Verification system and method for lightning protection design of aircraft fuel tanks

Abstract

The present disclosure relates to a verification system and method for the lightning protection design of aircraft fuel tanks. The verification system includes a lightning current waveform generating device and a test gas explosion verification device for verifying the flammability of the test gas. The test gas explosion verification device can completely separate the impact energy generated by the gas explosion from the aircraft fuel tank under test, greatly reducing the risk of damage to the structure of the aircraft fuel tank under test caused by the gas explosion impact. In addition, the verification system also includes an airtightness detection system for testing the airtightness of the aircraft fuel tank under test and the test bench before the test, which can greatly reduce the proportion of invalid tests due to test gas leakage. The aircraft fuel tank under test is also connected by inflation and exhaust pipelines to group multiple compartments in the aircraft fuel tank box section, which facilitates flexible and targeted detection tests and helps to locate the ignition source. The lightning current waveform generating device adopts a bus bar connection form that is flexible in layout and convenient for nearby access.

Description

Technical Field

[0001] This disclosure relates to a system and method for verifying an aircraft fuel tank and its lightning protection design. The system and method are used to detect whether a lightning strike on an aircraft fuel tank would generate arcs, sparks, or other dangerous ignition sources inside the tank that could cause the tank to explode, thereby determining the effectiveness of the aircraft fuel tank's lightning protection design. Background Art

[0002] Lightning strikes pose a significant threat to the safe operation of aircraft. If an aircraft is not designed with effective lightning protection, a lightning strike could generate ignition sources such as arcs and sparks inside the fuel tank, causing it to explode and potentially lead to a serious aviation accident.

[0003] Lightning ignition source detection test is an important means and method to detect and verify the effectiveness of the lightning protection design measures adopted by the aircraft fuel tank system.

[0004] However, lightning tests can easily cause irreversible destructive effects on the fuel tank of the aircraft being tested, such as possible explosion shocks, voltage accumulation effects and other adverse effects.

[0005] The present disclosure is improved with respect to, but not limited to, the above factors. Summary of the Invention

[0006] To this end, the present disclosure provides a verification system and method for an aircraft fuel tank and its lightning protection design. The aircraft fuel tank is manufactured based on the assembly configuration of an actual aircraft. The corresponding verification system and method enable efficient and cost-effective lightning testing of the aircraft fuel tank, significantly reducing the difficulty of conducting lightning tests on the entire fuel tank of an actual aircraft, shortening the testing cycle and reducing costs.

[0007] According to a first aspect of the present disclosure, a system for verifying the effectiveness of a lightning protection design for an aircraft fuel tank is provided. The system includes a lightning current waveform generator and a test gas explosion verification device for verifying the flammability of a test gas. The lightning current waveform generator is configured to output a lightning current waveform to the aircraft fuel tank to simulate a real lightning effect. The aircraft fuel tank includes:

[0008] one or more structural ribs within the interior of the aircraft fuel tank, the one or more structural ribs dividing the interior of the aircraft fuel tank into a plurality of compartments;

[0009] For each compartment, this includes:

[0010] an inflation nozzle provided on the first structural beam of the compartment for receiving the test gas into the compartment;

[0011] an exhaust nozzle provided on the second structural beam of the compartment, for exhausting gas in the compartment;

[0012] wherein the first structural beam is one of a front structural beam and a rear structural beam and the second structural beam is the other of the front structural beam and the rear structural beam, and the plurality of compartments are divided into a plurality of groups, and wherein the holes on the structural ribs between each group of compartments are sealed using a detachable non-conductive material so that each group of compartments is hermetically separated from each other.

[0013] According to one embodiment, the lightning current waveform generating device includes: four generators for generating four lightning current waveforms A wave, B wave, C wave and D wave that meet the requirements of standard SAEARP5412; a lightning current waveform output bus bar for converging the current components of the A wave, B wave, C wave and D wave generated by the four generators; a first flat electrode electrically connected to the lightning current waveform output bus bar; a lightning current grounding loop bus bar; and a second flat electrode electrically connected to the lightning current grounding loop bus bar.

[0014] According to another embodiment, the first flat electrode and the second flat electrode are electrically bonded to the aircraft fuel tank using a plurality of groups of fasteners arranged at equal intervals.

[0015] According to yet another embodiment, the system further comprises an airtightness detection device for detecting the airtightness of the aircraft fuel tank.

[0016] According to yet another embodiment, the air tightness detection device comprises a booster fan for filling air into the plurality of compartments of the aircraft fuel tank and a differential pressure gauge for monitoring the pressure difference between the aircraft fuel tank and the outside.

