Blade non-synchronous vibration test system and method and aero-engine test system
Patent Information
- Application Number
- CN202611531046.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-30
- Publication Date
- 2026-11-03
AI Technical Summary
Existing asynchronous vibration testing systems measure the vibration frequency of rotor blades by attaching strain gauges, which affects the aerodynamic shape of the blades and the dynamic characteristics of the rotor system, and cannot monitor the vibration status of all blades simultaneously.
A fiber optic blade tip timing measurement subsystem and a dynamic pressure measurement subsystem are adopted, with fiber optic sensors and dynamic pressure sensors installed respectively. Combined with a time synchronization module, non-contact blade vibration measurement and pressure pulsation frequency monitoring are realized to ensure time reference consistency. Asynchronous vibration is determined through a data integration and processing module.
It achieves non-contact blade vibration measurement without changing the blade shape or rotor system mass distribution, improving the reliability and success rate of the test. It can simultaneously monitor the vibration status of all blades and accurately distinguish between asynchronous vibration and flutter.
Smart Images
Figure CN123028685A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aero-engine blade vibration testing technology, and in particular, to a blade asynchronous vibration testing system. Furthermore, this invention also relates to a blade asynchronous vibration testing method incorporating the aforementioned blade asynchronous vibration testing system. Background Technology
[0002] Asynchronous vibration of fan blades is a new type of aeroelastic problem in aero-engine fan components, involving multiple disciplines such as aerodynamics, structural dynamics, and rotor dynamics. Asynchronous vibration is mainly characterized by non-integer order vibration frequencies in fan blades within a specific speed range, and the vibration stress may exceed the fatigue limit of the material, ultimately leading to blade fracture failure.
[0003] Unlike traditional synchronous vibration (caused by stator blade wake excitation, with vibration frequency being an integer multiple of the rotational speed), asynchronous vibration originates from unstable flow structures in the flow field, such as rotational instability, eddy shedding, and tip gap flow. The core characteristic of asynchronous vibration is that its vibration frequency is not an integer multiple of the rotor speed, but appears at non-integer order frequencies, and is usually accompanied by non-integer order frequency components in the pressure pulsations on the casing wall. By combining dynamic pressure monitoring and blade tip amplitude monitoring for simultaneous analysis, asynchronous vibration and flutter can be distinguished. Specifically, asynchronous vibration is forced vibration, caused by unstable flow in the flow field exciting non-integer natural frequencies of the blades. The time when the non-integer frequency that can excite blade vibration appears in the flow field is earlier than the time when the amplitude of the non-integer vibration of the blades increases. Flutter is self-excited vibration, where the blades vibrate first and continuously gain energy from the flow field during the vibration process, resulting in an increasingly larger vibration amplitude. The time when the amplitude of the non-integer vibration of the blades increases is earlier than the time when the non-integer frequency of vibration / flow coupling appears in the flow field. Therefore, accurate measurement of asynchronous vibration requires simultaneous acquisition of two key pieces of information: the dynamic pressure pulsation frequency of the casing wall and the vibration frequency of the rotor blades, and analysis of their temporal relationship.
