Aero-engine air-oil radiator fault monitoring method

Abstract

The application belongs to the field of gas turbine engine, and particularly relates to an aero-engine air-oil radiator fault monitoring method; through carrying out oil side flow resistance characteristic test on newly processed air-oil radiator, the oil side pressure difference ΔP and the oil side pressure difference ΔP correction coefficient θ are calculated according to the test record table, the oil side correction pressure difference ΔP is corrected, and the oil side correction pressure difference ΔP is obtained 理论修正 ; then the oil side flow resistance characteristic test is carried out on the actual working air-oil radiator product, the upper limit k 上限 and the lower limit k 下限 of the proportional coefficient parameter are calculated, the corrected flow resistance proportional coefficient k is calculated through the oil side correction pressure difference ΔP 理论修正 , and the abnormality is judged through the relationship between the flow resistance proportional coefficient k and the upper limit k 上限 and the lower limit k 下限 of the proportional coefficient parameter. The engine weight is reduced by avoiding opening the cover on the engine casing. The worker inspection efficiency is improved without stopping the engine for inspection.

Description

Technical Field

[0001] The present application relates to the field of gas turbine engines, and in particular to a method for monitoring faults in an aircraft engine air-oil radiator. Background Art

[0002] With the continuous advancement of aircraft engine technology, the heat dissipation requirements of the engine's oil system and high-power components have increased. This necessitates using an air-to-oil radiator to cool a stream of high-temperature oil using low-temperature external air. The cooled oil then flows to the engine and aircraft accessories being cooled, cooling the high-temperature accessories. Due to the significant temperature difference between the hot and cold sides of the air-to-oil radiator—two to three times that of the engine's fuel-to-oil radiator—this results in greater thermal stress within the air-to-oil radiator and a shorter mean time between failures. Furthermore, the air-to-oil radiator is located within the engine's external duct. Due to the obstruction of the casing, routine inspections cannot effectively determine if the air-to-oil radiator is experiencing leaks, blockages, or other abnormalities.

[0003] Existing technical solutions involve providing access panels or other inspection holes on the engine casing. After each engine run, workers use a borescope or visual inspection to check for leaks and other abnormalities in the air-oil cooler. However, these disadvantages are: 1) they consume maintenance time and require visual inspection, making inspection inefficient. 2) they require a dedicated access panel, increasing the weight of the engine. 3) they can only detect leaks and are unable to effectively detect blockages within the air-oil cooler. 4) they require the engine to be stopped for inspection, preventing real-time monitoring.

[0004] Therefore, how to more effectively monitor whether the air-lubricating oil radiator is abnormal is a problem that needs to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a method for monitoring faults of an aircraft engine air-oil radiator, so as to solve the problem that existing technical means cannot effectively monitor in real time whether the air-oil radiator is abnormal.

[0006] The technical solution of the present application is: a method for monitoring faults of an aircraft engine air-oil radiator, comprising:

[0007] Set up an air-oil radiator flow resistance characteristic test bench to conduct oil side flow resistance characteristic test on the newly processed air-oil radiator. After the test is completed, record all flow resistance characteristic data collected during the test in the test record sheet;

[0008] Based on the flow resistance characteristic data in the test record, a graph is drawn showing the change of the oil-side differential pressure ΔP of the air-oil radiator with the oil temperature T and the oil volume flow rate qv. The overall change trend of each state point on the change graph is obtained through interpolation. It is determined whether there are any state points in the change graph where the oil-side differential pressure results deviate from the overall trend. If so, the abnormal data is eliminated.