[0017] According to another embodiment, the test gas explosion verification device includes a test gas explosion verification chamber and a discharge electrode arranged inside the test gas explosion verification chamber, and the discharge electrode is connected to an electric spark igniter outside the test gas explosion verification chamber through a wire.

[0018] According to another embodiment, the test gas explosion verification chamber is made of a transparent material and is provided with an inflation nozzle, an exhaust nozzle, an external pressure release damper and an internal air supply damper, wherein the inflation nozzle and the exhaust nozzle are arranged in a diagonal direction at the upper and lower end corners at both ends of the test gas explosion verification chamber, and the inflation nozzle is connected to the exhaust nozzle of each of the multiple compartments of the aircraft fuel tank, and the external pressure release damper and the internal air supply damper are respectively arranged on the left and right sides, front and back sides or the top of the test gas explosion verification chamber.

[0019] According to yet another embodiment, the system further comprises a test gas dispensing system for dispensing flammable test gas, wherein the test gas dispensing system fills each compartment of the plurality of compartments of the aircraft fuel tank with the test gas through a filling nozzle of the compartment.

[0020] According to a second aspect of the present disclosure, there is provided a method for verifying the effectiveness of a lightning protection design of an aircraft fuel tank using the system according to the first aspect of the present disclosure, the method comprising:

[0021] selecting a group of compartments from the plurality of groups of compartments;

[0022] Deliver the test gas to a selected group of compartments and the test gas combustion and explosion verification device;

[0023] injecting lightning current into the aircraft fuel tank;

[0024] confirming that no explosion has occurred in the selected group of compartments; and

[0025] Verifying the flammability of the test gas by using the test gas explosion verification device;

[0026] After the plurality of compartment groups have undergone the above operations, it is determined that the lightning protection design of the aircraft fuel tank is effective.

[0027] According to one embodiment, the method further includes, before delivering the test gas into the selected set of compartments and the test gas combustion and explosion verification device, testing the air tightness of the selected set of compartments and the test gas combustion and explosion verification device using an air tightness testing device, wherein testing the air tightness includes:

[0028] Using the booster fan of the air tightness detection device to fill air into a selected group of compartments and the test gas explosion verification device, so that the pressure difference between the group of compartments and the test gas explosion verification device and the external atmosphere reaches a predetermined threshold;

[0029] monitoring the pressure difference for a predetermined duration using a pressure differential gauge of the airtightness detection device; and

[0030] During the predetermined duration, if the measured pressure difference remains within a predetermined percentage range of the predetermined threshold value, it is determined that the airtightness of the aircraft fuel tank and the test gas explosion verification device is good.

[0031] According to another embodiment, injecting lightning current into the aircraft fuel tank includes: using a lightning current waveform generator to generate a lightning current waveform that meets the requirements of standard SAE ARP5412; sinking the lightning current waveform into a lightning current waveform output bus; injecting the lightning current waveform from the lightning current waveform output bus into the aircraft fuel tank via a first flat electrode electrically bonded to the lightning current waveform output bus, and returning the lightning current waveform to the lightning current ground return bus via a second flat electrode electrically bonded to the lightning current ground return bus, wherein the first flat electrode and the second flat electrode are electrically bonded to the aircraft fuel tank using a plurality of sets of equally spaced fasteners.

[0032] According to another embodiment, determining that the selected group of compartments has not exploded includes determining that the selected group of compartments has not exploded by detecting that the temperature and / or pressure in the group of compartments has not changed by using a temperature sensor and / or a pressure sensor arranged in association with the selected group of compartments.

[0033] According to another embodiment, verifying that the test gas is flammable includes generating an electric spark in the test gas explosion verification chamber of the test gas explosion verification device by using an electric spark igniter to verify the flammability of the test gas.

[0034] Therefore, the present disclosure also sets a test gas explosion verification chamber in series after the aircraft fuel tank, so that the impact energy generated by the gas explosion can be completely separated from the aircraft fuel tank being tested, so that there is no risk of damage to the tested structure caused by the gas explosion impact.

[0035] The present disclosure further provides an airtightness detection system that uses a relatively high-pressure gas (higher than the test gas inflation pressure) (e.g., air) to test the airtightness of the tested aircraft fuel tank and the test gas explosion verification device (as well as the associated pipelines and valves) before the test. This can greatly reduce or even eliminate the situation where the test is invalid due to test gas leakage, effectively reduce the number of test repetitions, reduce test costs, and avoid extending the test cycle. In addition, after the test is completed, the airtightness detection system can be used to fill the tested aircraft fuel tank and the test gas explosion verification device with air and exhaust combustible gas to prevent the accidental explosion of trapped combustible gas and cause safety risks.

