Aero-engine rotor run-out test system and rotor run-out determination method

Abstract

This application provides an aero-engine rotor runout testing system, comprising: multiple laser displacement sensors, matched and positioned close to multiple test surfaces of the rotor under test, to obtain runout signals from the multiple test surfaces; one or more laser signal conditioners connected to the multiple laser displacement sensors, used to condition the optical signals of the laser displacement sensors into electrical signals; a laser speed sensor, positioned at a location matched to a keyed phase feedback module arranged on the rotor under test, to obtain the phase signal of the rotor under test through the laser speed sensor and the keyed phase feedback module; a data acquisition module, connected to one or more laser signal conditioners and the laser speed sensor, used to acquire measurement data from the laser displacement sensors and the laser speed sensor; and a data processing module, connected to the data acquisition module, used to process the signals acquired by the data acquisition module to obtain vibration characteristic values ​​of the rotor under test.

Description

Technical Field

[0001] This application belongs to the field of aero-engine testing technology, and specifically relates to an aero-engine rotor runout testing system and a method for determining rotor runout. Background Technology

[0002] Rotor dynamics testing of aero-engines is used to study the holographic vibration characteristics of the rotor. Dynamic testing requires multi-section shaft vibration testing of the rotor. During shaft vibration testing, factors such as misalignment of the coupling shafts, misalignment of the rotor's front and rear support rotation centers, poor roundness of the measurement surface, clearance and minimum oil film thickness of the sliding bearings, initial rotor bending, and misalignment of the test surface assembly can all cause a superimposed interference signal with the rotor's fundamental frequency and its harmonics to appear in the measured shaft vibration. This leads to errors in the test results. Furthermore, due to the large size, high rigidity, and small operational deflection of aero-engine rotors, the proportion of error values ​​in the test results is even larger, making it more difficult to guarantee the validity of the test.

[0003] In existing technologies, the measurement of various rotor runouts mainly employs the dial indicator method. This method involves placing a dial indicator in contact with the shaft, slowly rotating the shaft, and measuring the maximum radial runout by reading the dial indicator. However, this method cannot accurately describe the condition and magnitude of the circumferential movement error at different positions on the measured surface of the shaft. It cannot be detected at the rotor's actual operating speed, cannot be recorded, and cannot analyze the causes of the error movement. Summary of the Invention

[0004] The purpose of this application is to provide an aircraft engine rotor runout testing system and rotor runout determination method to solve or mitigate at least one of the problems in the background art.

[0005] In a first aspect, this application provides an aircraft engine rotor runout testing system, the system comprising:

[0006] Multiple laser displacement sensors (21) are matched and disposed at multiple test surfaces near the rotor (10) to obtain the runout signals of multiple test surfaces;

[0007] One or more laser signal conditioners (22) are connected to the laser displacement sensor (21) and are used to condition the optical signal of the laser displacement sensor (21) into an electrical signal;

[0008] A laser speed sensor (25) is set at the position of the key phase feedback module (26) arranged on the rotor (10) under test. The phase signal of the rotor (10) under test is obtained through the laser speed sensor (25) and the key phase feedback module (26).

[0009] A data acquisition module (23), which is connected to one or more of the laser signal conditioners (22) and the laser speed sensor (25), is used to acquire measurement data from the laser displacement sensor (21) and the laser speed sensor (25); and

[0010] The data processing module (24) is connected to the data acquisition module (23) and is used to process the signals acquired by the data acquisition module (23) to obtain the final vibration characteristic value of the rotor under test.

[0011] Furthermore, the number of laser signal conditioners (22) is multiple, and the number is the same as the number of laser displacement sensors (21).

[0012] Furthermore, the maximum measurable speed of the laser speed sensor (25) is not lower than the highest speed of the rotor (10) being measured.

[0013] On the other hand, this application provides a rotor runout determination method using any of the above-described aero-engine rotor runout testing systems, the method comprising:

[0014] A dynamic test was conducted on the rotor under test to obtain the measured vibration signals of each measured surface of the rotor and the rotor key phase signal during the dynamic test.