[0009] Obtain the lubricating oil side pressure difference △P, lubricating oil temperature T, and lubricating oil volume flow rate qv data from the change curve diagram after deleting abnormal data, use a polynomial to fit the relationship between the lubricating oil side pressure difference △P, lubricating oil temperature T, and lubricating oil volume flow rate qv, and obtain the fitting relationship: △P(T,qv)=F(T,qv); obtain the dynamic viscosity and temperature of the lubricating oil according to the lubricating oil type, obtain the inlet lubricating oil temperature, outlet lubricating oil temperature, and average inlet and outlet lubricating oil temperature of the radiator during the test according to the test record sheet, calculate the lubricating oil temperature rise correction coefficient θ, and correct the lubricating oil side pressure difference △P according to the lubricating oil temperature rise correction coefficient θ to obtain the lubricating oil side corrected pressure difference △P 理论修正 ;

[0010] The oil side flow resistance characteristic test was conducted on the air-oil radiator products that had different flow resistance failures, and the product test data results were obtained and the upper limit of the proportional coefficient parameter k was calculated. 上限 and the lower limit of the proportional coefficient parameter k 下限 ,Flow resistance fault includes flow resistance increase fault and flow resistance decrease fault;

[0011] When the engine equipped with air-oil radiator is running normally, collect the normal operation data of air-oil radiator and correct the pressure difference △P by the oil side. 理论修正 Calculate the corrected flow resistance proportional coefficient k and determine whether the corrected flow resistance proportional coefficient k is within the upper limit k of the proportional coefficient parameter 上限 and the lower limit of the proportional coefficient parameter k 下限 If so, it is considered that the k value is normal and the air-lubricating oil radiator is working normally.

[0012] Preferably, the lubricating oil side flow resistance characteristic test is specifically as follows:

[0013] Arrange temperature measuring points at the oil inlet of the radiator, volume flow measuring points at the inlet of the radiator, and pressure measuring points at the inlet and outlet of the radiator;

[0014] The flow resistance characteristic test of the air-lubricating oil radiator carried out covers all the working conditions in the test record table; different working conditions in the test record table are tested separately. For the test under each working condition, the inlet temperature data, inlet volume flow data, inlet and outlet pressure data of the radiator are recorded after the test data stabilizes for 3 minutes; the test requires that no fluid flows on the air side and only fluid flows on the lubricating oil side; considering the influence of heat leakage, the outer surface of the air-lubricating oil radiator is covered with insulation material.

[0015] Preferably, the test record table requires that the test conditions carried out by the air-oil radiator be able to cover M types of lubricating oil temperatures × N types of lubricating oil volume flow rates; the highest and lowest values ​​of the M types of lubricating oil temperatures selected in the test record table are derived from the highest and lowest temperatures that occur when the air-oil radiator is on the engine; the maximum value of the N types of lubricating oil volume flow rates selected in the test record table is derived from the maximum value that may occur when the air-oil radiator is on the engine; the minimum value of the lubricating oil volume flow rate is obtained by multiplying the maximum value of the N types of lubricating oil volume flow rates by a correction coefficient, and the correction coefficient is between 0.1 and 0.4.

[0016] Preferably, the specific method for determining whether there is a state point in the change curve diagram where the lubricating oil side pressure difference result deviates from the overall trend is: obtaining the overall interpolation in the overall change trend, and separately judging each state point, when the difference between the interpolation of a state point and the overall interpolation is greater than a set threshold, if so, then the state point is determined to be abnormal data.

[0017] Preferably, the fitting relationship is: ΔP 理论 (T,qv)=p00+p10*T+p01*qv+p20*T^2+p11*T*qv+p02*qv^2+p30*T^3+p21*T^2*qv+p12*T*qv^2.

[0018] Preferably, the oil side corrected pressure difference ΔP under the oil temperature rise condition is 理论修正 = lubricating oil side pressure difference △P×θ;

[0019] The calculation formula of the lubricating oil temperature rise correction coefficient θ is:

[0020]

[0021] Where θ is the correction coefficient of the pressure difference considering the oil temperature rise, μ is the dynamic viscosity of the oil, ρ is the density of the oil, T in is the lubricating oil temperature at the radiator inlet, T out is the outlet oil temperature of the radiator, T m is the average temperature of the lubricating oil at the inlet and outlet of the radiator, It represents the integral operation of the function from the inlet temperature to the outlet temperature, and the subscript T represents the physical property parameter at the temperature T.

