Aero-engine fuel metering characteristic monitoring method and system

Abstract

The application provides an aero-engine fuel metering characteristic monitoring method and system, the monitoring method comprising: collecting FMV opening degree, engine demand flow and flow data of an airborne flowmeter by an airborne computer to obtain a rated metering characteristic line and a measured metering characteristic line respectively, and determining metering accuracy; determining a calibration area of a main nozzle and an auxiliary nozzle, and when the measured metering characteristic line does not meet the metering accuracy, calculating metering flow data according to fuel distribution; judging whether the calculated metering flow data and the measured metering data are offset in the same trend; if so, the fuel metering characteristic drifts, and the fuel metering function is abnormal; otherwise, the airborne flowmeter is measured incorrectly, and the airborne flowmeter is abnormal. The above monitoring method uses the airborne flowmeter, FMV control data and fuel grading proportion data to detect the fuel metering characteristic under different working conditions, compares the detection data with an embedded fuel metering characteristic table, and judges whether the fuel metering characteristic is abnormal.

Description

Technical Field

[0001] This invention relates to the field of aircraft engine fuel control and health monitoring technology, specifically to a method and system for monitoring the fuel metering characteristics of aircraft engines. Background Technology

[0002] Traditional aero-engine fuel systems mainly consist of low-pressure pumps, high-pressure pumps, constant-pressure valves, actuators, high-pressure shut-off valves, airborne flow meters, fuel grading valves, first group of fuel nozzles, second group of fuel nozzles, metering valves, differential pressure valves, return valves, and over-rotation valves.

[0003] In order to perform necessary condition monitoring and fuel consumption calculation, aircraft engine fuel systems are usually equipped with onboard flow meters. After being pressurized by low-pressure pumps and high-pressure pumps, the fuel from the aircraft enters the fuel manifold and fuel nozzles through metering valves and high-pressure shut-off valves and is supplied to the engine combustion chamber.

[0004] The metering valve is used to measure the amount of fuel entering the engine combustion chamber. The high-pressure shut-off valve is used to maintain sufficient minimum servo pressure in the system and cut off the fuel supply to the engine combustion chamber after the engine stops. The differential pressure valve is used to ensure that the pressure difference before and after the metering valve is constant. In this way, controlling the position of the metering valve can control the amount of fuel entering the combustion chamber. The return valve is used to return the excess fuel supplied by the high-pressure pump to the low-pressure pump.

[0005] Fuel staging is designed to improve the atomization effect of fuel injectors. When the combustion chamber flow rate is low, fuel is supplied to the auxiliary fuel line injectors in the combustion chamber, while when the combustion chamber flow rate is high, fuel is supplied to the main fuel line injectors in the combustion chamber.

[0006] To meet the control requirements of the main and auxiliary fuel circuits in the combustion chamber, a fuel grading control valve is installed. This valve can be electrically or pressure-controlled, enabling on / off or continuous grading control. An airborne flow meter is located on the fuel mains. Pressure sensors are typically used to determine whether fuel supply is cut off. The combustion chamber back pressure sensor is a crucial sensor for the aero-engine cross-section, playing a vital role in the fuel-air ratio control mechanism.

[0007] As can be seen, the metering of fuel systems is usually done by fuel metering devices (FMU / HMU). Fuel metering devices have metering valves (FMV), which are spool valves that can be controlled by electrical signals. Changes in the flow area of ​​the spool valve can control the flow rate. At the same time, fuel metering devices usually use constant differential pressure control and have differential pressure valves and bypass valves to ensure the pressure drop before and after the FMV.

[0008] During engine operation, fuel contamination, component wear, and performance degradation can cause FMV metering characteristics to drift or become disordered at certain points. However, since fuel control has a large closed-loop correction function, as long as the fuel metering function still has a certain degree of monotonicity, it can complete engine control. As a result, it cannot identify fuel metering device malfunctions in time. If a malfunctioning fuel metering device continues to operate, it will increase the probability of fuel supply failure. In severe cases, it can cause major safety risks such as engine in-flight shutdown and uncontrolled thrust.

[0009] Based on this, the inventors of this application propose a method and system for monitoring the fuel metering characteristics of an aero-engine, in order to solve the above-mentioned technical problems. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to overcome the defect in the prior art that the failure of fuel metering device can not be detected in a timely manner, and to provide a method and system for monitoring the fuel metering characteristics of aero engines.

