Calibration device and method for blade tip timing system
By combining a laser vibrometer and a wedge prism tube, the problems of unreliable measurement point fixation and unreliable reference data in blade tip timing vibration measurement technology are solved, achieving high-precision calibration in the working state and ensuring the integrity of the blade disk structure and the accuracy of the measurement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2026-02-27
- Publication Date
- 2026-05-12
AI Technical Summary
Existing blade tip timing vibration measurement technology suffers from problems such as unreliable fixed measuring points, unreliable reference data, and inability to calibrate under working conditions.
By combining a laser vibrometer and a wedge prism tube, and by rotating the wedge prism tube coaxially and synchronously with the rotating shaft, non-contact calibration is performed using the measuring laser of the laser vibrometer. This establishes a calibration relationship between the blade tip timing system and the laser vibrometer, enabling high-precision measurement of blade vibration parameters.
It achieves high-precision calibration of blade vibration frequency and amplitude under working conditions, avoiding the damage to the bladed disk structure caused by traditional methods, improving the accuracy and reliability of calibration, and enabling calibration to be performed at the actual working speed of the bladed disk.
Smart Images
Figure CN122016029A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of precision photoelectric measurement technology, and in particular to a calibration device and method for a blade tip timing system. Background Technology
[0002] In large turbomachinery such as aero engines, gas turbines, and steam turbines, rotor blades need to withstand high loads under high-speed rotation conditions. To ensure the safe and stable operation of the equipment, it is necessary to measure key operating parameters during the blade rotation process in real time, including vibration frequency and vibration amplitude.
[0003] Blade tip timing vibration measurement technology is currently a hot research topic in online monitoring of blade vibration. The technical principle involves arranging a set of sensors on the casing to capture the time point at which each blade tip reaches the sensor, thereby calculating the circumferential displacement of the blade tip and ultimately deducing the blade's vibration frequency and amplitude. Its measurement principle is as follows: A blade tip timing sensor is mounted on the casing, a key phase sensor is mounted on the stator, and a key direction marker is affixed to the rotor's synchronous shaft. When a blade sweeps past the blade tip timing sensor, the measuring circuit generates a pulse signal to record the blade's arrival time relative to the key direction sensor. By comparing the measured blade arrival time with the theoretical arrival time under vibration-free conditions, and combining this with the current rotational speed, the blade vibration displacement can be obtained. Then, through a host computer program and relevant identification algorithms, parameters such as the blade vibration frequency and amplitude can be obtained.
[0004] To verify the measurement accuracy of the system and clarify its error range, system calibration is crucial. However, currently, there are few calibration methods for blade tip timing measurement systems, and their measurement accuracy needs improvement. The existing calibration schemes related to this invention mainly include the following two.
[0005] Relative displacement calibration method: Invention patent authorization number CN109000787: This method does not directly excite the blade in a rotating state, but instead installs the blade tip timing sensor on a vibration table. By controlling the vibration table to drive the sensor to vibrate, the relative motion between the blade and the sensor is used to simulate the working state of the rotating blade. The vibration frequency and amplitude set by the vibration table are used as reference standard values and compared with the measurement results of the blade tip timing system to determine the measurement error and achieve calibration.
[0006] Rotational Reference Calibration Method: 1. Patent No. CN115435734: This invention designs a device that fixes a laser displacement sensor to a blade disk using a custom bracket, achieving coaxial rotation between the sensor and the blade. Under these conditions, a reference standard value for the blade tip vibration displacement is collected, thereby completing the high-precision calibration of the blade tip timing measurement system. 2. Patent No. CN113959556: This invention fixes the blade and the laser displacement sensor simultaneously on a disk driven by a motor. The disk rotates, and the blade tip timing sensors are circumferentially distributed on a simulated casing around the disk, not rotating with the disk. The blade tip vibration displacement value measured under these conditions is used as a reference standard.
[0007] The relative displacement calibration method uses data measured by a timing sensor at the blade tip during vibration as a reference. However, since the vibration is not generated by the blade, this standard quantity differs fundamentally from the actual vibration displacement of the blade tip under rotational conditions. The rotational reference calibration method requires fixing the laser displacement sensor to the rotor using a specific bracket; however, at excessively high speeds, the bracket itself will also vibrate. The reference quantities used in existing technologies are inherently unreliable and cannot be used for high-precision calibration.