[0036] This disclosure also provides a flexible, convenient, and locally accessible busbar connection for connecting the aircraft fuel tank under test to the output of the lightning current waveform generator and the lightning current ground return. This facilitates local busbar connection of multiple test units, particularly large ones, significantly reducing the time required for hoisting and transporting them. Furthermore, this facilitates interleaving lightning tests between multiple test units, significantly improving test efficiency.

[0037] According to a third aspect of the present disclosure, an aircraft fuel tank is also provided, comprising: one or more structural ribs inside the aircraft fuel tank, the one or more structural ribs dividing the interior of the aircraft fuel tank into a plurality of compartments; for each compartment, it comprises: an inflation nozzle arranged on the structural rear beam of the compartment, for receiving test gas into the compartment; an exhaust nozzle arranged on the structural front beam of the compartment, for exhausting the gas in the compartment; wherein the plurality of compartments are divided into a plurality of groups, and wherein the holes on the structural ribs between each group of compartments are sealed using a detachable non-conductive material, so that each group of compartments is hermetically separated from each other.

[0038] According to one embodiment, the inflation nozzle and the exhaust nozzle are arranged in a diagonal direction at the end corners of the first structural beam and the second structural beam of the compartment.

[0039] According to another embodiment, the plurality of compartments are divided into groups based on compartment capacity and / or specific lightning protection verification objectives, such that the total capacity of each group of compartments does not exceed a predetermined threshold and meets the specific lightning protection verification objectives.

[0040] The foregoing has broadly outlined the features and technical advantages of examples according to the present disclosure so that the following detailed description may be better understood. Additional features and advantages will be described hereinafter. The concepts and specific examples disclosed may be readily used as a basis for modifying or designing other structures for implementing the same purposes as the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein, both in terms of their organization and method of operation, as well as the associated advantages, will be better understood by considering the following description in conjunction with the accompanying drawings. Each of the figures is provided for illustration and description purposes and does not define limitations on the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to understand in detail the manner in which the above-recited features of the present disclosure may be employed, reference may be made to various aspects of a more particular description of the content briefly summarized above, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only certain typical aspects of the disclosure and are not to be considered limiting of its scope, as the description may admit to other equally effective aspects. The same reference numerals in different drawings may identify the same or similar elements.

[0042] Figure 1 is a schematic diagram of an example aircraft fuel tank according to an embodiment of the present disclosure;

[0043] Figure 2 is a schematic diagram of an example arrangement of an inflation nozzle and an exhaust nozzle of a fuel tank compartment according to an embodiment of the present disclosure;

[0044] Figure 3 is a schematic diagram of an example system for verifying a lightning protection design of an aircraft fuel tank according to an embodiment of the present disclosure;

[0045] Figure 4 is a schematic diagram of connecting an example aircraft fuel tank to a bus bar in situ according to an embodiment of the present disclosure; and

[0046] Figure 5 is an example flow chart of an example method for verifying a lightning protection design of an aircraft fuel tank according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. This detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details.

[0048] As mentioned in the Background Technology section, conducting test gas explosion verification inside aircraft fuel tanks poses a risk of structural damage. For example, the explosive shock energy of combustible gas is closely related to its volume. Aircraft fuel tanks have a large internal volume, so using an ignition source to ignite the test gas inside to verify its flammability generates significant explosive shock energy, leading to the risk of structural damage.

[0049] Thus, the present disclosure provides a novel aircraft fuel tank and a system and method for verifying the effectiveness of its lightning protection design. By grouping the multiple compartments within the aircraft fuel tank and testing each group according to specific verification objectives, the present disclosure effectively reduces the amount of combustible gas introduced during a single test, thus preventing the potential for excessive explosive shock energy generated within the tested structure during a single test, which could adversely affect the tested structure. Furthermore, grouped testing also helps narrow the scope for locating the ignition source, requiring only the tank compartment filled with test gas to locate the ignition source, eliminating the need to search the entire aircraft fuel tank for the ignition source.

[0050] In addition, all fuel tank compartments disclosed in the present invention are equipped with inflation and exhaust nozzles, so that inflation and exhaust and testing can be carried out compartment by compartment or in groups, and the time for inflation and exhaust on the entire large aircraft fuel tank can be greatly shortened, thereby improving the ventilation efficiency of the test gas.

[0051] Reference below Figure 1 , which shows a schematic diagram of an example aircraft fuel tank 10 according to an embodiment of the present disclosure.

[0052] like Figure 1 As shown, the interior of the aircraft fuel tank 10 has one or more structural ribs 17, 18, 19, etc. These structural ribs divide the interior of the aircraft fuel tank 10 into a plurality of compartments 11, 12, etc. It will be understood by those skilled in the art that for the sake of simplicity, not all structural ribs are shown. Figure 1 As shown, a total of five structural ribs divide the interior space of the aircraft fuel tank 10 into six compartments. However, those skilled in the art will appreciate that more or fewer structural ribs may be provided as needed, depending on the aircraft model and the aircraft fuel tank test section selected for verification testing.

