the capacitance-voltage conversion process when using a standard voltage signal as input, thereby significantly improving the accuracy of the system response bandwidth measurement.

[0045] 2. Enhanced system adaptability: This invention can adapt to testing requirements in different frequency ranges and is suitable for various types of capacitive sensors; the generated capacitive signal changes with a sinusoidal trend, and its frequency and amplitude are adjustable, which can be changed according to user needs and application scenarios; by generating standard capacitive signals of different frequencies to simulate system input, a comprehensive measurement of the system response bandwidth can be achieved, overcoming the limitations of existing methods.

[0046] 3. Simplified testing process: This invention adopts a bipolar plate rotating structure, which generates a standard capacitance signal through rotational motion, avoiding complex circuit design and debugging processes, simplifying the design and use of the testing device, and improving testing efficiency.

[0047] 4. Ensuring stability under high temperature conditions: The capacitive blade tip clearance measurement system has the characteristics of high temperature resistance and resistance to gas corrosion. The measurement device designed in this invention also has these advantages and can operate stably under high temperature conditions, ensuring the reliability of measurement results.

[0048] 5. Real-time online measurement: The measuring device and method of the present invention support online real-time measurement, which can dynamically monitor the blade tip clearance during the operation of rotating machinery, and reflect the changes in system response bandwidth in a timely manner, which helps to improve the safety and performance of rotating machinery.

[0049] 6. Reduced costs: The device and method of the present invention have a simple structure, are easy to process, can be produced by any printed circuit board manufacturer, have a short processing cycle, and are inexpensive. Attached Figure Description

[0050] Figure 1 A schematic diagram of a capacitive blade tip clearance measurement system is shown.

[0051] Figure 2 The schematic diagram of the response bandwidth measurement device of the present invention is shown.

[0052] Figure 3 A schematic diagram of the sensitive plate of the response bandwidth measurement device in this invention is shown.

[0053] Figure 4 A schematic diagram of the receiving plate of the response bandwidth measuring device in this invention is shown.

[0054] Figure 5 The diagram shows the changes in electrode spacing caused by mechanical vibration and rotor tilt.

[0055] Figure 6 A schematic diagram of a bandwidth measurement scheme for a blade tip clearance measurement system using the present invention is shown.

[0056] Figure 7 A flowchart illustrating the process of using the present invention to measure the bandwidth of the blade tip clearance measurement system is shown.

[0057] Reference numerals: 1-Capacitive sensor, 11-Sensor probe, 12-Triaxial cable, 13-SMA connector, 2-Measurement system host, 21-Signal demodulation module, 22-Acquisition module, 3-Host computer, 4-Sensitive electrode plate, 5-Receiver electrode plate, 6-Controller, 7-Rotation axis, 8-Displacement stage, 81-Support rod A, 82-Support rod B, 83-Support ring, 84-Level, 9-Mounting base, 10-DC blocking capacitor; 41-Sensitive electrode, 42-Sensitive electrode plate insulation layer, 51-Receiver electrode, 52-Receiver electrode plate insulation layer. Detailed Implementation

[0058] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0059] The capacitive blade tip clearance measurement system mainly consists of a capacitive sensor 1, a signal demodulation module 21, a data acquisition module 22, a measurement system host 2, and a host computer 3, etc. Figure 1 As shown.

[0060] The capacitive sensor 1 consists of a sensor probe 11 and a triaxial cable 12. The triaxial cable 12 includes two sections, one long and one short. The shorter section is fixed to the tail of the sensor probe and connected to the longer section via an SMA connector, allowing the triaxial cable to be used with different capacitive sensor probes 11. The measurement is based on the principle of parallel plate capacitance. The sensor core forms one plate of a variable capacitor, and the rotating blade forms the other plate. The tip gap value is obtained by measuring the capacitance change between the two plates. The tip gap signal acquired by the sensor probe 11 is transmitted to the main unit of the measurement system via the low-noise triaxial cable 12.