[0008] Therefore, those skilled in the art are dedicated to developing a calibration device and method for a blade tip timing system to solve the three main problems of existing calibration technologies: fixed measurement points, unreliable reference data, and inability to calibrate under working conditions. Summary of the Invention
[0009] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to solve the problems of fixed measuring points, unreliable reference data, and inability to be calibrated in working condition in the existing blade tip timing vibration measurement technology.
[0010] To achieve the above objectives, the present invention provides a calibration device for a blade tip timing system, characterized in that it includes a laser vibrometer and a wedge prism tube, wherein the wedge prism tube is connected to the top of the rotating shaft of the impeller to be tested, the wedge prism tube is coaxial with and rotates synchronously with the rotating shaft, the laser vibrometer is placed outside the experimental platform, and the measuring laser emitted by the laser vibrometer is directed towards the top of the rotating shaft.
[0011] Furthermore, the wedge-shaped prism barrel is rigidly fixed to the top of the rotating shaft by a threaded top cover and a prism holder.
[0012] Furthermore, the shaft of the impeller under test is fixed by a bearing housing support casing, which is stably supported by a casing support plate. The blade tip timing sensor group is circumferentially and evenly mounted on the mounting casing of the blade tip timing system.
[0013] Furthermore, the wedge-shaped prism barrel is capable of axial movement.
[0014] A method for calibrating the axial displacement of the blade tip in a calibration device for a blade tip timing system, characterized by comprising the following steps: Step 1: For a selected blade, at multiple different stable speed points... The measurement will be performed below; Step 2: Establish the displacement of the blade tip timing system along the optical path. Reference axial displacement of laser vibrometer The calibration relationship between them; Step 3, with As the x-axis, with Plot all data points on the ordinate and perform linear fitting using the least squares method to obtain the axial displacement calibration curve for the blade:
[0015] Where 'a' is the proportionality coefficient. This is the zero-point offset; Step 4: By comparing multiple sets of rotational speeds and vibration conditions, establish the axial displacement output by the blade tip timing system. The laser vibrometer reference axial displacement The calibration relationship between them; Step 5: Repeat the acquisition under the same working conditions. The calibration results are used to calculate the mean and sample standard deviation, and the uncertainty of the calibration results is calculated.
[0016] Furthermore, in step 2, the laser vibrometer references the axial displacement. The displacement of the blade tip timing system along the optical path was measured by a synchronously rotating wedge prism. Axial displacement output by the blade tip timing system Conversion yields:
[0017] in, It is the angle between the optical path after the prism is deflected and the axis of the blade.
[0018] Furthermore, the mean With the sample standard deviation They are respectively represented as
[0019] Type A standard uncertainty is: .
[0020] Furthermore, in step 5, the uncertainty is expressed as:
[0021] The measurement error of the laser vibrometer is... And it can be treated as a uniform distribution, then Angle Measurement uncertainty.
[0022] A method for calibrating the blade vibration amplitude of a calibration device for a blade tip timing system, characterized by comprising the following steps: Step 1: Make the impeller under test rotate stably at a set speed, and apply excitation to the target blade through the excitation device to make the blade vibrate; Step 2: Establish the component of the vibration amplitude of the blade tip timing system along the optical path of the laser vibrometer. Reference amplitude of laser vibrometer The calibration relationship between them; Step 3: Change the excitation intensity and rotation speed to obtain N sets of data pairs covering the target amplitude range. ,by As the independent variable, with A least-squares fit is performed on the dependent variable to establish an amplitude calibration model:
[0023] Where a is the proportionality coefficient and b is the zero-point offset; Step 4: By comparing multiple sets of rotational speeds and vibration conditions, establish the vibration amplitude output by the blade tip timing system. With the reference amplitude of the laser vibrometer The calibration relationship between them.
[0024] Furthermore, in step 2, the laser vibrometer illuminates the target measuring point at the blade tip with a measuring spot via a wedge prism, thereby obtaining the reference amplitude of the laser vibrometer. The component of the vibration amplitude of the blade tip timing system along the optical path of the laser vibrometer. Represented as:
[0025] in, The angle between the direction of the light path of the laser vibrometer after refraction through the wedge prism and the measurement direction of the blade tip timing system. The vibration amplitude of the same blade and the same measuring point output by the blade tip timing system under the same rotational speed and excitation conditions as the reference amplitude of the laser vibration meter.
