A method for detecting and locating pulsating pressure faults of an aeroengine fuel pump
By collecting and processing the airflow pulsation pressure signal of the aero-engine, and using Fourier transform and cross-correlation calculation, the accurate detection and location of fuel pump failure frequency under the whole engine environment is realized, which solves the inefficiency problem of disassembling the test bench for testing in the existing technology and improves the engine testing efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AECC SHENYANG ENGINE RES INST
- Filing Date
- 2024-01-22
- Publication Date
- 2026-05-19
AI Technical Summary
In the existing technology, the detection and location of abnormal oil pressure fluctuations in the fuel pump of an aero-engine requires disassembly and transfer to a dedicated test bench for semi-physical dynamic oil pressure testing, which affects the efficiency of engine testing and is costly.
By collecting the pulsating pressure signals of the low-pressure compressor outlet, the high-pressure compressor outlet, and the low-pressure turbine afterflow pressure signals of the aero-engine, performing Fast Fourier Transform and Bessel 4th Order filtering, conducting cross-correlation calculations and normalization, and combining the Fast Fourier Transform of the fuel pump fuel pressure signal, the frequency of fuel pump failure is determined.
It enables the detection and location of fault frequencies without disassembling the fuel pump in the whole machine environment, saving costs and time and improving engine testing efficiency.
Smart Images
Figure CN117906962B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of aero-engines, and specifically relates to a method for detecting and locating pulsating pressure in aero-engine fuel pump failure. Background Technology
[0002] Due to fluid-structure interaction and other factors affecting fuel system components, fuel pumps in aero engines frequently generate abnormal frequency fluctuations in the fuel and air circuits. These frequencies are often low-frequency (5Hz–100Hz), easily coupling with the engine's natural frequencies, thus severely compromising the aero-engine's aerodynamic stability and mechanical strength. Therefore, a reliable and engineering-applicable detection method is needed to detect and locate abnormal fuel pump pressure fluctuations.
[0003] Currently, when the fuel pump is in the engine environment, it can only be confirmed whether the abnormal fault is caused by the fuel pump by disassembling it to a dedicated test bench for semi-physical oil pressure dynamic testing. Disassembling the pump body requires manpower and material resources and seriously affects the efficiency of engine testing.
[0004] Therefore, it is desirable to have a technical solution to overcome or at least mitigate one of the aforementioned defects of the prior art. Summary of the Invention
[0005] The purpose of this application is to provide a method for detecting and locating pulsating pressure in an aircraft engine fuel pump failure, in order to solve at least one problem existing in the prior art.
[0006] The technical solution of this application is:
[0007] A method for detecting and locating pulsating pressure in an aircraft engine fuel pump failure includes:
[0008] Step 1: Collect the pulsating pressure signal P1 of the low-pressure compressor outlet airflow, the pulsating pressure signal P2 of the high-pressure compressor outlet airflow, and the pulsating pressure signal P3 of the airflow after the low-pressure turbine.
[0009] Step 2: Perform fast Fourier transform on the low-pressure compressor outlet airflow pulsation pressure signal P1, the high-pressure compressor outlet airflow pulsation pressure signal P2, and the low-pressure turbine afterflow pulsation pressure signal P3 to extract the abnormal fuel fluctuation frequency fb in the pulsation pressure signal.
[0010] Step 3: Using the abnormal fuel fluctuation frequency fb as the center, a Bessel fourth-order filter is used to perform bandpass filtering on the low-pressure compressor outlet airflow pulsation pressure signal P1, the high-pressure compressor outlet airflow pulsation pressure signal P2, and the low-pressure turbine afterflow pulsation pressure signal P3.
[0011] Step Four
[0012] Cross-correlation calculations are performed on the low-pressure compressor outlet pulsating pressure signal P1 and the high-pressure compressor outlet pulsating pressure signal P2 after bandpass filtering to obtain the cross-correlation function.
[0013] Cross-correlation calculations were performed on the high-pressure compressor outlet airflow pulsation pressure signal P2 and the low-pressure turbine downstream airflow pulsation pressure signal P3 after bandpass filtering to obtain the cross-correlation function.
[0014] And the cross-correlation function Perform normalization processing;
[0015] Step 5: Based on the cross-correlation calculation results, determine whether the high-pressure compressor outlet airflow pulsation pressure signal P2 is the signal with the fastest pass frequency among the three signals. If so, proceed to step 6.
