An online diagnosis and treatment method for fuel pulsation faults in aeroengines

Abstract

The present invention provides an online diagnosis method for fuel pulsation faults of an aeroengine, comprising the following steps: S1: determining a measuring point; S2: collecting real-time data in real time and temporarily storing it in a buffer for a certain period of time; S3: calculating the fuel pulsation amplitude according to the data temporarily stored in the buffer in S2; S4: judging whether the engine is in a steady state according to the real-time relative physical speed feedback by the engine. If it is in a steady state, proceed to the next step; S5: setting a threshold value, judging the fuel pulsation fault and recording it according to the relationship between the fuel pulsation amplitude and the threshold value. In addition, a processing method for fuel pulsation faults is also provided, recording the key parameters of the engine when the pulsation fault occurs, and using these parameters to limit the safe operating range of the engine. This method realizes the online monitoring and diagnosis of fuel system pulsation faults of the engine through a small number of on-board parameters. The method provided by the present invention comprehensively judges faults according to the engine state and combines the key parameter pulsation amplitude, and the accuracy of the judgment result is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of fault diagnosis of aero-engine fuel systems, and particularly relates to an on-line diagnosis and processing method for fuel pulsation faults of aero-engines. Background Technique

[0002] In the actual operation of an aero-engine fuel system, due to the change in the volume of the fuel pump or the defect of components, hydraulic fluid is always output at a certain oscillation frequency. The pressure P and flow rate Q output from the outlet of the fuel pump are not absolutely stable. When this fluid enters hydraulic components such as pipes, valves, cylinders, and motors in the system, if the pipes or components have high stiffness, large vibration resistance, and no defects, the pressure pulsation will gradually decay and tend to a stable pressure flow; when the pressure oscillation frequency of the pulsating fluid is the same as or close to the natural frequency of the component or system, a resonance phenomenon will occur, increasing the amplitude of fuel pulsation, making the system unable to work, and even damaging the components. On the other hand, when there are defects or parameter mismatches in the system or components, disturbances will be generated with the load system, causing the fluid to generate more intense pulsation due to excitation, resulting in phenomena such as hydraulic shock, vibration, noise, cavitation, and erosion, making the system unstable. This hydraulic fluid pulsation will be transmitted to the controlled engine and affect the stable operation of the engine, resulting in phenomena such as unstable combustion, flame spraying at the nozzle, increased vibration, and increased fuel consumption rate. That is, as the state of the aero-engine rises, when a specific condition is reached, the fuel pressure or flow rate shows a periodic fluctuation with a fixed frequency, and a resonance phenomenon is formed by coupling with the engine gas path, which is called a fuel pulsation fault. If this phenomenon occurs during flight, it will seriously affect flight safety and even bring catastrophic consequences.

[0003] In existing engineering applications, a certain fuel system measures parameters such as the pressure P zb after the main fuel pump, the pressure P sf after the servo fuel pump, the inlet temperature T fin of the fuel system, the outlet temperature T f of the fuel system, and the fuel filter differential pressure S ryl etc., as the judgment basis for fault diagnosis of fuel system faults such as main fuel pump faults, servo fuel pump faults, fuel filter blockage, and fuel temperature rise, but the on-line diagnosis and evaluation of fuel system pulsation faults have not been realized. In the aero-engine fuel system, the fuel pulsation frequency shows a trend of increasing with the increase of speed and decreasing with the increase of fuel flow rate, and for different fuel system architecture forms, their frequencies are not the same, resulting in difficulty in using quantitative analysis of frequency or threshold to judge the impact of fuel pulsation on the system. Therefore, it is difficult to select parameters. In addition, fuel pulsation is usually excited when the engine runs to a specific state and is not easily present below this state. Therefore, it restricts the safe operation of the engine and cannot ensure the reliable completion of flight missions.

