Engine rotor multi-parameter measurement system and method

Abstract

The application discloses an engine rotor multi-parameter measurement system and method, and the system comprises a first optical comb, a second optical comb, a polarization maintaining optical fiber amplifier, a polarization maintaining optical fiber beam splitter, an integrated polarization maintaining optical fiber ring, an integrated polarization maintaining optical fiber beam combiner, a plurality of high-temperature-resistant optical fiber probes, a high-speed photoelectric detector and a data acquisition and processing system; the pulse repetition frequency of the first optical comb is greater than that of the second optical comb, and the two have a high repetition frequency difference; the plurality of high-temperature-resistant optical fiber probes respectively generate reference light pulses and measurement light pulses; the scanning light pulses emitted by the second optical comb respectively interfere with the plurality of reference light pulses and the plurality of measurement light pulses to generate double-comb interference reference signals and double-comb interference measurement signals; through processing of the reference signals and the measurement signals of each channel, the engine rotor speed, the blade tip clearance, the blade tip timing and the blade vibration parameters are obtained. The application has the advantages of high measurement speed, high measurement accuracy and multi-parameter synchronous measurement.

Description

Technical Field

[0001] This invention belongs to the field of engine testing technology, and specifically relates to an engine rotor multi-parameter measurement system and method. Background Technology

[0002] In large rotating machinery (such as aero-engines and gas turbines) operating under extreme conditions such as high load, high temperature, and high speed, blade tip clearance and blade vibration are key parameters directly affecting their performance and safety. Blade tip clearance affects the engine's energy utilization efficiency and stability, while blade vibration is related to component fatigue life and failure risk. These two factors not only influence each other but also work together under extreme conditions, potentially leading to serious equipment accidents. Therefore, in complex operating environments, it is essential to acquire real-time changes in blade tip clearance to optimize clearance control and to accurately monitor blade vibration to prevent failure risks, ensuring the long-term stable operation of the entire machine. Furthermore, any sudden changes in the shape and vibration amplitude of the rotor's axis trajectory (the motion trajectory formed around the center point of the shaft) during rotation can be early signs of equipment failure. The rotor's axis trajectory can partially reflect the rotor's dynamic characteristics and operating state, providing information on rotor imbalance, looseness, rubbing, bending, and torsion. Therefore, analyzing the axis trajectory can provide important basis for aero-engine rotor dynamics design and fault diagnosis. In summary, the demand for high-precision online testing of parameters such as rotor speed, blade tip clearance, vibration, and shaft center trajectory under complex scenarios such as high temperature, high pressure, and high speed is becoming increasingly urgent for key equipment such as aero engines and gas turbines.

[0003] Existing capacitive testing equipment suffers from the following problems: low measurement accuracy and repeatability, resulting in poor measurement accuracy and repeatability under different gaps and temperatures; insufficient response bandwidth, failing to meet the fine measurement requirements of irregularly shaped blade tips and blade tips with complex structures; probe size increases with the measurement range, making it inconvenient to use and potentially posing a safety hazard to the engine; more seriously, due to limitations in the measurement principle, it cannot measure next-generation engine blades such as fan blades made of resin-based composite materials and turbine guide vanes made of ceramic-based composite materials; and it cannot meet the development needs of future engines. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-parameter measurement system and method for engine rotors, which uses non-contact optical measurement technology to achieve high-speed, high-precision, and synchronous measurement of multiple parameters of engine rotors.

[0005] To achieve the above objectives, one aspect of the present invention provides an engine rotor multi-parameter measurement system, including a first optical comb, a second optical comb, a polarization-maintaining fiber amplifier, a polarization-maintaining fiber splitter, an integrated polarization-maintaining fiber circulator, an integrated polarization-maintaining fiber combiner, multiple high-temperature resistant fiber probes, a high-speed photodetector, and a data acquisition and processing system.

[0006] The first optical comb is used to emit a high repetition rate ultrafast laser pulse as a measurement optical pulse; the second optical comb is used to emit another high repetition rate ultrafast laser pulse as a scanning optical pulse; the pulse repetition frequency emitted by the first optical comb is greater than that of the second optical comb and the two have a high repetition rate difference.

[0007] The polarization-maintaining fiber amplifier is used to amplify the energy of the measurement light pulse emitted by the first optical comb. The amplified measurement light pulse enters the integrated polarization-maintaining fiber circulator. The integrated polarization-maintaining fiber circulator has multiple channels, which are the same number as the high-temperature resistant fiber probes. The measurement light pulses enter from the first port of each channel and are transmitted to multiple high-temperature resistant fiber probes through the second port.