[0061] The signal demodulation module 21 in the host computer 2 of the measurement system demodulates the changing capacitance signal output by the capacitance sensor 1 and converts the capacitance signal into a voltage signal; the acquisition module 22 acquires and performs preliminary processing of the voltage signal and transmits the data to the host computer 3; the host computer 3 performs further processing of the data, calculates the blade tip clearance value, and simultaneously stores and displays the data.

[0062] The response bandwidth measuring device replaces the sensor probe 11 and is connected to a long triaxial cable via an SMA connector; the response bandwidth measuring device of the capacitive blade tip clearance measuring system in this embodiment consists of a sensitive electrode 4, a receiving electrode 5, a rotating stage, a displacement stage 8, a DC blocking capacitor 10, etc., and the structural principle of the device is as follows. Figure 2 As shown.

[0063] The rotary table includes a rotating shaft 7, a mounting base 9, and a controller 6. The controller 6 controls the rotational speed of the rotating shaft 7 and displays the current rotational speed in real time. In this embodiment, a support rod A81 is provided on the mounting base 9, and one end of the displacement stage 8 is movably sleeved on the support rod A81. To ensure the horizontality of the receiving electrode plate 5 installed on the displacement stage 8, a support rod B82 is also provided on the mounting base 9. A support plate is installed on the support rod B82, and the other end of the displacement stage 8 is placed on the support plate. The horizontality of the receiving electrode plate 5 is adjusted by observing the level 84. The rotating shaft 7 is rotatably located in the middle of the mounting base 9.

[0064] The sensitive electrode plate 4 is fixed on the rotating shaft 7 as a rotating component and is composed of a printed circuit board (PCB).

[0065] The receiving electrode 5 is mounted and fixed on the displacement stage 8 and located above the sensitive electrode 4. It is made of a printed circuit board (PCB). The distance between the receiving electrode 5 and the sensitive electrode 4 can be changed by adjusting the height of the displacement stage 8.

[0066] The surfaces of the receiving electrode 5 and the sensitive electrode 4 facing each other are covered with a copper conductive layer, which constitutes the receiving electrode and the sensitive electrode respectively. The rest is an insulating layer. The sensitive electrode 4 is grounded. The receiving electrode 5 is connected in sequence to the core of the DC blocking capacitor 10 and the triaxial cable 12.

[0067] In the response bandwidth measuring device, the sensitive electrode 41 forms one pole of a variable capacitor, and the receiving electrode 51 forms the other pole of the variable capacitor. During the rotation of the sensitive plate, the area between the two electrodes changes, thereby causing a change in the capacitance of the response bandwidth measuring device. The shapes of the sensitive electrode 41 and the receiving electrode 51 are designed so that the change in capacitance between the plates is a standard sinusoidal signal.

[0068] The inner diameter of the sensitive electrode 4 is designed to be R. si The outer diameter is R so The petal shape of the sensitive electrode 41 is like Figure 3 As shown, R1 and R2 are the edges of the sensitive plates. The portion between R1 and R2 on the conductive layer is the sensitive electrode, forming an even number of petal-shaped structures. The remaining portion is an insulating layer. R1 and R2 can be represented by polar coordinate equations as follows:

[0069] R1 = R + τ[sin(Nφ) + 1]

[0070] R² = R - τ[sin(Nφ) + 1

[0071] Where R is the radius of the reference circle that separates the two sinusoidal waves formed by R1 and R2; N is the number of petal-shaped structures of the sensitive electrode; τ is the amplitude of the sinusoidal signal superimposed on the reference circle; φ represents the rotation angle of the rotor relative to the stator, φ = ωt, where ω is the angular velocity of the rotor. To ensure the integrity of the sensitive electrode 4, the inner diameter R of the sensitive electrode 4 is... si <R-2τ, outer diameter R of sensitive electrode 4 si >R+2τ.

