Method for monitoring precooler failure in an aircraft bleed air system

Abstract

The present application provides a method for monitoring a precooler failure in an aircraft bleed air system, wherein the aircraft bleed air system is supplied with air by an auxiliary bleed air subsystem. The method comprises calculating, using a numerical simulation method, a temperature difference between a simulated precooler and a simulated air conditioning component at different internal leakage amounts under simulated operating conditions, thereby obtaining a simulated corresponding relationship between the internal leakage amount and the temperature difference; obtaining QAR data for each flight segment of the aircraft, and extracting therefrom the actual operating condition of the precooler in each flight segment; obtaining, based on the simulated corresponding relationship between the internal leakage amount and the temperature difference under the simulated operating conditions, an actual corresponding relationship between the internal leakage amount and the temperature difference under the actual operating conditions; obtaining, based on a test internal leakage amount threshold of the precooler under the test operating conditions, an actual internal leakage amount threshold under the actual operating conditions; and calculating, using the actual corresponding relationship, an actual temperature difference threshold corresponding to the actual internal leakage amount threshold, thereby determining that the precooler has failed when the actual temperature difference between the precooler and the air conditioning component is lower than the actual temperature difference threshold.

Description

Technical Field

[0001] The present application relates to the field of aviation, and in particular to a method for monitoring precooler failure in an aircraft bleed air system. Background Art

[0002] During aircraft operation, if an internal leak occurs in the precooler (PCE) of the aircraft's bleed air system, hot air will continue to be blown out of the PCE inlet and exhaust ports near the engine blades. Because this hot air reaches temperatures of 200°C to 300°C, it will leak from the PCE and burn the engine blades for a long time, significantly reducing the engine's on-wing life.

[0003] The design documentation provided by the precooler supplier clearly specifies the permissible PCE leakage standards under specific operating conditions when tested using specialized ground-based tooling. When PCE internal leakage is minimal, meaning it falls within the standard, it has minimal impact on the normal operation of the airline aircraft. However, when PCE internal leakage exceeds the standard, representing an internal leakage failure, it can easily cause single-engine bleed air failure, impacting the normal operation of the airline aircraft. Therefore, it is crucial to accurately monitor PCE internal leakage in the aircraft's bleed air system to identify PCE failures and promptly perform repairs or replacements.

[0004] However, if Figure 1 As shown, the internal leakage fault inspection method provided in the PCE component maintenance manual requires first removing the PCE from the aircraft, and then placing the disassembled PCE in a specific tooling to perform an off-site test under test conditions. This is not directly applicable to the judgment of excessive internal leakage of the on-wing PCE under actual conditions in airline operations.

[0005] Moreover, if Figure 1 As shown, the PCE internal leakage fault detection method provided in the aforementioned component maintenance manual includes at least two steps: visual inspection and hot edge leakage testing. The visual inspection requires manual inspection to confirm that the PCE is intact, undamaged, and free of scratches or dents, that the cooling element's heat sink is in good condition, that the connectors are in good condition, and that the connecting components are correctly installed. Furthermore, the hot edge leakage test requires manual operation. Connecting caps T01, T02, and T03 are used to connect PCE port A to the air pressure source, port B to the pressure gauge, and port C to the air valve, respectively. Port D is sealed using cap T04. The air pressure source pressure is then adjusted to a predetermined value, and the PCE is placed in a water tank. The pressure is then gradually adjusted to a predetermined value and maintained for a predetermined time. The PCE internal leakage rate is then verified to be within the allowable range, and the absence of bubbles in the water tank confirms that the PCE internal leakage is within the permitted range, thus confirming that the PCE is not faulty.

[0006] As can be seen from the above, existing PCE internal leakage fault detection methods not only require disassembly of the PCE for off-site testing, but also perform this testing under test conditions that differ from actual operating conditions. This can lead to inaccurate PCE internal leakage detection and, therefore, cannot be directly applied to determining excessive PCE internal leakage during airline operations. Furthermore, as can be seen from the above description, existing PCE internal leakage fault detection methods require high costs for setting up testing tooling and involve a significant amount of manual judgment and operation, resulting in a significant workload and high labor and time costs. Summary of the Invention

[0007] Therefore, in order to overcome the problem that the existing precooler internal leakage detection method cannot be directly applied to the on-wing precooler internal leakage fault judgment in route operation and the detection workload is large, the present application proposes a method for monitoring precooler faults in the aircraft bleed air system.