[0022] Preferably, the upper limit k of the proportional coefficient parameter is 上限The specific acquisition method is as follows: collect air-lubricating oil radiator products with increased flow resistance caused by blockage, scaling, etc. in the accessory factory, with the number of products being no less than 2, and carry out the oil side flow resistance characteristic test according to the requirements of the test record sheet; divide the test data results of the product with abnormally increased flow resistance by the calculation result of the fitting relationship to obtain a series of proportional coefficients of flow resistance pressure difference, and calculate the average value and standard deviation of the proportional coefficient; the upper limit of the proportional coefficient parameter k 上限 As the reference upper limit of the proportional coefficient between the abnormally increased flow resistance and the calculated flow resistance pressure difference, the upper limit of the proportional coefficient parameter k 上限 is the mean of the proportionality coefficients minus the standard deviation of the proportionality coefficients.

[0023] Preferably, the lower limit k of the proportional coefficient parameter is 下限 The specific acquisition method is as follows: collect air-lubricating oil radiator products with flow resistance reduction failures such as cracks and leakage in the accessory factory, with the number of products being no less than 2, and carry out the oil side flow resistance characteristic test according to the requirements of the test record sheet; divide the test data results of the product with abnormally reduced flow resistance by the calculation results of the fitting relationship to obtain a series of proportional coefficients of flow resistance pressure difference, and calculate the average value and standard deviation; the lower limit of the proportional coefficient k 下限 As the reference lower limit of the proportional coefficient of abnormally reduced flow resistance and calculated flow resistance pressure difference, the lower limit of the proportional coefficient parameter k 下限 is the mean + standard deviation of the proportionality coefficient.

[0024] Preferably, the corrected flow resistance proportional coefficient k is obtained by arranging temperature and pressure measuring points at the oil side inlet and outlet of the air-oil radiator, arranging an oil volume flow measuring point at the inlet of the air-oil radiator, processing the monitoring data of the measuring points through the engine control system, and calculating the oil side corrected pressure difference ΔP according to the fitting relationship and the calculation formula of the oil temperature rise correction coefficient θ. 理论修正 , the actual pressure difference △P on the lubricating oil side obtained by the radiator inlet and outlet pressure measuring points 真实 Corrected pressure difference △P with lubricating oil side 理论修正 Divide the actual flow resistance and the theoretically corrected flow resistance to obtain the proportional coefficient k, k = △P 真实 / △P 理论修正 .

[0025] Preferably, when the k value is abnormal for five consecutive operating points or for one consecutive hour, it is considered that the air-lubricating oil radiator has failed and needs to be returned to the factory for repair.

[0026] The aircraft engine air oil radiator fault monitoring method of the present application has the following advantages:

[0027] 1. Using pressure, temperature, and other sensors to obtain performance data and compare it with theoretically calculated values ​​to indirectly monitor whether the air-oil radiator is malfunctioning. This eliminates the need for a cover on the engine casing, reduces engine weight, and eliminates the need for workers to shut down the engine for inspection, improving inspection efficiency.

[0028] 2. Through performance data monitoring, real-time monitoring can be achieved. When the air-lubricating oil radiator fails, it can be repaired in the first time to avoid more serious damage.

[0029] 3. Through performance data testing, in addition to discovering radiator oil leakage faults, it can also detect faults such as blockage inside the radiator that cause increased flow resistance, which workers cannot detect by visually inspecting the product appearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions provided by this application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0031] Figure 1 This is a schematic diagram of the medium flow in the air-lubricating oil radiator of this application;

[0032] Figure 2 This is a schematic diagram of the overall process of this application;

[0033] Figure 3 This is a graph showing the change of radiator pressure difference with temperature and volume flow rate;

[0034] Figure 4 This is a schematic diagram of the change in kinematic viscosity of the lubricating oil in this application with temperature. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] like Figure 1 The air-oil radiator contains two media, air and oil, which exchange heat. Air from the engine's outer casing flows along the fins on the outside of the air-oil radiator tubes, while high-temperature oil from engine or aircraft accessories flows through the air-oil radiator tubes. Under installed conditions, sensors measure the inlet and outlet temperatures and flow rates of the oil on the air-oil radiator's oil side.

