Vibration reduction effect verification test method of blade damper in rotation state

Abstract

The invention provides a verification test method for a vibration reduction effect of a blade damper in a rotating state. The verification test method comprises the following steps: S1, designing the damper; s2, carrying out modal calculation; s3, determining the rotating speed and the number of excitation nozzles; s4, carrying out excitation force calibration; s5, pasting a strain gauge; s6, testing the inherent frequency; s7, carrying out vibration strain response measurement; and S8, vibration reduction effect evaluation is carried out, if the design requirement is met, the operation is stopped, and if not, S1 is repeated. According to the invention, the damping effect of the damper can be evaluated in a rotating environment, the accuracy of the simulation environment is improved, and the test risk in the whole machine test process is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rotary machines, and particularly relates to a method for verifying damping effect of a blade damper in a rotary state. BACKGROUND

[0002] The blade is a key component of a gas turbine, and its damage is mostly caused by vibration. In the development process, the strength of the blade is evaluated through theoretical calculation, component test and whole machine test. However, there is a deviation between the theoretical calculation and the actual situation, and vibration often occurs. In order to reduce the manufacturing cost, people hope that a small structural improvement can be made on the already processed blade to avoid resonance, and the damper is born. However, the damping effect needs to be evaluated, and the best way is to verify it by test. The traditional method is to carry out a static blade vibration test, but its disadvantage is that it cannot better simulate the influence of vibration in the rotary environment of the gas turbine. Or test in the whole machine test, but the rupture of the blade caused by resonance often leads to the damage of multiple blades of the first stage or even multiple stages, resulting in huge test cost and risk, and prolonging the development cycle and even the risk of delaying the period.

[0003] Therefore, how to test the damping effect of the damper in the rotary environment is particularly important. SUMMARY

[0004] The present application aims to provide a method for verifying damping effect of a blade damper in a rotary state, which can better simulate the influence of vibration in the rotary environment of the gas turbine.

[0005] A method for verifying damping effect of a blade damper in a rotary state, comprising the following steps:

[0006] S1, damper design;

[0007] S2, modal calculation;

[0008] S3, determination of rotational speed and excitation nozzle number;

[0009] S4, excitation force calibration;

[0010] S5, strain gauge pasting;

[0011] S6, natural frequency test;

[0012] S7, vibration strain response measurement;

[0013] S8, damping effect evaluation, stop if the design requirements are met, otherwise repeat S1.

[0014] Furthermore, S1 includes the design of the damper shape, contact area, and mass parameters.

[0015] Furthermore, S2 includes calculation of resonance rotation speed, calculation of critical vibration mode, and calculation of vibration stress.

[0016] Furthermore, the formula for determining the number of nozzles in S3 is as follows:

[0017] f = N × n / 60 (1)

[0018] Where f is the excitation frequency (Hz), N is the number of nozzles, and n is the rotational speed (r / min).

[0019] Furthermore, the magnitude of the excitation force in S4 is calculated using the following formula:

[0020]

[0021] Where F is the tangential force (N), G is the liquid mass flow rate through the blade tip (kg / s), V1 is the liquid tangential velocity at the lower end of the blade tip (m / s), V0 is the liquid tangential velocity at the upper end of the blade tip (m / s), V0 = 0 m / s, and Q is the liquid volumetric flow rate (m³ / s). 3 / s), ρ is the liquid density (kg / m³) 3 ), where r is the radius of rotation of the blade tip (m), and n is the rotational speed (r / min);

[0022] The calibration is complete when the error between the calibrated excitation force and the calculated excitation force is within ±5%.

[0023] Furthermore, the strain gauge bonding area in S5 is determined based on the S2 mode calculation, and the selected area should be flat and have a relatively small stress gradient change.