[0072] The inner diameter of the receiving electrode 5 is designed to be R. ri The outer diameter is R ro The receiving electrode 51 is shaped as follows Figure 4 As shown, the receiving electrode 5 is fan-shaped, with an inner diameter of R3, an outer diameter of R4, and a central angle of λ. To ensure the integrity of the receiving electrode 5, the inner diameter R of the receiving electrode 5 is... ri <R3, outer diameter R of receiving plate 5 ri >R4.

[0073] Preferably, mechanical vibration and rotor tilt may cause a change Δd in the distance d between the sensitive electrode 4 and the receiving electrode 5, such as... Figure 5 As shown. An even number of receiving electrodes 51 are evenly distributed on the conductive layer of the receiving plate 5, with each pair of receiving electrodes 51 facing each other along the diameter. Figure 4 For example, there are 4 receiving electrodes 51. Let the area of ​​a single receiving electrode 51 be S, then the capacitance C between each pair of receiving electrodes 51 and the sensing electrode 41 is:

[0074]

[0075] Since Δd is an infinitesimal, (Δd) 2 Since it is a second-order infinitesimal, it can be ignored. Therefore, the average effect of multiple receiving electrodes 51 can be used to reduce the error introduced by the change of d.

[0076] Preferably, to ensure that the signals received by the multiple receiving electrodes 51 are in phase, the number M of the receiving electrodes 51 is an approximation of the number N of the petal-shaped sensitive electrodes 41.

[0077] Since the integral value of a periodic function is constant over one period, to avoid a constant output capacitance, the central angle of the sector ring of each receiving electrode 51 is...

[0078] Calculate the overlap area between the receiving electrode 51 and the sensing electrode 41. The area formula in polar coordinates is given below. The overlapping area is:

[0079]

[0080] The overlapping area S between the plates rs The capacitance C between the receiving electrode 51 and the sensing electrode 41 can be calculated as follows:

[0081]

[0082] Where d is the distance between the sensitive electrode and the receiving electrode; φ represents the rotation angle of the rotor relative to the stator, φ=ωt, ω is the rotational angular velocity of the rotor; N is the number of petal-shaped structures of the sensitive electrode; R1 and R2 are the edges of the sensitive electrode; M is the number of receiving electrodes; τ is the amplitude of the sinusoidal signal superimposed on the reference circumference.

[0083] Once the shapes of the receiving electrode 51 and the sensing electrode 41 are determined, the DC component is isolated by the DC blocking capacitor C1, leaving a sinusoidal signal with an amplitude of [value missing]. Frequency is

[0084] Before conducting the response bandwidth measurement experiment, the number N of sensitive electrodes 41 and the rotational angular velocity ω are determined according to the frequency band range of the object under test.

[0085] The bandwidth of the capacitive blade tip clearance measurement system is measured using the response bandwidth measurement device of the present invention. The system bandwidth measurement scheme is as follows: Figure 6 As shown, the response bandwidth measurement device based on the bipolar plate rotating structure can generate variable capacitance test signals at different frequencies. These signals are transmitted to the signal demodulation module via a three-coaxial cable to output a voltage signal. The output voltage signal is then acquired and stored. By comparing the amplitude of the output signal at different frequencies, the bandwidth of the blade tip clearance measurement system can be obtained.

[0086] The test procedure for bandwidth measurement of the capacitive blade tip clearance measurement system is as follows: Figure 7 As shown. After installing and debugging the experimental equipment under test, and assuming there are n test frequencies, adjust the control signal frequency of the response bandwidth measurement device based on the bipolar plate rotating structure. Record the output voltage of the signal demodulation module at different test frequencies, and compare the output signal amplitude. When the output signal amplitude decreases to 0.707 times the maximum amplitude, the upper limit value minus the lower limit value is the bandwidth of the blade tip clearance measurement system. If the signal amplitude output by the experimental equipment under test meets the requirements, the bandwidth of the experimental equipment under test is the selected operating frequency band. If the amplitude does not meet the requirements, the bandwidth of the experimental equipment under test is less than the operating frequency band, and the experimental equipment under test does not meet the requirements.