[0053] In one embodiment, the plurality of compartments inside the aircraft fuel tank 10 are divided into a plurality of groups. Figure 1 As can be seen in the figure, the six compartments inside the aircraft fuel tank 10 are divided into three groups, and the inflation nozzles and exhaust nozzles of each group of compartments are grouped together. In this embodiment, the compartments of each group are sealed from each other. For example, a detachable non-conductive material can be used to seal the holes on the structural ribs between each group of compartments to ensure that each group of compartments is sealed from each other. Figure 1 The holes in the structural ribs 18 can be sealed with a removable non-conductive material. Advantageously, the use of removable non-conductive material allows for easy removal after testing without affecting the conductive properties of the aircraft fuel tank 10. Of course, various other suitable methods can be used to hermetically separate the groups of compartments without departing from the scope of the present disclosure.

[0054] In another embodiment, the structural ribs in each group of compartments may be non-sealed. Figure 1 , the structural rib 17 is within the compartment group 11, 12, thereby the hole on this structural rib can not need to be closed.Yet, in a preferred embodiment, the hole on the structural rib 17 also can use detachable non-conductive material to close.

[0055] In a preferred embodiment of the present disclosure, the compartments within the aircraft fuel tank 10 are divided into multiple groups based on compartment capacity and / or specific lightning protection verification objectives, so that the total capacity of each group of compartments does not exceed a predetermined threshold. This can reduce or eliminate the risk of structural damage to the aircraft fuel tank 10 caused by the explosion shock in the event of an explosion during testing, while achieving the specific lightning protection verification objectives.

[0056] from Figure 1 As can be seen in the figure, each group of compartments includes two adjacent compartments from the plurality of compartments. However, those skilled in the art will appreciate that this is merely an example. Each group of compartments may include one, three, or more compartments. In the case of multiple compartments, these compartments may not be adjacent. In these cases, it is sufficient to ensure that each compartment to be tested is sealed from its adjacent compartments and that the total capacity of the compartments to be tested does not exceed a predetermined threshold.

[0057] For example, in a preferred embodiment, all structural ribs are sealed, making each compartment airtight. In a further embodiment, each group of compartments may include one or more non-adjacent compartments, so that in the event of an explosion, the explosion shock can be more evenly distributed across the entire aircraft fuel tank structure, thereby reducing damage to the aircraft fuel tank structure.

[0058] In addition, reference Figure 1 Each compartment has a first structural beam disposed in the compartment (at Figure 1 The inflation nozzle on the second structural beam (in the middle is the structural rear beam) and the second structural beam (in the middle is the structural rear beam) of the compartment Figure 1 The exhaust nozzles on the front beam of the structure are used to receive the test gas into the compartment and to exhaust the gas in the compartment. Figure 1 As can be seen in FIG, the compartment 11 has an inflatable nozzle 15 provided on the rear structural beam 13 of the compartment and an exhaust nozzle 16 provided on the front structural beam 14 of the compartment. It will be understood by those skilled in the art that for the sake of simplicity, not all inflatable nozzles and exhaust nozzles are provided on the compartment. Figure 1 In addition, those skilled in the art will also appreciate that the inflation nozzle may also be disposed on the rear structural beam of the compartment, and the exhaust nozzle may be disposed on the front structural beam of the compartment, to achieve the above-mentioned inflation and exhaust purposes.

[0059] In a preferred embodiment of the present disclosure, the inflation nozzle and the exhaust nozzle of each compartment are arranged at the end corners of the first structural beam and the second structural beam of the compartment in a diagonal direction. Figure 2Figure 1 shows a schematic diagram illustrating an exemplary arrangement of the inflation and exhaust nozzles for a fuel tank compartment according to an embodiment of the present disclosure. This arrangement facilitates the diffusion of test gas throughout the fuel tank compartment, thereby ensuring the flammability of the test gas within the fuel tank compartment and enhancing both inflation and exhaust efficiency. To ensure that the compartment is completely filled with test gas, in a preferred embodiment, the present disclosure opens the inflation and exhaust nozzles during inflation, injecting test gas into the compartment at least five times its volume, thereby fully displacing the air within the compartment and replacing it with the test gas.

[0060] In another embodiment, to reduce the impact of explosions, each set of compartments includes at least one pressure relief damper on its outer wall. For example, the maintenance access to an aircraft fuel tank can serve as a pressure relief damper. In the event of an explosion, the pressure relief damper opens to release pressure and indicate the occurrence of an explosion.