[0024] Further, S6 includes the following steps:

[0025] First, set the number of nozzles to N. Then, use a frequency sweep method to test the natural frequency of the blades. The rotor accelerates and then decelerates at a certain acceleration. Once the target speed is reached and the load is maintained, the liquid spraying vibration is activated during deceleration. The specific operating steps are as follows:

[0026] S6.1, based on the calculated resonance speed, add 500 r / min to set the target speed, maintain the target speed for 30s, and input information such as rotor size and weight. At the same time, turn on the vacuum pump to evacuate the test bench and keep the vacuum pump running throughout the test.

[0027] S6.2 start, rotor begins to speed up, at the same time, start strain data collection, when the rotor speed reaches the target speed, start to open the oil station, until the rotor speed reaches the excitation speed, stop the excitation and collection, if there is no obvious excitation peak value under the pressure, then according to the test site situation, increase the oil injection pressure or the speed, re-scan, if the peak value is still not found, the test equipment and test piece need to be checked and analyzed;

[0028] S6.3, the natural frequency test can preliminarily determine the resonance frequency and the resonance speed, according to the determined resonance speed, the design excitation speed of the test is adjusted, and is modified to be expanded by 500r / min upwards and downwards from the determined resonance speed as the new design excitation speed upper and lower limit.

[0029] Further, the S7 comprises the following steps:

[0030] After the S6 natural frequency test is completed, the resonance speed range and the resonance frequency can be determined, the vibration strain response measurement is carried out, the rotor is speeded up and slowed down at a small acceleration near the resonance speed, and excitation is carried out to ensure accurate resonance response, and the specific operation steps are as follows:

[0031] S7.1, set the predetermined target speed to be the resonance speed expanded by 500r / min upwards under the condition, input the excitation upper and lower limit speed and the corresponding acceleration of each section, and input the rotor size, weight and other information;

[0032] S7.2, start and speed up, at the same time, start strain data collection, when the speed reaches the target speed, start to open the oil station, the rotor is speeded up to the highest speed, and after being kept for 30s, starts to slow down, until the speed is lowered to the design excitation speed, the oil station and the strain collection device are kept normal operation;

[0033] S7.3, when the speed is lowered to the design excitation speed lower limit, the oil station is closed;

[0034] S7.4, after the rotor is completely stopped, the strain data collection is stopped, the data of the test is judged, if the data is normal, repeat S7.3 and S7.3, and repeat the test to ensure data repeatability, if the data is abnormal, immediately check the abnormal reason, and judge whether the test needs to be repeated according to the situation.

[0035] The beneficial effects of the present application are that the damping effect of the damper can be evaluated in a rotating environment, the accuracy of the simulation environment is improved, and the test risk in the whole machine test process is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The flowchart of the present application.

[0037] Figure 2A frequency test curve chart inherent to the present application.

[0038] Figure 3 A vibration strain response measurement curve chart of the present application. DETAILED DESCRIPTION

[0039] The present application is further described below in conjunction with the accompanying drawings.

[0040] As Figure 1 shown in the drawings, a blade damper rotation state vibration reduction effect verification test method comprises the following steps:

[0041] S1, damper design, including damper shape, contact area, mass, etc.

[0042] S2, modal calculation, for theoretically evaluating the damper vibration reduction effect, determining the resonance speed n, and analyzing the dangerous vibration mode (first-order bending, first-order torsion), and determining the dangerous point position according to the vibration stress distribution.

[0043] S3, according to the vibration frequency, the rotation speed and the number of nozzles are preliminarily determined, when the excitation frequency is the same as the test blade dynamic frequency, resonance is caused, and the excitation frequency is:

[0044] f=Nxn / 60 (1)

[0045] In the formula: f is the excitation frequency (Hz); N is the number of nozzles; n is the rotation speed (r / min).

[0046] S4, according to the determined resonance speed, excitation force calibration is carried out, and the excitation force size is calculated by the following formula:

[0047]

[0048] In the formula: F is the tangential force (N); G is the liquid mass flow rate passing through the blade tip (kg / s); V1 is the liquid tangential velocity at the lower end of the blade tip (m / s); V0 is the liquid tangential velocity at the upper end of the blade tip (m / s), V0=0 m / s; Q is the liquid volume flow rate (m / s); ρ is the liquid density (kg / m / s); r is the rotation radius of the blade tip (m); n is the rotation speed (r / min). 3 3

[0049] When the error between the size of the calibrated excitation force and the calculated excitation force is within ±5%, it is considered that the calibration is completed.