[0008] This application solves the above technical problems through the following technical solutions:

[0009] Specifically, according to one aspect of the present application, a method for monitoring a precooler failure in an aircraft bleed air system, the aircraft bleed air system being supplied with air by an auxiliary bleed air subsystem, is provided, the method comprising the following steps:

[0010] The temperature difference between the simulated precooler and the simulated air conditioning components at different internal leakage rates under simulated working conditions is calculated using numerical simulation methods, thereby obtaining a simulated correspondence between internal leakage rates and temperature differences.

[0011] The QAR data for each flight segment of the aircraft is obtained, and the actual operating conditions of the precooler in each segment are extracted from the QAR data. The actual corresponding relationship between the internal leakage and the temperature difference under the actual operating conditions is obtained based on the simulated corresponding relationship between the internal leakage and the temperature difference under the simulated operating conditions;

[0012] Obtaining an actual internal leakage threshold value under actual working conditions based on a test internal leakage threshold value of the precooler under test working conditions; and

[0013] The actual temperature difference threshold corresponding to the actual internal leakage threshold is calculated using the actual corresponding relationship, so that the precooler is judged to be faulty when the actual temperature difference between the precooler and the air conditioning component is lower than the actual temperature difference threshold.

[0014] The method provided in the present application for monitoring precooler failures in an aircraft bleed air system combines numerical simulation technology with engineering practice experience. There is no need to remove the precooler from the aircraft for off-site testing. The internal leakage of the precooler can be quickly determined when the aircraft precooler is on the wing. Combined with the test internal leakage threshold, the internal leakage failure of the precooler can be determined in a timely manner, thereby ensuring flight safety and greatly improving the service life of the aircraft.

[0015] Furthermore, this method combines the operating principles and processes of aircraft bleed air systems and utilizes numerical simulation technology to establish a model for the simulated correspondence between internal leakage and temperature differences, making it highly reusable. Furthermore, the actual correspondence between internal leakage and temperature differences is obtained by extracting actual operating conditions from QAR data, which is consistent with actual conditions and highly accurate.

[0016] In addition, the method provided in this application is more convenient for judging precooler failures. The PCE leakage situation in each flight segment can be known without disassembling the PCE. It also takes into account the actual working conditions of the aircraft bleed air system and conforms to the actual situation. Therefore, the accuracy is higher and it is more convenient for PCE performance trend analysis and route operation and maintenance work.

[0017] According to one embodiment of the present application, the method further includes extracting the precooler temperature and the air conditioning component temperature under actual working conditions from the QAR data, and obtaining the actual temperature difference through difference calculation.

[0018] According to one embodiment of the present application, the method further includes replacing the precooler when a precooler failure is determined. Determining whether the precooler internal leakage has reached a level requiring replacement based on dynamic replacement criteria. When a precooler internal leakage failure is determined, the faulty precooler is promptly replaced, thereby effectively reducing maintenance costs and improving route maintenance efficiency.

[0019] According to one embodiment of the present application, the step of calculating the temperature difference between the simulated precooler and the simulated air conditioning component at different internal leakage amounts under simulated working conditions includes:

[0020] Computational fluid dynamics modeling of the aircraft bleed air system is performed to obtain an aircraft bleed air system model. The operating parameters of the aircraft bleed air system model under simulated working conditions are set, and the internal leakage of the simulated precooler in the aircraft bleed air system model is continuously adjusted. Through numerical simulation calculations, the simulated precooler temperature and the temperature of the simulated air-conditioning component corresponding to each internal leakage in the aircraft bleed air system model are obtained, thereby obtaining the temperature difference between the simulated precooler and the simulated air-conditioning component at different internal leakage amounts.