[0011] The present invention solves the above-mentioned technical problems through the following technical solution:

[0012] This invention provides a method for monitoring the fuel metering characteristics of an aero-engine, characterized by comprising:

[0013] Step 1: The onboard computer collects the FMV opening degree, engine demand flow rate, and flow rate data from the onboard flow meter to obtain the rated metering characteristic line and the measured metering characteristic line, and determines the metering accuracy.

[0014] Step 2: Determine the verification areas of the main nozzle and the auxiliary nozzle, and when the measured metering characteristic line does not meet the metering accuracy, calculate the metering flow data back based on the fuel distribution.

[0015] Step 3: Determine whether the calculated flow rate data and the measured flow rate data deviate in the same trend. If they do, the fuel metering characteristics are drifting and the fuel metering function is abnormal. Otherwise, the airborne flow meter is measuring incorrectly and there is an abnormality in the airborne flow meter.

[0016] According to an embodiment of the present invention, in step 1,

[0017] Plot a curve of FMV opening versus engine demand flow with FMV as the horizontal axis; wherein the curve is the rated metering characteristic line.

[0018] According to an embodiment of the present invention, in step 1,

[0019] During engine operation, the controller receives flow data from the onboard flow meter and the opening degree of the FMV, and plots a curve of the FMV opening degree versus the measured fuel flow rate of the onboard flow meter; wherein, the curve is the measured metering characteristic line.

[0020] According to an embodiment of the present invention, step 2 includes:

[0021] Step 21: Determine the calibration areas for the main nozzle and auxiliary nozzle based on the flow range;

[0022] Step 22: Based on the data from the fuel main pressure sensor and the combustion chamber back pressure sensor, obtain the metered flow rate of the auxiliary fuel circuit verification area and the metered flow rate of the main fuel circuit verification area, respectively.

[0023] According to an embodiment of the present invention, in step 22,

[0024] When supplying fuel to the auxiliary fuel line, the data from the fuel main line pressure sensor is the pressure before the auxiliary nozzle. The fuel flow rate in the auxiliary fuel line is obtained based on the data from the fuel main line pressure sensor and the data from the combustion chamber back pressure sensor, and the metering flow rate in the auxiliary fuel line verification area is calculated.

[0025] When supplying fuel to the main fuel line, the data from the fuel manifold pressure sensor is the pressure before the main nozzle. The fuel flow rate in the main fuel line is obtained based on the data from the fuel manifold pressure sensor and the data from the combustion chamber back pressure sensor, and the metering flow rate in the main fuel line calibration area is calculated.

[0026] According to one embodiment of the present invention, in step 3,

[0027] A verification curve is plotted by back-calculating the metered flow rate and the FMV opening.

[0028] According to one embodiment of the present invention, the fault type of the fuel metering device is determined by comparing the measured metering characteristic line with the calibration curve.

[0029] According to one embodiment of the present invention, the life status of the fuel metering device is evaluated based on the calibration curve and the measured metering characteristic line.

[0030] According to one embodiment of the present invention, the metered flow rate is controlled by constant differential pressure.

[0031] This invention also provides a fuel metering characteristic monitoring system for an aircraft engine, characterized in that it includes:

[0032] The determination module uses an onboard computer to collect FMV opening, engine demand flow, and flow data from the onboard flow meter to obtain the rated metering characteristic line and the measured metering characteristic line, and to determine the metering accuracy.

[0033] The verification module determines the verification areas of the main nozzle and the auxiliary nozzle, and when the measured metering characteristic line does not meet the metering accuracy, it back-calculates the metering flow data based on the fuel distribution.

[0034] If the calculated flow rate data deviates from the actual measured flow rate data in the same trend, the fuel metering characteristics are drifting and the fuel metering function is abnormal; otherwise, the airborne flow meter is measuring incorrectly and there is an abnormality in the airborne flow meter.