[0026] This invention provides a method for calibrating a blade tip timing sensor using a laser vibration meter. The innovative design of altering the vibration measurement optical path with a wedge prism successfully solves three main problems of existing calibration techniques: fixed measurement points, unreliable reference data, and inability to calibrate under operating conditions. The measurement technology involved in this invention is non-contact, maintaining the integrity of the bladed disk structure, and has broad application prospects in the health monitoring and safety maintenance of high-end rotating machinery such as aero-engines and gas turbines.
[0027] The beneficial technical effects of the present invention are as follows: 1. Existing technologies use fixed measurement points, making it inconvenient to calibrate multiple locations and measurement points. The Rotating Reference Calibration (LDS) method requires a laser displacement sensor used as a reference to be fixed to the bladed disk using a dedicated bracket, achieving synchronous rotation between the measurement point and the blade. Each measurement point corresponds to one sensor, but the bracket disrupts the cyclic symmetry structure of the bladed disk, and the measurement point position is fixed after installation and cannot be adjusted. This invention uses a laser vibrometer for calibration, requiring only the measurement spot to illuminate the measurement point without altering the bladed disk structure, and the measurement point position is adjustable. Its core measurement component (wedge prism) is mounted at the top of the rotating shaft, not on the bladed disk. The measurement spot is projected onto the blade tip through the rotating wedge prism, eliminating the need for any additional structures on the bladed disk. By adjusting the direction of the laser vibrometer or the distance between the wedge prism and the bladed disk, flexible measurements of different measurement points on the blade can be achieved. Measurements of different blades and different locations (such as the blade tip and middle) on the same bladed disk can be realized without disrupting the cyclic symmetry and dynamic characteristics of the bladed disk.
[0028] 2. The reference quantities used in existing technologies are unreliable and cannot be used for high-precision calibration. The relative displacement calibration method uses data measured by a blade tip timing sensor during vibration as a reference. However, vibration is not generated by the blade itself, and this standard quantity differs fundamentally from the actual vibration displacement of the blade tip under rotation. The rotational reference calibration method requires fixing the laser displacement sensor to the rotor using a specific bracket; however, the bracket itself will vibrate at excessively high speeds. The method proposed in this invention uses data obtained from a laser vibrometer as a reference, and uses the blade tip vibration parameters measured by the Doppler laser vibrometer as the reference for calibrating the blade tip timing sensor. However, the laser vibrometer can only measure fixed points and cannot be applied to rotating objects. Therefore, this invention also designs an optical path synchronization device. The principle is to fix a wedge prism at the top of the blade disk shaft and rotate synchronously with the shaft. The wedge prism refracts the measurement light from the laser vibrometer, enabling the measurement spot of the laser vibrometer to rotate synchronously with the blade, thereby obtaining vibration data of the blade under rotation. This calibration method recreates the real-world scenario of blade tip vibration and uses parameters measured by a laser vibration meter as a reference, thereby improving the accuracy and reliability of the calibration results.
[0029] 3. Existing calibration schemes all involve calibrating the tip timing sensor by installing a sensor on the blade or modifying the basic structure of the bladed disk. However, in actual operation, the bladed disk often lacks the conditions for sensor installation, making calibration impossible under operating conditions. The sensor in this invention is not located in the rotation system; only a wedge prism is fixed to the top of the rotating shaft and does not contact the bladed disk, allowing calibration to be performed while the bladed disk is in operation. This invention utilizes the Doppler laser vibration measurement principle. Only the measurement spot illuminates the blade. When the blade vibrates, the frequency of the reflected light shifts. The vibration meter calculates the blade vibration parameters by detecting this shift and combining it with the laser wavelength and propagation speed. This eliminates the need for sensors on the blade or bladed disk and allows calibration of the tip timing sensor at any bladed disk rotation speed.