[0004] Existing asynchronous testing systems are mainly based on test runs. They measure the vibration frequency of rotor blades by attaching strain gauges to the blade surface using the test run system. The strain gauges transmit signals via leads, slip rings, or telemetry devices to the acquisition system. This approach is widely used in asynchronous vibration testing of fans / compressors, such as in "Experimental Study on Asynchronous Vibration of Rotor Blades Induced by Rotary Instability of High-Load Compressor" (Propulsion Technology, February 2023, Vol. 44, No. 2). However, using strain gauges to measure the vibration frequency of rotor blades has the following significant drawbacks: 1) Changing the aerodynamic shape of the blades affects the validity of the test; the strain gauges and their leads are attached to the blade surface, which will change the shape of some blades, affect the gas flow, and may ultimately affect the measurement results of pressure pulsation frequency, leading to misjudgment of asynchronous vibration. 2) Changes in the dynamic characteristics of the rotor system; strain gauges and their associated leads, slip rings or telemetry equipment can change the mass distribution of the rotor system of the test piece, which may prevent the test from running to the required operating speed and affect the smooth progress of the test; 3) Poor reliability and short service life at high speeds; the adhesion between the strain gauge and the blade is relatively small under the action of centrifugal force at high speeds, and the working time is short, making it easy to fall off or fail, which requires repeated testing, wasting test funds and test cycle. 4) It is impossible to monitor all blades at the same time; strain gauges can usually only be installed on a limited number of blades, making it impossible to achieve comprehensive monitoring of the vibration status of all blades in the entire stage. Summary of the Invention
[0005] This invention provides a blade asynchronous vibration testing system, method, and aero-engine test system to solve the technical problem that in the prior art, asynchronous vibration testing uses the method of attaching strain gauges to measure the vibration frequency of rotor blades. However, the strain gauges and leads change the shape of the blades, affecting the airflow and thus the effectiveness of the pressure pulsation measurement results.
[0006] According to one aspect of the present invention, a blade asynchronous vibration testing system is provided, comprising: The fiber optic blade tip timing measurement subsystem includes fiber optic sensors and a data acquisition module. Multiple fiber optic sensors are mounted on the housing and are used to detect the light pulse signal reflected from the blade tip when the rotor blade passes by. The data acquisition module of the fiber optic blade tip timing measurement subsystem is used to calculate the arrival time of each blade based on the arrival time of the light pulse signal, thereby obtaining the blade vibration frequency and amplitude. The dynamic pressure measurement subsystem includes a dynamic pressure sensor and a data acquisition module; multiple dynamic pressure sensors are respectively installed at multiple axial and circumferential positions on the casing wall to measure the pressure pulsation signal on the casing wall in real time and obtain the non-integer order pressure pulsation frequency. The time synchronization module is connected to the data acquisition module of the fiber optic leaf tip timing measurement subsystem and the data acquisition module of the dynamic pressure measurement subsystem, respectively, and is used to calibrate the system time of the two subsystems before the test so that the time reference of the fiber optic leaf tip timing measurement subsystem and the dynamic pressure measurement subsystem is consistent. The data processing module is communicatively connected to the data acquisition module of the fiber optic blade tip timing measurement subsystem and the data acquisition module of the dynamic pressure measurement subsystem, respectively, and is used to receive the blade vibration frequency and amplitude data and the pressure pulsation frequency data to determine asynchronous vibration.
[0007] As a further improvement to the above technical solution, the fiber optic sensor is installed on at least two axial sections of the casing, with at least one fiber optic sensor arranged on each axial section, and the installation position of the fiber optic sensor is selected near the position of maximum blade amplitude.
[0008] As a further improvement to the above technical solution, the dynamic pressure sensor is a Kulite dynamic pressure sensor, which is arranged on at least 6 axial sections of the fan rotor casing wall, at least 5 different axial positions along the rotor blade tip chord direction, at least 4 circumferential measuring points are arranged at each axial position, and at least 20 dynamic pressure measuring points are distributed in a rotor blade tip periodic channel.
[0009] As a further improvement to the above technical solution, the fiber optic blade tip timing measurement subsystem also includes a rotational speed reference module. The rotational speed reference module is used to measure a reference pulse generated for each rotation of the blade through one of the fiber optic sensors, and to calculate the rotor speed based on the reference pulse and the blade pulse sequence.
[0010] According to another aspect of the present invention, a method for testing asynchronous vibration of a blade is also provided, comprising the aforementioned asynchronous vibration testing system for a blade, the testing method comprising: S1. Test preparation and time calibration; S2. Dynamic pressure measurement; S3. Blade vibration measurement; S4. Determination of asynchronous vibration.