[0021] According to one embodiment of the present application, the step of calculating the temperature difference between the simulated precooler and the simulated air conditioning component at different internal leakage amounts under simulated working conditions further includes:

[0022] The equivalent thermal resistance method is used to equate the thermal conductivity resistance of the simulated bleed air duct, the thermal conductivity resistance of the insulation layer, and the convective heat transfer resistance on the surface of the insulation layer in the aircraft bleed air system model to the convective heat transfer resistance under the third-category boundary condition of the pipe wall in the numerical simulation method. The convective heat transfer coefficient of the outer surface of the entire simulated bleed air duct is calculated based on the equivalent convective heat transfer resistance.

[0023] According to one embodiment of the present application, the method further includes using a data analysis method to analyze and compile statistics on multiple operating conditions when the aircraft bleed air system actually works normally, so as to obtain a universal simulated operating condition.

[0024] The method provided in this application utilizes numerical simulation technology to simplify the aircraft bleed air system based on the actual configuration of the aircraft bleed air system and precooler, and on the operating principle of the aircraft bleed air system. This results in a simplified model of the aircraft bleed air system, significantly reducing the computational effort. Furthermore, the method provided in this application incorporates practical experience to obtain more universal simulation conditions and simplifies the heat exchange in the simulated aircraft bleed air ducts, solving for the convective heat transfer coefficient in the ducts using the equivalent resistance method.

[0025] According to one embodiment of the present application, the operating condition parameters of the simulated operating condition, the actual operating condition and the test operating condition include bleed air temperature, air conditioning component flow, air conditioning component pressure and air conditioning component temperature.

[0026] According to one embodiment of the present application, the step of extracting the actual operating conditions of the precooler in each flight segment from the QAR data includes calculating the mean of the bleed air temperature, the mean of the air-conditioning component flow, the mean of the air-conditioning component pressure and the mean of the air-conditioning component temperature in each flight segment, thereby forming the actual operating conditions corresponding to each flight segment.

[0027] According to one embodiment of the present application, the step of obtaining the actual internal leakage threshold includes using the hot air density calculation formula to calculate the hot air density corresponding to the actual working conditions, and taking the product value after multiplying the hot air density by the test internal leakage threshold as the actual internal leakage threshold.

[0028] According to one embodiment of the present application, the step of obtaining the actual corresponding relationship between the internal leakage amount and the temperature difference includes setting the hot air density unchanged, and based on the air-conditioning component flow and air-conditioning component temperature corresponding to the actual working conditions, using a linear interpolation method to perform linear calculation on the simulated corresponding relationship, thereby obtaining the actual corresponding relationship between the internal leakage amount and the temperature difference.

[0029] According to one embodiment of the present application, the actual temperature difference is the difference between the temperature at the outlet of the hot side of the precooler and the temperature at the inlet of the air conditioning component.

[0030] According to another aspect of the present application, a computer program product is provided, comprising a computer program, wherein when the computer program is executed by a machine, the method according to any one of the aforementioned embodiments is performed.

[0031] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present application.

[0032] The beneficial technical effects and advantages achieved by the method for monitoring precooler failure in an aircraft bleed air system and the computer program product according to the above-mentioned embodiments of the present application are:

[0033] By utilizing numerical simulation technology and combining the operating principles and processes of aircraft bleed air systems, a simplified model of the aircraft bleed air system was established, which is highly reusable. By analyzing multiple actual operating conditions of the aircraft bleed air system to obtain a universal benchmark operating condition, numerical simulation technology was then used to analyze the temperature changes associated with different internal leakage amounts under the benchmark operating condition. Simulation methods were then used to match the relationship between different internal leakage amounts and temperature changes, and the internal leakage amount was then reflected through temperature changes, which has a wide range of applications.

[0034] Furthermore, by combining the test internal leakage thresholds in the precooler design data, a temperature threshold is established to determine when internal leakage exceeds the standard and replacement is necessary. This QAR data, including temperature data, can be used to proactively detect and determine if precooler internal leakage on route aircraft exceeds the standard. This dynamic judgment standard allows for timely detection of precooler internal leakage failures, effectively reducing repair costs and improving route maintenance efficiency. Furthermore, during precooler fault monitoring, actual operating parameters are always considered, resulting in more accurate precooler fault monitoring results.