[0061] Next reference Figure 3 , which shows a schematic diagram of an example system 100 for verifying the lightning protection design of an aircraft fuel tank according to an embodiment of the present disclosure.

[0062] In one embodiment, the system 100 may be used to verify the fuel tanks of an aircraft (e.g., Figure 1 The effectiveness of the lightning protection design of the aircraft fuel tank 10) shown. Figure 3 As shown, the system 100 may include a lightning current waveform generating device 70, which is used to output a lightning current waveform to the aircraft fuel tank 10 to simulate the propagation effect of the lightning current waveform on the aircraft fuel tank when the aircraft fuel tank is struck by lightning during actual flight of the aircraft, thereby verifying the effectiveness of its lightning protection design.

[0063] As you can see, in Figure 3 In the illustrated embodiment, the lightning current waveform generating device 70 may include four generators 71 for respectively generating four lightning current waveforms, namely, A-wave, B-wave, C-wave, and D-wave, that meet the requirements of standard SAE ARP5412, a lightning current waveform output bus 73 for integrating the A-wave, B-wave, C-wave, and D-wave current components generated by the four generators 71, a first flat electrode 75a electrically bonded to the lightning current waveform output bus 73, a lightning current grounding return bus 76, and a second flat electrode 75b electrically bonded to the lightning current grounding return bus 76.

[0064] In a preferred embodiment, lightning current waveform output busbar 73 can be a low-impedance metal busbar (preferably made of pure copper) to channel the A-wave, B-wave, C-wave, and D-wave current components generated by the four distributed lightning current waveform generators 71 onto the same busbar. According to one embodiment of the present disclosure, the length of the busbar can be flexibly determined; for example, it can be arranged throughout the entire test site to facilitate local access to the test site.

[0065] In one embodiment, the flat electrodes 75a, 75b are low-impedance metal electrode plates. In a preferred embodiment, the first flat electrode 75a and the second flat electrode 75b are electrically bonded to the aircraft fuel tank 10 using multiple sets of fasteners arranged at equal intervals, such as Figure 3 In this way, using multiple sets of fasteners and arranging them at equal intervals facilitates the uniform injection of the lightning current waveform into the tested aircraft fuel tank 10, which is closer to the actual propagation effect of the lightning current on the aircraft fuel tank.

[0066] Of course, it can also be seen that the lightning current waveform generating device 70 may also include other components, such as a circuit breaker 72, a conductive belt 74 (such as a low-impedance flexible braided belt with adjustable length connected between the lightning current waveform output bus and the first flat electrode, and between the lightning current grounding loop bus and the second flat electrode), a grounding electrode 77, various pipelines and valves, etc., which will not be repeated here.

[0067] Therefore, the present disclosure provides a busbar connection form with flexible layout and convenient access to the aircraft fuel tank under test to connect the output end of the lightning current waveform generator and the lightning current grounding loop end. Figure 4 Figure 1 shows a schematic diagram of an example aircraft fuel tank in-situ busbar connection according to an embodiment of the present disclosure. This facilitates local busbar connection of multiple test units; it is particularly suitable for connecting large test units to the busbar, significantly reducing the time required for hoisting and transporting large test units. Furthermore, this facilitates interleaving lightning tests between multiple test units, significantly improving test efficiency.

[0068] As mentioned above, in the process of conducting lightning ignition source detection tests using the combustible gas method, a very important step is to verify the flammability of the test gas; that is, after injecting lightning current into the test object according to the lightning current waveform required by standard SAE ARP5416, if no lightning ignition source is detected, it is necessary to further use an ignition source (such as an ignition source with 200 microjoules of energy) that provides an electric spark with a specific energy value that meets the requirements of standard SAE ARP5412 to intentionally ignite the test gas to verify the flammability of the test gas in the internal cavity.

[0069] However, directly igniting the test gas in the internal cavity of the aircraft fuel tank may cause structural damage due to multiple and repeated explosion shocks, thereby causing the aircraft fuel tank to be scrapped.

[0070] Therefore, in another embodiment of the present disclosure, the system 100 may optionally include a test gas explosion verification device 60 for verifying the flammability of the test gas, such as Figure 3 shown.

[0071] In this embodiment, the test gas explosion verification device 60 may include a test gas explosion verification chamber 61 and a discharge electrode 65 arranged inside the test gas explosion verification chamber 61, wherein the discharge electrode 65 is connected to a spark igniter 67 (such as a 200 microjoule energy spark igniter) outside the test gas explosion verification chamber 61 via a wire 66. In this embodiment, by manipulating the spark igniter, the discharge electrode 65 inside the test gas explosion verification chamber 61 can be controlled to generate a spark of specific energy at its tip to ignite the test gas in the test gas explosion verification chamber 61. In particular, the spark igniter 67 can generate a spark with a specific energy value that meets the requirements of standard SAE ARP5412. In a specific embodiment, the specific energy of the spark is 200 microjoules.