[0015] Calculate the measured vibration spectrum of the tested surface of the rotor in the dynamic test, and obtain the vibration amplitude of the rotor's fundamental frequency and its harmonics in the spectrum;

[0016] The cross-power spectrum of the measured vibration signal and the rotor key phase signal in the calculation dynamics experiment is used to extract the fundamental frequency and its harmonics of the measured rotor vibration value and their relative phase with the key phase signal from the cross-power spectrum through narrowband filtering.

[0017] Calculate the actual vibration amplitude of the rotor at each frequency.

[0018] Furthermore, the spectrum of the measured vibration value of the measured surface of the rotor under test in the dynamic test is obtained by short-time windowed Fourier transform.

[0019] Furthermore, the relative phase between the measured vibration signal and the rotor key phase signal in the computational dynamics experiment is obtained through the cross power spectral density function.

[0020] Furthermore, the process of calculating the actual vibration amplitude of the rotor at each frequency includes:

[0021] Let the measured fundamental frequency or its harmonic vibration value of the rotor be f(t), the actual vibration value of the fundamental frequency or its harmonic vibration value be h(t), and the influence function of the rotor surface runout value on the rotational frequency or its harmonic vibration value be g(t). Then we have h(t) = f(t) - g(t).

[0022] make

[0023] In the formula, A, B, and C are the peak vibration values. This represents the phase difference between each signal and the key phase signal;

[0024] Then there is

[0025] Right now

[0026] Construct intermediate variables M and N, and let:

[0027] Then there is

[0028] The signal is determined by judging the positive and negative values ​​of intermediate quantities M and N. Phase compensation is used to obtain the true vibration amplitude of the rotor at each frequency.

[0029] Furthermore, the intermediate quantities M and N are related to the signal. The phase compensation satisfies:

[0030] When M and N > 0, the signal The phase compensation is 0;

[0031] When M > 0 and N < 0, the signal The phase compensation is 0;

[0032] When M < 0, N > 0, the signal The phase compensation is

[0033] When M < 0 and N < 0, the signal The phase compensation is

[0034] The method presented in this application can efficiently evaluate the runout magnitude in various aero-engine and gas turbine rotor dynamics tests, achieving high-precision and high-resolution measurements of runout values ​​and shaft vibration. It also subtracts interference from rotor runout values ​​at various frequencies in the measured vibration values ​​as needed, ensuring the accuracy of rotor characteristic analysis. Compared to the current dial indicator method for evaluating various rotor runouts, this method overcomes the limitation of dial indicator measurements failing to accurately describe and record the runout motion patterns at various circumferential positions on the measured shaft surface. It enables detection at the actual operating speed of the rotor, and through runout analysis of multiple cross-sections, it can also determine the cause of the runout. From a testing perspective, this application possesses technical characteristics such as a long sensor mounting distance relative to the measured surface and a large measurement range, enabling measurement tasks on special surfaces. It has low requirements for the structure of the measured rotor and is highly adaptable. Attached Figure Description

[0035] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0036] Figure 1 This is a graph showing the trend of fundamental frequency vibration values ​​of various sections as a function of rotational speed during a test of a certain type of engine fan rotor.

[0037] Figure 2 The dynamic runout of each test surface during slow-speed rotary turning of a certain type of engine fan rotor test.

[0038] Figure 3 This describes the effect of runout value on various frequencies during a test of a certain type of engine fan rotor.

[0039] Figure 4 This is a schematic diagram of the aircraft engine rotor runout testing system of this application.

[0040] Figure 5 This is a schematic diagram of the laser rotation speed sensor measurement in this application.

[0041] Figure 6 This is a schematic diagram of the jitter signal during slow turning in one embodiment of this application.

[0042] Figure 7 This is a schematic diagram of the relative phase of the slow turning wheel skipping signal in this embodiment of the present application.

[0043] Figure 8 This is a schematic diagram of the key phase signal waveform during slow rotation in this embodiment of the present application.

[0044] Figure 9 This is a schematic diagram of the key phase signal waveform when N = 7000 r / min in this embodiment of the present application. Detailed Implementation

[0045] 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.