[0035] At the same time, there is no need to remove the precooler from the aircraft for off-site testing. The internal leakage of the precooler can be quickly determined when the aircraft precooler is on the wing. Combined with the test internal leakage threshold, the internal leakage fault of the precooler in any flight segment can be discovered in time, thereby ensuring flight safety and aircraft service life, and making it more convenient for precooler performance trend analysis and route operation and maintenance work. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of off-site detection of precooler failure according to existing methods.

[0037] Figure 2 This is a schematic diagram of the existing aircraft bleed air system.

[0038] Figures 3A to 3B for Figure 2 A simplified schematic diagram of an existing aircraft bleed air system with air supplied by the auxiliary bleed air subsystem.

[0039] Figure 4 Flowchart of a method for monitoring a precooler failure in an aircraft bleed air system according to a preferred embodiment of the present application.

[0040] Figure 5 Based on Figure 4 A curve diagram showing the simulated corresponding relationship between the internal leakage amount and the temperature difference obtained by the method in FIG. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of this application more clear, the following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings showing multiple embodiments according to this application. It should be understood that all other embodiments obtained by ordinary technicians in this field based on the embodiments described in this application without expending creative effort will fall within the scope of protection of this application.

[0042] Existing aircraft bleed air systems such as Figure 2 As shown, under normal operating conditions, the bleed air system draws air from the engine compressor port. The air then passes through the pressure regulating shutoff valve (PRSOV) and the PCE to regulate temperature before being supplied to the left and right bleed air ducts through the fan bleed air valve (FAV). Ultimately, the air is distributed to the downstream air consumption systems on each side of the bleed air duct. Furthermore, the left and right bleed air ducts are connected by a cross-bleed air valve. If one side of the bleed air supply fails and shuts down, the bleed air from the other side can be supplied to both downstream air consumption systems simultaneously.

[0043] When the engine is not used for air supply, but the auxiliary bleed air system (APU) is used for air supply, the ball check valve (CBV) is open and the PRSOV is closed, the PCE and FAV are not working, and the high-pressure hot air flow provided by the APU will pass through the air conditioning unit (PACK) and be distributed to the downstream air system. Therefore, the aircraft bleed air system with only APU air supply can be simplified as follows Figure 3A As shown, it includes an APU located in the air supply line O and used for supplying air, a PACK located in the line P downstream of the APU and used for receiving the supply air flow, a PRSOV located in the bypass E of the line where the APU and PACK are located and in a closed state, and a PCE located between the PRSOV and the bypass inlet and in a non-working state.

[0044] The inventors of this application have found that it is more appropriate to detect whether the PCE has internal leakage and whether the internal leakage amount exceeds the standard when the PCE is not in operation. Figure 3A and Figure 3B A detailed analysis is conducted on the aircraft bleed air system when only APU air is supplied, when the PCE is normal and when the PCE has an internal leakage fault.

[0045] When the APU has not yet started to supply air, the pressure and temperature of the air in pipe P and bypass E are close to the ambient pressure and temperature; when the APU starts to supply air and the PACK works normally, the high-pressure hot air from the APU quickly enters pipe P through pipe O to provide air input for the PACK. At this time, since the PRSOV is closed and the PCE is not working, bypass E can be simplified to a closed state; when the APU supplies air and the PACK reaches a steady state, as shown in FIG. Figure 3AAs shown in Figure 1, the PACK inlet temperature PIT in the pipeline P is basically consistent with the temperature of the APU high-pressure hot air. The bypass E reaches a thermal equilibrium state and the temperature field therein is gradient distributed. At this time, the PCE hot outlet edge temperature BT is directly related to the temperature drop gradient based on the pipeline heat transfer coefficient. The temperature difference between the PCE hot outlet edge temperature BT and the PACK inlet temperature PIT is large. When an internal leakage fault occurs in the PCE, such as Figure 3B As shown, the thermal equilibrium state in bypass E is broken, and hot air passes through PCE to the external environment at a certain flow rate. At this time, the hot air flow rate passing through PCE increases, and the temperature difference between the PCE hot outlet edge temperature BT and the PACK inlet temperature PIT decreases.

