Test system for air bleed composition of an aeroengine

Abstract

The application provides an aero-engine bleed air component test system, which comprises a bleed air flow path, an ambient air flow path, a bleed air online analysis device and an ambient air online analysis device. The bleed air flow path is connected with the bleed air online analysis device and used for analyzing the components of the engine bleed air. The ambient air flow path is connected with the ambient air online analysis device and used for analyzing the components of the ambient air. The test system further comprises a switching flow path, which is connected with the bleed air flow path and the ambient air flow path. In a first test state, the switching flow path is closed, the engine bleed air in the bleed air flow path enters the bleed air online analysis device, and the ambient air in the ambient air flow path enters the ambient air online analysis device. In a second test state, the switching flow path is opened, and the ambient air in the ambient air flow path enters the bleed air online analysis device.

Description

Technical Field

[0001] This invention relates to aircraft engine testing, and more particularly to a testing system for the composition of aircraft engine bleed air. Background Technology

[0002] Typical civil aircraft use an Environmental Control System (ECS) to provide air for cabin pressurization and air conditioning, with engine bleed air being the primary source. If an engine malfunctions, leading to mechanical wear or leaks of working fluids (lubricating oil, hydraulic fluid, etc.) within the air supply, toxic gases may be generated and mixed into the airflow, eventually entering the cabin along with the ECS air supply. To ensure flight safety and reduce the impact of cabin air pollution from engine bleed air on the health of the crew and passengers, it is necessary to measure the concentration of toxic substances in the engine bleed air.

[0003] However, currently there are only standards for the concentration levels of pollutants in engine bleed air, and no specific scheme for the system design and implementation steps of bleed air pollution analysis exists. Furthermore, engine bleed air measurement results are significantly affected by the composition of ambient air. The CO and CO2 content generated in engine bleed air is usually low, the compositional difference between bleed air and ambient air is small, and there is almost no change in CO and CO2 content during transmission. The measured content is often lower than the analyzer drift (which is not limited to zero-point drift here because CO2 is present in ambient air). Therefore, the largest error in the measurement often comes from the analyzer's own drift, and these errors or drifts cannot be eliminated by zero-point calibration or range calibration of the analyzer itself, for example, using clean air standard substances. The validity of the measurement data cannot be quickly determined during the measurement process. Summary of the Invention

[0004] The purpose of this invention is to provide a testing system for the components of bleed air in aero-engines, which can evaluate the effectiveness of online analysis of test data while eliminating the influence of ambient air on the measurement results.

[0005] This invention provides a testing system for the composition of bleed air from an aero-engine, including a bleed air flow path, an ambient air flow path, an online bleed air analysis device, and an online ambient air analysis device; wherein, the bleed air flow path includes a bleed air NDIR test flow path, and the ambient air flow path includes an air NDIR test flow path; the online bleed air analysis device includes a first online bleed air analyzer for analyzing the concentrations of carbon monoxide and carbon dioxide generated by the bleed air; the online ambient air analysis device includes a first online ambient air analyzer for analyzing the concentrations of carbon monoxide and carbon dioxide in ambient air; the bleed air NDIR test flow path is connected to the first online bleed air analyzer, and the air NDIR test flow path is connected to the first online ambient air analyzer; The test system further includes a first switching pipeline and a second switching pipeline. The first end of the first switching pipeline is connected to the air NDIR test flow path, and the first end of the second switching pipeline is connected to the bleed air NDIR test flow path. In a first test state, the second end of the first switching pipeline is disconnected from the first bleed air online analyzer, and the second end of the second switching pipeline is disconnected from the first ambient air online analyzer. Engine bleed air in the bleed air NDIR test flow path enters the first bleed air online analyzer, and ambient air in the air NDIR test flow path enters the first ambient air online analyzer. If, in the first test state, the first bleed air online analyzer and the first ambient air online analyzer... If the first difference between the measured values ​​is greater than or equal to the maximum error value, then the first difference is taken as the actual value of the engine bleed air; if the first difference is less than the maximum error value, then the system switches to the second test state; wherein, the maximum error value is the absolute value of the sum of the maximum errors of the first bleed air online analyzer and the first ambient air online analyzer; in the second test state, the second end of the first switching pipeline is connected to the first bleed air online analyzer, and the second end of the second switching pipeline is connected to the first ambient air online analyzer. The engine bleed air in the bleed air NDIR test flow path enters the first ambient air online analyzer, and the ambient air in the air NDIR test flow path enters the second bleed air online analyzer. The online bleed air analyzer; if the second difference between the measured value of the first bleed air online analyzer in the first test state and the measured value in the second test state, and the third difference between the measured value of the first ambient air online analyzer in the second state and the measured value in the first test state, are both greater than or equal to the maximum resolution value, then the larger of the second difference and the third difference is taken as the actual value of the engine bleed air; if the second difference or the third difference is less than the maximum resolution value, then troubleshooting operations are performed on the first bleed air online analyzer and the first ambient air online analyzer; wherein, the maximum resolution value is the negative of the sum of the resolutions of the first bleed air online analyzer and the first ambient air online analyzer.

[0006] In one embodiment, the bleed air path further includes a bleed air particulate matter testing path, and the ambient air path further includes an air particulate matter testing path; the bleed air online analysis device further includes a second bleed air online analyzer for analyzing the particulate matter concentration of the bleed air; the bleed air particulate matter testing path is connected to the second bleed air online analyzer, and the air particulate matter testing path is connected to the second ambient air online analyzer; the testing system further includes a third switching pipeline, which connects the bleed air particulate matter testing path and the air particulate matter testing path; in the first test state, the third switching pipeline is turned off, the engine bleed air in the bleed air particulate matter testing path enters the second bleed air online analyzer, and the ambient air in the air particulate matter testing path enters the second ambient air online analyzer; if the measured value of the second bleed air online analyzer in the first test state is greater than or equal to the measured value of the second ambient air online analyzer in the first test state with the maximum error ratio, then the second bleed air online analyzer in the first test state is... The fourth difference between the measured value of the bleed air online analyzer and the measured value of the second ambient air online analyzer is taken as the actual value of the engine bleed air; otherwise, the system switches to the second test state. The maximum error ratio is 100% minus the sum of the maximum errors of the second bleed air online analyzer and the second ambient air online analyzer. In the second test state, the bleed air particulate matter test flow path is closed, the third switching pipeline is opened, and ambient air in the air particulate matter test flow path enters the second bleed air online analyzer. If the measured value of the second bleed air online analyzer in the second test state is greater than or equal to the product of the maximum error ratio and the measured value of the second ambient air online analyzer in the second test state, and less than or equal to the measured value of the second ambient air online analyzer in the second test state divided by the maximum error ratio, then the fourth difference is taken as the actual value of the engine bleed air; otherwise, troubleshooting operations are performed on the second bleed air online analyzer and the second ambient air online analyzer.

[0007] In one embodiment, an air-entraining particulate matter test flow path is provided with an air-entraining particulate matter valve at a position upstream of the second air-entraining online analyzer; the first end of the third switching pipeline is connected to the air-entraining particulate matter test flow path at a position upstream of the second ambient air online analyzer; the second end of the third switching pipeline is connected to the air-entraining particulate matter test flow path at a position both upstream of the second air-entraining online analyzer and downstream of the air-entraining particulate matter valve.

[0008] In one embodiment, the third switching pipeline is provided with a switching valve, which is used to control the on / off state of the third switching pipeline; in the first test state, the particulate matter exhaust valve is open and the switching valve is closed; in the second test state, the particulate matter exhaust valve is closed and the switching valve is open.