[0037] Specifically relates to a method for monitoring faults of an aircraft engine air oil radiator, such as Figure 2 , including the following steps:

[0038] Step S100: Set up an air-oil radiator flow resistance characteristic test bench to conduct an oil side flow resistance characteristic test on a newly processed air-oil radiator. After the test is completed, register all flow resistance characteristic data collected during the test in a test record sheet. The flow resistance characteristic data includes oil temperature, oil pressure, oil volume flow rate, etc. The obtained flow resistance characteristic data is used as a benchmark for fault detection.

[0039] The air-lubricating oil radiator flow resistance characteristic test bench can provide lubricating oil of different temperatures and flow rates to the air-lubricating oil radiator. The lubricating oil side flow resistance characteristic test is as follows:

[0040] A temperature measuring point is arranged at the oil side inlet of the radiator, a volume flow measuring point is arranged at the inlet of the radiator, and a pressure measuring point is arranged at the inlet and outlet of the radiator.

[0041] The flow resistance characteristics test for the air-oil radiator covered all operating conditions listed in the test record. Each condition was tested separately. For each condition, the radiator inlet temperature, inlet volume flow rate, and inlet and outlet pressure data were recorded after the test data stabilized for three minutes. The test required no fluid flow on the air side, with only fluid flow on the oil side. To account for heat leakage, the outer surface of the air-oil radiator was covered with insulation material.

[0042] The test record form requires that the test conditions carried out on the air-oil radiator can cover M types of oil temperatures × N types of oil volume flow rates.

[0043] The highest and lowest values ​​of the M oil temperatures selected in the test record are the highest and lowest temperatures that may occur on the engine with the air oil radiator. The intermediate temperatures should be evenly distributed between the highest and lowest temperatures.

[0044] The maximum value of the N oil volume flow rates selected in the test record sheet should be the maximum value that the air-oil cooler may experience on the engine. The minimum oil volume flow rate is obtained by multiplying the maximum value of the N oil volume flow rates by a correction factor. The recommended correction factor is between 0.1 and 0.4.

[0045] The test record table is shown in Table 1:

[0046] Table 1 Test record (recording radiator pressure difference results)

[0047]

[0048] Step S200, as Figure 3Based on the flow resistance characteristic data in the test record, plot the oil-side differential pressure ΔP of the air-oil radiator as it changes with the oil temperature T and the oil volume flow rate qv. Interpolate the overall trend of each state point on the curve to determine if there are any points in the curve where the oil-side differential pressure results deviate from the overall trend. If so, remove the abnormal data.

[0049] The specific judgment method is to obtain the overall interpolation in the overall change trend and judge each state point separately. When the difference between the interpolation of a state point and the overall interpolation is greater than the set threshold, if so, the state point is judged to be abnormal data.

[0050] Step S300: Obtain the oil side pressure difference ΔP, oil temperature T, and oil volume flow rate qv data in the change curve after deleting the abnormal data, and use a polynomial to fit the relationship between the oil side pressure difference ΔP, oil temperature T, and oil volume flow rate qv to obtain the fitting relationship: Δ

[0051] P(T,qv)=F(T,qv). The fitting relationship is preferably Formula (1), where pxx is the undetermined coefficient in the fitting formula.

[0052] △P 理论 (T,qv)=p00+p10*T+p01*qv+p20*T^2+p11*T*qv+

[0053] p02*qv^2+p30*T^3+p21*T^2*qv+p12*T*qv^2(1).