[0011] As a further improvement to the above technical solution, step S2 includes: By using multiple dynamic pressure sensors installed on the casing wall, the pressure pulsation signal on the casing wall is measured in real time to obtain the non-integer order pressure pulsation frequency in the flow field. As a further improvement to the above technical solution, step S3 includes: Multiple fiber optic sensors mounted on the casing are used to detect the tip-reflected light pulse signals of the rotor blades in real time as they pass by, and the arrival time of each blade is recorded. The vibration displacement of each blade is calculated based on the deviation between the arrival time and the reference time. The vibration displacement data of each blade is subjected to spectral analysis to obtain the non-integer order vibration frequency of the rotor blades.
[0012] As a further improvement to the above technical solution, step S3 includes: If the time interval between the arrival of each blade at the fiber optic sensor is equal, it is a standard pulse sequence, and the rotor blade is judged not to vibrate; if the blade tip deviates along the rotation direction, and the time when the blade arrives at the sensor is earlier or later than the standard time, it is judged that the blade is vibrating, and the time difference between the earlier or later arrival is a measure of the blade vibration displacement; the vibration amplitude and phase of each blade are calculated based on the time difference.
[0013] As a further improvement to the above technical solution, step S4 includes: The pressure pulsation frequency obtained from the dynamic pressure measurement step and the blade vibration frequency obtained from the blade vibration measurement step are substituted into the asynchronous vibration determination formula for determination, where is the rotor frequency and is the circumferential mode number of the disturbance source; when the formula is true, the current vibration is determined to be asynchronous blade vibration.
[0014] As a further improvement to the above technical solution, step S5 is also included: Based on the asynchronous vibration determination result, an asynchronous vibration alarm signal is output. The alarm signal includes the rotational speed range, vibration frequency, and vibration amplitude of the asynchronous vibration.
[0015] According to another aspect of the present invention, an aero-engine test system is also provided, which includes the aforementioned blade asynchronous vibration test system.
[0016] The present invention has the following beneficial effects: The fiber optic blade tip timing measurement subsystem of this testing system includes multiple fiber optic sensors, fiber optic amplifiers, signal conditioning modules, and data acquisition modules. The fiber optic sensors, mounted on the housing, detect the reflected light pulse signals from the blade tips as the rotor blades pass by. The data acquisition module calculates the arrival time of each blade based on the arrival time of the light pulse signals, thereby obtaining the blade vibration frequency and amplitude. Using fiber optic sensors achieves non-contact blade vibration measurement, eliminating the need to attach any sensors or leads to the blade surface, preserving the blade shape, and not affecting the flow field state. This ensures the validity of the pressure pulsation measurement results and the authenticity of the test data. Furthermore, since the fiber optic sensors are only mounted on the housing, they do not alter the mass distribution and dynamic characteristics of the rotor system, preventing issues such as the rotor system failing to reach the target speed. This improves the reliability and success rate of the test. Moreover, the fiber optic sensors are fixedly mounted on the housing, unaffected by high-speed centrifugal force, ensuring reliable operation, long lifespan, and reusability. This avoids test failures and repeated tests caused by strain gauges easily detaching at high speeds, saving on testing costs. The dynamic pressure measurement subsystem includes multiple dynamic pressure sensors, a signal amplifier, and a data acquisition module. The dynamic pressure sensors are installed at multiple axial and circumferential positions on the casing wall to measure pressure pulsation signals in real time, obtaining non-integer order pressure pulsation frequencies. A time synchronization module connects to the data acquisition modules of both the fiber optic blade tip timing measurement subsystem and the dynamic pressure measurement subsystem. This module calibrates the system time of both subsystems before the test, ensuring consistency in their time bases and guaranteeing the time correspondence between the dynamic pressure signal and the blade tip amplitude signal. This ensures the comparability of the dynamic pressure signal and the blade tip amplitude signal in time, providing a reliable time basis for accurately distinguishing asynchronous vibration and flutter. The data processing module receives blade vibration frequency and amplitude data, as well as pressure pulsation frequency data, to determine asynchronous vibration. This system can simultaneously acquire the arrival times of all blades in the entire stage, enabling simultaneous monitoring of the vibration state of all blades and identifying abnormal vibrations in individual blades. This overcomes the limitation of strain gauges, which can only measure a limited number of blades.