[0009] In one embodiment, a first switching ball valve is installed upstream of the first bleed air online analyzer in the bleed air NDIR test flow path; the secondary inlet end of the first switching ball valve is connected to the second end of the first switching pipeline; the main inlet end and outlet end of the first switching ball valve are connected to the bleed air NDIR test flow path; a second switching ball valve is installed upstream of the first ambient air online analyzer in the air NDIR test flow path; the secondary inlet end of the second switching ball valve is connected to the second end of the second switching pipeline; the main inlet end and outlet end of the second switching ball valve are connected to the ambient air flow path; in the first test state, bleed air passes through the bleed air NDIR test flow path, the main inlet end of the first switching ball valve, and the... The air enters the first online bleed air analyzer via the outlet end; ambient air enters the first online ambient air analyzer via the air NDIR test flow path and the main inlet and outlet ends of the second switching ball valve; in the second test state, ambient air enters the first online bleed air analyzer sequentially via the air NDIR test flow path, the first switching pipeline, the secondary inlet end of the first switching ball valve, the outlet end of the first switching ball valve, and the bleed air NDIR test flow path; engine bleed air enters the first online ambient air analyzer sequentially via the bleed air NDIR test flow path, the second switching pipeline, the secondary inlet end of the second switching ball valve, the outlet end of the second switching ball valve, and the air NDIR test flow path.

[0010] In one embodiment, the testing system further includes a first bleed gas offline acquisition device for collecting bleed gas for offline volatile organic compound (VOC) concentration analysis and a first ambient air offline acquisition device for collecting ambient air for offline VOC concentration analysis; the bleed gas flow path further includes a bleed gas GC / MS test flow path, and the ambient air flow path further includes an air GC / MS test flow path; the first bleed gas offline acquisition device is connected to the bleed gas GC / MS test flow path, and the number of the first bleed gas offline acquisition devices is at least two; the first ambient air offline acquisition device is connected to the air GC / MS test flow path, and the number of the first ambient air offline acquisition devices is at least two.

[0011] In one embodiment, the bleed gas GC / MS test flow path is provided with a bleed gas sampling valve and a bleed gas sampling flow path valve at a position upstream of the first bleed gas offline acquisition device; the bleed gas sampling valve is used to control the opening and closing of the first bleed gas offline acquisition device; the bleed gas sampling flow path valve is used to control the on / off state of the bleed gas GC / MS test flow path; and / or the air GC / MS test flow path is provided with an air sampling valve and an air sampling flow path valve at a position upstream of the first ambient air offline acquisition device; the air sampling valve is used to control the opening and closing of the first ambient air offline acquisition device; the air sampling flow path valve is used to control the on / off state of the air GC / MS test flow path.

[0012] In one embodiment, the testing system further includes a second offline bleed gas acquisition device for collecting bleed gas for offline aldehyde and ketone compound concentration analysis and a second offline ambient air acquisition device for collecting ambient air for offline aldehyde and ketone compound concentration analysis; the bleed gas flow path further includes a bleed gas DNPH test flow path, and the ambient air flow path further includes an air DNPH test flow path; the second offline bleed gas acquisition device is connected to the bleed gas DNPH test flow path, and the number of the second offline bleed gas acquisition devices is at least two; the second offline ambient air acquisition device is connected to the air DNPH test flow path, and the number of the second offline ambient air acquisition devices is at least two.

[0013] In one embodiment, the induced air DNPH test flow path is equipped with an induced air supply pressure gauge, an induced air inlet valve, and an induced air ozone removal device located upstream of the second induced air offline acquisition device; the induced air DNPH test flow path is equipped with an induced air outlet valve and an induced air exhaust pressure gauge located downstream of the second induced air offline acquisition device; an induced air extraction pump is installed at the discharge end of the induced air DNPH test flow path, and induced air extraction regulating valves are connected in parallel at both ends of the induced air extraction pump; and / or the air DNPH test flow path is equipped with an ambient air supply pressure gauge, an ambient air inlet valve, and an ambient air ozone removal device located upstream of the second ambient air offline acquisition device; an ambient air outlet valve and an ambient air exhaust pressure gauge are installed at the downstream end of the air DNPH test flow path; an ambient air extraction pump is installed at the discharge end of the air DNPH test flow path, and ambient air extraction regulating valves are connected in parallel at both ends of the ambient air extraction pump.

[0014] In one embodiment, the bleed air flow path further includes a bleed air sampling pipeline; the bleed air sampling pipeline is equipped with a bleed air pressure reducing regulating valve and a pressure gauge after the bleed air valve; the bleed air pressure reducing regulating valve is used to regulate the pressure of the sample gas from the engine bleed air, and the pressure gauge after the bleed air valve is used to measure the pressure value of the sample gas from the engine bleed air after pressure reduction; and / or the bleed air flow path further includes a bleed air sampling pipeline; the ambient air flow path further includes an air sampling pipeline; the bleed air sampling pipeline is equipped with a bleed air sampling pump located upstream of the bleed air NDIR test flow path and a bleed air sampling regulating valve connected in parallel with the bleed air sampling pump; the bleed air sampling pump is used to pressurize the bleed air NDIR test flow path; the bleed air sampling regulating valve is used to regulate the return flow of the bleed air sampling pump.

[0015] The engine bleed air composition testing system of this invention utilizes bleed air flow paths and ambient air flow paths to collect sample air from the engine bleed air and ambient air respectively. By subtracting the ambient air composition values, the influence of ambient air on the engine bleed air measurement results is eliminated, thus correcting the engine bleed air composition measurement results and improving measurement accuracy. Simultaneously, for the analysis of components generated by the engine, such as CO and CO2 with very similar contents, the test state is changed using a first switching pipeline and a second switching pipeline: In the first test state, a first online bleed air analyzer analyzes the engine bleed air composition, and a first online ambient air analyzer analyzes the ambient air composition; the difference between the two is taken as the actual measured value of the engine bleed air. In the second test state, both the first online bleed air analyzer and the first online ambient air analyzer analyze the bleed air composition; the validity of the online analysis test data is evaluated by using the consistency between the two readings.

[0016] The first online air intake analyzer and the first online ambient air analyzer of the present invention employ dual-channel switching to acquire more measurement data to determine the validity of the data, thereby further improving the accuracy of the determination. Attached Figure Description

[0017] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0018] Figure 1 This is a schematic diagram of an embodiment of a test system for the composition of bleed air in an aircraft engine according to the present invention. Detailed Implementation

[0019] Typical civil aircraft use an Environmental Control System (ECS) to provide air for cabin pressurization and air conditioning, with engine bleed air being the primary source. If an engine malfunctions, causing mechanical wear or leaks of working fluids (lubricating oil, hydraulic fluid, etc.) within the air source, toxic gases may be generated and mixed into the airflow, then enter the cabin along with the ECS air supply. These toxic gases entering the cabin can irritate the eyes, nose, and throat of crew members and passengers, causing headaches, dizziness, and fatigue. At high concentrations, they can also lead to acute or chronic symptoms such as difficulty breathing, blurred vision, and cognitive impairment. Crew members with long-term exposure to toxic gases face further health risks. To ensure flight safety and reduce the impact of engine bleed air pollution on the health of crew and passengers, engine manufacturers need to measure the concentration of toxic substances in engine bleed air to identify potential pollution problems as early as possible. This allows for improvements in engine design to ensure a healthy and comfortable supply of engine bleed air to the cabin.