[0016] Step 6: Acquire the fuel pump fuel pressure signal Pf, perform fast Fourier transform on the fuel pump fuel pressure signal Pf, and determine whether there is a frequency component with frequency fb. If so, the abnormal fuel fluctuation frequency fb is the fuel pump fault frequency.
[0017] In at least one embodiment of this application, in step one, the sampling frequency for acquiring the low-pressure compressor outlet airflow pulsating pressure signal P1, the high-pressure compressor outlet airflow pulsating pressure signal P2, and the low-pressure turbine afterflow pulsating pressure signal P3 is set to 5 k / s.
[0018] In at least one embodiment of this application, in step one, the frequency response of the pulsating pressure sensing element of the low-pressure compressor outlet airflow pulsating pressure signal P1, the high-pressure compressor outlet airflow pulsating pressure signal P2, and the low-pressure turbine after-airflow pulsating pressure signal P3 is not less than 1 kHz.
[0019] In at least one embodiment of this application, in step two, the abnormal fuel fluctuation frequency fb has the following characteristics:
[0020] The pulsating pressure signal P1 at the outlet of the low-pressure compressor, the pulsating pressure signal P2 at the outlet of the high-pressure compressor, and the pulsating pressure signal P3 after the low-pressure turbine all exist.
[0021] The frequency value does not change with engine speed or the frequency value decreases with the increase of engine speed, and the decrease is within 4Hz.
[0022] In at least one embodiment of this application, in step three, bandpass filtering is performed with a frequency bandwidth of ±5%*fb.
[0023] In at least one embodiment of this application, step four, the cross-correlation calculation process includes:
[0024] The formula for calculating the cross-correlation function of discrete signals x and y is:
[0025]
[0026] Where N is the number of accumulations, and τ is the delay between the two signals;
[0027] If one of the two signals is delayed by m, and the outputs of the two signals are x(t) and x(tm) respectively, then the formula for calculating the cross-correlation function is transformed as follows:
[0028]
[0029] Where E[] represents the expectation.
[0030] In at least one embodiment of this application, in step six, the length of the pressure tapping tube for acquiring the fuel pump fuel pressure signal Pf is no greater than L:
[0031]
[0032] Where 'a' is the local speed of sound.
[0033] The invention has at least the following beneficial technical effects:
[0034] The method for detecting and locating pulsating pressure faults in aircraft engine fuel pumps disclosed in this application can be carried out in the whole-aircraft environment, using pulsating pressure measuring points in whole-aircraft testing, without the need to install additional sensor measuring points. Compared with existing detection methods, it does not require disassembling the fuel pump, saving costs and improving fault detection efficiency. Furthermore, by using the pulsating pressure phase detection method for fault location, the detection and location have higher accuracy. Attached Figure Description
[0035] Figure 1 This is a schematic diagram of the abnormal fuel fluctuation frequency fb characteristic of one embodiment of this application;
[0036] Figure 2 This is a schematic diagram of the cross-correlation calculation results of P1 and P2 with fb of 22Hz in one embodiment of this application. Detailed Implementation
[0037] 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 some, but not all, embodiments of this application. 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. All other embodiments obtained by those skilled in the art based on the embodiments of this application 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.
[0038] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.
[0039] The following is in conjunction with the appendix Figures 1 to 2 This application will be described in further detail.
[0040] This application provides a method for detecting and locating pulsating pressure in an aircraft engine fuel pump failure, including the following steps:
[0041] Step 1: Collect the pulsating pressure signal P1 of the low-pressure compressor outlet airflow, the pulsating pressure signal P2 of the high-pressure compressor outlet airflow, and the pulsating pressure signal P3 of the airflow after the low-pressure turbine.
[0042] Step 2: Perform fast Fourier transform on the low-pressure compressor outlet airflow pulsation pressure signal P1, the high-pressure compressor outlet airflow pulsation pressure signal P2, and the low-pressure turbine afterflow pulsation pressure signal P3 to extract the abnormal fuel fluctuation frequency fb in the pulsation pressure signal.
[0043] Step 3: Using the abnormal fuel fluctuation frequency fb as the center, a Bessel fourth-order filter is used to perform bandpass filtering on the low-pressure compressor outlet airflow pulsation pressure signal P1, the high-pressure compressor outlet airflow pulsation pressure signal P2, and the low-pressure turbine afterflow pulsation pressure signal P3.
[0044] Step Four
[0045] Cross-correlation calculations are performed on the low-pressure compressor outlet pulsating pressure signal P1 and the high-pressure compressor outlet pulsating pressure signal P2 after bandpass filtering to obtain the cross-correlation function.