[0035] The positive and progressive effects of this invention are as follows:

[0036] This invention relates to a method for monitoring the fuel metering characteristics of aero-engines. Without adding extra sensors or other structures, it utilizes airborne flow meters, FMV control data, and fuel grading ratio data to detect fuel metering characteristics under different operating conditions. The detected data is compared with a built-in fuel metering characteristic table to determine whether any abnormalities have occurred in the fuel metering characteristics. Simultaneously, trend analysis is performed on the metering characteristics over multiple flight cycles, ultimately enabling online monitoring of fuel metering characteristics and providing data support for condition-based maintenance of control system accessories. Attached Figure Description

[0037] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0038] Figure 1 Schematic diagram of hardware for monitoring fuel metering characteristics of aero engines;

[0039] Figure 2 A schematic diagram illustrating the measured metrological characteristic line, the rated metrological characteristic line, and the metrological accuracy range for the invention;

[0040] Figure 3 This is a schematic diagram showing the characteristics of the main nozzle and the auxiliary nozzle of the present invention;

[0041] Figure 4 This is a flowchart illustrating the judgment process of the fuel metering characteristic monitoring method for aero-engines according to the present invention. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0044] Reference Figure 1 The diagram illustrates a schematic of an online monitoring scheme for fuel metering characteristics in an aero-engine, which mainly includes an electro-hydraulic servo valve 601, a high-pressure shut-off valve 602, an airborne flow meter 603, a fuel mains pressure sensor 604, a staged valve (including a linear displacement sensor) 605, a staged electro-hydraulic servo valve 606, a secondary fuel line nozzle 607, a combustion chamber back pressure sensor 608, a main fuel line nozzle 609, a metering valve (including a linear displacement sensor) 610, a constant pressure differential valve 611, a throttle nozzle 612, a throttle nozzle 613, and a return fuel valve 614.

[0045] The electro-hydraulic servo valve 601 switches the constant pressure Pc and return oil pressure Pb in the control chambers at both ends of the metering valve 610 according to the electrical signal sent by the electronic controller, so as to realize the up and down movement of the metering valve 610. The metering valve 610 has a window, and the window area changes accordingly when it moves up and down, and the fuel flow also changes accordingly.

[0046] The upper chamber of the constant pressure differential valve 611 senses the pressure P2 behind the metering valve 610, and the lower chamber senses the pressure P1 before the metering valve 610. Where P2 + spring force = P1.

[0047] The high-pressure servo oil pressure Ps passes through the throttle nozzle 612 and simultaneously flows to the lower chamber of the return valve 614 and the side window of the differential pressure valve 611. If the metering valve 610 moves or other reasons cause the sum of the pressure P2 after the metering valve 610 and the spring force to be different from the pressure P1 before the metering valve 610, the differential pressure valve 611 will move up and down, and the area of ​​the side window of the differential pressure valve 611 will also change accordingly, further changing the pressure in the lower chamber of the return valve 614. The return valve 614 moves up and down, providing negative feedback compensation for the P1 pressure, restoring the relationship that the sum of the pressure P2 after the metering valve 610 and the spring force is equal to the pressure P1 before the metering valve 610, ensuring that the differential pressure before and after the metering valve 610 is equal.

[0048] The return valve 614 consists of two nested valves. The inner valve directly senses the pressure before and after the metering valve 610 on both its upper and lower sides, which is used to increase the speed of differential pressure control.

[0049] Specifically, the metering valve 610 has a thin-walled orifice structure, and its flow pressure difference conforms to the thin-walled orifice cutoff formula:

[0050] Wf = μA√2ΔPρ, where Wf is the metering flow rate, μ is the flow coefficient, A is the area of ​​the metering valve window 606, ΔP is the pressure difference across the metering valve, ΔP = P1 - P2, and ρ is the fuel density. After ΔP is constant, Wf ∝ A, ensuring the linearity and accuracy of the metering flow rate. Furthermore, the relationship Wf ∝ A can be pre-calibrated for feedforward control of the engine.

[0051] The throttle nozzle 613 is used to adjust the movement speed of the return valve 614, thereby increasing the damping of the system and improving its stability.

[0052] The function of the high-pressure shut-off valve 602 is to increase the back pressure of the constant differential pressure control system, thereby increasing the system pressure to maintain system stability. At the same time, it increases the system servo pressure under low flow conditions and reduces fuel leakage downstream after the system fuel supply is shut off. The high-pressure shut-off valve 602 can move up and down. To reduce the driving force required for the high-pressure shut-off valve 602 to operate, a small hole structure is provided on the oil distribution structure to balance the fuel pressure on the oil distribution structure. The high-pressure shut-off valve 602 has an end face seal, which can reduce oil leakage downstream after the high-pressure shut-off valve 602 is closed.