[0020] Currently, in China, only GJB 241A-2010, "General Specifications for Aircraft Turbojet and Turbofan Engines," sets forth clear requirements for the concentration levels of 13 pollutants (carbon dioxide, carbon monoxide, ethanol, methanol, hydrogen peroxide, ozone, etc.) in the bleed air of military engines. However, it does not provide specific guidance on the system design and implementation procedures for bleed air pollution analysis. The international standard ARP 4418A, "Procedure for Sampling and Measurement of Engine and APU Generated Contaminants in Bleed Air Supplies from Aircraft Engines," lists nine categories of toxic substances as markers (carbon dioxide, carbon monoxide, formaldehyde, benzene, inhalable particulate matter, etc.), clearly defining the concentration limits and measurement principles for each marker, but it does not provide specific solutions for the design of bleed air analysis systems and experimental equipment.

[0021] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the invention and not to limit it. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the invention without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, the invention is intended to cover these modifications and variations that fall within the scope of the appended claims and their equivalents.

[0022] As used herein, the terms “upstream” and “downstream” refer to the relative directions of fluid flow within a fluid path. For example, “upstream” refers to the direction from which fluid flows, and “downstream” refers to the direction from which fluid flows.

[0023] The term "Environmental Control System" (ECS) refers to a system that draws air from the engine and transmits high-temperature, high-pressure gas to the aircraft to provide a gas source for the aircraft's air conditioning system, wing anti-icing, pressurization, fuel tank inerting, and water tank pressurization.

[0024] Based on the provisions of ARP 4418A, this invention provides a testing system for the components of bleed air in aero engines, taking into account factors such as the type and concentration of toxic substance markers to be measured and the characteristics of aero engine whole-engine testing.

[0025] Figure 1 The system architecture of an embodiment of the test system for the bleed air composition of an aero-engine according to the present invention is shown. Figure 1 As shown, the testing system of this invention employs dual-channel sample gas collection: engine bleed air and ambient air. The testing system includes a bleed air flow path and an ambient air flow path. Specifically, the bleed air flow path includes a bleed air sampling pipe 100 and an air sampling pipe 200, used to collect and transmit sample gas from engine bleed air and ambient air, respectively. One channel enters the testing system through a bleed air sampling nozzle 101 on the bleed air sampling pipe 100, and the other channel enters the testing system through an ambient air sampling nozzle 201 on the air sampling pipe 200. Simultaneous collection and analysis by the bleed air sampling pipe 100 and the air sampling pipe 200 eliminates the influence of ambient air on the measurement results. The bleed air sampling nozzle 101 and the ambient air sampling nozzle 201 are used to collect sample gas from engine bleed air and ambient air, respectively.

[0026] The testing system of the present invention uses the bleed air sampling pipeline 100 and the air sampling pipeline 200 to collect sample gas of engine bleed air and sample gas of ambient air, respectively. By subtracting the ambient air component value, the influence of ambient air on the engine bleed air measurement results is eliminated, thereby correcting the engine bleed air component measurement results and improving the measurement accuracy.

[0027] The testing system of this invention can measure the concentrations of particulate matter, volatile organic compounds, aldehydes and ketones, as well as carbon monoxide and carbon dioxide. The induced gas sampling line 100 and the air sampling line 200 can be connected, respectively, to analytical devices and piping accessories for measuring the concentrations of the aforementioned components via corresponding branches.

[0028] The determination of particulate matter concentration includes online measurement of the mass concentration of inhalable particulate matter and fine particulate matter. Inhalable particulate matter (PM10) refers to particulate matter with an aerodynamic equivalent diameter of 0–10 μm, abbreviated as PM10. Fine particulate matter (PM2.5) refers to particulate matter with an aerodynamic equivalent diameter of 0–2.5 μm, abbreviated as PM2.5.

[0029] The determination of volatile organic compound concentration refers to the offline determination of volatile organic compounds in gas, using canister sampling gas chromatography-mass spectrometry (GC / MS).

[0030] The determination of aldehydes and ketones, including formaldehyde, acetaldehyde, and acrolein, was performed offline using high performance liquid chromatography (Acidified 2,4-dinitrophenylhydrazine-High Performance Liquid Chromatography, DNPH-HPLC).

[0031] Online determination of carbon monoxide and carbon dioxide concentrations was performed using non-dispersive infrared spectroscopy (NDIR).

[0032] The testing system for aircraft engine bleed air components of this invention provides a complete flow path layout for the acquisition, transmission, and analysis of engine bleed air components. It can simultaneously collect and transmit sample gases for aldehydes and ketones, volatile organic compounds, CO, CO2, and inhalable particulate matter. It enables real-time online analysis of CO, CO2, and inhalable particulate matter, and allows for the simultaneous measurement and acquisition of multiple toxic substance markers, saving sampling time. This invention can simultaneously collect and analyze engine bleed air sample gas and ambient air components, eliminating the influence of ambient air on the measurement results by subtracting the ambient air component values.

[0033] Specifically, the testing system of the present invention further includes an online bleed air analysis device and an online ambient air analysis device. The online bleed air analysis device is used to analyze the composition of engine bleed air. The online ambient air analysis device is used to analyze the composition of ambient air. The online bleed air analysis device and the online ambient air analysis device are limited to components that can be measured and analyzed online, including but not limited to particulate matter, carbon monoxide, and carbon dioxide.

[0034] In one embodiment, the bleed air flow path includes a bleed air NDIR test flow path 611, and the ambient air flow path includes an air NDIR test flow path 621. The bleed air online analysis device includes a first bleed air online analyzer 613 for analyzing the concentrations of carbon monoxide and carbon dioxide generated by the bleed air. The ambient air online analysis device includes a first ambient air online analyzer 623 for analyzing the concentrations of carbon monoxide and carbon dioxide in ambient air. The bleed air NDIR test flow path 611 is connected to the first bleed air online analyzer 613, and the air NDIR test flow path 621 is connected to the first ambient air online analyzer 623.

[0035] Both the first online air intake analyzer 613 and the first online ambient air analyzer 623 include a CO detector and a CO2 detector, which are used to detect CO concentration and CO2 concentration, respectively.

[0036] Considering that the CO and CO2 contents generated in the engine bleed air are very close, the measured contents are often lower than the zero point drift of the instrument, and the validity of the measurement data cannot be quickly determined during the measurement process, the test system of the present invention also includes multiple switching pipelines.

[0037] In this embodiment, the testing system further includes a first switching pipeline 614 and a second switching pipeline 624. The first end of the first switching pipeline 614 is connected to the air NDIR test flow path 621, and the first end of the second switching pipeline 624 is connected to the bleed air NDIR test flow path 611.

[0038] The testing system of this invention includes a first testing state (which can be understood as a normal testing state) and a second testing state (which can be understood as an abnormal testing state). When a switching trigger condition is met, the first testing state is switched to the second switching testing state. Optionally, situations such as troubleshooting of the analysis device or discovery of abnormal measurement by the analysis device can be used as the above-mentioned switching trigger condition. The first and second testing states of the first bleed air online analyzer 613 and the first ambient air online analyzer 623 are described below:

[0039] In the first test state, the second end of the first switching pipeline 614 is disconnected from the first bleed air online analyzer 613, and the second end of the second switching pipeline 624 is disconnected from the first ambient air online analyzer 623. That is, both the first switching pipeline 614 and the second switching pipeline 624 are disconnected, and no gas can flow in the pipelines. The engine bleed air in the bleed air NDIR test flow path 611 enters the first bleed air online analyzer 613, and the ambient air in the air NDIR test flow path 621 enters the first ambient air online analyzer 623.