[0087] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A response bandwidth measurement device for a capacitive tip clearance measurement system based on a bipolar plate rotating structure, wherein the capacitive tip clearance measurement system comprises a capacitive sensor, a measurement system host, and a host computer connected in sequence. The measurement system host includes a signal demodulation module and a data acquisition module. The capacitive sensor consists of interconnected sensor probes and a triaxial cable. The triaxial cable includes two sections, one long and one short. The short section of the triaxial cable is fixed to the tail of the sensor probe and connected to the long section of the triaxial cable via an SMA connector, so that the triaxial cable can be applied to different capacitive sensor probes. The measurement is based on the principle of parallel plate capacitance. The core electrode of the sensor probe forms one plate of a variable capacitor, and the rotating blade forms the other plate. The blade tip gap signal is obtained by measuring the capacitance change between the two plates. The blade tip gap signal acquired by the sensor probe is transmitted to the host computer of the measurement system via a three-coaxial cable. The signal demodulation module demodulates the blade tip gap signal output by the capacitance sensor, converting it into a voltage signal. The acquisition module acquires and performs preliminary processing on the voltage signal and transmits the data to the host computer. The host computer further processes the data to obtain the blade tip gap value, and simultaneously stores and displays the value. Its characteristic is that... Replace the sensor probe with a response bandwidth measuring device and connect it to a long section of triaxial cable via an SMA connector; The response bandwidth measuring device consists of a sensitive electrode, a receiving electrode, a rotating stage, a displacement stage, and a DC blocking capacitor. The rotary table includes a rotating shaft, a mounting base, and a controller. The controller controls the rotational speed of the rotating shaft and displays the current rotational speed in real time. A support rod is provided on the mounting base, and the displacement table is movably sleeved on the support rod. The rotating shaft is rotatably located in the middle of the mounting base. The sensitive electrode plate, as a rotating component, is fixed on the rotating shaft and is constructed from a PCB board. The receiving electrode plate is mounted and fixed on the displacement stage and located above the sensitive electrode plate. It is made of PCB board. The distance between the receiving electrode plate and the sensitive electrode plate can be changed by adjusting the height of the displacement stage. The surfaces of the receiving electrode and the sensitive electrode opposite each other are covered with a copper conductive layer, which respectively constitutes the receiving electrode and the sensitive electrode. The rest is an insulating layer. The sensitive electrode is grounded, and the receiving electrode is connected in sequence to the core of the DC blocking capacitor and the long section of the triaxial cable. The sensitive electrode forms one pole of the variable capacitor, and the receiving electrode forms the other pole. During the rotation of the sensitive plate, the area between the two electrodes changes, causing a change in the capacitance of the response bandwidth measuring device. The shapes of the sensitive electrode and the receiving electrode are designed so that the change in capacitance between the plates is a standard sinusoidal signal.

2. The response bandwidth measuring device of the capacitive tip clearance measuring system based on a bipolar plate rotating structure according to claim 1, characterized in that, An even number of sensitive electrodes are provided on the conductive layer of the sensitive electrode plate, and the inner diameter of the sensitive electrode plate is R. si The outer diameter is R so R1 and R2 are the edges of the sensitive electrodes, and the portion between R1 and R2 is the sensitive electrode itself, forming an even number of petal-shaped structures. The remaining portion is an insulating layer. R1 and R2 can be represented by polar coordinate equations as follows: R1=R+τ[sin(N φ )+1] R2=R-τ[sin(N φ )+1] Where R is the radius of the reference circle that can separate the two sine waves formed by R1 and R2; N is the number of petal-shaped structures of the sensitive electrode; τ is the amplitude of the sine signal superimposed on the reference circle; φ represents the rotation angle of the rotor relative to the stator, φ=ωt, ω is the rotational angular velocity of the rotor; To ensure the integrity of the sensitive electrode plate, the inner diameter R of the sensitive electrode plate... si <R-2τ, outer diameter R of the sensitive electrode plate so >R+2τ.