[0046] Cross-correlation calculations were performed on the high-pressure compressor outlet airflow pulsation pressure signal P2 and the low-pressure turbine downstream airflow pulsation pressure signal P3 after bandpass filtering to obtain the cross-correlation function.
[0047] And the cross-correlation function Perform normalization processing;
[0048] Step 5: Based on the cross-correlation calculation results, determine whether the high-pressure compressor outlet airflow pulsation pressure signal P2 is the signal with the fastest pass frequency among the three signals. If so, proceed to step 6.
[0049] Step 6: Acquire the fuel pump fuel pressure signal Pf, perform fast Fourier transform on the fuel pump fuel pressure signal Pf, and determine whether there is a frequency component with frequency fb. If so, the abnormal fuel fluctuation frequency fb is the fuel pump fault frequency.
[0050] The method for detecting and locating pulsating pressure in an aero-engine fuel pump failure disclosed in this application, in step one, firstly, under the condition of a complete engine test, collects the pulsating pressure signals P1 (low-pressure compressor outlet airflow), P2 (high-pressure compressor outlet airflow), and P3 (low-pressure turbine afterflow airflow) of the aero-engine through a pulsating pressure sensing unit. The sampling frequency is set to 5 kHz, and the pulsating pressure sensing unit used needs to meet dynamic testing requirements; the frequency response of the pulsating pressure sensing unit should not be lower than 1 kHz.
[0051] The method for detecting and locating pulsating pressure in an aircraft engine fuel pump failure according to this application, in step two, involves performing Fast Fourier Transform (FFT) processing on the P1, P2, and P3 signals to extract the abnormal fuel fluctuation frequency fb, which may represent the fuel pump failure frequency, from the pulsating signals. The abnormal fuel fluctuation frequency fb has the following characteristics:
[0052] (1) It exists in the low-pressure compressor outlet airflow pulsation pressure signal P1, the high-pressure compressor outlet airflow pulsation pressure signal P2, and the low-pressure turbine after airflow pulsation pressure signal P3.
[0053] (2) The frequency value does not change with the engine speed or the frequency value decreases with the increase of the engine speed, and the decrease is within 4Hz. Figure 1 The figure shows a typical fb frequency, and the abnormal fuel fluctuation frequency fb decreases slightly as the engine speed increases.
[0054] In the method for detecting and locating pulsating pressure of aero-engine fuel pump failure in this application, in step three, a bandpass filter is performed with the abnormal fuel fluctuation frequency fb as the center and the frequency bandwidth of ±5%*fb. The filter type used is a Bessel fourth-order filter to filter signals P1, P2, and P3.
[0055] In the method for detecting and locating pulsating pressure faults in the fuel pump of an aircraft engine disclosed in this application, step four involves performing cross-correlation calculations on the bandpass signals P1, P2, and P3 obtained in step three to obtain the cross-correlation function. And then normalize it.
[0056] The calculation process of the cross-correlation function is as follows:
[0057] The formula for calculating the cross-correlation function of discrete signals x and y is:
[0058]
[0059] Where N is the number of accumulations, and τ is the delay between the two signals;
[0060] If one of the two signals is delayed by m, and the outputs of the two signals are x(t) and x(tm) respectively, then the formula for calculating the cross-correlation function is transformed as follows:
[0061]
[0062] Where E[] represents the expectation.
[0063] According to the autocorrelation property, when m = τ To obtain the maximum value. If m is a positive value, it means that a signal is most correlated with another signal after a time interval of m.
[0064] In this embodiment, the cross-correlation calculation results of signals P1 and P2 are as follows: Figure 2 As shown, P1 lags P2 by 56 ms.
[0065] In the method for detecting and locating pulsating pressure faults in the fuel pump of an aircraft engine disclosed in this application, in step six, when the pulsating pressure signal P2 at the outlet airflow of the high-pressure compressor is the signal with the fastest bandpass frequency among the three signals, the fuel pump fuel pressure signal Pf is acquired. The Pf test needs to meet the dynamic pressure test principle, and the length of the pressure tapping tube for acquiring the fuel pump fuel pressure signal Pf is no greater than L.
[0066]
[0067] Where 'a' is the local speed of sound.
[0068] Finally, by performing FFT processing on the Pf signal, we can observe whether a frequency component with frequency fb is found in the spectrum. If it is found, it indicates that the fault frequency fb is generated by the fuel pump.