[0040] If, under the first test condition, the first difference between the measured values ​​of the first bleed air online analyzer 613 and the first ambient air online analyzer 623 is greater than or equal to the maximum error value, then the first difference is taken as the actual value of the engine bleed air. Under this test condition, the two analyzers are used for simultaneous analysis, and the difference between them is taken as the actual measured values ​​of engine CO and CO2.

[0041] Conversely, if the first difference is less than the maximum error value, the system switches to the second testing state. In other words, "the first difference being less than the maximum error value" is the switching trigger condition for CO and CO2 testing. It should be noted that the maximum error value is the absolute value of the sum of the maximum errors of the first online bleed air analyzer 613 and the first online ambient air analyzer 623. For example, if the maximum error of the CO detector in the first online bleed air analyzer 613 is ±1 ppm, and the maximum error of the CO detector in the first online ambient air analyzer 623 is ±1 ppm, then the maximum error value is 2 ppm.

[0042] In the second test state, the second end of the first switching pipe 614 is connected to the first bleed air online analyzer 613, and the second end of the second switching pipe 624 is connected to the first ambient air online analyzer 623. The engine bleed air in the bleed air NDIR test flow path 611 enters the first ambient air online analyzer 623 through the second switching pipe 624, and the ambient air in the air NDIR test flow path 621 enters the second bleed air online analyzer 613 through the first switching pipe 614.

[0043] If the second difference between the measured value of the first bleed air online analyzer 613 in the first test state and the measured value in the second test state, and the third difference between the measured value of the first ambient air online analyzer 623 in the second state and the measured value in the first test state, are both greater than or equal to the maximum resolution value, then the larger of the second and third differences is taken as the actual value of the engine bleed air. If either the second or third difference is less than the maximum resolution value, then troubleshooting operations are performed on the first bleed air online analyzer 613 and the first ambient air online analyzer 623. It should be noted that the maximum resolution value is the negative of the sum of the resolutions of the first bleed air online analyzer 613 and the first ambient air online analyzer 623.

[0044] By exchanging the two sample gases, differences as low as the resolution level can be measured, which is far below the drift index of the analyzer itself (generally at least 10 times the resolution). Therefore, this invention can achieve a lower detection limit, which cannot be achieved by conventional methods of calibration using clean air.

[0045] For example, the concentration of CO2 in ambient air is about 400 ppm, which is significantly different from the concentration at the zero point and the range point. Drift error cannot be eliminated by conventional zero-point calibration or range calibration alone.

[0046] Since the concentration of components in CO / CO2 measurements will not change due to switching of flow paths, a dual-path switching method is adopted to obtain more measurement data to determine the validity of the data.

[0047] In this embodiment, specifically, a first switching ball valve 612 is disposed on the upstream side of the first bleed gas online analyzer 613 in the bleed gas NDIR test flow path 611. The first switching ball valve 612 includes a main inlet end, a secondary inlet end, and an outlet end. Gas can enter from the main inlet end or the secondary inlet end and exit from the outlet end.

[0048] The secondary inlet end of the first switching ball valve 612 is connected to the second end of the first switching pipeline 614.

[0049] The main inlet and outlet of the first switching ball valve 612 are connected to the bleed air NDIR test flow path 611, respectively.

[0050] A second switching ball valve 622 is installed upstream of the first ambient air online analyzer 623 in the air NDIR test flow path 621. The second switching ball valve 622 includes a main inlet end, a secondary inlet end, and an outlet end. Gas can enter from the main inlet end or the secondary inlet end and exit from the outlet end.

[0051] The secondary inlet end of the second switching ball valve 622 is connected to the second end of the second switching pipeline 624.

[0052] The main inlet and outlet of the second switching ball valve 622 are connected to the air NDIR test flow path 621, respectively.

[0053] The first switching ball valve 612 and the second switching ball valve 622 can be three-way ball valves. The ball valve core is driven by the driving mechanism to rotate around its own axis by a specific angle. The preset through hole / flow channel on the valve core is precisely matched with the pipeline interface on the valve body, thereby realizing the on / off, reversal or merging / diversion of different flow paths.

[0054] In the first test state, engine bleed air enters the first bleed air online analyzer 613 through bleed air NDIR test flow path 611, the main inlet end of the first switching ball valve 612, and the outlet end of the first switching ball valve 612; ambient air enters the first ambient air online analyzer 623 through air NDIR test flow path 621 and the main inlet end of the second switching ball valve 622, and the outlet end of the second switching ball valve 622.

[0055] In the second test state, ambient air sequentially enters the first bleed air online analyzer 613 via air NDIR test flow path 621, first switching pipeline 614, secondary inlet end of first switching ball valve 612, outlet end of first switching ball valve 612, and bleed air NDIR test flow path 611; engine bleed air sequentially enters the first ambient air online analyzer 623 via bleed air NDIR test flow path 611, second switching pipeline 624, secondary inlet end of second switching ball valve 622, outlet end of second switching ball valve 622, and air NDIR test flow path 621.

[0056] For example, in a carbon monoxide test, the maximum error of the CO detector in the first bleed air online analyzer 613 is ±1 ppm, with a resolution of 0.1 ppm. The maximum error of the CO detector in the first ambient air online analyzer 623 is ±1 ppm, with a resolution of 0.1 ppm. Then, let a = the reading of the CO detector in the first bleed air online analyzer 613 under the first test state (i.e., before switching) - the reading of the CO detector in the first ambient air online analyzer 623 under the first test state (i.e., before switching), with a maximum error of 2 ppm. b1 = the reading of the CO detector in the first bleed air online analyzer 613 under the first test state (i.e., before switching) - the reading of the CO detector in the first bleed air online analyzer 613 under the second test state (i.e., after switching), with a maximum resolution impact of 0.2 ppm. b2 = the reading of the CO detector in the first ambient air online analyzer 623 under the second test state (i.e., after switching) - the reading of the CO detector in the first ambient air online analyzer 623 under the first test state (i.e., before switching), with a maximum resolution impact of 0.2 ppm.

[0057] If a ≥ 2ppm (maximum error value), the value of a is directly used to represent the actual CO concentration of the engine bleed air (excluding environmental influences).

[0058] If a < 2ppm, switch to the second test state and measure the values ​​of b1 and b2.

[0059] After switching to the second test state, if both b1 and b2 are ≥ -0.2ppm (maximum resolution value), the larger value between b1 and b2 is used to represent the actual CO concentration of the engine bleed air (excluding environmental influences).

[0060] If b1 <-0.2ppm or b2 <-0.2ppm, it is considered a measurement abnormality and should be troubleshooted first.

[0061] For example, in a carbon dioxide test, the maximum error of the CO2 detector in the first bleed air online analyzer 613 is ±100 ppm, with a resolution of 1 ppm. The maximum error of the CO2 detector in the first ambient air online analyzer 623 is ±100 ppm, with a resolution of 1 ppm. Let a = (Reading of the CO2 detector in the first bleed air online analyzer 613 under the first test state) - (Reading of the CO2 detector in the first ambient air online analyzer 623 under the first test state) with a maximum error of 200 ppm. b1 = (Reading of the CO2 detector in the first bleed air online analyzer 613 under the first test state (i.e., before switching)) - (Reading of the CO2 detector in the first bleed air online analyzer 613 under the second test state) with a maximum resolution impact of 2 ppm. b2 = (Reading of the CO2 detector in the first ambient air online analyzer 623 under the second test state (i.e., after switching)) - (Reading of the CO2 detector in the first ambient air online analyzer 623 under the first test state) with a maximum resolution impact of 2 ppm.