3. The response bandwidth measuring device of the capacitive blade tip clearance measuring system based on a bipolar plate rotating structure according to claim 1, characterized in that, An even number of receiving electrodes are provided on the conductive layer of the receiving plate, and the inner diameter of the receiving plate is R. ri The outer diameter is R ro The receiving electrode is shaped like a fan ring, with an inner diameter of R3, an outer diameter of R4, and a central angle of λ. To ensure the integrity of the receiving electrode, the inner diameter R of the receiving electrode plate... ri <R3, outer diameter R of the receiving electrode ri >R4.

4. The response bandwidth measuring device of the capacitive tip clearance measuring system based on a bipolar plate rotating structure according to claim 1, characterized in that, Mechanical vibration and rotor tilt can cause a change in the distance d between the sensitive electrode and the receiving electrode by Δd. An even number of receiving electrodes are uniformly distributed on the conductive layer of the receiving electrode, with each pair of receiving electrodes facing each other along the diameter. Let the area of ​​a single receiving electrode be S, then the capacitance C between each pair of receiving electrodes and the sensitive electrode is: Ignore (Δd) 2 By utilizing the averaging effect of several receiving electrodes, the error introduced by the change in the distance d between the sensitive electrode and the receiving electrode is reduced.

5. The response bandwidth measuring device of the capacitive tip clearance measuring system based on a bipolar plate rotating structure according to claim 1, characterized in that, To ensure that the signals received by several receiving electrodes are in phase, the number of receiving electrodes M is an approximation of the number of sensitive electrodes N.

6. The response bandwidth measuring device of the capacitive tip clearance measuring system based on a bipolar plate rotating structure according to claim 1, characterized in that, The central angle of the sector ring of each receiving electrode Calculate the overlap area between the receiving electrode and the sensing electrode. The formula for the sector area in polar coordinates is given. Where r(θ) is the radius of the sector and θ is the central angle, then the overlapping area is: The overlapping area S between the plates rs The capacitance C between the receiving electrode and the sensing electrode is calculated as follows: Where d is the distance between the sensitive electrode and the receiving electrode; φ represents the rotation angle of the rotor relative to the stator, φ=ωt, ω is the rotational angular velocity of the rotor; N is the number of petal-shaped structures of the sensitive electrode; R1 and R2 are the edges of the sensitive electrode; M is the number of receiving electrodes; τ is the amplitude of the sinusoidal signal superimposed on the reference circumference. Once the shapes of the receiving and sensing electrodes are determined, the DC component is isolated by the DC blocking capacitor C1, leaving a sinusoidal signal with an amplitude of [value missing]. Frequency is Before conducting the response bandwidth measurement experiment, the number of sensitive electrodes N and the rotational angular velocity ω need to be determined based on the frequency band range of the object being measured.

7. The response bandwidth measuring device of the capacitive tip clearance measuring system based on a bipolar plate rotating structure according to claim 1, characterized in that, The upper surface of the displacement stage is equipped with a level, and the support rods include support rod A and support rod B. To ensure that the displacement stage remains level, two methods are used: Firstly, support rings are movably installed on both support rod A and support rod B, allowing them to move up and down. The displacement platform is sleeved on support rod A and support rod B, and the displacement platform is kept horizontal by adjusting the position of the support rings and observing the level. Another method is to have a support ring that can be moved up and down on the support rod B, and a support plate installed on the support ring. One end of the displacement stage is sleeved on the support rod A, and the other end is placed on the support plate. The displacement stage is kept horizontal by adjusting the position of the support ring and observing the level.

8. A measurement method based on the response bandwidth measuring device according to any one of claims 1-7, characterized in that, include: The bandwidth of the capacitive blade tip clearance measurement system is measured using a response bandwidth measuring device. The response bandwidth measuring device generates variable capacitance test signals at different frequencies, which are transmitted to the signal demodulation module via a three-coaxial cable to output voltage signals. The corresponding output voltage signals are then acquired and stored. Finally, the amplitude of the output signals at different frequencies is compared to obtain the bandwidth of the blade tip clearance measurement system.

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

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