[0072] In a further embodiment, to facilitate explosion verification, the test gas explosion verification chamber 61 may be made of a transparent material to allow observation of the explosion by the human eye or by camera. In a preferred embodiment, the test gas explosion test chamber 61 is made of transparent organic glass with a thickness of not less than 8 mm. This allows the spark at the tip of the discharge electrode 65 to be easily captured and photographed through the chamber 61 using a high-speed camera, thereby facilitating monitoring of the test process and determining its effectiveness.

[0073] In this embodiment, the test gas explosion verification chamber 61 is further provided with an inflating nozzle 62 and an exhaust nozzle 63, wherein the inflating nozzle 62 and the exhaust nozzle 63 are arranged at the upper and lower corners of the two ends of the test gas explosion verification chamber 61 in a diagonal direction (similar to Figure 2 The inflation nozzle 62 is connected to the exhaust nozzle of each compartment of the aircraft fuel tank 10, so that the test gas explosion verification chamber 61 is connected to the downstream of the aircraft fuel tank 10 in the air flow direction.

[0074] In a further embodiment, the test gas explosion verification chamber 61 further comprises an externally opening pressure relief damper 64a and an internally opening air supply damper 64b, respectively arranged on the left and right sides, front and rear sides, or top of the test gas explosion verification chamber 61, as shown in the figure. The externally opening pressure relief damper 64a is used to open under pressure during an explosion to relieve pressure and indicate that the test gas is flammable. The internally opening air supply damper 64b is used to replenish flammable gas and / or air into the test gas explosion verification chamber 61 when necessary, thereby preventing damage to the test chamber structure due to "instantaneous high negative pressure" and improving the pressure tolerance of the flammable gas explosion device.

[0075] Optionally, the test gas explosion verification chamber 61 is isolated from the aircraft fuel tank 10 and the outside world by valves 68 and 69. Therefore, when verifying the flammability of the test gas, valves 68 and 69 are first closed, and the spark igniter 67 is operated to generate an electric spark at the tip of the discharge electrode 65 to attempt to ignite the combustible gas in the chamber, thereby verifying the flammability of the test gas.

[0076] It can be seen that the test gas explosion verification chamber 61 has a simple structure, uses conventional materials, is easy to assemble and disassemble on the test bench, and can be replaced individually, so it is low-cost and effectively prevents damage to the aircraft fuel tank 10.

[0077] The inventors also discovered that maintaining the flammability of the test gas is a crucial prerequisite for ensuring the effectiveness of lightning tests. Disassembly and assembly, piping connections on the test bench, and valve opening and closing operations can easily cause test gas leakage, affecting the configuration ratio of the flammable gas and, consequently, the flammability of the test gas. This, in turn, can lead to ineffective lightning tests and the need for repeated testing, increasing testing costs and cycle times.

[0078] Therefore, in yet another embodiment of the present disclosure, the system 100 may optionally include an airtightness detection device 40 for detecting the airtightness of the aircraft fuel tank 10 .

[0079] from Figure 3 As can be seen in the figure, the airtightness testing device 40 may include a booster fan 41 for filling the multiple compartments of the aircraft fuel tank 10 with air, and a differential pressure gauge 43 for monitoring the pressure difference between the aircraft fuel tank 10 and the outside world. Of course, the airtightness testing device 40 may also include various valves 42 and 45 for controlling the opening and closing of airflow. Those skilled in the art will appreciate that the airtightness testing device 40 may be any suitable airtightness testing instrument that includes or partially includes the aforementioned components to achieve the same airtightness testing purpose.

[0080] In an embodiment where the system 100 includes a test gas combustion and explosion verification device 60, the airtightness detection device 40 can verify the airtightness of both the aircraft fuel tank 10 and the test gas combustion and explosion verification chamber 61. In this embodiment, the connection devices (such as valves 34, 35, and 36) between the aircraft fuel tank 10 and the test gas combustion and explosion verification chamber 61 are opened, and the various connection devices (such as valves 31, 32, 33, and 69) on the filling nozzle of the aircraft fuel tank 10 and the exhaust nozzle of the test gas combustion and explosion verification chamber 61 are also opened. The outlet (such as valve 45) of the test gas combustion and explosion verification chamber 61 to the outside (e.g., outdoors) is closed. Air is then introduced into the aircraft fuel tank 10 and the test gas combustion and explosion verification chamber 61 by opening valve 42 of the airtightness detection device 40, so that the pressure differential measured by the differential pressure gauge 43 does not fall below a predetermined threshold (such as 2 kPa). Thereafter, the reading change of the differential pressure gauge may be monitored within a predetermined duration (such as half an hour), and when the pressure difference change is lower than a predetermined percentage (such as 0.1%), it may be determined that the airtightness is good.