[0017] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description
[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram illustrating the relationship between rotationally unstable flow in different coordinate systems according to a preferred embodiment of the present invention; Figure 2This is a schematic diagram of a fan test piece measuring the vibration frequency of rotor blades using an optical fiber probe according to a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of a fan test piece measuring pressure pulsation frequency using a Kulite probe according to a preferred embodiment of the present invention; Figure 4 This is a schematic diagram of dynamic static pressure measurement on the casing wall of a fan test piece according to a preferred embodiment of the present invention. Detailed Implementation
[0019] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.
[0020] Figure 1 This is a schematic diagram illustrating the relationship between rotationally unstable flow in different coordinate systems according to a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of a fan test piece measuring the vibration frequency of rotor blades using an optical fiber probe according to a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of a fan test piece measuring pressure pulsation frequency using a Kulite probe according to a preferred embodiment of the present invention; Figure 4 This is a schematic diagram of dynamic static pressure measurement on the casing wall of a fan test piece according to a preferred embodiment of the present invention.
[0021] like Figures 1 to 4 As shown, the blade asynchronous vibration testing system of this embodiment includes: The fiber optic blade tip timing measurement subsystem includes multiple fiber optic sensors, fiber optic amplifiers, signal conditioning modules, and data acquisition modules. The fiber optic sensors are mounted on the casing and are used to detect the light pulse signals reflected from the blade tips when the rotor blades pass by. The data acquisition module calculates the arrival time of each blade based on the arrival time of the light pulse signals, thereby obtaining the blade vibration frequency and amplitude. The dynamic pressure measurement subsystem includes multiple dynamic pressure sensors, a signal amplifier, and a data acquisition module. The dynamic pressure sensors are installed at multiple axial and circumferential positions on the casing wall to measure the pressure pulsation signal on the casing wall in real time and obtain the non-integer order pressure pulsation frequency. The time synchronization module is connected to the data acquisition modules of the fiber optic blade tip timing measurement subsystem and the dynamic pressure measurement subsystem, respectively. It is used to calibrate the system time of the two subsystems before the test to make their time bases consistent and ensure the time correspondence between the dynamic pressure signal and the blade tip amplitude signal. The necessity of time synchronization is that asynchronous vibration is forced vibration (flow field disturbance excitation precedes blade vibration), while flutter is self-excited vibration (blade vibration precedes flow field coupling). Only by ensuring that the dynamic pressure signal and the blade tip amplitude signal are comparable in time can the two phenomena be accurately distinguished based on the order of their appearance. The data processing module communicates with the data acquisition modules of the fiber optic blade tip timing measurement subsystem and the dynamic pressure measurement subsystem. It is used to receive blade vibration frequency and amplitude data as well as pressure pulsation frequency data to determine asynchronous vibration.