[0054] Step S400: When the air-oil radiator is assembled on the engine, the oil temperature at the radiator inlet will decrease due to the cooling effect of the air. Unlike air, fuel and other media, the physical properties of oil will change dramatically in the low temperature zone. Figure 3 Therefore, the average inlet and outlet parameters of the air-lubricating oil radiator cannot be used to reflect the overall situation, and corrections need to be made to the theoretical calculation results that do not consider the oil temperature rise.

[0055] Obtain the dynamic viscosity and temperature of the lubricating oil according to the lubricating oil type. Obtain the inlet and outlet lubricating oil temperatures and the average inlet and outlet lubricating oil temperatures of the radiator during the test according to the test record sheet. Calculate the lubricating oil temperature rise correction coefficient θ. Correct the lubricating oil side pressure difference △P according to the lubricating oil temperature rise correction coefficient θ to obtain the lubricating oil side corrected pressure difference △P 理论修正 Corrected oil side pressure difference △P considering oil temperature rise 理论修正 =Lubricating oil side pressure difference △P×θ.

[0056] like Figure 4The oil temperature rise correction coefficient θ is calculated by integration. The calculation formula of the oil temperature rise correction coefficient θ is:

[0057]

[0058] Where θ is the correction coefficient of the pressure difference considering the oil temperature rise, μ is the dynamic viscosity of the oil, ρ is the density of the oil, T in is the lubricating oil temperature at the radiator inlet, T out is the outlet oil temperature of the radiator, T m is the average temperature of the lubricating oil at the inlet and outlet of the radiator, It represents the integral operation of the function from the inlet temperature to the outlet temperature, and the subscript T represents the physical property parameter at the temperature T.

[0059] Step S500: Perform oil side flow resistance characteristic tests on air-oil radiator products that have experienced different flow resistance failures, obtain product test data results, and calculate the upper limit of the proportional coefficient parameter k. 上限 and the lower limit of the proportional coefficient parameter k 下限 ,Flow resistance fault includes flow resistance increase fault and flow resistance decrease fault;

[0060] Upper limit k of the proportional coefficient parameter 上限 The specific acquisition method is: collect air-lubricating oil radiator products with increased flow resistance caused by blockage, scaling, etc. in the accessory factory, with the number of products being no less than 2, and carry out the oil side flow resistance characteristic test according to the requirements of the test record sheet. Divide the test data results of the product with abnormally increased flow resistance by the calculation results of the fitting relationship to obtain a series of proportional coefficients of flow resistance pressure difference, and calculate the average value and standard deviation of the proportional coefficient. The upper limit of the proportional coefficient parameter k 上限 As the reference upper limit of the proportional coefficient between the abnormally increased flow resistance and the calculated flow resistance pressure difference, the upper limit of the proportional coefficient parameter k 上限 is the mean of the proportionality coefficients minus the standard deviation of the proportionality coefficients.

[0061] Proportional coefficient parameter lower limit k 下限 The specific acquisition method is: collect air-lubricating oil radiator products with cracks, leaks, etc. that cause flow resistance reduction failures in the accessory factory, with the number of products being no less than 2, and carry out the oil side flow resistance characteristic test according to the requirements of the test record sheet. Divide the test data results of the product with abnormally reduced flow resistance by the calculation results of the fitting relationship to obtain a series of proportional coefficients of flow resistance pressure difference, and calculate the average value and standard deviation. The lower limit of the proportional coefficient k 下限 As the reference lower limit of the proportional coefficient of abnormally reduced flow resistance and calculated flow resistance pressure difference, the lower limit of the proportional coefficient parameter k 下限 is the mean + standard deviation of the proportionality coefficient.