[0046] In aero-engine shaft vibration testing, radial runout is a common problem in non-contact shaft vibration measurements. Rotor runout refers to the periodic voltage fluctuations output by the sensor system when the shaft is at extremely low speeds (i.e., in a turning state) and there is no shaft vibration. Ideally, when the shaft is not vibrating, the output of the displacement testing system should be a stable DC voltage signal proportional to the clearance. However, due to rotor runout, even without shaft vibration, the output of the displacement testing system is superimposed with a fluctuating voltage signal on the DC signal. Moreover, the frequency of this fluctuating voltage signal is the rotational frequency and its harmonics, which greatly affects the test results.

[0047] Figure 1 The figure shows the trend of fundamental frequency vibration values ​​of various test sections as a function of rotational speed during a dynamic test of a certain type of aero-engine fan rotor. As can be seen from the figure, the vibration value of curve 1 (Signal woliu1) shows no significant change across the entire rotational speed range, remaining almost constant. According to rotor dynamics theory, this is clearly impossible and cannot be caused by the characteristics of the fan rotor; there must be a factor affecting the test results. To verify this judgment, the test instrument speed was reduced to 100 r / min. At this low speed, deflection is negligible, and the measured results are considered to be caused by runout. The verification results are as follows... Figure 2 As shown, the fluctuations are significant within one rotation cycle of the rotor.

[0048] To determine the impact of rotor runout on various frequencies in the frequency band, a short-time windowed Fourier transform was performed on the runout signal. The calculation results are as follows: Figure 3 As shown, the frequency primarily affected by the vibration is the rotor's fundamental frequency and its harmonics. Figure 1 As can be seen from the results, the fluctuation value of the test surface where curve 1 is located accounts for a large proportion of the fundamental frequency test results, and also has a significant impact on the harmonics of the fundamental frequency.

[0049] To address the impact of rotor runout on test results in real rotor dynamics tests of aero-engines, this application first proposes an aero-engine rotor runout testing system. This system 20 includes: multiple laser displacement sensors 21, one or more laser signal conditioners 22, a laser speed sensor 25, a data acquisition module 23, and a data processing module 24. The multiple laser displacement sensors 21 are matched and positioned close to multiple test surfaces of the rotor 10 under test to measure the vibration and runout values ​​of these surfaces. The measurement data from the laser displacement sensors 21 is conditioned by one or more laser signal conditioners 22 and then sent to the data acquisition module 23. Simultaneously, the laser speed sensor 25 is positioned to match the key phase feedback module 26 arranged on the rotor 10 under test. The phase signal of the rotor 10 under test is measured by the laser speed sensor 25 and the key phase feedback module 26 and sent to the data acquisition module 23. Finally, the data processing module 24 is connected to the data acquisition module 23 to process the signals acquired by the data acquisition module 23 to obtain the final vibration and runout values ​​of the rotor under test.

[0050] The laser displacement sensor 21 in this application, with its tiny measuring spot, can measure the rotor from a considerable distance, making it suitable for precise measurement of small components. The laser displacement sensor 21 has a long mounting distance relative to the measured surface and a large measuring range, enabling it to perform measurements on special surfaces, such as the scorching metal surface of the rotor during rotor heating tests. There is no actual contact between the laser displacement sensor 21 and the measured object during the measurement process; this non-contact measurement principle ensures high-precision measurement without wear and interference.

[0051] In this application, in order to subtract the runout value from the test results, a reference point is established on the rotor 10 under test to determine the relative positional relationship between the runout value / measured value at slow turning speed and operating speed, thus ensuring the quality of the subtraction. Therefore, in this application, a reference signal, namely a key phase signal, is formed by setting a laser speed sensor 25 and a key phase feedback module 26, and the same frequency as the rotor is obtained through this key phase signal.

[0052] like Figure 5 The schematic diagram shown is a laser speed sensor measurement diagram. In this embodiment of the application, LT2 is used. Taking a laser rotation speed system as an example, the laser rotation speed sensor 25 can sense the rotational speed of rotating equipment and output analog voltage pulse data for reference to the relationship between vibration and rotational speed. At a distance of up to 20 inches (51 cm), the maximum measurable rotational speed is 100,000 revolutions per minute. When a suitable pulse signal is acquired, the LED indicator 251 on the laser rotation speed sensor 25 will highlight it. A standard BNC connector can be directly connected to a device with... A constant current powered data acquisition module or signal conditioner. Unlike other magnetic tachometers that require the measured component to be a ferrous metal, the LT2 only requires reflective paper (i.e., the key phase feedback module 26) to be attached to the measured shaft.