[0008] Multiple high-temperature resistant fiber optic probes generate reference optical pulses and measurement optical pulses respectively. The reference optical pulses are generated by Fresnel reflection at the end of the high-temperature resistant fiber optic probes, and the measurement optical pulses are generated by reflection from the blade tips of the rotor blades of the engine under test. The reference optical pulses and measurement optical pulses are output from the third port of the integrated polarization-maintaining fiber circulator and enter the integrated polarization-maintaining fiber combiner.

[0009] The scanning light pulse emitted by the second optical comb is split into multiple scanning light pulses proportionally by the integrated polarization-maintaining fiber beam splitter, which is the same as the number of high-temperature resistant fiber probes. The multiple scanning light pulses are then combined with multiple reference light pulses and multiple measurement light pulses respectively to interfere, generating a double-comb interference reference signal and a double-comb interference measurement signal.

[0010] The high-speed photodetector has the same number of measurement channels as the high-temperature resistant fiber optic probe, which are used to detect reference signals and measurement signals respectively. The data acquisition and processing system is used to acquire and process the reference signals and measurement signals output by each channel of the high-speed photodetector to obtain the engine rotor speed, blade tip clearance, blade tip timing and blade vibration parameters.

[0011] Another aspect of the present invention provides a method for measuring multiple parameters of an engine rotor, which utilizes the above-described system to perform multi-parameter measurements of the engine rotor, including:

[0012] By accurately distinguishing the moment when the dual-comb interferometric measurement signal is generated, the engine speed is obtained by calculating the time it takes for the same rotor blade to rotate once.

[0013] The engine blade tip clearance is obtained by processing the double-comb interference reference signal and the double-comb interference measurement signal and calculating the phase difference between the measurement signal and the reference signal.

[0014] Engine blade tip timing is obtained by measuring the arrival time of the blades with lag or advance compared to when there is no vibration.

[0015] Engine blade vibration is obtained by measuring tip timing through different measurement channels.

[0016] According to the engine rotor multi-parameter measurement system and method of the present invention, a high repetition rate difference dual optical comb is used as the light source. Combining multi-channel dual comb interferometry technology and time discrimination technology, the engine rotor speed, blade tip clearance, blade tip timing and blade vibration are synchronously measured based on a single measurement system. It has the advantages of high measurement speed, high measurement accuracy and synchronous measurement of multiple parameters. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0018] Figure 1 This is a schematic diagram of the structure of an engine rotor multi-parameter measurement system according to an embodiment of the present invention;

[0019] Figure 2 The first embodiment of the present invention k A schematic diagram of the signals obtained from each measurement channel;

[0020] Figure 3 This is a schematic diagram of the reference signal and measurement signal for the blade tip clearance according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] One embodiment of the present invention provides a multi-parameter measurement system for engine rotors based on a high repetition rate difference dual optical comb, such as... Figure 1As shown, the measurement system of this embodiment includes a first optical comb 1, a second optical comb 2, a polarization-maintaining fiber amplifier 3, a polarization-maintaining fiber bundler 4, an integrated polarization-maintaining fiber circulator 5, an integrated polarization-maintaining fiber combiner 6, multiple high-temperature resistant fiber optic probes, an engine rotor system 11, a high-speed photodetector 12, and a data acquisition and processing system 13. In this embodiment, the number of high-temperature resistant fiber optic probes is four, including a first high-temperature resistant fiber optic probe 7, a second high-temperature resistant fiber optic probe 8, a third high-temperature resistant fiber optic probe 9, and a fourth high-temperature resistant fiber optic probe 10.

[0023] The first optical comb 1 and the second optical comb 2 emit two high-repetition-rate (HRPR) ultrafast laser pulses. The first optical comb 1 generates one HRPR ultrafast laser pulse, which serves as the measurement laser pulse; the second optical comb generates another HRPR ultrafast laser pulse, which serves as the scanning laser pulse. The first optical comb 1 and the second optical comb 2 provide the system with a highly coherent and stable light source. The first optical comb 1 serves as the measurement laser, and the second optical comb 2 serves as the scanning laser. The pulse repetition frequency emitted by the first optical comb 1 is higher than that of the second optical comb 2, and the two optical combs have a high repetition rate difference, which is on the order of MHz.