[0004] Regarding the influence of fuel pulsation, in the paper "Numerical Study on the Influence of Fuel Pulsation on Temperature Field" by Zhu Dongqing, Wu Penglong, Liu Yong et al. from Nanjing University of Aeronautics and Astronautics, transient simulations were carried out on fuel pulsation in uniform inlet, radial velocity distortion inlet, and circumferential velocity distortion inlet, and the influence of fuel pulsation on the combustion chamber temperature field in different inlet velocity flow fields was analyzed. It was also proved that fuel pulsation has a coupling effect on the temperature parameters at the combustion chamber outlet section, and the influence degree is the largest in the radial distortion inlet. It was proved that fuel pulsation will cause changes in the parameters at the combustion chamber outlet section and even produce a coupling effect.

[0005] In the paper "Research on Fault Diagnosis Method of Hydraulic Pump Pulsation Model" by Wang Shaoping et al. from Beihang University, mainly by monitoring the fuel flow Q, analyzing the change of the pump source pulsation parameter Q under the hydraulic pump clearance fault, and giving a reference threshold method for judging this kind of fault. In engineering, the fuel flow Q parameter is only used in the test stage, and the measurement curve has many burrs. Even if an advanced filtering algorithm is used, it is very difficult to obtain a satisfactory signal waveform. Coupled with the similarity between the burr signal and the pulsation signal, it increases the difficulty of judgment. Therefore, it is very difficult to select this parameter to judge fuel pulsation.

[0006] Regarding the judgment of engine state, in the patent "Disposal Algorithm for Aircraft Engine Onboard Sensor Faults" by Han Wenjun et al., a method of using the change rate of high / low pressure rotor speed to judge the transient state and steady state was proposed. When the speed change rate is 0, it is judged as the steady state. In actual engineering applications, there are always burrs in the speed signal. It is very difficult to accurately judge as the steady state when the change rate is 0, and there is a problem of misjudgment. Summary of the Invention

[0007] To solve the above problems, the purpose of the present invention is to provide an online diagnosis method for fuel pulsation faults of aircraft engines. The method includes the following steps:

[0008] S1: Determine the measuring points of the pressure P after the main fuel pump zb and the pressure P after the servo fuel pump sf ;

[0009] S2: Real-time collect the pressure P after the main fuel pump zb , the pressure P after the servo fuel pump sf , and the total pressure P3 of the air at the compressor outlet, and temporarily store the real-time data for a certain period of time in the buffer;

[0010] S3: Calculate the fuel pulsation amplitude according to the data temporarily stored in the buffer in S2

[0011] S4: Judge whether the engine is in a steady state according to the real-time relative physical speed fed back by the engine. If it is in a steady state, proceed to the next step;

[0012] S5: Set a threshold value. Based on the relationship between the fuel pulsation amplitude obtained in S3 and the threshold value, judge the fuel pulsation fault. If there is a fault, record the real-time relative physical speed N2, the engine inlet temperature T2, and the total pressure P3 of the air at the compressor outlet at the moment when the fault occurs.

[0013] The online diagnosis method for fuel pulsation faults of an aeroengine provided by the present invention also has the following feature: the measuring points of the pressure Pzb after the main fuel pump and the pressure Psf after the servo fuel pump are set on a straight section of the pipeline. The straight section before the measuring point is not less than 170 mm, and the measuring point position avoids the intersection or bifurcation point of the fuel pipeline.

[0014] The online diagnosis method for fuel pulsation faults of an aeroengine provided by the present invention also has the following feature: the certain time period in S2 is 2 s.

[0015] The online diagnosis method for fuel pulsation faults of an aeroengine provided by the present invention also has the following feature: S3 includes the following steps:

[0016] S3.1: Calculate the number of samples n in the buffer.

[0017] S3.2: Calculate the effective value of the samples in the buffer

[0018] S3.3: Calculate the maximum value P zb.max 、P sf.max 、P 3.max ;

[0019] S3.4: Calculate the fuel pulsation amplitude according to the data obtained in S3.2 and S3.3

[0020] The online diagnosis method for fuel pulsation faults of an aeroengine provided by the present invention also has the following feature: the effective value of the samples in S3.2 is:

[0021]

[0022]

[0023]

[0024] where t is the current moment and T is the sampling period.