[0053] In this application, the runout value is extracted and deducted by combining laser displacement measurement and key phase tracking positioning.

[0054] Therefore, this application also provides a method for determining rotor runout using the above-mentioned aero-engine rotor runout test system, the method comprising the following steps:

[0055] 1) Rotate the rotor 10 under test at the lowest speed at which the starter motor can run stably. Measure and store the vibration values ​​of each measured surface and the key phase signal of the rotor at this time. Since the speed is low at this time and the aero-engine rotor is rigid, the deflection of the rotor can be considered negligible. The measured value is the runout value of the rotor support system on the measured surface.

[0056] 2) Calculate the runout spectrum of the measured surface using short-time windowed Fourier transform, and record the vibration amplitude of the rotor's fundamental frequency and its harmonics in the spectrum;

[0057] 3) Calculate the cross power spectrum of the measured runout value and the key phase signal using the cross power spectral density function, and extract the fundamental frequency of the runout of the rotor test surface and its harmonics and the relative phase of the key phase signal from the cross power spectrum through narrowband filtering.

[0058] The influence of the runout values ​​of various test sections of a certain type of aero-engine fan rotor on the fundamental frequency and their relative phase with the key phase signal are as follows: Figure 6 and Figure 7 As shown.

[0059] Since the runout value has a significant impact on the rotor's fundamental frequency and its harmonics, to verify the effectiveness of the key phase signal as a reference for the rotational frequency and its harmonics, this embodiment of the application selects the key phase signal of a certain type of engine fan rotor at slow turning speed and speed N = 7000 r / min, and compares its waveforms with the time-domain signals of the rotational frequency, second harmonic, and third harmonic obtained through linear phase filtering. Figure 8 and Figure 9 As shown.

[0060] It can be seen that at two different rotational speeds, the relative positions of the original signal of the laser speed sensor and its filtered frequency, second harmonic, and third harmonic on the time axis are consistent. This indicates that the laser speed sensor signal can be used as a reliable key phase signal for the frequency and its harmonic vibrations. In other words, the laser speed sensor signal can be used as a reference signal for the frequency and its multiple harmonics, and the amplitude of the jumping frequency that needs to be deducted can be deducted according to the requirements of the analysis.

[0061] 4) Perform a high-speed test on the rotor under test according to the normal procedure, and record the measured vibration signals of each tested surface and the rotor key phase signal during the test;

[0062] 5) Calculate the measured vibration spectrum of the tested surface in the high-speed test using short-time windowed Fourier transform, and record the vibration amplitude of the rotor fundamental frequency and its harmonics in the spectrum;

[0063] 6) Calculate the cross power spectrum of the measured vibration signal and the key phase signal during high speed using the cross power spectral density function, and extract the fundamental frequency and its harmonics of the measured rotor vibration value and their relative phase with the key phase signal from the cross power spectrum by narrowband filtering;

[0064] 7) Calculate the actual vibration values ​​(deflection values) of the rotor at each frequency:

[0065] Let the measured fundamental frequency or its harmonic vibration value of the rotor be f(t), the actual vibration value of the fundamental frequency or its harmonic vibration value be h(t), and the influence function of the rotor surface runout value on the rotational frequency or its harmonic vibration value be g(t). Then we have: h(t) = f(t) - g(t).

[0066] make:

[0067] In the formula, A, B, and C are the peak vibration values. This represents the phase difference between each signal and the key phase signal;

[0068] Then there is

[0069] Right now

[0070] Construct intermediate variables M and N, and let:

[0071] Then there is

[0072] Due to uncertainty The range of values ​​for M and N also needs to be determined, as shown in Table 1.

[0073] Table 1 Value table

[0074]

[0075] The actual vibration amplitude of the rotor at each frequency can be obtained using the above method.