[0030] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the overall structural layout of a calibration device for a blade tip timing system according to a preferred embodiment of the present invention. Figure 2 This is a schematic diagram of the laser path of a calibration device for a blade tip timing system according to a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a fixed prism clamp of a blade tip timing system according to a preferred embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of an adjustable prism clamp for a blade tip timing system according to a preferred embodiment of the present invention; Figure 5 This is a schematic diagram of the tip displacement of an adjustable prism clamp in a tip timing system according to a preferred embodiment of the present invention. Figure 6 This is a schematic diagram of the optical path deflection of an adjustable prism clamp in a leaf tip timing system according to a preferred embodiment of the present invention. Among them, 1-laser vibration meter, 2-wedge prism tube, 3-bearing seat support casing, 4-impeller to be tested, 5-mounting casing, 6-casing support plate. Detailed Implementation
[0032] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.
[0033] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.
[0034] 1. Calibration device
[0035] This invention provides a calibration device for a blade tip timing system, the overall structure of which is as follows: Figure 1 As shown. The system adopts a horizontal arrangement. Its core lies in using an optical path deflection component that rotates coaxially with the rotor to guide the measuring spot of a fixed laser vibrometer onto the rotating blades, thus achieving non-contact, high-precision calibration. The shaft of the impeller 4 under test is fixed by a bearing housing supporting the housing 3 and is driven to rotate by a drive device to simulate real working conditions. The laser vibrometer 1, serving as the core measurement reference, is placed outside the experimental platform, and its emitted measuring laser is directed towards the top of the shaft. A wedge-shaped prism tube 2 is rigidly connected to the top of the shaft, such as... Figure 3 and Figure 4 As shown, the wedge prism is rigidly fixed inside the lens barrel by a threaded top cover and a prism holder, ensuring that it can achieve high coaxiality and synchronous rotation with the rotating shaft.
[0036] like Figure 2 As shown, the laser beam emitted by the laser vibrometer 1 illuminates a high-speed rotating wedge prism. After refraction, the measurement spot is precisely projected onto a predetermined position at the blade tip of the impeller 4 under test. By axially moving the wedge prism tube 2, the illumination point of the measurement spot on the blade can be flexibly changed, thereby enabling measurements at different positions on a single blade or on different blades. This design solves the problem of fixed measurement points in traditional methods. The blade tip timing sensor group is circumferentially and uniformly mounted on the mounting housing 5 of the calibration blade tip timing system (BTT) to capture the pulse signal generated when the blade arrives. The entire housing structure is stably supported by the housing support plate 6. During the entire measurement process, only a small wedge prism tube 2 with high concentricity rotates with the rotor. No additional structures need to be installed on the impeller 4 under test, thus fully preserving the cyclic symmetry and dynamic characteristics of the impeller. This allows calibration to be performed at the actual operating speed of the impeller, achieving calibration under operating conditions.
[0037] 2. Calibration method for blade tip axial displacement
[0038] Based on the aforementioned calibration device, this invention provides a method for calibrating the axial displacement output of a blade tip timing system. Under rotating conditions, the blade will deform under the combined action of centrifugal and aerodynamic loads, such as... Figure 5 As shown, the blade tip displacement can be expressed as axial displacement (a) and torsional displacement (d).
[0039] Among the above displacement types, axial displacement affects dynamic stress assessment and also changes the blade axial / inter-blade clearance and aerodynamic performance, and is often a key monitoring target in engineering applications.
[0040] Axial displacement calibration process: For a selected blade, at multiple different stable speed points... Measurements were taken below. In the first... At each rotational speed point, the laser vibrometer (LDV) measures the reference axial displacement of the blade tip along the optical path using a synchronously rotating wedge prism. .like Figure 6 As shown, based on the angle between the light path after prism deflection and the blade axis... The axial displacement output by the calibration tip timing system (BTT) will be used. Displacement along the optical path .
[0041]
[0042] Thus, a series of data pairs were obtained ( By comparing multiple sets of rotational speeds and vibration conditions, a calibration relationship can be established between the axial displacement output of the BTT system and the reference axial displacement of the laser vibration meter.
[0043] by As the x-axis, with Plot all data points using the ordinate. The axial displacement calibration curve for the blade can be obtained by performing a linear fit using the least squares method.
[0044] Where 'a' is the proportionality coefficient. This is the zero-point offset.
[0045] By comparing multiple sets of rotational speeds and vibration conditions, a calibration relationship can be established between the axial displacement output by the blade tip timing system and the reference displacement provided by the laser vibration meter, thereby completing the calibration.