[0050] S5, strain gauge pasting, according to the dangerous point position obtained by S2 modal calculation, strain gauges are pasted, and the selected area should be flat and the stress gradient change should be relatively small. ​​

[0051] S6, natural frequency test is conducted.

[0052] Firstly, the number of nozzles is set to N, and the blade is firstly tested for natural frequency by using the sweep frequency method. The rotor is firstly accelerated and then decelerated at a certain acceleration, and the liquid injection excitation is started when the rotor reaches the target speed and is kept at the target speed before the rotor is decelerated. The test curve is shown in Figure 2 , and the specific operation steps are as follows:

[0053] S6.1, the target speed is set to the calculated resonance speed plus 500 r / min, the rotor size, weight and other information are input, the vacuum pump is turned on, the test bench is vacuumized, and the vacuum pump is kept running during the test;

[0054] S6.2, start, the rotor starts to accelerate, and the strain data acquisition is started at the same time. When the rotor reaches the target speed and is kept at the target speed, the oil injection excitation is started, and the excitation and acquisition are stopped until the rotor is decelerated to the excitation speed. If there is no obvious excitation peak under this pressure, the oil injection pressure or the speed is increased according to the test site conditions, and the sweep frequency is re-performed. If the peak is still not found, the test equipment and test piece need to be checked and analyzed;

[0055] S6.3, the resonance frequency and resonance speed are preliminarily determined by the natural frequency test, the design excitation speed of the test is adjusted according to the determined resonance speed, and the new design excitation speed upper and lower limits are modified to be 500 r / min above and below the determined resonance speed.

[0056] S7, vibration strain response measurement is conducted.

[0057] After the natural frequency test is completed, the resonance speed range and the resonance frequency can be determined, and the vibration strain response measurement is conducted on this basis. The rotor is accelerated and then decelerated at a small acceleration near the resonance speed, and the excitation is started to ensure accurate resonance response. The test curve is shown in Figure 3 , and the specific operation steps are as follows:

[0058] S7.1, the predetermined target speed is set to the resonance speed under this condition plus 500 r / min (which can be adjusted appropriately according to the test site conditions), the excitation upper and lower limits and the corresponding acceleration of each section are input, and the rotor size, weight and other information are input;

[0059] S7.2, start and accelerate, and start the strain data acquisition at the same time. When the rotor reaches the target speed and is kept at the target speed, the oil station is started. The rotor is accelerated to the highest speed and is kept at the highest speed for 30 s, and then starts to decrease until the rotor is decreased to the design excitation speed, and the oil station and the strain acquisition device are kept running normally;

[0060] S7.3, when the rotating speed drops to the lower limit of the design excitation rotating speed, the oil station is closed;

[0061] S7.4, after the rotor is completely stopped, the strain data collection is stopped, the data of the test is judged, if the data is normal, S7.2 and S7.3 are repeated, the test is repeated to ensure the data repeatability; if the data is abnormal, the abnormal reason is immediately checked, and whether the test needs to be repeated is judged according to the situation.

[0062] S8, the damping vibration reduction effect evaluation is carried out, if the damping vibration reduction effect reaches the design requirement, the test is stopped, otherwise, the test is repeated until it is satisfied.

[0063] It should be noted that when the damping vibration reduction effect test is carried out, except the damper, the installation positions of the remaining parts are the same, and cannot be changed at will. The new test rotor needs to be re-pasted and wired, balanced and installed on the test bed, each test group carries out the liquid jet excitation test according to the above test steps, until all the tests are completed.

[0064] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for verifying the damping effect of a blade damper in a rotating state, characterized by, It comprises the following steps: S1, damper design; S2, modal calculation; S3, rotational speed and excitation nozzle number determination; S4, excitation force calibration; S5, strain gauge sticking; S6, natural frequency test; S7, vibration strain response measurement; S8, vibration reduction effect evaluation, stop if design requirements are met, otherwise repeat S1.