[0062] Step S600: When the engine equipped with the air-oil radiator is operating normally, the normal operating data of the air-oil radiator is collected and the pressure difference ΔP is corrected by the oil side. 理论修正 Calculate the corrected flow resistance proportional coefficient k and determine whether the corrected flow resistance proportional coefficient k is within the upper limit k of the proportional coefficient parameter 上限 and the lower limit of the proportional coefficient parameter k 下限 If so, it is considered that the k value is normal and the air-lubricating oil radiator is working normally.

[0063] The specific method for obtaining the corrected flow resistance proportional coefficient k is as follows: arrange temperature and pressure measuring points at the oil side inlet and outlet of the air-oil radiator, arrange oil volume flow measuring points at the inlet of the air-oil radiator, process the monitoring data of the measuring points through the engine control system, and calculate the oil side corrected pressure difference △P based on the fitting relationship and the calculation formula of the oil temperature rise correction coefficient θ 理论修正 , the actual pressure difference △P on the lubricating oil side obtained by the radiator inlet and outlet pressure measuring points 真实 Corrected pressure difference △P with lubricating oil side 理论修正 Divide the actual flow resistance and the theoretically corrected flow resistance to obtain the proportional coefficient k, k = △P 真实 / △P 理论修正 .

[0064] When the k value is abnormal for 5 consecutive operating points or for 1 consecutive hour, it is considered that the air-lubricating oil radiator has failed and needs to be returned to the factory for repair.

[0065] In summary, this application conducts a test on the flow resistance characteristics of the oil side of a newly processed air-oil radiator, draws a change curve through the test data table and eliminates abnormal data, and then calculates the oil side pressure difference △P according to the change curve, and then calculates the oil temperature rise correction coefficient θ to correct the oil side pressure difference △P, and obtains the oil side corrected pressure difference △P 理论修正 Then, the oil side flow resistance characteristic test was carried out on the actual working air-oil radiator products, and the product test data results were obtained and the upper limit of the proportional coefficient parameter k was calculated. 上限 and the lower limit of the proportional coefficient parameter k 下限 , by correcting the pressure difference △P on the lubricating oil side 理论修正 Calculate the corrected flow resistance proportional coefficient k, and calculate the flow resistance proportional coefficient k and the proportional coefficient parameter upper limit k 上限 and the lower limit of the proportional coefficient parameter k 下限 The relationship between the corresponding air lubricating oil radiator is used to determine whether it is abnormal.

[0066] It has the following advantages:

[0067] 1. Using pressure, temperature, and other sensors to obtain performance data and compare it with theoretically calculated values ​​to indirectly monitor whether the air-oil radiator is malfunctioning. This eliminates the need for a cover on the engine casing, reduces engine weight, and eliminates the need for workers to shut down the engine for inspection, improving inspection efficiency.

[0068] 2. Through performance data monitoring, real-time monitoring can be achieved. When the air-lubricating oil radiator fails, it can be repaired in the first time to avoid more serious damage.

[0069] 3. Through performance data testing, in addition to discovering radiator oil leakage faults, it can also detect faults such as blockage inside the radiator that cause increased flow resistance, which workers cannot detect by visually inspecting the product appearance.

[0070] Finally, it should be noted that the drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention. Other structures can refer to common designs. In the absence of conflicts, the same embodiment and different embodiments of the present invention can be combined with each other.