[0053] According to the electrical signal sent by the electronic controller, the graded electro-hydraulic servo valve 606 switches the constant pressure Pc and return oil pressure Pb in the control chambers at both ends of the graded valve (including the linear displacement sensor) 605, so as to realize the up and down movement of the graded valve. The fuel graded valve has a window, and the window area changes accordingly when it moves up and down, and the flow ratio between the main oil circuit 609 and the auxiliary oil circuit 607 changes accordingly.

[0054] When the engine is in low-speed, cruising, or other low-operation conditions, the stage valve 605 is on the upper side, and the fuel supply is mainly provided by the auxiliary fuel circuit. At this time, the fuel ratio of the auxiliary fuel circuit is relatively high. When the engine is in low-speed, takeoff, climb, or other low-operation conditions, the stage valve 605 is on the lower side, and the fuel supply is mainly provided by the main fuel circuit. At this time, the fuel ratio of the main fuel circuit is relatively high.

[0055] Based on the above schematic diagram of the online monitoring scheme for fuel metering characteristics of aero-engines, this invention proposes a method for monitoring fuel metering characteristics of aero-engines, the monitoring method comprising:

[0056] S1. The onboard computer collects the FMV opening degree, engine demand flow rate, and flow rate data from the onboard flow meter to obtain the rated metering characteristic line and the measured metering characteristic line, and determines the metering accuracy.

[0057] Please refer to Figure 2 Since the flow rate is controlled by a constant differential pressure, the flow rate Wf is only related to the opening of the metering valve FMV. Therefore, this invention plots a curve of FMV opening versus engine demand flow rate Wf with FMV as the horizontal axis. The curve is determined by metering calibration or the consistency of metering device manufacturing; therefore, this curve can be defined as the rated metering characteristic line.

[0058] During engine operation, the controller receives the flow rate value and FMV opening from the onboard flow meter. Based on these two data, a curve can be plotted between the FMV opening and the measured fuel flow rate from the onboard flow meter. This curve can be defined as the measured metering characteristic line.

[0059] The range for selecting and plotting the measured flow characteristic curve is determined according to the airborne flow measurement range, generally with Wf greater than 200 kg / h.

[0060] S2. Determine the verification areas of the main nozzle and the auxiliary nozzle, and when the measured metering characteristic line does not meet the metering accuracy, calculate the metering flow data back based on the fuel distribution.

[0061] It should be noted that the main fuel line fuel ratio is the ratio of the main fuel line fuel to the metered fuel (Wf), which can be referred to as P%. Specifically, it can be obtained based on the calibration relationship of the staged valve positions. The fuel manifold pressure sensor measures the parameter P22, and the combustion chamber back pressure sensor measures the parameter Ps3.

[0062] Please refer to Figure 3 The stage valve, main fuel line nozzle, and auxiliary fuel line nozzle form a series flow path. When the auxiliary fuel line is the main fuel line, the stage valve is at the top. At this time, the throttling area of ​​the stage valve is much larger than that of the auxiliary fuel line nozzle. Therefore, the flow resistance of the auxiliary fuel line nozzle is much larger than that of the stage valve. Thus, P22 is the pressure before the auxiliary nozzle. The auxiliary fuel line fuel flow rate Wf can be found using P22 and Ps3. The value of Wf in the auxiliary fuel line check area can be obtained by using the ratio of Wf to (1-P%).

[0063] Similarly, when the main fuel supply is in operation, the stage valve is at the bottom, and the throttling area of ​​the stage valve is much larger than that of the main fuel nozzle. Therefore, the flow resistance of the main fuel nozzle is much greater than that of the stage valve. Thus, P22 is the pressure before the main nozzle. Using P22 and Ps3 at this time, the fuel flow rate of the main fuel circuit can be found, and the value of Wf in the main fuel circuit check area can be calculated using the ratio of the fuel flow rate of the main fuel circuit to P%.

