Vibration sensor in-situ calibration method based on engine blade frequency as excitation source

Abstract

The invention provides a vibration sensor in-situ calibration method based on engine blade frequency as an excitation source. Periodic pneumatic excitation of engine rotor blades is used as a natural calibration source, the frequency range is wide, the excitation energy is high, and vibration of the natural calibration source is homologous with vibration of a real working condition; building a multi-physics field coupling calibration model; according to the phase synchronization calibration technology, an engine ignition signal is adopted as a time reference, and phase difference calibration among multiple sensors is achieved. The engine vibration sensor in-situ calibration method has the advantages that the calibration system construction and test verification of the engine vibration sensor are completed by using the vibration sensor in-situ calibration method in which the engine blade passing frequency is used as an excitation source, and an engine vibration sensor dynamic calibration scheme is provided. After the scheme is applied, the calibration period is greatly shortened, the calibration precision is improved, the problem that calibration cannot be implemented in flight is solved, and the flight safety and reliability of an aircraft engine are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aero-engine reliability testing and monitoring, and particularly relates to a vibration sensor in-situ calibration method based on engine blade frequency as an excitation source. BACKGROUND

[0002] An aero-engine is a complex high-speed rotating machine. Vibration inevitably occurs in rotating machines. The whole engine vibration is mainly composed of periodic vibration caused by rotor imbalance and random vibration caused by gas flow in the engine flow passage, combustion, etc. Due to the differences between the assembly precision and the dynamic balance during assembly and the actual working conditions of the engine, the actual engine rotor always has a certain residual imbalance. The purpose of measuring the whole engine vibration on the engine test bed is to test the quality of engine part processing, assembly and rotor dynamic balance. At present, many domestic aero-engine test beds still use analog vibration measuring instruments, and special vibration sensors are used to complete the vibration measurement of the engine. The vibration velocity sensor uses the magneto-inductive principle to convert the vibration signal into an electric signal. It mainly consists of a magnetic circuit system, an inertial mass, a spring damper and other parts. Due to the heavy weight of the vibration velocity sensor and the small temperature range (generally not more than 200℃), piezoelectric acceleration sensors are used in more and more new types of vibration sensors. The piezoelectric accelerometer is designed according to the piezoelectric effect of certain materials. The output electric signal is proportional to the vibration acceleration, and the vibration velocity and vibration displacement can be measured through an integration circuit. The piezoelectric sensor also has high-frequency measurement and response capability, but due to its structural characteristics, the measurement results of the sensor often drift and deviate, so it is necessary to calibrate the sensor from time to time to ensure the test accuracy.

[0003] Traditional sensor calibration requires disassembling the sensor and sending it to the laboratory, which leads to engine downtime and extended flight suspension period, affecting the use efficiency. Moreover, the existing online calibration often relies on external excitation equipment, which cannot be completed during flight, greatly affecting the engine operation efficiency. The use of the sensor itself in the high-temperature and high-pressure environment of the whole engine part leads to the drift of the sensor sensitivity (typical value 0.5-2% / 100℃). The sensors arranged on the whole engine are often aimed at the vibration characteristics of different parts, and the phase consistency calibration of multiple sensors is missing, which affects the vibration vector analysis accuracy and leads to distortion of the engine vibration measurement. SUMMARY

[0004] The purpose of this invention is to prevent engine vibration test sensors from becoming uncalibrated during flight, thereby affecting the stability and reliability of engine component vibration testing. It proposes an in-situ calibration system for vibration sensors based on the engine's own blade passage frequency as the excitation source. Innovatively, it utilizes the engine's natural rotor as the excitation source, effectively achieving real-world, same-source calibration of engine vibration sensors. This effectively assesses the accuracy of the vibration measurement instruments, solving the pain points of long offline calibration cycles and the inability to perform calibration assessments during flight. It also avoids interference factors such as sensor sensitivity drift and loss of multi-source phase consistency accuracy caused by high-temperature and high-pressure environments. This provides the most direct technical support for ensuring the accuracy of engine vibration output test results and the reliability of the health management system.

[0005] This invention provides an in-situ calibration method for vibration sensors based on engine blade frequency as the excitation source: 1) Using the periodic aerodynamic excitation of engine rotor blades as a natural calibration source offers the following advantages: 1) Wide frequency range (typically 1-20kHz, covering the sensor's operating frequency band). 2) High excitation energy (rotor dynamic stress can reach over 1000 MPa). 3) Vibration originates from the same source as real-world operating conditions.

[0006] 2) Construction of a multiphysics coupling calibration model.

[0007] S_{cal}(f)=\frac{V_{raw}(f)}{A_{bpf}(f)}\times H_T(T)\times H_P(P), where Scal(f) is the frequency-dependent sensitivity; Abpf(f) is the amplitude of the blade passing through the frequency (inverted by the blade strain gauge); Ht(T) is the temperature compensation factor (calibration curve of -40~800 degrees); Hp(P) is the pressure compensation factor (calibrated from 0-5MPa).

