Radial large-displacement vibration testing method for rotating disc with blades

Abstract

The invention belongs to the technical field of aero-engines, and particularly relates to a radial large-displacement vibration testing method for a rotating disc with blades, which comprises the following steps: at least two testing blocks a and b are mounted on a rotor, the testing blocks are symmetrically arranged on two sides to form a V-shaped structure, the testing block a is mounted on the side surface of the rotating disc, and the testing block b is mounted on the side surface of the rotating disc; the testing block b is mounted at the axial symmetry position of the testing block a, the thickness of one side of the testing block a is smaller than that of the other side; a displacement sensor is arranged near the test block and is used for detecting a signal when the test block passes; acquiring an output signal of the displacement sensor when the rotor rotates, and respectively acquiring time intervals t1 and t2 when the test block a and the test block b pass through the sensor; based on the change of the time interval t1 and t2, the vibration amplitude of the rotor is calculated, and the vibration amplitude is deduced through the tangent speed and the geometrical relation of the test blocks.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to a method for testing radial large displacement vibration of a bladed turntable. Background Technology

[0002] Generally, slender shaft rotors with rotating disks will generate significant vibrations when the imbalance of the rotating disk is large or when the rotor exceeds the critical speed.

[0003] For this type of rotor vibration, non-contact displacement sensors are generally used for direct testing. Figure 1 As shown). However, if the rotating disk has additional structural components such as blades (Figure 2(a)), non-contact displacement testing cannot be achieved. Furthermore, even if the sensor test surface meets the test requirements, large vibrations ( Figure 3 It may still exceed the sensor installation distance, resulting in invalid sensor test results or even damage to the sensor.

[0004] In the situation shown in Figure 2, existing testing methods generally involve removing the test sensor at the rotating disk location and only testing the location with minimal vibration (e.g., Figure 1 In this process, only sensors numbered 1 and 3 are retained to indirectly determine the vibration status of the rotating disk.

[0005] The disadvantages of existing technology are:

[0006] 1. When the rotating disk has structural components such as blades, or when the vibration value is large, direct testing cannot be performed;

[0007] 2. When using other position sensors to indirectly determine the maximum vibration value, the distance between the sensor installation position and the rotating disk or fulcrum must be accurate.

[0008] 3. When the position of the rotating disk changes (is no longer in the middle position), the indirect test results cannot accurately reflect the maximum vibration value of the rotor system. Summary of the Invention

[0009] To address the aforementioned problems, this application provides a rotor vibration testing method for testing the vibration amplitude of a rotating disk on a rotor, comprising the following steps:

[0010] At least two test blocks, a and b, are installed on the rotor. The test blocks are arranged symmetrically on both sides to form a V-shaped structure. Test block a is installed on the side of the rotating disk, and test block b is installed at the axis symmetrical position of test block a. The line of symmetry between test block a and test block b passes through the axis of the rotating disk. The thickness of one side of test block a is less than that of the other side, and the thickness of both sides of test block b is the same.

[0011] A displacement sensor is installed near the test block to detect the signal when the test block passes by;

[0012] The output signal of the displacement sensor is collected when the rotor rotates, and the time intervals Δt1 and Δt2 between test block a and test block b passing through the sensor are obtained respectively.

[0013] Based on the changes in the time intervals Δt1 and Δt2, the vibration amplitude of the rotor is calculated, whereby the vibration amplitude is derived from the tangential velocity and the geometric relationship of the test block.

[0014] Preferably, the thick edge of test block a is used as the test trigger point to mark the start point of time in the displacement sensor signal.

[0015] Preferably, a pretreatment step is included before installing the test block:

[0016] The direction of rotor imbalance is determined by vibration testing and key phase testing;

[0017] The installation position of test block a is selected based on the direction of the imbalance, ensuring that the direction of the imbalance is located in the middle area of ​​test block a.

[0018] Preferably, the displacement sensor is an axial test displacement sensor, and the distance between the installation position and the test block meets the sensor installation requirements to accurately capture the motion signal of the test block.

[0019] Preferably, during the signal acquisition step, the rotor vibrates when Δt1 = Δt2.

[0020] Preferably, the step of calculating the vibration amplitude includes:

[0021] Assuming the test block is fixed while the displacement sensor moves, a geometric model is established, where the distance between the sensor installation position and the axis is R, and the arc length of the test block changes as S1 and S2; S1 represents the arc length of the test block when the vibration is maximum, and S2 represents the arc length of the test block when the vibration is minimum.

[0022] Based on the principle that the tangential velocity Vq remains constant, the radial distance R1 when the vibration is at its maximum and the radial distance R2 when the vibration is at its minimum are calculated using trigonometric function formulas.