[0064] S3. If the calculated flow rate data deviates from the actual measured flow rate data in the same trend, the fuel metering characteristics are drifting and the fuel metering function is abnormal; otherwise, the airborne flow meter is measuring incorrectly and there is an abnormality in the airborne flow meter.

[0065] It is known that the fuel distribution back-calculated Wf will also be used to plot a verification curve with the FMV opening. This verification process is used to determine whether the onboard flow rate has experienced characteristic drift, leading to inaccurate flow measurement. When the measured metering characteristic line exceeds the metering accuracy requirement range of the rated metering characteristic line, and the fuel distribution back-calculated data Wf also shows a similar trend of deviation, then the fuel metering characteristic has drifted, and the fuel metering device has suffered from wear, contamination, or other malfunctions, requiring immediate replacement of the fuel metering device.

[0066] When the fuel distribution back-calculation data Wf shows an opposite trend of deviation, it indicates that the flow meter has a measurement error and there is an abnormality in the fuel flow meter.

[0067] For example, wear on the metering valve can cause the flow rate to exceed the rated metering value at the same opening. Simultaneously, if the flow rate calculated from the pressure value is also higher than that of the main or auxiliary nozzle, it indicates that the metering valve's metering characteristics have drifted and it needs to be replaced.

[0068] However, if the flow rate calculated from the pressure value is not higher than the flow rate of the main nozzle or the auxiliary nozzle, it indicates that the onboard flow meter is malfunctioning and needs to be repaired or replaced.

[0069] Please refer to Figure 4 The judgment process for one implementation method with a measurement accuracy of 5% is as follows:

[0070] Step 1: First determine the rated metrological characteristic line, the measured metrological characteristic line, and the metrological accuracy;

[0071] Step 2: Compare whether the measured metrological characteristic curves meet the required metrological accuracy range.

[0072] Step 3: Judgment process. If the measured metrological characteristic curve meets the required metrological accuracy range, return to step 2; otherwise, proceed to step 4.

[0073] Step 4: Verify the Wf data calculated from the fuel distribution data to determine if there is a deviation in the same trend; among them, the characteristics of the auxiliary nozzle are set for a flow rate of less than 3000 kg / h; the characteristics of the main nozzle are set for a flow rate between 5000 kg / h and 7000 kg / h.

[0074] Step 5: Determine if they follow the same trend;

[0075] If the calculated Wf deviates from the measured data in the same trend, the fuel metering characteristics are drifting and the fuel metering function is abnormal; otherwise, the airborne flow meter is measuring incorrectly and there is an abnormality in the airborne flow meter.

[0076] It should be noted that the monitoring method proposed in this invention can detect fuel metering characteristics in real time during each flight cycle, allowing for continuous monitoring of these characteristics. Furthermore, by using accumulated data to predict and assess the lifespan of the metering unit, early warnings can be provided.

[0077] Meanwhile, the monitoring method proposed in this invention uses the original control system sensors for detection and calculation without adding new sensors or other structures, which simplifies the measurement process and can promptly identify the fault type of the fuel metering device, avoiding major safety risks such as engine in-flight shutdown and uncontrolled thrust.

[0078] This invention also proposes an aircraft engine fuel metering characteristic monitoring system, comprising:

[0079] The determination module uses an onboard computer to collect FMV opening, engine demand flow, and flow data from the onboard flow meter to obtain the rated metering characteristic line and the measured metering characteristic line, and to determine the metering accuracy.

[0080] The verification module determines the verification areas of the main nozzle and the auxiliary nozzle, and when the measured metering characteristic line does not meet the metering accuracy, it back-calculates the metering flow data based on the fuel distribution.

[0081] If the calculated flow rate data deviates from the actual measured flow rate data in the same trend, the fuel metering characteristics are drifting and the fuel metering function is abnormal; otherwise, the airborne flow meter is measuring incorrectly and there is an abnormality in the airborne flow meter.

[0082] In summary, this invention does not add any additional sensors or other structures. It utilizes airborne flow meters, FMV control data, and fuel grading ratio data to detect fuel metering characteristics under different operating conditions. The detected data is compared with the built-in fuel metering characteristic table to determine whether the fuel metering characteristics are abnormal.

[0083] Meanwhile, trend analysis of metering characteristics across multiple flight cycles enables online monitoring of fuel metering characteristics and provides data support for condition-based maintenance of control system accessories.