[0046] The above analysis shows that when the PCE is within the allowable internal leakage range and the APU air supply conditions remain the same, the temperature difference between the PCE and the PACK has a certain relationship with the PCE internal leakage. Therefore, the relationship between the temperature difference between the PCE and the PACK and the PCE internal leakage can be obtained through fluid mechanics numerical simulation methods. The PCE internal leakage can be monitored based on the obtained temperature difference between the PCE and the PACK, and PCE internal leakage faults can be discovered in a timely manner and the faulty PCE can be replaced in a timely manner.

[0047] Based on the above concept, the present application provides a method for monitoring PCE failure in an aircraft bleed air system, wherein the aircraft bleed air system is supplied with air by an auxiliary bleed air subsystem, such as Figure 4 As shown, the method includes the following steps:

[0048] S1. Calculate the temperature difference between the simulated PCE and the simulated PACK at different internal leakage amounts under simulated working conditions using a numerical simulation method, thereby obtaining a simulated corresponding relationship between the internal leakage amount and the temperature difference;

[0049] S2. Acquire the QAR data of each flight segment of the aircraft, extract the actual operating condition of the PCE in each flight segment from the QAR data, and obtain the actual corresponding relationship between the internal leakage amount and the temperature difference under the actual operating condition based on the simulated corresponding relationship between the internal leakage amount and the temperature difference under the simulated operating condition;

[0050] S3. Obtaining an actual internal leakage threshold value under actual working conditions based on the test internal leakage threshold value of the PCE under the test working conditions; and

[0051] S4. Calculate the actual temperature difference threshold value corresponding to the actual internal leakage threshold value using the actual corresponding relationship, and determine that the PCE is faulty when the actual temperature difference between the PCE and the PACK is lower than the actual temperature difference threshold value.

[0052] In step S1, according to Figure 3A and Figure 3BA simplified aircraft bleed air system with APU bleed air and PACK working properly is constructed. Based on the actual configuration of PCE, numerical simulation software is used to conduct computational fluid dynamics (CFD) two-dimensional simulation of the aircraft bleed air system. Specifically, it includes computational fluid dynamics modeling of the aircraft bleed air system to obtain an aircraft bleed air system model, setting the operating parameters of the aircraft bleed air system model under simulated working conditions, and continuously adjusting the internal leakage of the simulated PCE in the aircraft bleed air system model. Through numerical simulation calculations, the simulated PCE temperature and the simulated PACK temperature corresponding to each internal leakage in the aircraft bleed air system model are obtained, thereby obtaining the following: Figure 5 The temperature difference between the simulated PCE and the simulated PACK at different internal leakage levels is shown. Exemplarily, the numerical simulation software is StarCCM+. Preferably, the simulated operating conditions are relatively general PCE operating conditions obtained by analyzing and statistically analyzing multiple operating conditions of the actual normal operation of the aircraft bleed air system using data analysis methods.

[0053] As can be seen above, the temperature gradient distribution in bypass E is related to the pipeline heat exchange coefficient. Therefore, optionally, in step S1, when performing computational fluid dynamics modeling of the aircraft bleed air system, the heat exchange in the aircraft bleed air duct is simplified based on actual conditions to solve for the pipeline heat exchange coefficient. Specifically, since the APU bleed air duct is enclosed in an insulating layer and its flow rate to the PACK is relatively high, the APU-to-PACK duct can be set to be approximately adiabatic. The portion of the duct from the bypass E inlet to the PCE hot outlet at temperature BT is only subject to system leakage and has a very low flow rate. Therefore, the heat exchange between this portion of the duct and the external environment can be ignored. Therefore, when performing CFD modeling, the equivalent thermal resistance method can be used to equate the thermal conductivity resistance of the simulated bleed air duct, the thermal conductivity resistance of the insulation layer, and the convective heat transfer resistance on the surface of the insulation layer in the aircraft bleed air system model to the convective heat transfer resistance under the third-category boundary conditions of the pipe wall in the numerical simulation method. Based on the equivalent convective heat transfer resistance, the convective heat transfer coefficient of the outer surface of the entire simulated bleed air duct can be calculated, and the temperature gradient can be determined.