[0022] Understandably, the fiber optic blade tip timing measurement subsystem of this test system includes multiple fiber optic sensors, fiber optic amplifiers, signal conditioning modules, and data acquisition modules. The fiber optic sensors, mounted on the housing, detect the reflected light pulse signals from the blade tips as the rotor blades pass by. The data acquisition module calculates the arrival time of each blade based on the arrival time of the light pulse signals, thereby obtaining the blade vibration frequency and amplitude. Using fiber optic sensors achieves non-contact blade vibration measurement, eliminating the need to attach any sensors or leads to the blade surface, preserving the blade's shape, and not affecting the flow field state. This ensures the validity of the pressure pulsation measurement results and the authenticity of the test data. Furthermore, since the fiber optic sensors are only mounted on the housing, they do not alter the mass distribution and dynamic characteristics of the rotor system, preventing issues such as the rotor system failing to reach the target speed. This improves the reliability and success rate of the test. Moreover, the fiber optic sensors are fixedly mounted on the housing, unaffected by high-speed centrifugal force, ensuring reliable operation, long lifespan, and reusability. This avoids test failures and repeated tests caused by strain gauges easily detaching at high speeds, saving resources. The experimental budget and time constraints; the dynamic pressure measurement subsystem includes multiple dynamic pressure sensors, signal amplifiers, and a data acquisition module; the dynamic pressure sensors are installed at multiple axial and circumferential positions on the casing wall to measure the pressure pulsation signal on the casing wall in real time to obtain the non-integer order pressure pulsation frequency; the time synchronization module is connected to the data acquisition modules of the fiber optic blade tip timing measurement subsystem and the dynamic pressure measurement subsystem respectively, and calibrates the system time of the two subsystems before the experiment to ensure that their time bases are consistent, ensuring the time correspondence between the dynamic pressure signal and the blade tip amplitude signal, and ensuring that the dynamic pressure signal and the blade tip amplitude signal are comparable in time, providing a reliable time basis for accurately distinguishing asynchronous vibration and flutter; the data integration and processing module receives the blade vibration frequency and amplitude data as well as the pressure pulsation frequency data to determine asynchronous vibration. This system can simultaneously acquire the arrival time of all blades in the entire stage, realize the simultaneous monitoring of the vibration state of all blades, and can identify the abnormal vibration of individual blades, overcoming the limitation of strain gauges that can only measure a limited number of blades.
[0023] In some preferred embodiments, the fiber optic sensor is mounted on at least two axial sections of the housing (e.g., Figure 2 As shown in sections 1 and 5, at least one fiber optic sensor is arranged in each axial section. The installation position of the fiber optic sensor is selected near the position of maximum blade amplitude to ensure that the rotor blade tip signal can be measured throughout the test, and at the same time, it is arranged as close as possible to the position of maximum blade amplitude. The fiber optic sensor is a multimode fiber optic sensor mounted on the fan casing. The sensor operates based on the principle of light reflection; it emits a light beam through an optical fiber to the blade tip. The reflected light signal is received by the same or receiving optical fiber and converted into a pulse signal via photoelectric conversion. When the blade vibrates, the blade tip shifts along the rotation direction, changing the time it takes for the blade to reach the sensor. Vibration parameters such as blade amplitude, phase, and frequency are obtained from this change. The fiber optic amplifier amplifies and shapes the weak light signal received by the fiber optic sensor, converting it into a standard TTL pulse signal. The data acquisition module can utilize a high-speed counter / timer board. In addition, more fiber optic sensors are arranged at multiple circumferential positions in the fan casing to identify the circumferential modes of blade vibration. By arranging multiple fiber optic sensors at different angles around the casing, the amplitude and phase of blade vibration measured by each sensor differ. Based on the amplitude and phase data measured by each sensor, the least squares fitting method can be used to reconstruct the circumferential vibration distribution pattern of the blade and identify the number of circumferential modes and the number of nodal diameters of asynchronous vibration. The modal identification results can be used to further analyze the location and propagation direction of the excitation source of asynchronous vibration, providing a basis for the study of the mechanism of asynchronous vibration and the design of suppression measures.
[0024] In some preferred embodiments, the dynamic pressure sensor is a Kulite dynamic pressure sensor, arranged in at least six axial sections (e.g., ...) of the fan rotor casing wall. Figure 3 As shown in sections 1 to 6, at least 5 different axial positions are arranged along the chord length of the rotor blade tip, and at least 4 circumferential measuring points are arranged at each axial position. At least 20 dynamic pressure measuring points are distributed in a rotor blade tip periodic channel. This arrangement can completely capture the circumferential and axial pressure disturbances caused by the rotating unstable flow.