2. The method according to claim 1, wherein Said S1 includes damper shape, contact area and mass parameter design.

3. The method according to claim 1, wherein Said S2 includes resonance rotational speed calculation, dangerous vibration mode calculation and vibration stress calculation.

4. The method according to claim 1, wherein The formula for determining the number of nozzles in S3 is: f = N x n / 60 (1) Wherein, f is the excitation frequency (Hz), N is the number of nozzles, n is the rotational speed (r / min).

5. The method according to claim 1, wherein The excitation force size in S4 is calculated by the following formula: wherein F is the tangential force (N), G is the mass flow rate of the liquid through the blade tip (kg / s), Vi is the tangential velocity of the liquid at the lower end of the blade tip (m / s), Vo is the tangential velocity of the liquid at the upper end of the blade tip (m / s), Vo = 0 m / s, Q is the volume flow rate of the liquid (m 3 / s), p is the density of the liquid (kg / m 3 ), r is the radius of rotation of the blade tip (m), and n is the rotational speed (r / min); When the error between the calibrated excitation force size and the calculated excitation force size is within ±5%, the calibration is completed.

6. The method according to claim 1, wherein The strain gauge sticking position in S5 is determined according to the modal calculation in S2, and the selected area should be flat and have relatively small stress gradient change.

7. The method according to claim 1, wherein Said S6 comprises the following steps: First, set the number of nozzles to N, use the sweep frequency method to test the natural frequency of the blade first, and the rotor first increases in speed and then decreases in speed, and opens the liquid excitation when the rotational speed reaches the target rotational speed and the load is maintained, the specific operation steps are as follows: S6.1, set the target rotational speed by increasing 500 r / min according to the calculated resonance rotational speed, maintain the target rotational speed for 30 s, and input the rotor size, weight and other information, at the same time, open the vacuum pump, vacuumize the test bench, and always keep the vacuum pump running during the test; S6.2, start, the rotor starts to increase in speed, at the same time, the strain data acquisition is started, when the rotor decreases in speed after reaching the target speed, the oil excitation is started, until the excitation and collection are stopped when the speed reaches the excitation speed, if there is no obvious excitation peak under this pressure, then increase the oil pressure or speed according to the test site conditions, and re-sweep, if the peak is still not found, the test equipment and test piece need to be checked and analyzed; S6.3, the resonance frequency and resonance rotational speed can be preliminarily determined from the natural frequency test, the design excitation speed of the test is adjusted according to the determined resonance rotational speed, and is modified to extend 500 r / min upwards and downwards from the determined resonance rotational speed as the new design excitation speed upper and lower limit.

8. The method according to claim 1, wherein Said S7 comprises the following steps: After the natural frequency test in S6 is completed, the resonance speed range and the resonance frequency can be determined, the vibration strain response measurement is carried out, the rotor increases in speed and decreases in speed at a small acceleration near the resonance speed, and excitation is carried out at the same time to ensure accurate resonance response, the specific operation steps are as follows: S7.1, set the predetermined target rotational speed to extend 500 r / min upwards from the resonance speed under this condition, input the excitation upper and lower limit speed and the corresponding acceleration of each section, input the rotor size, weight and other information; S7.2, start-up and speed-up, meanwhile start strain data collection, when the speed reaches the target speed, keep load, then start to reduce the speed, when the speed reaches the target speed, open the oil station, the rotor speed-up to the highest speed, keep load for 30s, then start to reduce the speed, until the speed reduces to the design excitation speed, keep the oil station and strain collection device running normally; S7.3, when the speed reduces to the lower limit of the design excitation speed, close the oil station; S7.4, after the rotor completely stops, stop the strain data collection, judge the data of this test, if the data is normal, repeat S7.3 and S7.3, repeat the test to ensure the data repeatability; if the data is abnormal, immediately find out the abnormal reason, judge whether the test needs to be repeated according to the situation.

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