[0024] The polarization-maintaining fiber amplifier 3 amplifies the energy of the measurement light pulse emitted from the first optical comb. The amplified light pulse enters the integrated polarization-maintaining fiber circulator 5. The integrated polarization-maintaining fiber circulator 5 separates the forward and reverse propagating light, allowing the laser to propagate along a predetermined port sequence. The integrated polarization-maintaining fiber circulator 5 has four channels. The measurement light pulse enters through the first port of each channel and is transmitted through the second port to the first high-temperature resistant fiber optic probe 7, the second high-temperature resistant fiber optic probe 8, the third high-temperature resistant fiber optic probe 9, and the fourth high-temperature resistant fiber optic probe 10. The four high-temperature resistant fiber optic probes generate reference light pulses and measurement light pulses. The reference light pulse is generated by Fresnel reflection at the fiber-air interface, and the measurement light pulse is generated by reflection from the tips of the engine rotor blades. The four high-temperature resistant fiber optic probes are evenly mounted on the engine casing, with a spacing of 90° between them. The high-temperature resistant fiber can be polyimide fiber, copper-plated fiber, aluminum-plated fiber, gold-plated fiber, or sapphire fiber, among other high-temperature resistant fibers.

[0025] The measurement light pulse undergoes Fresnel reflection at the end of the high-temperature resistant fiber optic probe (the boundary between the fiber and the air). The Fresnel-reflected light pulse returns to the second port along the original path and is output from the third port, denoted as the reference light pulse. The light pulses emitted by the first high-temperature resistant fiber optic probe 7, the second high-temperature resistant fiber optic probe 8, the third high-temperature resistant fiber optic probe 9, and the fourth high-temperature resistant fiber optic probe 10 are transmitted to the blade tips of the engine rotor system 11. After being reflected by the blade tips, the measurement light returns to the corresponding high-temperature resistant fiber optic probe and enters the second port of each channel of the integrated polarization-maintaining circulator 5, and is output from the third port, denoted as the measurement light pulse. The reference light pulse and the measurement light pulse are output from the third port of the polarization-maintaining fiber circulator 5 and enter the polarization-maintaining fiber combiner 6.

[0026] The scanning light pulse emitted by the second optical comb 2 enters the polarization-maintaining fiber beam splitter 4 and is divided into four scanning light pulses in equal proportion. These four scanning light pulses then enter the polarization-maintaining fiber beam combiner 6. The four scanning light pulses interfere with the four reference light pulses and the four measurement light pulses, respectively, generating reference signals and measurement signals. The high-speed photodetector 12 has four detection channels, which detect the reference signal and measurement signal of each channel.

[0027] The number of acquisition channels in the data acquisition and processing system 13 is consistent with the number of high-temperature resistant fiber optic probes. The sampling rate of each channel is consistent with the pulse repetition frequency of the first optical comb, and each channel is synchronously triggered for acquisition by the same clock. The processing system processes multi-channel measurement signals simultaneously. Specifically, the data acquisition and processing system 13 has four channels, which respectively acquire and process the reference signal and measurement signal of each channel to obtain parameters such as engine rotor speed, blade tip clearance, blade tip timing, and vibration.

[0028] The working principle of the engine rotor multi-parameter measurement system in this embodiment of the invention is as follows: When the rotating blades pass through the high-temperature resistant fiber optic probes in sequence, the blades reflect the measurement light back to the measurement system. The system will detect the periodic double-comb interferometric measurement signal. The measurement system can record the arrival time of the blades. Based on the periodic signal, the time for the rotor to rotate one revolution can be calculated, thereby obtaining the engine rotor speed. The acquired time-domain double-comb interferometric reference signal and double-comb interferometric measurement signal are subjected to Fourier transform to extract their phase spectrum information. By unwrapping the phase spectrum, the slope of the phase with respect to frequency can be obtained, and the phase difference between the measurement signal and the reference signal can be calculated, thereby obtaining the blade tip clearance. During the rotor rotation, due to blade vibration, the blade tip will shift forward or backward. Therefore, the arrival time of the blade will be delayed or advanced compared to the absence of vibration. That is, blade vibration directly affects the blade arrival time. By analyzing and calculating this time series, the blade tip timing and blade vibration can be obtained.

[0029] Embodiments of the present invention also provide a method for measuring multiple parameters of an engine rotor, which uses the system described in the above embodiments to measure multiple parameters of the engine rotor, including engine rotor speed, blade tip clearance, blade tip timing, and blade vibration.