[0046] Repeatedly acquire under the same working conditions Second calibration result Their mean and sample standard deviation are respectively
[0047] The Type A standard uncertainty of the calibration result is then taken as...
[0048] The sources of Type B uncertainty can be attributed to: 1. The uncertainty measured by the laser vibrometer. 1. Instrument error; 2. Angle The measurement error. These sources are first converted into standard uncertainty according to instrument specifications or certificates. The measurement error of the laser vibrometer is... And since it can be treated as a uniform distribution, the Type B uncertainty is taken as...
[0049] included angle Measurement uncertainty It can be calculated using the uncertainty assessment formula.
[0050] The uncertainty of combination at this point is:
[0051] 3. Calibration method for blade vibration amplitude
[0052] Based on the aforementioned calibration device, this invention is used to calibrate the vibration amplitude output by a blade tip timing (BTT) system. The core idea of this invention is to use the vibration amplitude measured by a laser vibrometer (LDV) as a reference standard. The LDV measures the component of the vibration amplitude at the measuring point along the LDV optical path, while the amplitude output by the BTT system can be understood as the amplitude of the circumferential vibration at the measuring point. Therefore, the amplitude measured by the BTT should be converted to the LDV measurement direction before establishing a calibration relationship with the LDV measurement results.
[0053] In practice, the impeller is first stabilized at a set speed, and then an excitation device is used to apply excitation to the target blade, causing it to vibrate. Subsequently, the LDV (Laser-Driven Vibration) beam is projected onto the target measuring point at the blade tip via a wedge prism, obtaining a reference amplitude in the LDV direction. .
[0054] Synchronized with LDV, the BTT system outputs the vibration amplitude of the same blade and the same measuring point under the same rotational speed and excitation conditions. To make the results of the two systems comparable in the same measurement direction, let's assume... The diagram shows the angle between the direction of the light path after LDV refraction through the wedge prism and the direction of BTT measurement. Figure 6 If the values are the same (θ can be determined by the clamping geometry or obtained through a finite element model), then the component of the vibration amplitude measured by BTT in the LDV direction can be expressed as:
[0055] The amplitude of BTT in the LDV measurement direction was calculated. Aligning the LDV and BTT data using the speed signal ensures that each operating condition receives a pair of amplitude data. Subsequently, the excitation intensity and rotational speed were changed to obtain N sets of data pairs covering the target amplitude range. .by As the independent variable, with A least-squares fit is performed on the dependent variable to establish an amplitude calibration model:
[0056] Where 'a' is the proportionality coefficient and 'b' is the zero-point offset. By comparing multiple sets of rotational speeds and vibration conditions, a calibration relationship between the BTT system output and the LDV reference amplitude can be established, thereby completing the calibration of the BTT system vibration amplitude.
[0057] Technical Advantages: This invention employs non-destructive testing for the reference value measurement of the blade tip timing sensor. The core measurement components are mounted at the top of the rotating shaft, eliminating the need for supports or sensors on the impeller or blades. This avoids measurement errors introduced by the added mass damaging the impeller's cyclic structure, ensuring the true dynamic characteristics of the measured object. It solves the high cost problem of existing technologies where one sensor corresponds to one measurement point, improving equipment utilization. Except for the wedge prism that rotates with the shaft, the core measurement components of this invention are all located outside the transmission system. The measured reference value is directly derived from the data during impeller rotation, allowing calibration of the blade tip timing sensor at the actual operating speed of the impeller. This means that calibration can be completed without stopping or disassembling the machine, solving the problem of on-site online calibration.
[0058] Performance advantages: Utilizing a laser vibrometer with higher measurement accuracy, the calibration results are far more accurate and reliable than those obtained using relative displacement calibration and rotational reference calibration methods. This invention's measurement method allows for the detection of multiple measurement points on a single device, reducing sensor installation and debugging time, improving sensor calibration efficiency, and enabling calibration across the entire speed range of the impeller disk. The measurement range covers the entire real-world operating state of the equipment from startup and operation to shutdown.
[0059] Production Implementation: The calibration system of this invention mainly consists of a commercial laser vibrometer, a custom-designed wedge prism, and a wedge prism adjustment structure. The laser vibrometer is a mature product; the innovation of this device lies in its design of a structure that can alter the optical path while achieving rotation at the same speed, thus reducing development costs. When deployed to customers such as aero-engine manufacturers and gas turbine manufacturers, no structural changes to the bladed disk rotor are required; only a wedge prism needs to be added to the end of the shaft, reducing operational complexity.