[0008] 3) Phase synchronization calibration technology uses the engine ignition signal as a time reference to achieve phase difference calibration between multiple sensors (accuracy <0.5 degrees).

[0009] The principle is as follows Figure 1 As shown.

[0010] Benchmarking Phase (Engine Test Bench): The load was applied in steps within the 80%~100% speed range, and the original sensor output V_raw and the measured acceleration A_ref of the blade strain gauge were recorded.

[0011] Generate the transfer function matrix: H(f,t,p) = A_ref(f,t,p) / V_raw(f,t,p) Online calibration phase (in flight): Real-time monitoring BPF harmonic components (fundamental to 5th harmonic).

[0012] When the signal-to-noise ratio of a certain order BPF is monitored to be greater than 20 dB, calibration is triggered.

[0013] Call the H(f) matrix corresponding to the current working condition (t, p) to compensate the output.

[0014] Self-diagnosis mechanism: If the calibration deviation exceeds ±5% for 3 consecutive times, a sensor failure alarm is triggered.

[0015] Phase consistency verification: when the phase difference of BPF response between multiple sensors exceeds ±2 degrees, automatic correction is performed.

[0016] Advantages of the present application: using the blade passing frequency of the engine as the excitation source of the vibration sensor, the calibration system of the engine vibration sensor is built and tested, and a dynamic calibration scheme for the engine vibration sensor is proposed. After the application of this scheme, the calibration period is greatly reduced, the calibration accuracy is improved, the problem of unable to implement calibration in flight is solved, and the flight safety and reliability of the aircraft engine are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Principle diagram of the in-situ calibration system of the vibration sensor using the blade passing frequency of the engine as the excitation source; Figure 2 Signal feedback unit diagram; Figure 3 Sensor calibration module unit diagram; Figure 4 Vibration calibration output signal acquisition, analysis and evaluation unit diagram; Figure 5 Calibration evaluation test system schematic diagram. DETAILED DESCRIPTION

[0018] The present application will be further explained below in conjunction with specific embodiments, but is not limited to the present application. The structures, proportions, sizes, etc. shown in the drawings of the specification are only used to cooperate with the content disclosed in the specification, to be understood and read by those skilled in the art, and do not have technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effect and purpose that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application.

[0019] Example 1: 1. Reference establishment stage (engine test bench): In 80%~100% speed range, load step by step, record the sensor raw output V_raw and the measured acceleration A_ref of the blade strain gauge.

[0020] Generate transfer function matrix: H(f, t, p) = A_ref(f, t, p) / V_raw(f, t, p) 2. Online calibration phase (in flight): Real-time monitoring of BPF harmonic components (fundamental to 5th harmonic).

[0021] When the signal-to-noise ratio of a certain order BPF is greater than 20dB, trigger calibration.

[0022] Call the H(f) matrix corresponding to the current working condition (t, p) to compensate the output.

[0023] 3. Self-diagnosis mechanism If the calibration deviation exceeds ±5% for 3 consecutive times, trigger sensor fault alarm.

[0024] Phase consistency check: when the phase difference of BPF response between multiple sensors exceeds ±2 degrees, automatically correct.

[0025] 4. The technical effects are shown in the following table.

[0026]

[0027]

[0028] The details of the present application are known.

[0029] Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for in-situ calibration of a vibration sensor based on engine blade frequency as the excitation source, characterized in that: Specifically The periodic aerodynamic excitation of the engine rotor blades is used as a natural calibration source. The frequency range covers the sensor's operating frequency band, the excitation energy is high, and it is from the same source as the vibration under real working conditions. The multiphysics coupling calibration model is constructed as follows: S_{cal}(f) = \frac{V_{raw}(f)}{A_{bpf}(f)}\timesH_T(T)\times H_P(P), where Scal(f) is the frequency-dependent sensitivity; Abpf(f) is the amplitude of the blade passing frequency acceleration; Ht(T) is the temperature compensation factor; Hp(P) is the pressure compensation factor; Phase synchronization calibration technology uses the engine ignition signal as the time reference to realize the phase difference calibration between multiple sensors.

2. The in-situ calibration method for vibration sensors based on engine blade frequency as the excitation source according to claim 1, characterized in that: During the benchmark establishment phase, a machine test bench was used: The loading was applied in steps within the 80%~100% speed range, and the original sensor output V_raw and the measured acceleration A_ref of the blade strain gauge were recorded. Generate the transfer function matrix: H(f,t,p) = A_ref(f,t,p) / V_raw(f,t,p) Online calibration phase: Real-time monitoring of BPF harmonic components (fundamental frequency to 5th harmonic). Calibration is triggered when a certain order BPF signal-to-noise ratio is detected to be >20dB. Call the H(f) matrix corresponding to the current working condition (t,p) to compensate the output; Self-diagnostic mechanism: If the calibration deviation exceeds ±5% for three consecutive times, a sensor fault alarm will be triggered. Phase consistency verification: Automatic correction when the phase difference of the BPF response between multiple sensors exceeds ±2 degrees.

Images