[0030] (1) Measurement of engine rotor speed

[0031] As the rotating blades sequentially pass through the high-temperature resistant fiber optic probe, they generate periodic double-comb interferometry signals. The engine speed is obtained by precisely identifying the moments when the double-comb interferometry signals are generated and calculating the time it takes for the same rotor blade to complete one revolution. Figure 2 The following is the first k The signal measured by each measurement channel has an arrival time interval between the pulses from the first blade and the pulse from the second blade. tk1 And so on, the interval between the i-th leaf and the (i+1)-th leaf is t ki If the rotor system has a total of [number] blades... N a The time required for the rotor to complete one revolution T for:

[0032]

[0033] The rotational speed (revolutions per minute) measured by the k-th channel can be expressed as:

[0034]

[0035] (2) Measurement of engine blade tip clearance

[0036] The engine blade tip clearance is obtained by processing the double-comb interference reference signal and the double-comb interference measurement signal, and calculating the phase difference between the measurement signal and the reference signal. Figure 3 The diagram shows the reference and measured signals for the blade tip clearance. By performing a Fourier transform on the acquired time-domain reference and measured signals, their phase spectrum information can be extracted. Unwrapping the phase spectrum yields the slope of the phase with respect to frequency, allowing the calculation of the blade tip clearance. k The tip gap of a specific blade measured by a single measurement channel can be expressed as:

[0037]

[0038] in, c At the speed of light, n g The refractive index of air, φ k2 and φ k1 These represent the phases of the Fourier transform signals of the measured signal and the reference signal, respectively. f The frequency of the signal after Fourier transform is given.

[0039] (3) Timing and vibration measurement of engine blade tips

[0040] Engine blade tip timing is obtained by measuring the arrival time of the blades relative to a state without vibration, resulting in either lag or advancement. During rotor rotation, blade vibration causes the blade tips to shift forward or backward, thus affecting their arrival time compared to an ideal (vibration-free) condition. In other words, blade vibration directly impacts blade arrival time. Figure 2 As shown, let the first... k The ideal arrival time of a specific blade measured by each measurement channel. The actual arrival time is tki Then the first k The timing difference at the tip of the specific leaf being tested, measured by each measurement channel, is:

[0041]

[0042] Based on the tip timing information, the vibration amplitude of the blade under test can be calculated. The vibration amplitude of the specific blade under test measured by the k-th measurement channel is:

[0043]

[0044] in, R The radius of the engine rotor. n This refers to the engine speed.

[0045] (4) Measurement of sampling frequency for timing and vibration of engine blade tips

[0046] The sampling frequency for blade tip timing and vibration is related to the number of probes and the rotational speed. For uniformly distributed probes, blade tip timing and vibration signals can be recorded uniformly. The sampling frequency is the product of the number of probes and the rotational frequency (engine speed per second). Therefore, the sampling frequency for blade tip timing and vibration is:

[0047]

[0048] in, N b The number of measurement channels is the number of high-temperature resistant fiber optic probes. T This represents the time required for the rotor to rotate one revolution. According to the formula, the more high-temperature resistant fiber optic probes there are, the faster the rotation speed, the higher the sampling frequency for blade tip timing and vibration, and the wider the vibration frequency bandwidth that the system can measure.

[0049] In summary, the engine rotor multi-parameter measurement system and method of the present invention have the following beneficial effects:

[0050] 1. This system uses a high repetition rate difference dual optical comb as the light source, and combines dual-comb interferometry technology with time discrimination technology, which has the characteristics of fast measurement speed and high measurement accuracy.

[0051] 2. The optical system of this invention is an all-fiber structure, and a single system can be used to simultaneously measure multiple parameters such as engine rotor speed, blade tip clearance, blade tip timing and vibration. The system is simple, stable and easy to apply in engineering.

[0052] 3. This invention has a multi-channel measurement function, which can monitor the tip clearance of blades in different parts of the engine (fan, compressor, turbine) or blades at different positions in the same part in real time, and can also improve the sampling frequency of engine rotor blade vibration.

[0053] 4. This invention employs non-contact optical measurement technology, which has advantages such as high precision, resistance to electromagnetic interference, and strong adaptability. It is also applicable to both metallic and non-metallic composite materials.