[0025] In some preferred embodiments, the fiber optic blade tip timing measurement subsystem further includes a rotational speed reference module. The rotational speed reference module is used to measure a reference pulse generated for each rotation of the blade through one of the fiber optic sensors, and to calculate the rotor speed based on the reference pulse and the blade pulse sequence, thereby realizing rotational speed measurement and blade number identification.
[0026] In some preferred embodiments, the data processing module is communicatively connected to the data acquisition modules of the two subsystems to receive blade vibration frequency / amplitude data and pressure pulsation frequency data, and performs the following analysis: Spectral analysis was performed on the blade vibration data to extract non-integer order vibration frequencies; Spectral analysis was performed on dynamic pressure data to extract non-integer order pressure pulsation frequencies; Perform asynchronous vibration assessment; Based on the temporal relationship between pressure pulsation and blade vibration, asynchronous vibration and flutter can be distinguished.
[0027] On the other hand, a preferred embodiment of the present invention also provides a method for testing asynchronous vibration of blades, which applies the above-mentioned asynchronous vibration testing system for blades, and the testing method includes: S1. Test preparation and time calibration; Specifically, before the fan test run begins, the system time of the data acquisition modules of the fiber optic blade tip timing measurement subsystem and the dynamic pressure measurement subsystem is calibrated through the time synchronization module to ensure that the time base of the two subsystems is consistent. S2. Dynamic pressure measurement; Specifically, after the fan starts running, the pressure pulsation signal of the casing wall is measured in real time by using Kulite dynamic pressure sensors installed at 20 measuring points in 6 cross-sectional positions on the casing wall; the sampling frequency is set to ensure complete capture of the fan rotor passing frequency and its harmonics, as well as non-integer order pressure pulsation signals; S3. Blade vibration measurement; S4. Determination of asynchronous vibration.
[0028] In some preferred embodiments, step S2 includes: Multiple dynamic pressure sensors installed on the casing wall are used to measure the pressure pulsation signal on the casing wall in real time, thereby obtaining the non-integer order pressure pulsation frequency in the flow field. ; Step S3 includes: Multiple fiber optic sensors mounted on the casing are used to detect the tip-reflected light pulse signals of the rotor blades in real time as they pass by, recording the arrival time of each blade. The vibration displacement of each blade is calculated based on the deviation between the arrival time and the reference time. Spectral analysis is performed on the vibration displacement data of each blade to obtain the non-integer order vibration frequencies of the rotor blades. Specifically, fiber optic sensors installed in the casing detect the reflected light pulse signals from the blade tips as the rotor blades pass by in real time. For each rotation of the blade, each fiber optic sensor generates a pulse sequence equal to the number of blades. The data acquisition module records the arrival time of each pulse. For each blade, its actual arrival time is compared with the reference time (the theoretical arrival time when the blade is not vibrating), the arrival time difference is calculated, and the vibration displacement of the blade is determined based on the time difference. A fast Fourier transform is performed on the vibration displacement time series of each blade to obtain the vibration spectrum of the rotor blade, from which non-integer order vibration frequencies are extracted.