[0062] If a ≥ 200 ppm (maximum error value), the value of a is directly used to represent the actual CO2 concentration of the engine bleed air (excluding environmental influences).

[0063] If a < 200ppm, switch to the second test state and measure the values ​​of b1 and b2.

[0064] After switching to the second test state, if both b1 and b2 are ≥ -2ppm (maximum resolution value), the larger of b1 and b2 is used to represent the actual CO2 concentration of the engine bleed air (excluding environmental influences). It should be noted that the larger value of b1 and b2 is used to tighten the requirements: since there are maximum limits for engine bleed air pollution, for multiple measurement results, the maximum value should also meet the limit requirements, so multiple measurement values ​​are often evaluated based on the maximum value.

[0065] If b1 < -2ppm or b2 < -2ppm, it is considered a measurement abnormality and the problem should be troubleshooted first.

[0066] Continue to refer to Figure 1 In one embodiment, the online bleed air analysis device further includes a second online bleed air analyzer 313 for analyzing the particulate matter concentration of the bleed air. The online ambient air analysis device further includes a second online ambient air analyzer 322 for analyzing the particulate matter concentration of ambient air. A bleed air particulate matter valve 312 is provided upstream of the second online bleed air analyzer 313 in the bleed air particulate matter test flow path 311. The bleed air particulate matter valve 312 may be a solenoid valve.

[0067] The testing system also includes a third switching conduit 323. The first end of the third switching conduit 323 is connected to the air particulate matter test flow path 321, located upstream of the second ambient air online analyzer 322. The second end of the third switching conduit 323 is connected to the bleed air particulate matter test flow path 311, located upstream of the second bleed air online analyzer 313 and downstream of the bleed air particulate matter valve 312.

[0068] In this embodiment, the third switching pipeline 323 is further provided with a switching valve 324, which is used to control the opening and closing of the third switching pipeline 323 and can be selected as a solenoid valve.

[0069] The particulate matter test also includes a first test state and a second test state.

[0070] In the first test state, the bleed air particulate matter valve 312 is open, and the switching valve 324 is closed. Engine bleed air passes through the bleed air sampling line 100, the bleed air particulate matter test flow path 311, and the bleed air particulate matter valve 312 before entering the second bleed air online analyzer 313. Ambient air passes through the air sampling line 200 and the air particulate matter test flow path 321 before entering the second ambient air online analyzer 322. The two analyzers are used for simultaneous analysis, and the difference between the two is taken as the actual particulate matter concentration measurement value of the engine bleed air.

[0071] If the measured value of the second bleed air online analyzer 313 in the first test state is greater than or equal to the measured value of the second ambient air online analyzer 322 in the first test state with the maximum error ratio, then the fourth difference between the measured value of the second bleed air online analyzer 313 and the measured value of the second ambient air online analyzer 322 in the first test state is taken as the actual value of the engine bleed air. Otherwise, the system switches to the second test state. It can be understood that the maximum error ratio is 100% minus the sum of the maximum errors of the second bleed air online analyzer 313 and the second ambient air online analyzer 322.

[0072] Because particles suffer significant losses inside the engine compressor, the particulate matter measurement value of the bleed air is often lower than that of the outside air. Therefore, when the bleed air measurement value is significantly lower than that of the outside air, ambient air can be introduced into the second bleed air online analyzer 313, i.e., switching to the second test state.

[0073] In the second test state, the particulate matter test flow path 311 is closed, and the third switching line 323 is opened, allowing ambient air from the particulate matter test flow path 321 to enter the second online air intake analyzer 313. Specifically, the particulate matter valve 312 is closed, and the switching valve 324 is opened, allowing ambient air to enter the second online air intake analyzer 313 via the air sampling line 200, the particulate matter test flow path 321, and the third switching line 323. Simultaneously, ambient air enters the second online ambient air analyzer 322 via the air sampling line 200 and the particulate matter test flow path 321.

[0074] If the measured value of the second bleed air online analyzer 313 under the second test state is greater than or equal to the product of the maximum error ratio and the measured value of the second ambient air online analyzer 322 under the second test state, and less than or equal to the value of the measured value of the second ambient air online analyzer 322 under the second test state divided by the maximum error ratio, then the fourth difference value is taken as the actual value of the engine bleed air. Otherwise, troubleshooting operations are performed on the second bleed air online analyzer 313 and the second ambient air online analyzer 322.

[0075] For example, the maximum error of the second bleed air online analyzer 313 and the second ambient air online analyzer 322 is ±20% of the reading, which is a maximum error ratio of 60%. Otherwise, troubleshooting should be carried out to improve the validity of the test data.

[0076] It is understandable that the particle concentration in the pipeline may change due to switching operations. This is because there are losses during particle transmission, valve operation may generate particles, and the resulting pipeline vibration may cause particles adhering to the pipeline wall to re-enter the airflow. Therefore, when measuring particulate matter concentration, a single-path switching is used, that is, both the second online air intake analyzer 313 and the second online ambient air analyzer 322 measure the particulate matter concentration in the ambient air. Since particles in the ambient air are relatively stable, the consistency of the particulate matter concentration measured by the two analyzers is used to determine the reliability of the instrument data.

[0077] Considering the rapid fluctuations in particle concentration generated or lost during engine and bleed air system operation, even if dual-path switching is used to obtain bleed air particulate matter concentration data, the validity of the data cannot be proven. Therefore, dual-path switching is unnecessary.

[0078] In one embodiment, the testing system further includes a first bleed air offline acquisition device 414 for collecting bleed air for offline volatile organic compound concentration analysis and a first ambient air offline acquisition device 424 for collecting ambient air for offline volatile organic compound concentration analysis.

[0079] The bleed air flow path also includes a bleed air GC / MS control flow path 411 and two bleed air GC / MS test flow paths 412. The bleed air GC / MS control flow path 411 is connected to the bleed air sampling pipeline 100 and the two bleed air GC / MS test flow paths 412. The bleed air GC / MS control flow path 411 is equipped with a bleed air sampling flow controller 413, which is used to adjust the sample gas flow rate of the engine bleed air entering the first bleed air offline acquisition device 414.

[0080] The first bleed gas offline acquisition device 414 is connected to the bleed gas GC / MS test flow path. There are at least two first bleed gas offline acquisition devices 414, and the number of corresponding pipeline accessories is the same as the number of first bleed gas offline acquisition devices 414.

[0081] The bleed gas GC / MS control flow path 411 is located upstream of the first bleed gas offline acquisition device 414 and is equipped with a bleed gas sampling valve 415 and a bleed gas sampling flow path valve 416.

[0082] The bleed air sampling valve 415 serves as the root valve of the first bleed air offline collection device 414, and can be manually controlled to open and close the first bleed air offline collection device 414.

[0083] The bleed gas sampling flow path valve 416 is used to control the on / off state of the bleed gas GC / MS test flow path 412, and can be a solenoid valve.

[0084] The first bleed air offline acquisition device 414 is used to collect and store sample gas from the engine bleed air for offline GC / MS analysis, and can be optionally a sampling container. When one of the two first bleed air offline acquisition devices 414 is sampling, the other can be replaced and prepared for sampling; after replacement, when sampling resumes, the other idle first bleed air offline acquisition device 414 can be replaced and prepared for sampling. This alternating cycle allows for the collection and analysis of multiple samples, eliminating engine test waiting time caused by replacing volatile organic compound (VOC) collection elements, improving testing efficiency, and saving testing costs.