[0025] The online diagnosis method for fuel pulsation faults of an aeroengine provided by the present invention also has the following feature: the fuel pulsation amplitude is:

[0026]

[0027]

[0028]

[0029] The on-line diagnosis method for fuel pulsation faults of an aero-engine provided by the present invention further has the following feature that in S4, the steady state is the state where the real-time relative physical speed N2 feedback by the engine reaches the expected value N2Dem within the duration. If the difference ΔN 20 (t) is not greater than the threshold value within 250 ms, and the threshold value is taken as 1.0%, then it is judged as the steady state. The calculation formula is as follows:

[0030] ΔN 20 (t) = |N2(t) - N2 Dem(t)| ≤ 1.0%.

[0031] The on-line diagnosis method for fuel pulsation faults of an aero-engine provided by the present invention further has the following feature that in S5, the threshold values are respectively and Then,

[0032] When it is diagnosed as "large pressure pulsation after the main fuel pump", otherwise it is normal;

[0033] When it is diagnosed as "large pressure pulsation after the servo fuel pump", otherwise it is normal;

[0034] When and there is at least one of "pressure pulsation after the main fuel pump" or "pressure pulsation after the servo fuel pump" at the same time, it is diagnosed as "fuel system pulsation fault".

[0035] Another object of the present invention is to provide a method for processing fuel pulsation faults of an aero-engine. The fault diagnosis of the processing method uses the diagnosis method described in any one of the foregoing, and if a fuel pulsation fault occurs in the engine, the fault is processed.

[0036] The method for processing fuel pulsation faults of an aero-engine provided by the present invention further has the following feature that the fault processing method includes:

[0037] Modifying the recorded N corresponding to T2 2.limit , P 3.limit values through the fuel pulsation control module, and executing the modified parameter limit to achieve the safe operation of the engine. The maximum speed of the safe operation of the engine does not exceed the maximum speed N 2.limit allowed for the engine operation, and the highest pressure does not exceed the highest pressure P 3.limit allowed for the engine.

[0038] Beneficial effects

[0039] The online diagnostic method for fuel pulsation faults of an aeroengine provided by the present invention realizes online monitoring and diagnosis of fuel pulsation faults in the engine fuel system through a small number of onboard parameters; the method provided by the present invention combines the pressure P zb behind the main fuel pump and the pressure P sf behind the servo fuel pump, and comprehensively judges faults based on the pulsation amplitude of the total pressure P3 of the air at the compressor outlet. The judgment result has a high accuracy rate. Moreover, the method comprehensively analyzes fuel pulsation faults through the relationship of the relative change amount of the fluctuation amplitude of the pressure signals of the pressure P zb behind the main fuel pump, the pressure P sf behind the servo fuel pump, and the total pressure P3 of the air at the compressor outlet, and has a high calculation efficiency.

[0040] The fuel pulsation fault handling method of an aeroengine provided by the present invention proposes safety state limit control measures after a fault occurs, enabling the engine to retain the flexibility of normal operation within the limit range, and implementing safety state limit control when exceeding the limit range. Brief Description of the Drawings

[0041] Figure 1 It is a schematic diagram of the measuring point positions of the fault online diagnostic method provided by an embodiment of the present invention.

[0042] Figure 2 It is a fault logic diagram of the fault online diagnostic method provided by an embodiment of the present invention.

[0043] Figure 3 It is a strategy logic diagram of the fault handling method provided by an embodiment of the present invention. Detailed Embodiments

[0044] The present invention will be further described in detail below in conjunction with the drawings and embodiments. It should be noted, however, that these embodiments are not intended to limit the present invention. Any equivalent transformation or substitution in terms of function, method, or structure made by those of ordinary skill in the art based on these embodiments shall fall within the protection scope of the present invention.