[0029] In some preferred embodiments, step S3 includes: If the time interval between the arrival of each blade at the fiber optic sensor is equal, it is a standard pulse sequence, and the rotor blade is judged to be not vibrating; if the blade tip deviates along the rotation direction, and the time when the blade arrives at the sensor is earlier or later than the standard time, it is judged that the blade is vibrating, and the time difference between the earlier or later arrival is a measure of the blade vibration displacement; the vibration amplitude and phase of each blade are calculated based on the time difference. In some preferred embodiments, step S4 includes: The pressure pulsation frequency obtained in the dynamic pressure measurement step The blade vibration frequency obtained from the blade vibration measurement step Substitute into the asynchronous vibration judgment formula Make a judgment, among which For rotor speed, The circumferential mode number of the disturbance source; when the formula holds true, the current vibration is determined to be asynchronous blade vibration; simultaneously, based on the temporal sequence of the pressure pulsation signal and the blade vibration signal, asynchronous vibration is further distinguished from flutter: if the non-integer order frequency of the pressure pulsation occurs earlier than the non-integer order frequency of the blade vibration, it is determined to be asynchronous vibration (forced vibration); if the non-integer order frequency of the blade vibration occurs earlier than the non-integer order frequency of the pressure pulsation, it is determined to be flutter (self-excited vibration). It should be noted that for the compressor rotor, there are three coordinate systems: the rotor blade relative coordinate system R, the casing absolute coordinate system F, and the rotationally unstable flow structure coordinate system Q. The rotationally unstable flow structure can be regarded as a disturbance source. It is both the source of the pulsation signal measured by the pressure pulsation sensor on the casing in the fixed coordinate system and the source of aerodynamic excitation felt in the rotor coordinate system R. Assume the frequency of the disturbance caused by rotational instability is Then the frequency observed in the fixed coordinate system is: (1) in, Let α be the frequency of the disturbance sensed by the casing wall, and α be the circumferential mode number of the corresponding disturbance source. Let be the circumferential rotational velocity of the disturbance source relative to the casing coordinate system F. Similarly, the frequency observed in the rotor blade relative coordinate system is: (2) in, The frequency of the disturbance felt by the rotor blades. Let be the circumferential rotational velocity of the disturbance source relative to the rotor coordinate system R. Figure 1 It can be seen that, (3) in, Let R be the circumferential rotational speed of the rotor coordinate system relative to the absolute coordinate system of the casing, i.e., the rotational speed of the rotor. Let be the circumferential rotational velocity of the rotor coordinate system relative to the disturbance source, i.e. Then equation (3) can be written as: (4) Subtracting equation (1) from equation (2), we can obtain: (5) f0 = Ω0 / 2π is the rotor frequency; because and The measured result is always positive, but since the propagation direction of the disturbance source is different, (5) can be written as: (6) In formula (6) The frequency of pressure pulsations that can be measured on the casing. It is the disturbance frequency sensed on the rotor blade. This formula is the relationship between the non-integer order frequency obtained from dynamic pressure monitoring and the non-integer order frequency obtained from blade tip amplitude monitoring once the flow / vibration coupling phenomenon occurs.
[0030] In some preferred embodiments, step S5 is also included: Based on the asynchronous vibration determination result, an asynchronous vibration alarm signal is output. The alarm signal includes the rotational speed range, vibration frequency, vibration amplitude, and corresponding blade number of the asynchronous vibration.
[0031] On the other hand, a preferred embodiment of the present invention also provides an aero-engine test system, which applies the above-mentioned blade asynchronous vibration test system.
[0032] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.
[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A blade asynchronous vibration testing system, characterized in that, include: The fiber optic leaf tip timing measurement subsystem includes a fiber optic sensor and a data acquisition module; Multiple fiber optic sensors are mounted on the casing to detect the light pulse signal reflected from the blade tip when the rotor blade passes by. The data acquisition module of the fiber optic blade tip timing measurement subsystem is used to calculate the arrival time of each blade based on the arrival time of the light pulse signal, thereby obtaining the blade vibration frequency and amplitude. The dynamic pressure measurement subsystem includes a dynamic pressure sensor and a data acquisition module; Multiple dynamic pressure sensors are respectively installed at multiple axial and circumferential positions on the casing wall to measure the pressure pulsation signal of the casing wall in real time and obtain the non-integer order pressure pulsation frequency; the dynamic pressure sensors are arranged in at least 6 axial sections on the fan rotor casing wall, at least 5 different axial positions along the rotor blade tip chord direction, at least 4 circumferential measuring points are arranged at each axial position, and at least 20 dynamic pressure measuring points are distributed in a rotor blade tip periodic channel; The time synchronization module is connected to the data acquisition module of the fiber optic leaf tip timing measurement subsystem and the data acquisition module of the dynamic pressure measurement subsystem, respectively, and is used to calibrate the system time of the two subsystems before the test so that the time reference of the fiber optic leaf tip timing measurement subsystem and the dynamic pressure measurement subsystem is consistent. The data processing module is communicatively connected to the data acquisition modules of the fiber optic blade tip timing measurement subsystem and the dynamic pressure measurement subsystem, respectively. It receives the blade vibration frequency and amplitude data, as well as the pressure pulsation frequency data, to determine asynchronous vibration. It also processes the pressure pulsation frequency data obtained from the dynamic pressure measurement subsystem. The blade vibration frequency obtained by the fiber optic blade tip timing measurement subsystem Substitute into the asynchronous vibration determination formula Make a judgment, among which For rotor speed, The number of circumferential modes of the disturbance source; when the formula holds true, the current vibration is determined to be asynchronous vibration of the blade.