[0081] In another embodiment of the present disclosure, the system 100 may further include a temperature sensor and / or a pressure sensor ( Figure 3 (not shown) to monitor whether the temperature and / or pressure in the group of compartments changes during the detection process, and thereby determine whether the group of compartments has exploded.

[0082] Continue to refer Figure 3 System 100 may also optionally include a test gas dispensing system 50 for dispensing flammable test gas. As shown, test gas dispensing system 50 can inject test gas into each of the multiple compartments of aircraft fuel tank 10 through a gas filling nozzle located therein. In one embodiment, test gas dispensing system 50 is configured to prepare a test gas mixture having a ratio that complies with the requirements of SAE ARP 5416.

[0083] In another embodiment, the test gas preparation system 50 may include a gas cylinder 51, a flow control valve 52, a gas flow meter 53, a gas mixing chamber 54, a valve 55, a gas volume meter 56, and the like. In this embodiment, a mixture of hydrogen (5%), oxygen (12%), and argon (83%) is used as the test gas when conducting lightning ignition source detection tests using the combustible gas method according to SAE ARP5416. Three gas cylinders 51 store hydrogen, oxygen, and argon, respectively. By adjusting the flow control valves 52 and observing the gas flow meter 53, the hydrogen, oxygen, and argon are delivered to the gas mixing chamber 54 in the required proportions for premixing. Valve 55 is used to open and close the flow of combustible gas into the aircraft fuel tank 10. In a preferred embodiment, the total volume of combustible gas filled into the aircraft fuel tank 10 is generally no less than five times the capacity of the fuel tank compartment being tested, which is monitored by the gas volume meter 56. In a preferred embodiment, the flow rate regulation and control of the hydrogen, oxygen and argon gases, gas mixing, and the total volume of the combustible gas can all be automatically achieved through computer numerical control.

[0084] It can be understood that corresponding test gas transmission pipelines 20 and valves (such as 30-36, 42, 45, 55, 68, 69, etc.) exist between the devices included in the system 100 to transport gas within the system 100. No further details will be given here.

[0085] Next reference Figure 5 , which shows an example flow chart of an example method 500 for verifying a lightning protection design of an aircraft fuel tank according to an embodiment of the present disclosure.

[0086] In one embodiment of the present disclosure, the method 500 may be performed by Figure 3 The system 100 shown is implemented and can be Figure 1 An aircraft fuel tank 10 is shown.

[0087] Specifically, the method 500 may include selecting a group of compartments from among the plurality of groups of compartments at block 510. For example, this selection may be made by controlling various valves based on a specific inspection purpose. Figure 3 Taking the fuel tank compartment group (compartment 11 + compartment 12) as an example, valves 31 and 34 need to be opened, and valves 32, 33, 35, and 36 need to be closed.

[0088] Then, at block 520, the method 500 may include delivering the test gas to the set of compartments and the test gas explosion verification device. For example, a test gas preparation system may be started to prepare the test gas and deliver it to the compartments and the test gas explosion verification device. Figure 3Still taking the above-mentioned fuel tank compartment group (compartment 11 + compartment 12) as an example, valves 55, 68, 69, and 45 are further opened, and the three flow regulating valves 52 are adjusted respectively so that the gas flow displayed by the gas flow meter 53 meets the combustible gas configuration ratio recommended by the standard SAEARP5416; the hydrogen, oxygen, and argon output from the gas cylinder 51 are pre-mixed in the gas mixing chamber 54 and then transported to the fuel tank compartments 11 and 12; when it is observed that the total gas filling amount of the combustible gas displayed on the gas volume meter 56 exceeds 5 times the total capacity of the tested fuel tank compartment group, the filling operation is stopped and all valves are closed.