[0045] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0046] In addition, terms such as "first", "second", "third", etc. are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0047] The terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] As Figures 1-3 shown, this embodiment provides an online diagnosis method for fuel pulsation faults of an aeroengine, and the method includes the following steps:

[0049] Step 1, the control system selects the real-time acquisition data of the pressure P zb behind the main fuel pump, the pressure P sf behind the servo fuel pump, and the total pressure P3 of the air at the compressor outlet as the main parameters for judging fuel pulsation, and temporarily stores the real-time data within 2 s in the buffer.

[0050] Optionally, the response times of the measurement sensors for P zb and P sf and P3 need to be less than 5 ms, and the sampling frequency at the acquisition end is not less than 1 kHz.

[0051] Step 2, as Figure 1 , determine the fuel pressure measurement point positions according to the strength of fuel pulsation at different measurement point positions.

[0052] The strength of the fuel pulsation means that as the pressure pulsation of the fuel system increases with the increase of the pipeline length, there is a certain attenuation effect on the pressure pulsation. At the same time, the operation of fuel accessories and the vibration of the engine affect the strength of fuel pulsation. Therefore, P zb and P sf measurement points are set in the straight section of the pipeline. The straight section in front of the measurement points is at least 170 mm, and the straight section behind the measurement points can be appropriately reduced. It is prohibited to set measurement points at the intersection or bifurcation point of the fuel pipeline. The measurement point position of P3 is arranged according to the requirements of the control system.

[0053] Step 3, according to the fuel pressure measurement value, adopt a real-time calculation method to calculate the magnitude of the fuel pulsation amplitude.

[0054] The real-time calculation method: for P zb and Psf Filter the P3 measurement signal and extract the data within the time period of ΔT before each sampling moment t for each parameter, and temporarily store the data in the controller memory.

[0055] The controller memory includes a temporary storage area for all the collected data of the controller. The capacity of the temporary storage area for fuel pulsation calculation is at least 12 MB.

[0056] Calculate the effective value and the maximum value within the time period of ΔT, and calculate the real-time pulsation amplitude of the three parameters P zb 、P sf 、P3 within the time period of ΔT = 2 seconds. The specific calculation steps are as follows:

[0057] Step 3.1 Calculate the sampling data samples: If the sampling frequency is 1 kHz, then the sampling data period T = 1 ms, and the number of sample data n for each input parameter within the time period of ΔT is:

[0058] n = ΔT / T

[0059] Step 3.2 Calculate the mean value of the parameters P zb 、P sf 、P3 at the moment t Take the data samples within the time period of ΔT before the moment t to calculate the effective value.

[0060]

[0061]

[0062]

[0063] Step 3.3 Calculate the maximum value P zb 、P sf 、P3 of the parameters at the moment t zb.max 、P sf.max 、P 3.max : Obtain the maximum value in the sample data within the time period of ΔT before the moment t:

[0064] P zb.max (t) = MAX[|P zb (t - T)|, |P zb (t - 2T)|, …, |P zb (t - nT)|]

[0065] P sf.max (t) = MAX[|P sf (t - T)|, |P sf (t - 2T)|, …, |P sf (t - nT)|]

[0066] P 3.max(t) = MAX[|P3(t - T)|, |P3(t - 2T)|, …, |P3(t - nT)|] (k = 1, 2…n)

[0067] Step 3.4 Calculate P at time t zb and P sf and the pulsation amplitude of the P3 parameter Obtain the maximum pulsation amplitude in the sample data within the time period of ΔT before time t.

[0068]

[0069]

[0070]

[0071] Step 4, judge the engine state. When the steady state is satisfied, perform comprehensive diagnosis of fuel pulsation faults;

[0072] The engine state refers to the engine operating state, including the steady state and the transient state.