2. The blade asynchronous vibration testing system according to claim 1, characterized in that, The fiber optic sensors are installed on at least two axial sections of the casing, with at least one fiber optic sensor arranged on each axial section. The installation positions of the fiber optic sensors are selected near the position of maximum blade amplitude.
3. The blade asynchronous vibration testing system according to claim 1, characterized in that, The dynamic pressure sensor is a Kulite dynamic pressure sensor.
4. The blade asynchronous vibration testing system according to claim 1, characterized in that, The fiber optic blade tip timing measurement subsystem also includes a rotational speed reference module, which is used to measure a reference pulse generated for each rotation of the blade through one of the fiber optic sensors, and to calculate the rotor speed based on the reference pulse and the blade pulse sequence.
5. A method for testing asynchronous vibration of blades, characterized in that, The blade asynchronous vibration testing system as described in any one of claims 1-4, wherein the testing method comprises: S1. Test preparation and time calibration; S2. Dynamic pressure measurement; S3. Blade vibration measurement; S4. Determination of asynchronous vibration.
6. The method for testing asynchronous vibration of blades according to claim 5, characterized in that, Step S2 includes: Multiple dynamic pressure sensors installed on the casing wall are used to measure the pressure pulsation signal on the casing wall in real time, thereby obtaining the non-integer order pressure pulsation frequency in the flow field. ; Step S3 includes: Multiple fiber optic sensors mounted on the casing are used to detect the tip-reflected light pulse signals of the rotor blades in real time as they pass by, and the arrival time of each blade is recorded. The vibration displacement of each blade is calculated based on the deviation between the arrival time and the reference time. Spectral analysis is performed on the vibration displacement data of each blade to obtain the non-integer order vibration frequencies of the rotor blades. .
7. The method for testing asynchronous vibration of blades according to claim 5, characterized in that, Step S3 includes: If the time interval between the arrival of each blade at the fiber optic sensor is equal, it is a standard pulse sequence, and the rotor blade is judged not to vibrate; if the blade tip deviates along the rotation direction, and the time when the blade arrives at the sensor is earlier or later than the standard time, it is judged that the blade is vibrating, and the time difference between the earlier or later arrival is a measure of the blade vibration displacement; the vibration amplitude and phase of each blade are calculated based on the time difference.
8. The method for testing asynchronous vibration of blades according to claim 6, characterized in that, Step S4 includes: The pressure pulsation frequency obtained in the dynamic pressure measurement step The blade vibration frequency obtained from the blade vibration measurement step Substitute into the asynchronous vibration determination formula Make a judgment, among which For rotor speed, The number of circumferential modes of the disturbance source; when the formula holds true, the current vibration is determined to be asynchronous vibration of the blade.
9. The method for testing asynchronous vibration of blades according to claim 5, characterized in that, It also includes step S5: Based on the asynchronous vibration determination result, an asynchronous vibration alarm signal is output. The alarm signal includes the rotational speed range, vibration frequency, and vibration amplitude of the asynchronous vibration.
10. An aircraft engine test system, characterized in that, The blade asynchronous vibration testing system as described in any one of claims 1-4 is applied.