[0071] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for monitoring faults of an aircraft engine air-oil radiator, characterized in that: include: Set up an air-oil radiator flow resistance characteristic test bench to conduct oil side flow resistance characteristic test on the newly processed air-oil radiator. After the test is completed, record all flow resistance characteristic data collected during the test in the test record sheet; Based on the flow resistance characteristic data in the test record, a graph is drawn showing the change of the oil-side differential pressure ΔP of the air-oil radiator with the oil temperature T and the oil volume flow rate qv. The overall change trend of each state point on the change graph is obtained through interpolation. It is determined whether there are any state points in the change graph where the oil-side differential pressure results deviate from the overall trend. If so, the abnormal data is eliminated. Obtain the lubricating oil side pressure difference △P, lubricating oil temperature T, and lubricating oil volume flow rate qv data from the change curve diagram after deleting abnormal data, use a polynomial to fit the relationship between the lubricating oil side pressure difference △P, lubricating oil temperature T, and lubricating oil volume flow rate qv, and obtain the fitting relationship: △P(T,qv)=F(T,qv); obtain the dynamic viscosity and temperature of the lubricating oil according to the lubricating oil type, obtain the inlet lubricating oil temperature, outlet lubricating oil temperature, and average inlet and outlet lubricating oil temperature of the radiator during the test according to the test record sheet, calculate the lubricating oil temperature rise correction coefficient θ, and correct the lubricating oil side pressure difference △P according to the lubricating oil temperature rise correction coefficient θ to obtain the lubricating oil side corrected pressure difference △P 理论修正 ; The oil side flow resistance characteristic test was conducted on the air-oil radiator products that had different flow resistance failures, and the product test data results were obtained and the upper limit of the proportional coefficient parameter k was calculated. 上限 and the lower limit of the proportional coefficient parameter k 下限 ,Flow resistance fault includes flow resistance increase fault and flow resistance decrease fault; When the engine equipped with air-oil radiator is running normally, collect the normal operation data of air-oil radiator and correct the pressure difference △P by the oil side. 理论修正 Calculate the corrected flow resistance proportional coefficient k and determine whether the corrected flow resistance proportional coefficient k is within the upper limit k of the proportional coefficient parameter 上限 and the lower limit of the proportional coefficient parameter k 下限 If so, it is considered that the k value is normal and the air-lubricating oil radiator is working normally.

2. The method for monitoring failure of an aircraft engine air-oil radiator according to claim 1, wherein: The lubricating oil side flow resistance characteristic test is specifically as follows: Arrange temperature measuring points at the oil inlet of the radiator, volume flow measuring points at the inlet of the radiator, and pressure measuring points at the inlet and outlet of the radiator; The flow resistance characteristic test of the air-lubricating oil radiator carried out covers all the working conditions in the test record table; different working conditions in the test record table are tested separately. For the test under each working condition, the inlet temperature data, inlet volume flow data, inlet and outlet pressure data of the radiator are recorded after the test data stabilizes for 3 minutes; the test requires that no fluid flows on the air side and only fluid flows on the lubricating oil side; considering the influence of heat leakage, the outer surface of the air-lubricating oil radiator is covered with insulation material.

3. The method for monitoring failure of an aircraft engine air-oil radiator according to claim 2, wherein: The test record form requires that the test conditions carried out on the air-oil radiator be able to cover M types of oil temperatures × N types of oil volume flow rates; The highest and lowest values ​​of the M types of lubricating oil temperatures selected in the test record table are the highest and lowest temperatures of the air-lubricating oil radiator on the engine; The maximum value among the N types of lubricating oil volume flow rates selected in the test record table is the maximum value that may occur on the engine for the air-lubricating oil radiator; The minimum value of the lubricating oil volume flow rate is obtained by multiplying the maximum value of N types of lubricating oil volume flow rates by a correction coefficient, and the correction coefficient is between 0.1 and 0.

4.

4. The method for monitoring failure of an aircraft engine air-oil radiator according to claim 1, wherein: The specific method for determining whether there is a state point in the change curve diagram where the lubricating oil side pressure difference result deviates from the overall trend is as follows: obtain the overall interpolation in the overall change trend, and judge each state point separately. When the difference between the interpolation value of a state point and the overall interpolation is greater than the set threshold, if so, the state point is judged to be abnormal data.

5. The method for monitoring failure of an aircraft engine air-oil radiator according to claim 1, wherein: The fitting relationship is: △P 理论 (T,qv)=p00+p10*T+p01*qv+p20*T^2+p11*T*qv+p02*qv^2+p30*T^3+p21*T^2*qv+p12*T*qv^2; where pxx is the unknown coefficient in the fitting relationship.