[0085] The ambient air flow path also includes an air GC / MS control flow path 421 and two air GC / MS test flow paths 422. The air GC / MS control flow path 421 is connected to the air sampling pipeline 200 and the two air GC / MS test flow paths 422. The air GC / MS control flow path 421 is equipped with an air sampling flow controller 423, which is used to regulate the sample gas flow rate of the ambient air entering the first ambient air offline acquisition device 424.

[0086] The first ambient air offline acquisition device 424 is connected to the air GC / MS test flow path 422. The number of the first ambient air offline acquisition devices 424 is at least two, and the number of corresponding pipeline accessories is the same as the number of the first ambient air offline sampling devices.

[0087] The air GC / MS test flow path 422 is located upstream of the first ambient air offline acquisition device 424 and is equipped with an air sampling valve 425 and an air sampling flow path valve 426.

[0088] The air sampling valve 425 serves as the root valve of the first ambient air offline collection device 424, and can be manually controlled to open and close the first ambient air offline collection device 424.

[0089] The air sampling flow path valve 426 is used to control the on / off state of the air GC / MS test flow path 422, and can be a solenoid valve.

[0090] The first ambient air offline acquisition device 424 is used to collect and store sample gas from the ambient air for offline analysis by GC / MS, and can be optionally a sampling container. When one of the two first ambient air offline acquisition devices 424 is sampling, the other can be replaced and prepared for sampling; after replacement, when sampling resumes, the other idle first ambient air offline acquisition device 424 can be replaced and prepared for sampling. This alternating cycle allows for the collection and analysis of multiple samples, eliminating the engine test waiting time caused by replacing volatile organic compound (VOC) collection elements, improving testing efficiency, and saving test costs.

[0091] In one embodiment, the testing system of the present invention further includes a second offline air collection device 516 for collecting air for offline aldehyde and ketone compound concentration analysis and a second offline ambient air collection device 526 for collecting ambient air for offline aldehyde and ketone compound concentration analysis.

[0092] The bleed gas flow path also includes a bleed gas DNPH control flow path 511 and two parallel bleed gas DNPH test flow paths 512. The bleed gas DNPH control flow path 511 is connected to the bleed gas sampling pipeline 100 and the two bleed gas DNPH test flow paths 512. A second bleed gas offline acquisition device 516 is connected to the bleed gas DNPH test flow path 512. There are at least two second bleed gas offline acquisition devices 516, and the number of corresponding pipeline accessories is the same as the number of second bleed gas offline acquisition devices 516.

[0093] The DNPH control flow path 511 is equipped with a DNPH sampling flow controller 513, which is used to adjust the sample gas flow rate entering the DNPH test flow path 512 to keep it constant.

[0094] The induced draft DNPH test flow path 512, located upstream of the second induced draft offline acquisition device 516, is equipped with an induced draft supply pressure gauge 518a, an induced draft inlet valve 514, and an induced draft ozone removal device 515. The induced draft DNPH test flow path 512, located downstream of the second induced draft offline acquisition device 516, is equipped with an induced draft outlet valve 517 and an induced draft exhaust pressure gauge 518b. An induced draft pump 519a is installed at the discharge end of the induced draft DNPH test flow path 512, and induced draft pump regulating valves 519b are connected in parallel across both ends of the pump 519a.

[0095] The bleed gas inlet valve 514 is used to open and close the bleed gas DNPH test flow path 512, and can be a solenoid valve. The bleed gas ozone removal device 515 is used to remove ozone from the sample gas to protect the second bleed gas offline acquisition device 516 from interference, and can be an ozone removal column.

[0096] The second eliminator offline acquisition device 516 is used to collect aldehydes and ketones for subsequent offline analysis and can be selected as a collection column. While one of the two second eliminator offline acquisition devices 516 is sampling, the other can be replaced and prepared for sampling; after replacement, when sampling resumes, the other idle second eliminator offline acquisition device 516 can be replaced and prepared for sampling. This alternating cycle allows for the collection and analysis of multiple samples, eliminating engine test waiting time caused by replacing aldehyde and ketone compound collection elements, improving testing efficiency, and saving testing costs.

[0097] The bleed gas outlet valve 517 is used for the synchronous opening and closing of the bleed gas DNPH test flow path 512, and can be a solenoid valve. When it is necessary to replace the bleed gas ozone removal device 515 and the second bleed gas offline acquisition device 516, the bleed gas inlet valve 514 and the bleed gas outlet valve 517 must be closed simultaneously to prevent gas from flowing through the bleed gas outlet valve 517 during non-sampling periods.

[0098] The bleed air supply pressure gauge 518a is connected to two bleed air DNPH test flow paths 512 and is located upstream of the bleed air inlet valve 514. It is used to monitor the pressure at the supply end of the bleed air DNPH test flow path 512.

[0099] The bleed air exhaust pressure gauge 518b is connected to two bleed air DNPH test flow paths 512 and is located downstream of the bleed air outlet valve 517. It is used to monitor the pressure at the exhaust end of the bleed air DNPH test flow path 512.

[0100] The bleed gas pump 519a is connected to the discharge end of the two bleed gas DNPH test flow paths 512 and is used to extract sample gas from the bleed gas DNPH test flow paths 512.

[0101] The bleed air extraction regulating valve 519b is connected in parallel to both ends of the bleed air extraction pump 519a. It is used to regulate the return flow of the bleed air extraction pump 519a so that the outlet pressure of the bleed air extraction pump 519a reaches the set value, controls the outlet back pressure of the bleed air DNPH test flow path 512, and improves the repeatability of the measurement results of aldehydes and ketones.

[0102] The ambient air flow path also includes an air DNPH control flow path 521 and two parallel air DNPH test flow paths 522. The air DNPH control flow path 521 is connected to the air sampling pipeline 200 and the two air DNPH test flow paths 522.

[0103] The second ambient air offline acquisition device 526 is connected to the air DNPH test flow path 522. There are at least two second ambient air offline acquisition devices 526, and the number of corresponding pipeline accessories is the same as the number of second ambient air offline acquisition devices 526.

[0104] The air DNPH control flow path 521 is equipped with an air DNPH sampling flow controller 523, which is used to adjust the sample gas flow rate entering the air DNPH test flow path 522 to keep it constant.

[0105] The air DNPH test flow path 522 is located upstream of the second ambient air offline acquisition device 526 and is equipped with an ambient air supply pressure gauge 528a, an ambient air inlet valve 524, and an ambient air ozone removal device 525.

[0106] The air DNPH test flow path 522 is located downstream of the second ambient air offline acquisition device 526 and is equipped with an ambient air outlet valve 527 and an ambient air exhaust pressure gauge 528b. An ambient air extraction pump 529a is installed at the exhaust end of the air DNPH test flow path 522, and ambient air extraction regulating valves 529b are connected in parallel at both ends of the ambient air extraction pump 529a.

[0107] The air intake valve 524 is used to open and close the air DNPH test flow path 522, and can be a solenoid valve. The air ozone removal device 525 is used to remove ozone from the sample gas to protect the second ambient air offline acquisition device 526 from interference, and can be an ozone removal column.

[0108] The second ambient air offline sampling device 526 is used to collect aldehydes and ketones for subsequent offline analysis and can be selected as a sampling column. While one of the two second ambient air offline sampling devices 526 is sampling, the other can be replaced and prepared for sampling; after replacement, when sampling resumes, the other idle second ambient air offline sampling device 526 can be replaced and prepared for sampling. This alternating cycle allows for the collection and analysis of multiple samples, eliminating the environmental commissioning wait time caused by replacing aldehyde and ketone compound sampling elements, improving testing efficiency, and saving experimental costs.