[0060] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
Claims
1. A calibration device for a blade tip timing system, characterized in that, The instrument includes a laser vibrometer and a wedge prism tube. The wedge prism tube is connected to the top of the rotating shaft of the impeller to be tested. The wedge prism tube is coaxial with and rotates synchronously with the rotating shaft. The laser vibrometer is placed outside the experimental platform, and the measuring laser emitted by the laser vibrometer is directed towards the top of the rotating shaft.
2. The calibration device for a blade tip timing system as described in claim 1, characterized in that, The wedge-shaped prism barrel is rigidly fixed to the top of the rotating shaft by a threaded top cover and a prism holder.
3. The calibration device for a blade tip timing system as described in claim 1, characterized in that, The shaft of the impeller under test is fixed by a bearing housing support casing, which is stably supported by a casing support plate. The blade tip timing sensor group is circumferentially and evenly installed on the mounting casing of the blade tip timing system.
4. The calibration device for a blade tip timing system as described in claim 1, characterized in that, The wedge-shaped prism barrel is capable of axial movement.
5. The blade tip axial displacement calibration method of the calibration device for a blade tip timing system as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: For a selected blade, at multiple different stable speed points... The measurement will be performed below; Step 2: Establish the displacement of the blade tip timing system along the optical path. Reference axial displacement of laser vibrometer The calibration relationship between them; Step 3, with As the x-axis, with Plot all data points on the ordinate and perform linear fitting using the least squares method to obtain the axial displacement calibration curve for the blade: Where 'a' is the proportionality coefficient. This is the zero-point offset; Step 4: By comparing multiple sets of rotational speeds and vibration conditions, establish the axial displacement output by the blade tip timing system. The laser vibrometer reference axial displacement The calibration relationship between them; Step 5: Repeat the acquisition under the same working conditions. The calibration results are used to calculate the mean and sample standard deviation, and the uncertainty of the calibration results is calculated.
6. The blade tip axial displacement calibration method as described in claim 5, characterized in that, In step 2, the laser vibrometer references the axial displacement. The displacement of the blade tip timing system along the optical path was measured by a synchronously rotating wedge prism. Axial displacement output by the blade tip timing system Conversion yields: in, It is the angle between the optical path after the prism is deflected and the axis of the blade.
7. The blade tip axial displacement calibration method as described in claim 5, characterized in that, The mean With the sample standard deviation They are respectively represented as Type A standard uncertainty is: 。 8. The blade tip axial displacement calibration method as described in claim 7, characterized in that, In step 5, the uncertainty is expressed as: The measurement error of the laser vibrometer is... And it can be treated as a uniform distribution, then Angle Measurement uncertainty.
9. A method for calibrating the blade vibration amplitude of a calibration device for a blade tip timing system as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Make the impeller under test rotate stably at a set speed, and apply excitation to the target blade through the excitation device to make the blade vibrate; Step 2: Establish the component of the vibration amplitude of the blade tip timing system along the optical path of the laser vibrometer. Reference amplitude of laser vibrometer The calibration relationship between them; Step 3: Change the excitation intensity and rotation speed to obtain N sets of data pairs covering the target amplitude range. ,by As the independent variable, with A least-squares fit is performed on the dependent variable to establish an amplitude calibration model: Where a is the proportionality coefficient and b is the zero-point offset; Step 4: By comparing multiple sets of rotational speeds and vibration conditions, establish the vibration amplitude output by the blade tip timing system. With the reference amplitude of the laser vibrometer The calibration relationship between them.
10. The blade vibration amplitude calibration method as described in claim 9, characterized in that, In step 2, the laser vibrometer illuminates the target measuring point at the blade tip with a measuring spot via a wedge prism, thereby obtaining the reference amplitude of the laser vibrometer. The component of the vibration amplitude of the blade tip timing system along the optical path of the laser vibrometer. Represented as: in, The angle between the direction of the light path of the laser vibrometer after refraction through the wedge prism and the measurement direction of the blade tip timing system. The vibration amplitude of the same blade and the same measuring point output by the blade tip timing system under the same rotational speed and excitation conditions as the reference amplitude of the laser vibration meter.