6. The method for monitoring faults of an aircraft engine air-oil radiator according to claim 1, wherein: Corrected oil side pressure difference △P under the above oil temperature rise conditions 理论修正 = lubricating oil side pressure difference △P×θ; The calculation formula of the lubricating oil temperature rise correction coefficient θ is: Where θ is the correction coefficient of the pressure difference considering the oil temperature rise, μ is the dynamic viscosity of the oil, ρ is the density of the oil, T in is the lubricating oil temperature at the radiator inlet, T out is the outlet oil temperature of the radiator, T m is the average temperature of the lubricating oil at the inlet and outlet of the radiator, represents the integral operation of the function from the inlet temperature to the outlet temperature, and the subscript T represents the physical property parameter at temperature T; is the dynamic viscosity of the lubricating oil at the average temperature of the inlet and outlet of the radiator, It is the density of the lubricating oil at the average temperature of the inlet and outlet of the radiator.

7. The method for monitoring failure of an aircraft engine air-oil radiator according to claim 1, wherein: The upper limit k of the proportional coefficient parameter 上限 The specific acquisition method is as follows: collect air-lubricating oil radiator products with increased flow resistance caused by blockage, scaling, etc. in the accessory factory, with the number of products being no less than 2, and carry out the oil side flow resistance characteristic test according to the requirements of the test record sheet; divide the test data results of the product with abnormally increased flow resistance by the calculation result of the fitting relationship to obtain a series of proportional coefficients of flow resistance pressure difference, and calculate the average value and standard deviation of the proportional coefficient; the upper limit of the proportional coefficient parameter k 上限 As the reference upper limit of the proportional coefficient between the abnormally increased flow resistance and the calculated flow resistance pressure difference, the upper limit of the proportional coefficient parameter k 上限 is the mean of the proportionality coefficients minus the standard deviation of the proportionality coefficients.

8. The method for monitoring failure of an aircraft engine air-oil radiator according to claim 1, wherein: The lower limit of the proportional coefficient parameter k 下限 The specific acquisition method is as follows: collect air-lubricating oil radiator products with flow resistance reduction failures such as cracks and leakage in the accessory factory, with the number of products being no less than 2, and carry out the oil side flow resistance characteristic test according to the requirements of the test record sheet; divide the test data results of the product with abnormally reduced flow resistance by the calculation results of the fitting relationship to obtain a series of proportional coefficients of flow resistance pressure difference, and calculate the average value and standard deviation; the lower limit of the proportional coefficient k 下限 As the reference lower limit of the proportional coefficient of abnormally reduced flow resistance and calculated flow resistance pressure difference, the lower limit of the proportional coefficient parameter k 下限 is the mean + standard deviation of the proportionality coefficient.

9. The method for monitoring faults of an aircraft engine air-oil radiator according to claim 1, wherein: The specific method for obtaining the corrected flow resistance proportional coefficient k is as follows: temperature and pressure measuring points are arranged at the inlet and outlet of the oil side of the air-oil radiator, and an oil volume flow measuring point is arranged at the inlet of the air-oil radiator. The monitoring data of the measuring points are processed by the engine control system, and the corrected pressure difference ΔP on the oil side is calculated according to the fitting relationship and the calculation formula of the oil temperature rise correction coefficient θ. 理论修正 , the actual pressure difference △P on the lubricating oil side obtained by the radiator inlet and outlet pressure measuring points 真实 Corrected pressure difference △P with lubricating oil side 理论修正 Divide the actual flow resistance and the theoretically corrected flow resistance to obtain the proportional coefficient k, k = △P 真实 / △P 理论修正 .

10. The method for monitoring failure of an aircraft engine air-oil radiator according to claim 1, wherein: When the k value is abnormal for 5 consecutive operating points or for 1 consecutive hour, it is considered that the air-lubricating oil radiator has failed and needs to be returned to the factory for repair.

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