[0084] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation", "connection", "joining", and "fixing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can also refer to mechanical connections. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0085] This application uses specific terms to describe embodiments of the application. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0086] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. An aircraft engine fuel metering characteristic monitoring method, characterized in that, include: Step 1: The onboard computer collects the FMV opening degree, engine demand flow rate, and flow rate data from the onboard flow meter to obtain the rated metering characteristic line and the measured metering characteristic line, and determines the metering accuracy. Step 2: Determine the verification areas of the main nozzle and the auxiliary nozzle, and when the measured metering characteristic line does not meet the metering accuracy, calculate the metering flow data back based on the fuel distribution. Step 3: Determine whether the calculated flow rate data and the measured flow rate data deviate from each other in the same trend; If the trend is the same, the fuel metering characteristics will drift and the fuel metering function will be abnormal. Conversely, if the airborne flow meter is measuring incorrectly, it indicates an abnormality in the airborne flow meter.

2. The method for monitoring the fuel metering characteristics of an aero-engine according to claim 1, characterized in that, In step 1, Plot a curve of FMV opening versus engine demand flow with FMV as the horizontal axis; wherein the curve is the rated metering characteristic line.

3. The method for monitoring the fuel metering characteristics of an aero-engine according to claim 1, characterized in that, In step 1, During engine operation, the controller receives flow data from the onboard flow meter and the opening degree of the FMV, and plots a curve of the FMV opening degree versus the measured fuel flow rate of the onboard flow meter; wherein, the curve is the measured metering characteristic line.

4. The method for monitoring the fuel metering characteristics of an aero-engine according to claim 1, characterized in that, Step 2 includes: Step 21: Determine the calibration areas for the main nozzle and auxiliary nozzle based on the flow range; Step 22: Based on the data from the fuel main pressure sensor and the combustion chamber back pressure sensor, obtain the metered flow rate of the auxiliary fuel circuit verification area and the metered flow rate of the main fuel circuit verification area, respectively.

5. The method for monitoring the fuel metering characteristics of an aero-engine according to claim 4, characterized in that, In step 22, When supplying fuel to the auxiliary fuel line, the data from the fuel main line pressure sensor is the pressure before the auxiliary nozzle. The fuel flow rate in the auxiliary fuel line is obtained based on the data from the fuel main line pressure sensor and the data from the combustion chamber back pressure sensor, and the metering flow rate in the auxiliary fuel line verification area is calculated. When supplying fuel to the main fuel line, the data from the fuel manifold pressure sensor is the pressure before the main nozzle. The fuel flow rate in the main fuel line is obtained based on the data from the fuel manifold pressure sensor and the data from the combustion chamber back pressure sensor, and the metering flow rate in the main fuel line calibration area is calculated.

6. The method for monitoring the fuel metering characteristics of an aero-engine according to claim 1, characterized in that, In step 3 A verification curve is plotted by back-calculating the metered flow rate and the FMV opening.

7. The method for monitoring the fuel metering characteristics of an aero-engine according to claim 6, characterized in that, The fault type of the fuel metering device is determined by comparing the measured metering characteristic line with the verification curve.

8. The method for monitoring the fuel metering characteristics of an aero-engine according to claim 7, characterized in that, The lifespan status of the fuel metering device is evaluated based on the calibration curve and the measured metering characteristic line.

9. The method for monitoring the fuel metering characteristics of an aero-engine according to claim 1, characterized in that, The flow rate is controlled by constant differential pressure.

10. A fuel metering characteristic monitoring system for an aircraft engine, characterized in that, include: The determination module uses an onboard computer to collect FMV opening, engine demand flow, and flow data from the onboard flow meter to obtain the rated metering characteristic line and the measured metering characteristic line, and to determine the metering accuracy. The verification module determines the verification areas of the main nozzle and the auxiliary nozzle, and when the measured metering characteristic line does not meet the metering accuracy, it back-calculates the metering flow data based on the fuel distribution. If the calculated flow rate data deviates from the measured flow rate data in the same trend as the actual flow rate data, then the fuel metering characteristics are drifting and the fuel metering function is abnormal. Conversely, if the airborne flow meter is measuring incorrectly, it indicates an abnormality in the airborne flow meter.

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