[0054] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A multi-parameter measurement system for an engine rotor, characterized in that, It includes a first optical comb, a second optical comb, a polarization-maintaining fiber amplifier, a polarization-maintaining fiber splitter, an integrated polarization-maintaining fiber circulator, an integrated polarization-maintaining fiber combiner, multiple high-temperature resistant fiber probes, a high-speed photodetector, and a data acquisition and processing system. The first optical comb is used to emit a high repetition rate ultrafast laser pulse as a measurement optical pulse; the second optical comb is used to emit another high repetition rate ultrafast laser pulse as a scanning optical pulse; the pulse repetition frequency emitted by the first optical comb is greater than that of the second optical comb and the two have a high repetition rate difference. The polarization-maintaining fiber amplifier is used to amplify the energy of the measurement light pulse emitted by the first optical comb. The amplified measurement light pulse enters the integrated polarization-maintaining fiber circulator. The integrated polarization-maintaining fiber circulator has multiple channels, which are the same number as the high-temperature resistant fiber probes. The measurement light pulses enter from the first port of each channel and are transmitted to multiple high-temperature resistant fiber probes through the second port. Multiple high-temperature resistant fiber optic probes generate reference optical pulses and measurement optical pulses respectively. The reference optical pulses are generated by Fresnel reflection at the end of the high-temperature resistant fiber optic probes, and the measurement optical pulses are generated by reflection from the blade tips of the rotor blades of the engine under test. The reference optical pulses and measurement optical pulses are output from the third port of the integrated polarization-maintaining fiber circulator and enter the integrated polarization-maintaining fiber combiner. The scanning light pulse emitted by the second optical comb is split into multiple scanning light pulses proportionally by the integrated polarization-maintaining fiber beam splitter, which is the same as the number of high-temperature resistant fiber probes. The multiple scanning light pulses are then combined with multiple reference light pulses and multiple measurement light pulses respectively to interfere, generating a double-comb interference reference signal and a double-comb interference measurement signal. The high-speed photodetector has the same number of measurement channels as the high-temperature resistant fiber optic probe, which are used to detect reference signals and measurement signals respectively. The data acquisition and processing system is used to acquire and process the reference signals and measurement signals from each channel output by the high-speed photoelectric detector to obtain the engine rotor speed, blade tip clearance, blade tip timing, and blade vibration parameters.

2. The system as described in claim 1, characterized in that, The repetition frequency difference between the first and second optical combs is on the order of MHz.

3. The system as described in claim 1 or 2, characterized in that, There are four high-temperature resistant fiber optic probes, which are evenly installed on the engine casing with a spacing of 90° between them.

4. The system as described in claim 3, characterized in that, The high-temperature resistant fiber optic probe uses polyimide fiber, copper-plated fiber, aluminum-plated fiber, gold-plated fiber, or sapphire fiber.

5. The system as described in claim 1 or 2, characterized in that, The number of acquisition channels in the data acquisition and processing system is consistent with the number of high-temperature resistant fiber optic probes. The sampling rate of each channel is consistent with the pulse repetition frequency of the first optical comb. Each channel is synchronously triggered for acquisition by the same clock. The data acquisition and processing system synchronously processes the measurement signals of multiple channels.

6. A method for measuring multiple parameters of an engine rotor, characterized in that, Performing multi-parameter measurement of an engine rotor using the system of any one of claims 1-5, comprising: By accurately distinguishing the moment when the dual-comb interferometric measurement signal is generated, the engine speed is obtained by calculating the time it takes for the same rotor blade to rotate once. The engine blade tip clearance is obtained by processing the double-comb interference reference signal and the double-comb interference measurement signal and calculating the phase difference between the measurement signal and the reference signal. Engine blade tip timing is obtained by measuring the arrival time of the blades with lag or advance compared to when there is no vibration. Engine blade vibration is obtained by measuring tip timing through different measurement channels.

7. The method as described in claim 6, characterized in that, Engine speed n Represented as: in, t ki Let be the interval between the i-th leaf and the (i+1)-th leaf. N a This represents the number of rotor blades.

8. The method as described in claim 6 or 7, characterized in that, No. k The tip gap of a specific blade under test is measured by one measurement channel. d k Represented as: in, c At the speed of light, n g The refractive index of air, φ k2 and φ k1 These represent the phases of the Fourier transform signals of the measured signal and the reference signal, respectively. f The frequency of the signal after Fourier transform is given.

9. The method as described in claim 6 or 7, characterized in that, No. k The time difference Δ at the tip of the specific leaf under test measured by each measurement channel. t ki for: in, For the first k The ideal arrival time of a specific blade is measured by a measurement channel. t ki This refers to the actual arrival time.

10. The method as described in claim 9, characterized in that, The amplitude of the specific blade being measured is measured by the k-th measurement channel. y k for: in, R The radius of the engine rotor. n This refers to the engine speed.

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