[0054] The simulated bleed air duct wall thermal resistance is calculated using the cylindrical coordinate heat conduction formula in fluid mechanics based on the corresponding outer and inner radii, thermal conductivity of the wall material, and length. The conductive thermal resistance of the insulation layer and the convective heat transfer resistance on the insulation surface are determined empirically. The equivalent thermal resistance is the sum of the wall thermal resistance, the conductive thermal resistance of the insulation layer, and the convective heat transfer resistance on the insulation surface. The aforementioned pipeline heat transfer coefficient, which is directly related to the temperature drop gradient, is the reciprocal of the equivalent thermal resistance.

[0055] After the model is established, the operating parameters for the simulated operating conditions must be set in step S1. These parameters typically include bleed air temperature, PACK flow rate, PACK pressure, and PACK temperature. Optionally, the APU bleed air temperature, PACK inlet pressure, PACK inlet flow rate, and PACK inlet temperature can be adjusted as needed to obtain simulation results under different operating conditions.

[0056] After completing the model establishment and working condition setting, the internal leakage value is continuously adjusted to obtain the following through numerical simulation calculation method: Figure 5 The simulated correspondence between the internal leakage of the simulated precooler and the temperature difference is shown in FIG. Figure 3A and Figure 5 As shown in the figure, when the PCE internal leakage is zero, the temperature difference between the PCE heat outlet edge temperature (BT) and the pack inlet temperature (PIT) is maximum. As the PCE internal leakage increases within a certain range, the temperature difference between the PCE heat outlet edge temperature (BT) and the pack inlet temperature (PIT) gradually decreases. When the PCE internal leakage reaches a certain value, the temperature difference between the PCE heat outlet edge temperature (BT) and the pack inlet temperature (PIT) becomes smaller, and the effect of increasing internal leakage on the steady-state temperature is negligible. These CFD simulation results are consistent with the results of the qualitative analysis, indicating that the simulated relationship between internal leakage and temperature difference is consistent with actual conditions.

[0057] In step S2, after each flight segment is completed, the quick access recorder (QAR) data from the aircraft's wireless quick access recorder (WQAR) is transmitted to the ground via a wireless network. The QAR data includes a continuous record of the PCE hot edge outlet temperature and PACK inlet temperature data under the APU air supply before takeoff, and records the APU bleed air temperature, APU bleed air pressure, PCE upstream pressure, PACK inlet temperature, PACK inlet flow, and PACK inlet pressure data. Therefore, after decoding the original QAR data with reference to the ARINC specification, the specific actual operating conditions corresponding to each flight segment and the PCE temperature and PACK temperature under the specific actual operating conditions can be extracted from the file generated after decoding.

[0058] Specifically, for each flight segment, the step of extracting the PCE temperature and PACK temperature under specific actual operating conditions from the file generated after decoding includes filtering out the columns containing the bleed air temperature data, PACK inlet flow data, PACK inlet pressure data, PACK inlet temperature data, and PCE hot edge outlet temperature data according to the table header names in the decoded file, and then extracting the corresponding columns from the file to form a data table, thereby obtaining the operating parameter data corresponding to the specific actual operating condition, thereby forming the specific actual operating condition.

[0059] Alternatively, considering that actual operating conditions before takeoff are relatively stable, for each flight segment, the mean bleed air temperature, the mean pack inlet flow rate, the mean pack inlet pressure, and the mean pack inlet temperature can be calculated to determine the actual operating conditions corresponding to each segment. Simultaneously, the mean PCE hot edge outlet temperature can be calculated to obtain the mean temperature difference between the PCE hot edge outlet temperature and the pack inlet temperature under the corresponding actual operating conditions.

[0060] In step S2, obtaining the actual correspondence between the amount of internal leakage and the temperature difference includes setting the hot air density constant and, based on the PACK inlet flow rate and PACK inlet temperature corresponding to the actual operating conditions, linearly calculating the simulated correspondence obtained in step S1 using a linear interpolation method, thereby obtaining the actual correspondence between the amount of internal leakage and the temperature difference under the corresponding actual operating conditions. Optionally, when determining the amount of internal leakage thresholds under different actual operating conditions, the actual correspondence under different actual operating conditions can be used to calculate the temperature difference thresholds corresponding to the amount of internal leakage thresholds under different actual operating conditions, thereby timely monitoring PCE internal leakage faults under different actual operating conditions, thereby forming dynamic replacement standards for different actual operating conditions.