[0109] The air outlet valve 527 is used for the synchronous opening and closing of the air DNPH test flow path 522, and can be a solenoid valve. When it is necessary to replace the air ozone removal device 525 and the second ambient air offline acquisition device 526, the air inlet valve 524 and the air outlet valve 527 must be closed simultaneously to prevent gas from flowing through the air outlet valve 527 during non-sampling periods.

[0110] Air supply pressure gauge 528a is connected to two air DNPH test flow paths 522 and is located upstream of air intake valve 524. It is used to monitor the pressure at the air supply end of air DNPH test flow path 522.

[0111] Air exhaust pressure gauge 528b is connected to two air DNPH test flow paths 522 and is located downstream of air outlet valve 527. It is used to monitor the pressure at the exhaust end of air DNPH test flow path 522.

[0112] The air pump 529a is connected to the discharge end of the two air DNPH test flow paths 522 and is used to extract sample gas from the air DNPH test flow paths 522.

[0113] An air extraction regulating valve 529b is connected in parallel across the two ends of an air extraction pump 529a to regulate the return flow of the air extraction pump 529a, so that the outlet pressure of the air extraction pump 529a reaches the set value, thereby controlling the outlet back pressure of the air DNPH test flow path 522 and improving the repeatability of the measurement results of aldehydes and ketones.

[0114] The testing system of this invention employs two test flow paths: a layout of two parallel test flow paths for testing engine bleed air sample gas and a layout of two parallel test flow paths for testing ambient air sample gas. During testing, only one of the bleed air and ambient air test flow paths is opened, while the other is closed. In this way, the engine bleed air sample gas and ambient air sample gas are collected and analyzed only through one of the test flow paths. Of course, three or more test flow paths can also be used.

[0115] The testing system of this invention is designed for the collection of aldehydes, ketones, and volatile organic compounds (VOCs) sample gases. It adopts a dual-path offline sampling layout, meaning that during engine testing, one test flow path is used for sampling, while the other test flow path is used for replacing the sampling element and preparing for sampling. After sampling is completed in one test flow path, the system switches to the other test flow path for sampling. This eliminates the engine test waiting time caused by replacing the sampling elements for aldehydes, ketones, and VOCs, achieving zero waiting time for engine testing, improving testing efficiency, and saving testing costs.

[0116] The testing system of this invention employs a flow rate and outlet pressure coupling control method for testing the concentration of aldehydes and ketones, ensuring that the flow rate and pressure remain consistent for each sampling. By maintaining constant control over the flow rate and pressure during the sampling process, the repeatability of subsequent offline detection results can be guaranteed.

[0117] Due to the high cost of aero-engine testing, this invention aims to reduce the sampling frequency as much as possible for various test materials, thereby minimizing engine downtime caused by replacing sampling components during testing and achieving the goal of reducing testing costs.

[0118] Furthermore, the bleed air sampling pipeline 100 is equipped with a bleed air sampling pump 110 located upstream of the bleed air NDIR test flow path 611 and downstream of the bleed air DNPH control flow path 511, and a bleed air sampling regulating valve 120 connected in parallel with the bleed air sampling pump 110. The bleed air sampling pump 110 is used to pressurize the bleed air NDIR test flow path 611 to meet the sample injection requirements of the first bleed air online analyzer 613. The bleed air sampling regulating valve 120 is used to regulate the return flow of the bleed air sampling pump 110, ensuring that the outlet pressure of the bleed air sampling pump 110 reaches the set value, preventing excessively high sample gas pressure from the engine bleed air, which could cause water vapor condensation and affect the measurement validity.

[0119] An air sampling pump 210 is located upstream of the air NDIR test flow path 621 and downstream of the air DNPH control flow path 521 on the air sampling pipeline 200, along with an air sampling regulating valve 220 connected in parallel with the air sampling pump 210. The air sampling pump 210 pressurizes the air NDIR test flow path 621 to meet the sample injection requirements of the first ambient air online analyzer 623. The air sampling regulating valve 220 adjusts the return flow of the air sampling pump 210 to ensure that the outlet pressure of the air sampling pump 210 reaches a set value, preventing excessively high ambient air sample pressure from causing water vapor condensation and affecting the measurement validity.

[0120] In one embodiment, the bleed air sampling pipeline 100 is provided with a bleed air pressure reducing regulating valve 130 and a pressure gauge 140 after the bleed air valve. The bleed air pressure reducing regulating valve 130 is used to regulate the pressure of the sample gas from the engine bleed air, and the pressure gauge 140 after the bleed air valve is used to measure the pressure value of the sample gas after pressure reduction, so as to realize the pressure regulation of the sample gas from the engine bleed air, so that the sample gas pressure is reduced to the atmospheric pressure level, and the sampling pressure requirements of each test flow path are met.

[0121] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A testing system for the composition of bleed air in an aircraft engine, characterized in that, This includes the exhaust air path, the ambient air path, the online exhaust air analyzer, and the online ambient air analyzer; among which, The airflow path includes an airflow NDIR test path, and the ambient airflow path includes an air NDIR test path. The online bleed air analysis device includes a first online bleed air analyzer for analyzing the concentrations of carbon monoxide and carbon dioxide generated by the bleed air; the online ambient air analysis device includes a first online ambient air analyzer for analyzing the concentrations of carbon monoxide and carbon dioxide in the ambient air. The bleed air NDIR test flow path is connected to the first bleed air online analyzer, and the air NDIR test flow path is connected to the first ambient air online analyzer. The testing system further includes a first switching pipeline and a second switching pipeline, wherein the first end of the first switching pipeline is connected to the air NDIR test flow path, and the first end of the second switching pipeline is connected to the bleed air NDIR test flow path. In the first test state, the second end of the first switching pipeline is disconnected from the first bleed air online analyzer, the second end of the second switching pipeline is disconnected from the first ambient air online analyzer, the engine bleed air in the bleed air NDIR test flow path enters the first bleed air online analyzer, and the ambient air in the air NDIR test flow path enters the first ambient air online analyzer. If, under the first test state, the first difference between the measured values ​​of the first bleed air online analyzer and the first ambient air online analyzer is greater than or equal to the maximum error value, then the first difference is taken as the actual value of the engine bleed air. If the first difference is less than the maximum error value, then switch to the second test state; wherein, the maximum error value is the absolute value of the sum of the maximum errors of the first online air analyzer and the first online ambient air analyzer; In the second test state, the second end of the first switching pipeline is connected to the first bleed air online analyzer, the second end of the second switching pipeline is connected to the first ambient air online analyzer, the engine bleed air in the bleed air NDIR test flow path enters the first ambient air online analyzer, and the ambient air in the air NDIR test flow path enters the first bleed air online analyzer. If the second difference between the measured value of the first bleed air online analyzer in the first test state and the measured value in the second test state, and the third difference between the measured value of the first ambient air online analyzer in the second test state and the measured value in the first test state, are both greater than or equal to the maximum resolution value, then the larger of the second difference and the third difference is taken as the actual value of the engine bleed air; if the second difference or the third difference is less than the maximum resolution value, then troubleshooting operations are performed on the first bleed air online analyzer and the first ambient air online analyzer; wherein, the maximum resolution value is the negative of the sum of the resolutions of the first bleed air online analyzer and the first ambient air online analyzer.