[0023] The peak vibration value P is derived from the difference between R1 and R2.

[0024] Preferably, in the geometric model, the expression for the peak vibration P is:

[0025] .

[0026] Preferably, the calculation process for the vibration peak value P is as follows:

[0027] Given that the tangential velocity Vq passing through the sensor remains constant, we obtain...

[0028] ;

[0029] but:

[0030] ;

[0031] ;

[0032] The angles α and β corresponding to S1 and S2 are:

[0033] ;

[0034] ;

[0035] According to trigonometric function formulas:

[0036] ;

[0037] Then we can get R1:

[0038] ;

[0039] Similarly, we can obtain R2:

[0040] ;

[0041] By subtracting R1 and R2, the peak value P of the rotor vibration can be obtained.

[0042] .

[0043] A rotor vibration testing system for implementing the method, characterized in that it comprises:

[0044] Test block assembly: includes at least two V-shaped test blocks that can be mounted on the rotor;

[0045] Displacement sensor: used to detect the motion signal of the test block;

[0046] Data acquisition unit: Connected to the displacement sensor, used to record time interval data;

[0047] Processing unit: Used to calculate vibration amplitude based on time data and output the results.

[0048] 10. The system according to claim 9, wherein the processing unit integrates an algorithm capable of automatically identifying the trigger point of the test block and calculating the vibration peak value.

[0049] 1. It can directly test the vibration amplitude of rotating disks with structural components such as blades, and when the rotor vibration value is large;

[0050] 2. Avoid test failures or even damage to the sensor due to excessive vibration and impact during direct radial testing. Attached Figure Description

[0051] Figure 1 It is a routine rotor vibration test;

[0052] Figure 2a This is a schematic diagram of a rotating disk with blades;

[0053] Figure 2b This is a schematic diagram showing significant rotor vibration.

[0054] Figure 3 This is a schematic diagram of the axial test;

[0055] Figure 4a This is a schematic diagram of the structure of test block a.

[0056] Figure 4b This is a schematic diagram of the test block b structure.

[0057] Figure 5 This is a diagram showing the installation of the test block.

[0058] Figure 6 This is a schematic diagram of the test signal.

[0059] Figure 7 This is a schematic diagram of the displacement sensor testing position changes.

[0060] Figure 8 This is a schematic diagram of the displacement sensor test signal during rotor vibration.

[0061] Figure 9 This is a schematic diagram for calculating displacement vibration values. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only a part of the embodiments of this application, not all of them. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings. The technical solution adopted by this invention is as follows: On the side of the rotating disk, a test block is installed using the existing balance hole of the rotating disk, and the installation direction of the displacement sensor is changed to axial testing. The radial displacement of the rotating disk is calculated by the change in the time it takes for the test block to pass through the displacement sensor. A schematic diagram is shown in Figure 3. Two test blocks are required, where one side of test block a has a thickness of B, which is 0.2 mm thicker than the other side with a thickness of A. The thickness of test block b is the same as the thickness A of test block a. The mounting hole spacing is consistent with the balance hole spacing of the rotating disk. A schematic diagram is shown in Figure 4. In the schematic diagram, the value of C must be greater than the maximum vibration value of the rotor.

[0063] The displacement sensor is installed in the middle of the test block (as shown in Figure 1), and the distance between the sensor and the test block meets the sensor installation requirements.

[0064] Before the test block is installed, it is necessary to conduct normal vibration tests and key phase tests to obtain the direction of rotor imbalance.

[0065] Install test block a in the direction of rotor imbalance, ensuring that the direction of imbalance is as close as possible to the center of test block a. Install test block b at an axisymmetric position of test block a. The schematic diagram is shown in Figure 5, where 1 represents the rotor imbalance direction; 2 represents test block a; and 3 represents test block b.

[0066] As the rotor rotates, the signal measured by the axial displacement sensor is shown in Figure 6.

[0067] In Figure 6, the thick edge of test block a is used as the test trigger point, and the time interval between two trigger points is T, representing one rotation of the rotor. △t1 is the time taken for test block a to pass the displacement sensor, and △t2 is the time taken for test block b to pass the displacement sensor. When the rotor is not vibrating, △t1 = △t2.

[0068] When the rotor vibrates, since the position of the displacement sensor remains unchanged, the corresponding positions of test block a and test block b will change as they pass the displacement sensor with the rotating disk, as shown in Figure 7.

[0069] Because the test block is V-shaped, the time it takes for the test block to pass through the displacement sensor will change. A schematic diagram of the signal acquired by the displacement sensor is shown in Figure 8.