[0069] The method for detecting and locating pulsating pressure faults in aero-engine fuel pumps disclosed in this application can detect abnormal oil pressure fluctuation faults in fuel pumps under full-engine testing conditions. It can locate whether the abnormal frequency is generated by the main fuel pump without disassembling the fuel pump. It can be achieved using conventional pulsating pressure measuring points under full-engine conditions, without the need for other additional testing conditions, which greatly saves manpower and material costs and improves the efficiency of aero-engine testing.
[0070] 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 detecting and locating pulsating pressure in an aircraft engine fuel pump malfunction, characterized in that, include: Step 1: Collect the pulsating pressure signal P1 of the low-pressure compressor outlet airflow, the pulsating pressure signal P2 of the high-pressure compressor outlet airflow, and the pulsating pressure signal P3 of the airflow after the low-pressure turbine. Step 2: Perform fast Fourier transform on the low-pressure compressor outlet airflow pulsation pressure signal P1, the high-pressure compressor outlet airflow pulsation pressure signal P2, and the low-pressure turbine afterflow pulsation pressure signal P3 to extract the abnormal fuel fluctuation frequency fb in the pulsation pressure signal. Step 3: Using the abnormal fuel fluctuation frequency fb as the center, a Bessel fourth-order filter is used to perform bandpass filtering on the low-pressure compressor outlet airflow pulsation pressure signal P1, the high-pressure compressor outlet airflow pulsation pressure signal P2, and the low-pressure turbine afterflow pulsation pressure signal P3. Step Four Cross-correlation calculations are performed on the low-pressure compressor outlet pulsating pressure signal P1 and the high-pressure compressor outlet pulsating pressure signal P2 after bandpass filtering to obtain the cross-correlation function. ; Cross-correlation calculations were performed on the high-pressure compressor outlet airflow pulsation pressure signal P2 and the low-pressure turbine downstream airflow pulsation pressure signal P3 after bandpass filtering to obtain the cross-correlation function. ; And the cross-correlation function , Perform normalization processing; Step four, the cross-correlation calculation process includes: The formula for calculating the cross-correlation function of discrete signals x and y is: ； Where N is the number of accumulations. The delay between the two signals; If one of the two signals is delayed by m, the outputs of the two signals are respectively and Then the formula for calculating the cross-correlation function is transformed into: ； Where E[] represents the expectation; Step 5: Based on the cross-correlation calculation results, determine whether the high-pressure compressor outlet airflow pulsation pressure signal P2 is the signal with the fastest pass frequency among the three signals. If so, proceed to step 6. Step 6: Acquire the fuel pump fuel pressure signal Pf, perform fast Fourier transform on the fuel pump fuel pressure signal Pf, and determine whether there is a frequency component with frequency fb. If so, the abnormal fuel fluctuation frequency fb is the fuel pump fault frequency.
2. The method for detecting and locating pulsating pressure in an aircraft engine fuel pump malfunction according to claim 1, characterized in that, In step one, the sampling frequency for acquiring the low-pressure compressor outlet airflow pulsation pressure signal P1, the high-pressure compressor outlet airflow pulsation pressure signal P2, and the low-pressure turbine downstream airflow pulsation pressure signal P3 is set to 5 k / s.
3. The method for detecting and locating pulsating pressure in an aircraft engine fuel pump malfunction according to claim 1, characterized in that, In step one, the frequency response of the pulsating pressure sensing element of the low-pressure compressor outlet airflow pulsating pressure signal P1, the high-pressure compressor outlet airflow pulsating pressure signal P2, and the low-pressure turbine afterflow pulsating pressure signal P3 is not less than 1kHz.
4. The method for detecting and locating pulsating pressure in an aircraft engine fuel pump malfunction according to claim 1, characterized in that, In step two, the abnormal fuel fluctuation frequency fb has the following characteristics: The pulsating pressure signal P1 at the outlet of the low-pressure compressor, the pulsating pressure signal P2 at the outlet of the high-pressure compressor, and the pulsating pressure signal P3 after the low-pressure turbine all exist. The frequency value does not change with engine speed or the frequency value decreases with the increase of engine speed, and the decrease is within 4Hz.
5. The method for detecting and locating pulsating pressure in an aircraft engine fuel pump malfunction according to claim 1, characterized in that, In step three, bandpass filtering is performed with a frequency bandwidth of ±5%*fb.
6. The method for detecting and locating pulsating pressure in an aircraft engine fuel pump malfunction according to claim 1, characterized in that, In step six, the length of the pressure tap for acquiring the fuel pump fuel pressure signal Pf should not exceed L: ； Where 'a' is the local speed of sound.