[0073] The steady state is the state where the real-time relative physical speed N2 feedback by the engine reaches the expected value N2Dem within a continuous time period. According to the difference ΔN 20 (t) not greater than the threshold value, and the threshold value is taken as 1.0%, then it is judged as the steady state. The calculation formula is as follows:

[0074] ΔN 20 (t) = |N2(t) - N2 Dem(t)| ≤ 1.0%

[0075] The transient state is the state where the real-time relative physical speed N2 feedback by the engine exceeds the expected value N2Dem at time t. According to the difference ΔN 21 (t) between the speed N2(t) at time t and the expected value N2Dem satisfies not less than the threshold value for judgment. The threshold value is taken as 2%, and the calculation formula is as follows:

[0076] ΔN 21 (t) = |N2(t) - N2 Dem(t)| ≥ 2%

[0077] Step 5, if Figure 2 , set the threshold value. According to the relationship between the pulsation amplitudes of the three parameters of P zb and P sf and P3 and the threshold value, comprehensively diagnose the pulsation fault of the fuel system, and record the current acquisition values of N2, T2, and P3 at the moment of fault occurrence;

[0078] The threshold value is obtained based on experimental data analysis. The threshold value of this system is taken as 2.4%, The threshold value is taken as 2.0%, the threshold value is taken as 0.4%. When the engine is in a steady state, the fault diagnosis is as follows:

[0079] When the output status word is "1", and an alarm message of "Large pressure pulsation of the main fuel pump" is issued. Otherwise, the output status word is "0", and no alarm message is issued.

[0080] When the output status word is "1", and an alarm message of "Large pressure pulsation of the servo fuel pump" is issued. Otherwise, the output status word is "0", and no alarm message is issued.

[0081] When the output status word is "1", and an alarm message of "Aerodynamic instability" is issued. Otherwise, the output status word is "0", and no alarm message is issued;

[0082] For the comprehensive diagnosis, when "Large pressure pulsation of the main fuel pump" or "Large pressure pulsation of the servo fuel pump" appears, through the "OR" gate, the status word is still "1". At this time, if "Aerodynamic instability" appears, after passing through the "AND" gate, the status word is still "1", then it is judged as "Fuel pulsation fault". Otherwise, no "Fuel pulsation fault" is issued.

[0083] For the collected values of N2, T2, and P3, according to the current collected values of parameters such as the rotational speed N2(t1), the total inlet temperature T2(t1) of the engine, and the total air pressure P3(t1) at the outlet of the compressor corresponding to the moment t1 when the "Fuel pulsation fault" occurs.

[0084] Step 6, if Figure 3 , according to the diagnosis result, realize the control of the engine safety state limit.

[0085] The engine safety state limit is the maximum rotational speed N 2.limit and the highest pressure P 3.limit state. The control system ensures that the engine operates within a safe range by setting the limits of N 2.limit and P 3.limit parameters.

[0086] The control is a separate fuel pulsation control module of the controller. When a "Fuel system pulsation fault" occurs, the fuel pulsation control module works. Inside the module, the set values of N 2.limit and P 3.limit are modified by software, and the modified parameter limits are executed to control the engine safety state not to exceed the set value, realizing the control of the engine safety state limit.

[0087] The N 2.limit and P 3.limitThe set value is an internal parameter set by the control system to prevent the engine operating parameters from exceeding a certain parameter, and limits N2 ≤ N during the engine operation 2.limit 、P3 ≤ P 3.limit .

[0088] The N2 limit law is that N 2.limit is a function of T2, N 2.limit = f(T2), and the P3 limit law is that P 3.limit = constant value, so that the engine always operates within the range allowed by the parameter limit law to protect the engine safety.

[0089] When the "fuel system pulsation fault" occurs, it triggers the operation of the fuel pulsation control module. This module compares the total inlet temperature T2 of the engine with T2(t1) at the time of the fault. When T2 ≥ T2(t1) is satisfied, the following N 2.limit 、P 3.limit set value modification measures are executed within the module:

[0090] N 2.limit = f(T2) - 1%

[0091] P 3.limit = P3(t1) - 50

[0092] After taking this control measure, the deterioration of fuel pulsation is avoided, the safe isolation of the engine operation state is achieved, and the safe flight of the aircraft is guaranteed.