2. The testing system as described in claim 1, characterized in that, The airflow path also includes an airflow particulate matter testing path, and the ambient air flow path also includes an air particulate matter testing path. The online air intake analysis device also includes a second online air intake analyzer for analyzing the particulate matter concentration of the air intake; The ambient air online analysis device also includes a second ambient air online analyzer for analyzing the particulate matter concentration in ambient air; The air-entraining particulate matter test flow path is connected to the second air-entraining online analyzer, and the air particulate matter test flow path is connected to the second ambient air online analyzer; The testing system also includes a third switching pipeline, which connects the induced draft particulate matter test flow path and the air particulate matter test flow path; In the first test state, the third switching pipeline is turned off, the engine bleed air in the bleed air particulate matter test flow path enters the second bleed air online analyzer, and the ambient air in the air particulate matter test flow path enters the second ambient air online analyzer. If the measured value of the second bleed air online analyzer in the first test state is greater than or equal to the measured value of the second ambient air online analyzer in the first test state with the maximum error ratio, then the fourth difference between the measured value of the second bleed air online analyzer in the first test state and the measured value of the second ambient air online analyzer is taken as the actual value of the engine bleed air. Conversely, the test switches to the second test state; wherein the maximum error ratio is 100% minus the sum of the maximum errors of the second online air analyzer and the second online ambient air analyzer; In the second test state, the air-induced particulate matter test flow path is turned off, the third switching pipeline is opened, and the ambient air in the air-induced particulate matter test flow path enters the second air-induced particulate matter online analyzer. If, under the second test condition, the measured value of the second bleed air online analyzer is greater than or equal to the product of the maximum error ratio and the measured value of the second ambient air online analyzer under the second test condition, and less than or equal to the measured value of the second ambient air online analyzer under the second test condition divided by the maximum error ratio, then the fourth difference is taken as the actual value of the engine bleed air; otherwise, troubleshooting operations are performed on the second bleed air online analyzer and the second ambient air online analyzer.

3. The testing system as described in claim 2, characterized in that, The air-entraining particulate matter test flow path is located upstream of the second air-entraining online analyzer and is equipped with an air-entraining particulate matter valve. The first end of the third switching pipeline is connected to the position of the air particulate matter test flow path located upstream of the second ambient air online analyzer; The second end of the third switching pipeline is connected to the position of the air-entraining particulate matter test flow path located upstream of the second air-entraining online analyzer and downstream of the air-entraining particulate matter valve.

4. The testing system as described in claim 3, characterized in that, The third switching pipeline is equipped with a switching valve, which is used to control the on / off state of the third switching pipeline; In the first test state, the air-guiding particulate valve is open, and the switching valve is closed; In the second test state, the air-drawing particulate valve is closed, and the switching valve is open.

5. The testing system as described in claim 1, characterized in that, The bleed air NDIR test flow path is provided with a first switching ball valve located upstream of the first bleed air online analyzer; The secondary inlet end of the first switching ball valve is connected to the second end of the first switching pipeline; The main inlet and outlet of the first switching ball valve are connected to the bleed air NDIR test flow path; The air NDIR test flow path is provided with a second switching ball valve located upstream of the first ambient air online analyzer; The secondary inlet end of the second switching ball valve is connected to the second end of the second switching pipeline; The main inlet and outlet of the second switching ball valve are connected to the ambient air flow path; In the first test state, bleed air enters the first bleed air online analyzer through the bleed air NDIR test flow path, the main inlet end and the outlet end of the first switching ball valve; ambient air enters the first ambient air online analyzer through the air NDIR test flow path and the main inlet end and the outlet end of the second switching ball valve. In the second test state, ambient air sequentially enters the first bleed air online analyzer via the air NDIR test flow path, the first switching pipeline, the secondary inlet end of the first switching ball valve, the outlet end of the first switching ball valve, and the bleed air NDIR test flow path; engine bleed air sequentially enters the first ambient air online analyzer via the bleed air NDIR test flow path, the second switching pipeline, the secondary inlet end of the second switching ball valve, the outlet end of the second switching ball valve, and the air NDIR test flow path.

6. The testing system as described in any one of claims 1-5, characterized in that, The testing system also includes a first offline priming gas acquisition device for collecting priming gas for offline volatile organic compound concentration analysis and a first offline ambient air acquisition device for collecting ambient air for offline volatile organic compound concentration analysis. The airflow path also includes an airflow GC / MS test path, and the ambient air flow path also includes an airflow GC / MS test path. The first bleed gas offline acquisition device is connected to the bleed gas GC / MS test flow path, and the number of the first bleed gas offline acquisition devices is at least two. The first ambient air offline acquisition device is connected to the air GC / MS test flow path, and the number of the first ambient air offline acquisition devices is at least two.

7. The testing system as described in claim 6, characterized in that, The bleed gas GC / MS test flow path is located upstream of the first bleed gas offline acquisition device and is equipped with a bleed gas sampling valve and a bleed gas sampling flow path valve. The bleed air sampling valve is used to control the opening and closing of the first bleed air offline collection device; The bleed gas sampling flow path valve is used to control the on / off state of the bleed gas GC / MS test flow path; and / or The air GC / MS test flow path is located upstream of the first environmental air offline acquisition device and is equipped with an air sampling valve and an air sampling flow path valve. The air sampling valve is used to control the opening and closing of the first ambient air offline collection device; The air sampling flow path valve is used to control the on / off state of the air GC / MS test flow path.

8. The testing system as described in any one of claims 1-5, characterized in that, The testing system also includes a second offline air acquisition device for collecting air for offline aldehyde and ketone compound concentration analysis and a second offline ambient air acquisition device for collecting ambient air for offline aldehyde and ketone compound concentration analysis. The airflow path also includes an air DNPH test path, and the ambient air flow path also includes an air DNPH test path. The second bleed air offline acquisition device is connected to the bleed air DNPH test flow path, and the number of the second bleed air offline acquisition devices is at least two; The second ambient air offline acquisition device is connected to the air DNPH test flow path, and the number of the second ambient air offline acquisition devices is at least two.

9. The testing system as described in claim 8, characterized in that, The DNPH test flow path is located upstream of the second offline DNPH acquisition device and is equipped with a DNPH pressure gauge, a DNPH inlet valve and a DNPH ozone removal device. The DNPH test flow path is located downstream of the second offline DNPH data acquisition device and is equipped with a DNPH exhaust valve and a DNPH exhaust pressure gauge. The discharge end of the DNPH test flow path is equipped with a bleed air pump, and bleed air pump regulating valves are connected in parallel at both ends of the bleed air pump; and / or The air DNPH test flow path is located upstream of the second ambient air offline acquisition device and is equipped with an ambient air supply pressure gauge, an ambient air inlet valve, and an ambient air ozone removal device. The air DNPH test flow path is located downstream of the second ambient air offline acquisition device and is equipped with an ambient air outlet valve and an ambient air exhaust pressure gauge. An ambient air pump is installed at the discharge end of the air DNPH test flow path, and ambient air pump regulating valves are connected in parallel at both ends of the ambient air pump.

10. The testing system as described in any one of claims 1-5, characterized in that, The bleed air flow path further includes a bleed air sampling pipeline; the bleed air sampling pipeline is equipped with a bleed air pressure reducing regulating valve and a pressure gauge after the bleed air valve; the bleed air pressure reducing regulating valve is used to adjust the pressure of the sample gas from the engine bleed air, and the pressure gauge after the bleed air valve is used to measure the pressure value of the sample gas after pressure reduction; and / or The bleed air path further includes a bleed air sampling pipeline; the ambient air path further includes an air sampling pipeline; the bleed air sampling pipeline is equipped with a bleed air sampling pump located upstream of the bleed air NDIR test path and a bleed air sampling regulating valve connected in parallel with the bleed air sampling pump; the bleed air sampling pump is used to pressurize the bleed air NDIR test path; the bleed air sampling regulating valve is used to regulate the return flow of the bleed air sampling pump.

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