[0061] In step S3, the PCE design manual provides the PCE test internal leakage threshold under test conditions, and this test internal leakage threshold is a volume flow rate. Therefore, according to the principle of maintaining a constant allowable leakage ratio, the hot air density corresponding to the actual operating conditions can be calculated using the hot air density calculation formula. This hot air density is then multiplied by the test internal leakage threshold to obtain the actual internal leakage threshold. The calculation formula for hot air density ρ is as follows:

[0062]

[0063] Among them, P is the actual pressure of hot air, P0 is the standard physical atmospheric pressure, and T is the Celsius temperature of hot air.

[0064] In step S4, the precooler temperature and the air conditioning unit temperature under actual operating conditions are extracted from the QAR data, and an actual temperature difference is obtained by difference calculation. When the actual temperature difference is lower than an actual temperature difference threshold, it is determined that the precooler is faulty, and the faulty precooler is replaced in a timely manner. Alternatively, the average of the precooler temperature and the average of the air conditioning unit temperature under actual operating conditions is extracted from the QAR data, and an actual temperature difference average is obtained by difference calculation. When the actual temperature difference average is lower than an actual temperature difference threshold, it is determined that the precooler is faulty, and the faulty precooler is replaced in a timely manner.

[0065] When facing a new flight segment, the specific actual working conditions of the flight segment can be compared with the working conditions corresponding to the actual corresponding relationship to determine the corresponding specific actual corresponding relationship; the specific actual working conditions of the flight segment can be compared with the working conditions corresponding to the actual internal leakage threshold to determine the corresponding specific actual internal leakage threshold; the specific temperature difference threshold is obtained through the specific actual internal leakage threshold and the specific actual corresponding relationship, so as to judge whether the precooler is faulty based on whether the actual temperature difference of the flight segment is the specific temperature difference threshold, and then judge whether the precooler needs to be replaced.

[0066] Optionally, the method also includes distinguishing between normal and abnormal precooler internal leakage segments based on route aircraft operational fault records. Using QAR data, the precooler upstream and downstream temperature, pressure, and flow data for segments with and without excessive internal leakage are screened. This data is used to correct the numerical simulation results, thereby directly deriving the actual precooler operating temperature difference threshold.

[0067] In addition, the present application also provides a computer program product, comprising a computer program, which performs any one of the methods described herein when executed by a machine.

[0068] According to the method and computer program product provided in the present application, there is no need to remove the precooler from the aircraft for off-site testing. The internal leakage of the precooler can be quickly determined when the aircraft precooler is on the wing. Combined with the test internal leakage threshold, the internal leakage fault of the precooler in any flight segment can be discovered in time, thereby ensuring flight safety and aircraft service life, and making it easier to analyze the performance trend of the precooler and carry out route operation and maintenance.

[0069] Furthermore, numerical simulation technology, combined with the operating principles and processes of aircraft bleed air systems, has established a simplified model of the system, making it highly reusable. By analyzing multiple actual operating conditions of aircraft bleed air systems to obtain a common baseline operating condition, numerical simulation technology is then used to analyze the temperature changes associated with different internal leakage amounts under these baseline conditions. Simulation techniques are then used to match the relationship between different internal leakage amounts and temperature changes, and the temperature changes can then reflect the internal leakage amount, resulting in a wide range of applications.

[0070] Furthermore, by combining the test internal leakage thresholds in the precooler design data, a temperature threshold was established to indicate when internal leakage exceeds the standard and replacement is necessary. This QAR data, including temperature data, can be used to proactively detect and determine if precooler internal leakage on route aircraft exceeds the standard. This dynamic judgment standard allows for timely detection of precooler internal leakage failures, effectively reducing repair costs and improving route maintenance efficiency. Furthermore, during precooler fault monitoring, actual operating conditions are always taken into account, resulting in more accurate precooler fault monitoring results.

[0071] Although specific embodiments of the present application have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of protection of the present application is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and such changes and modifications shall fall within the scope of protection of the present application.