[0093] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and variations can still be made, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. An online diagnosis method for fuel pulsation faults of an aero-engine, characterized in that, The method includes the following steps: S1: Determine the measuring points of the pressure P after the main fuel pump zb and the pressure P after the servo fuel pump sf ; S2: Real-time collect the pressure P after the main fuel pump zb and the pressure P after the servo fuel pump sf , the total pressure P3 of the air at the compressor outlet, and temporarily store the real-time data for a certain period in the buffer; S3: Calculate the fuel pulsation amplitude based on the data temporarily stored in the buffer in S2 , , ; S4: Determine whether the engine is in a steady state according to the real-time relative physical speed feedback by the engine. If it is in a steady state, proceed to the next step; S5: Set a threshold value. According to the relationship between the fuel pulsation amplitude obtained in S3 and the threshold value, judge the fuel pulsation fault. If there is a fault, record the relative physical speed N2, the engine inlet temperature T2, and the total pressure P3 of the air at the compressor outlet at the moment when the fault occurs. The S3 includes the following steps: S3.1: Calculate the number of samples n in the buffer; S3.2: Calculate the sample valid values in the buffer , , ; S3.3: Calculate the sample maximum value P in the buffer zb.max and P sf.max and P 3.max ; S3.4: Calculate the fuel pulsation amplitude based on the data obtained in S3.2 and S3.3 and and , The fuel pulsation amplitude in S3.4 , , is as follows: where t is the current moment.

2. The online diagnosis method for fuel pulsation faults of an aero-engine according to claim 1, wherein, The measuring point of the post-main fuel pump pressure P zb and the post-servo fuel pump pressure P sf is set on the straight section of the pipeline. The straight section before the measuring point shall be not less than 170 mm, and the measuring point position shall avoid the intersection or bifurcation point of the fuel pipeline.

3. The online diagnosis method for fuel pulsation faults of an aeroengine according to claim 1, characterized in that, The certain time period in S2 is 2 s.

4. The on-line diagnosis method for fuel pulsation fault of an aero-engine according to claim 1, characterized in that, The sample effective value in S3.2 is: (k = 1, 2…n), where T is the sampling period.

5. The on-line diagnosis method for fuel pulsation fault of an aero-engine according to claim 1, characterized in that The steady state in S4 is a state where the real relative physical speed N2 fed back by the engine reaches the expected value N2Dem within a continuous duration. If the difference △N 20 (t) is not greater than the threshold value within 250 ms, and the threshold value is taken as 1.0%, then it is judged as a steady state. The calculation formula is as follows: 。 6. The on-line diagnosis method for fuel pulsation faults of an aeroengine according to claim 1, characterized in that, The thresholds in S5 are Δ , Δ and Δ , respectively. When ≥△ It is diagnosed as "large pressure pulsation after the main fuel pump", otherwise it is normal; When ≥△ It is diagnosed as "large pressure pulsation after the servo fuel pump", otherwise it is normal; When ≥△ and there is at least one of "large pressure pulsation after the main fuel pump" or "large pressure pulsation after the servo fuel pump" at the same time, it is diagnosed as "fuel system pulsation failure".

7. A method for processing fuel pulsation faults of an aeroengine, characterized in that The fault diagnosis of the processing method uses the diagnosis method described in any one of claims 1-6. If a fuel pulsation fault occurs in the engine, modify the limit protection control logic to limit the safe operating range of the engine to below the parameter values at the time when the pulsation fault occurs.

8. The method for processing the fuel pulsation fault of an aero-engine according to claim 7, wherein, The fault handling method includes: Modify the set values of N corresponding to T2 and P through the fuel pulsation control module, and execute the modified parameter limits to achieve the safe operation of the engine. The maximum rotational speed of the safe operation of the engine does not exceed the maximum rotational speed N 2. limit permitted for the engine operation, and the maximum pressure does not exceed the maximum pressure P 3. limit permitted for the engine.

2. limit 3. limit .

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