[0070] Since the test block and the displacement sensor are in relative motion, we can assume that the test block is stationary while the displacement sensor is moving. The schematic diagram is shown in Figure 9.

[0071] In Figure 9, R represents the distance between the sensor installation position and the axis, S1 represents the arc length of the test block when the vibration is at its maximum, S2 represents the arc length of the test block when the vibration is at its minimum, R1 represents the radial distance when the vibration is at its maximum, and R2 represents the radial distance when the vibration is at its minimum.

[0072] Since the position of the displacement sensor remains unchanged, the tangential velocity Vq passing through the sensor remains unchanged at the same rotational speed.

[0073]

[0074] but:

[0075]

[0076]

[0077] The angles α and β corresponding to S1 and S2 are:

[0078]

[0079]

[0080] According to trigonometric function formulas:

[0081]

[0082] Then we can get R1:

[0083]

[0084] Similarly, we can obtain R2:

[0085]

[0086] By subtracting R1 and R2, the peak value P of the rotor vibration can be obtained.

[0087] .

[0088] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A rotor vibration testing method for testing the vibration amplitude of a rotating disk on a rotor, characterized in that, Includes the following steps: At least two test blocks, a and b, are installed on the rotor. The test blocks are arranged symmetrically on both sides to form a V-shaped structure. Test block a is installed on the side of the rotating disk, and test block b is installed at the axis symmetrical position of test block a. The line of symmetry between test block a and test block b passes through the axis of the rotating disk. The thickness of one side of test block a is less than that of the other side, and the thickness of both sides of test block b is the same. A displacement sensor is installed near the test block to detect the signal when the test block passes by; The output signal of the displacement sensor is collected when the rotor rotates, and the time intervals Δt1 and Δt2 between test block a and test block b passing through the sensor are obtained respectively. Based on the changes in the time intervals Δt1 and Δt2, the vibration amplitude of the rotor is calculated, whereby the vibration amplitude is derived from the tangential velocity and the geometric relationship of the test block.

2. The rotor vibration testing method according to claim 1, characterized in that, The thick edge of test block a is used as the test trigger point to mark the start point of time in the displacement sensor signal.

3. The rotor vibration testing method according to claim 1, characterized in that, Before installing the test block, a pretreatment step is included: The direction of rotor imbalance is determined by vibration testing and key phase testing; The installation position of test block a is selected based on the direction of the imbalance, ensuring that the direction of the imbalance is located in the middle area of ​​test block a.

4. The rotor vibration testing method according to claim 1, characterized in that, The displacement sensor is an axial displacement sensor, and its installation position and distance from the test block meet the sensor installation requirements to accurately capture the motion signal of the test block.

5. The rotor vibration testing method according to claim 1, characterized in that, During the signal acquisition process, when Δt1 = Δt2, the rotor experiences no vibration.

6. The rotor vibration testing method according to claim 5, characterized in that, The step of calculating the vibration amplitude includes: Assuming the test block is fixed while the displacement sensor moves, a geometric model is established, where the distance between the sensor installation position and the axis is R, and the arc length of the test block changes as S1 and S2; S1 represents the arc length of the test block when the vibration is maximum, and S2 represents the arc length of the test block when the vibration is minimum. Based on the principle that the tangential velocity Vq remains constant, the radial distance R1 when the vibration is at its maximum and the radial distance R2 when the vibration is at its minimum are calculated using trigonometric function formulas. The peak vibration value P is derived from the difference between R1 and R2.

7. The rotor vibration testing method according to claim 6, characterized in that, In the geometric model, the expression for the vibration peak value P is: 。 8. The rotor vibration test method according to claim 7, characterized in that, The calculation process for the peak vibration P is as follows: Given that the tangential velocity Vq passing through the sensor remains constant, we obtain... ； but: ； ； The angles α and β corresponding to S1 and S2 are: ； ； According to trigonometric function formulas: ； Then we can get R1: ； Similarly, we can obtain R2: ； By subtracting R1 and R2, the peak value P of the rotor vibration can be obtained; 。 9. A rotor vibration testing system for implementing the method according to any one of claims 1-8, characterized in that, include: Test block assembly: includes at least two V-shaped test blocks that can be mounted on the rotor; Displacement sensor: used to detect the motion signal of the test block; Data acquisition unit: Connected to the displacement sensor, used to record time interval data; Processing unit: Used to calculate vibration amplitude based on time data and output the results.

10. The system according to claim 9, characterized in that, The processing unit integrates an algorithm that can automatically identify the trigger point of the test block and calculate the vibration peak value.

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