Claims

1. A method for monitoring a precooler failure in an aircraft bleed air system, wherein: The aircraft bleed air system is supplied with air by an auxiliary bleed air subsystem, and the method comprises the following steps: The temperature difference between the simulated precooler and the simulated air conditioning components at different internal leakage rates under simulated working conditions is calculated using numerical simulation methods, thereby obtaining a simulated correspondence between internal leakage rates and temperature differences. Acquiring QAR data for each flight segment of the aircraft, extracting the actual operating condition of the precooler in each flight segment from the QAR data, and obtaining the actual corresponding relationship between the internal leakage and the temperature difference under the actual operating condition based on a simulated corresponding relationship between the internal leakage and the temperature difference under the simulated operating condition; Obtaining an actual internal leakage threshold value under the actual working condition based on a test internal leakage threshold value of the precooler under the test working condition; and The actual temperature difference threshold value corresponding to the actual internal leakage threshold value is calculated using the actual corresponding relationship, and the precooler is judged to be faulty when the actual temperature difference between the precooler and the air conditioning component is lower than the actual temperature difference threshold value.

2. The method according to claim 1, further comprising: The precooler temperature and the air conditioning component temperature under the actual working condition are extracted from the QAR data, and the actual temperature difference is obtained by difference calculation.

3. The method according to claim 1, further comprising: When it is determined that the precooler fails, the precooler is replaced.

4. The method according to claim 1, wherein The step of calculating the temperature difference between the simulated precooler and the simulated air conditioning component at different internal leakage amounts under simulated working conditions includes: Computational fluid dynamics modeling is performed on the aircraft bleed air system to obtain an aircraft bleed air system model, operating parameters of the aircraft bleed air system model under simulated operating conditions are set, and the internal leakage of a simulated precooler in the aircraft bleed air system model is continuously adjusted. Through numerical simulation calculations, simulated precooler temperatures and simulated air-conditioning component temperatures corresponding to each internal leakage in the aircraft bleed air system model are obtained, thereby obtaining a temperature difference between the simulated precooler and the simulated air-conditioning component at different internal leakage amounts.

5. The method according to claim 4, wherein The step of calculating the temperature difference between the simulated precooler and the simulated air conditioning component at different internal leakage amounts under the simulated working condition further includes: By using the equivalent thermal resistance method, the thermal conductivity resistance of the simulated bleed air duct, the thermal conductivity resistance of the thermal insulation layer, and the convective heat transfer resistance on the surface of the thermal insulation layer in the aircraft bleed air system model are equivalent to the convective heat transfer resistance under the third-category boundary condition of the pipe wall in the numerical simulation method, thereby calculating the convective heat transfer coefficient of the outer surface of the entire simulated bleed air duct based on the equivalent convective heat transfer resistance.

6. The method according to claim 1, further comprising: A data analysis method is used to analyze and collect statistics on multiple working conditions when the aircraft bleed air system actually works normally, so as to obtain the universal simulated working condition.

7. The method according to claim 1, wherein The operating parameters of the simulated operating condition, the actual operating condition and the test operating condition include bleed air temperature, air conditioning component flow, air conditioning component pressure and air conditioning component temperature.

8. The method according to claim 7, wherein: The steps of extracting the actual working conditions from the QAR data include: The average value of the bleed air temperature, the average value of the air conditioning component flow rate, the average value of the air conditioning component pressure, and the average value of the air conditioning component temperature in each flight segment are calculated, thereby forming an actual working condition corresponding to each flight segment.

9. The method according to claim 1, wherein The step of obtaining the actual internal leakage threshold comprises: The hot air density corresponding to the actual working condition is calculated using a hot air density calculation formula, and the product value of the hot air density and the test internal leakage threshold is used as the actual internal leakage threshold.

10. The method according to claim 1, wherein The steps for obtaining the actual corresponding relationship between the internal leakage amount and the temperature difference include: The hot air density is assumed to be substantially unchanged, and based on the air conditioning component flow and the air conditioning component temperature corresponding to the actual working conditions, the simulated corresponding relationship is linearly calculated using a linear interpolation method to obtain the actual corresponding relationship between the internal leakage amount and the temperature difference.

11. The method according to any one of the preceding claims, wherein The actual temperature difference is the difference between the temperature at the hot side outlet of the precooler and the temperature at the inlet of the air conditioning component.

12. A computer program product comprising a computer program, wherein when the computer program is executed by a machine, the method according to any one of claims 1 to 11 is performed.

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