[0076] The method presented in this application can efficiently evaluate the runout magnitude in various aero-engine and gas turbine rotor dynamics tests, achieving high-precision and high-resolution measurements of runout values ​​and shaft vibration. It also subtracts interference from rotor runout values ​​at various frequencies in the measured vibration values ​​as needed, ensuring the accuracy of rotor characteristic analysis. Compared to the current dial indicator method for evaluating various rotor runouts, this method overcomes the limitation of dial indicator measurements failing to accurately describe and record the runout motion patterns at various circumferential positions on the measured shaft surface. It enables detection at the actual operating speed of the rotor, and through runout analysis of multiple cross-sections, it can also determine the cause of the runout. From a testing perspective, this application possesses technical characteristics such as a long sensor mounting distance relative to the measured surface and a large measurement range, enabling measurement tasks on special surfaces. It has low requirements for the structure of the measured rotor, strong adaptability, and can be applied in special tests such as rotor heating tests.

[0077] 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 method for determining rotor runout using an aero-engine rotor runout testing system, characterized in that, The system includes: Multiple laser displacement sensors (21) are matched and disposed at multiple test surfaces near the rotor (10) under test to obtain the runout signals of multiple test surfaces; One or more laser signal conditioners (22) are connected to the laser displacement sensor (21) and are used to condition the optical signal of the laser displacement sensor (21) into an electrical signal; A laser speed sensor (25) is set at the position of the key phase feedback module (26) arranged on the rotor (10) under test. The phase signal of the rotor (10) under test is obtained through the laser speed sensor (25) and the key phase feedback module (26). Data acquisition module (23), which is connected to one or more of the laser signal conditioners (22) and the laser speed sensor (25), is used to acquire measurement data from the laser displacement sensor (21) and the laser speed sensor (25); and The data processing module (24) is connected to the data acquisition module (23) and is used to process the signals acquired by the data acquisition module (23) to obtain the final vibration characteristic value of the rotor under test. The method includes: A dynamic test was conducted on the rotor under test to obtain the measured vibration signals of each measured surface of the rotor and the rotor key phase signal during the dynamic test. Calculate the measured vibration spectrum of the tested surface of the rotor in the dynamic test, and obtain the vibration amplitude of the rotor's fundamental frequency and its harmonics in the spectrum; The cross-power spectrum of the measured vibration signal and the rotor key phase signal in the calculation dynamics experiment is used to extract the fundamental frequency and its harmonics of the measured rotor vibration value and their relative phase with the key phase signal from the cross-power spectrum through narrowband filtering. The process of calculating the actual vibration amplitude of the rotor at each frequency includes: Let the measured fundamental frequency or its harmonic vibration value of the rotor be f(t), and the actual vibration value of the fundamental frequency or its harmonic vibration value be h(t). The influence function of the rotor's measured surface runout on the rotational frequency or its harmonic vibration value is given by: Then there is ; make , , ; In the formula, A, B, and C are the peak values ​​of vibration, and φ1, φ2, and φ3 are the phase differences between each signal and the key phase signal; Then there is ; Right now ; Construct intermediate variables M and N, and let: , ; Then there is , ; The phase compensation of signal φ3 is determined by judging the positive and negative values ​​of intermediate quantities M and N, thus obtaining the true vibration amplitude of the rotor at each frequency. The intermediate quantities M and N satisfy the following phase compensation with signal φ3: When M and N > 0, the phase compensation of signal φ3 is 0; When M > 0 and N < 0, the phase compensation of signal φ3 is 0; When M < 0 and N > 0, the phase compensation of signal φ3 is 180 - φ3; When M < 0 and N < 0, the phase compensation of signal φ3 is -180 - φ3.

2. The method for determining rotor runout as described in claim 1, characterized in that, The number of laser signal conditioners (22) is multiple, and the number is the same as the number of laser displacement sensors (21).

3. The method for determining rotor runout as described in claim 1 or 2, characterized in that, The maximum measurable speed of the laser speed sensor (25) is not lower than the highest speed of the rotor (10) being measured.

4. The method for determining rotor runout as described in claim 1, characterized in that, The spectrum of the measured vibration value of the tested surface of the rotor under test in the dynamic test is obtained by short-time windowed Fourier transform.

5. The method for determining rotor runout as described in claim 1, characterized in that, In the computational dynamics experiment, the relative phase between the measured vibration signal and the rotor key phase signal was obtained through the cross power spectral density function.

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