[0089] At block 530, method 500 may then include injecting a lightning current into the aircraft fuel tank under test. In one embodiment, this may include: generating a lightning current waveform using a lightning current waveform generating device; channeling the lightning current waveform to a lightning current waveform output bus; injecting the lightning current waveform from the lightning current waveform output bus into the aircraft fuel tank via a first flat electrode electrically bonded to the lightning current waveform output bus, and returning the lightning current waveform to the lightning current ground return bus via a second flat electrode electrically bonded to the lightning current ground return bus. Further according to this embodiment, the first flat electrode and the second flat electrode are electrically bonded to the aircraft fuel tank using a plurality of sets of equally spaced fasteners. For example, in combination with Figure 3 Injecting lightning current into the aircraft fuel tank 10 may include closing the circuit breaker 72, connecting the lightning current waveform generator 71 to the system 100; controlling the four lightning current waveform generators 71 through the control panel 78 to generate four lightning current waveforms A wave, B wave, C wave and D wave that meet the requirements of the standard SAE ARP5412; the lightning current is output through the lightning current waveform output bus 73, the conductive strip 74 (at Figure 3 The fuel tank 10 is injected into the aircraft through the flat electrode 75b, the conductive tape 74 (at the top) and the flat electrode 75a. Figure 3 below) and the lightning current ground return bus 76, and outputs to the ground electrode 77.

[0090] Subsequently, at block 540, method 500 may include determining that the group of compartments has not exploded. In one embodiment, determining that the group of compartments has not exploded includes determining that the group of compartments has not exploded by monitoring the temperature and / or pressure within the group of compartments using temperature sensors and / or pressure sensors associated with the group of compartments. In this embodiment, if the change in temperature and / or pressure measured by the temperature sensors and / or pressure sensors is within any suitable predetermined range (e.g., 0.5%, 2%, or any other suitable value, etc.), it may be determined that the group of compartments has not exploded.

[0091] In another embodiment, whether the pressure relief damper on the outer wall of a selected group of compartments is opened to determine whether the group of compartments explodes. In this embodiment, if the pressure relief damper is not opened, it can be determined that no explosion occurs.

[0092] If an explosion is confirmed, the aircraft fuel tank's lightning protection design is deficient or ineffective, and the defect is located within the selected group of compartments. This can prompt the designer to inspect the selected group of compartments, modify the design, and / or add lightning protection measures (e.g., using insulating sealant to fillet or seal the defective area).

[0093] If it is determined that no explosion has occurred, the method 500 may include, at block 550, verifying the flammability of the test gas using a test gas explosion verification device. In one embodiment, verifying the flammability of the test gas includes generating an electric spark in the test gas explosion verification chamber of the test gas explosion verification device using a spark igniter to verify the flammability of the test gas. Figure 3 The spark igniter 67 can be controlled to generate a spark with a specific energy value (such as a spark with an energy of 200 microjoules) at the tip of the discharge electrode 65 that meets the requirements of the standard SAEARP5412, and detect whether the test gas is flammable in the test gas explosion verification chamber 61: if the gas is flammable, it indicates that the lightning protection design measures adopted on the aircraft fuel tank are effective; if the gas is not flammable, it indicates that the test is invalid and needs to be repeated. Figure 3 In the embodiment of the present invention, the flammability of the test gas is determined by the opening of the pressure relief damper 64a during the explosion. Of course, this determination can also be made by any other suitable temperature and / or pressure sensor, which will not be described in detail here.

[0094] Finally, method 500 may include, at block 560 , determining that the lightning protection design of the tested aircraft fuel tank is effective after the plurality of groups of compartments have undergone the aforementioned testing operations.

[0095] In a preferred embodiment, before the test gas is delivered to the selected set of compartments and the test gas explosion verification device, an airtightness test device can be activated to perform an airtightness test on the aircraft fuel tank lightning protection design verification system (including the selected fuel tank compartments, the test gas explosion verification device, and associated pipes and valves, etc.). If the airtightness test passes, the test gas is then filled; if the airtightness test fails, the gas leak is located and repaired until the airtightness test passes.

[0096] Therefore, optionally, as shown in the dotted box 515, the method 500 may also include air tightness verification. For example, the method 500 may include, before delivering the test gas to a selected group of compartments and the test gas explosion verification device, detecting the air tightness of the aircraft fuel tank and the test gas explosion verification device (including the selected fuel tank compartments, the test gas explosion verification device and the associated pipes and valves) through an air tightness detection device. In this embodiment, the method 500 may include: using the booster fan of the air tightness detection device to fill the selected group of compartments and the test gas explosion verification device with air so that the pressure difference between the group of compartments and the test gas explosion verification device and the outside atmosphere reaches a predetermined threshold; using the pressure differential gauge of the air tightness detection device to monitor the pressure difference for a predetermined duration; and during the predetermined duration, if the measured pressure difference remains within a predetermined percentage range of the predetermined threshold, it is determined that the air tightness of the aircraft fuel tank and the test gas explosion verification device is good. Combined Figure 3 This may include closing valves 45 and 55, locking the outward-opening pressure relief damper 64a and the inward-opening air supply damper 64b on the test gas explosion verification chamber 61, locking the pressure relief damper (if any) on the aircraft fuel tank 10, and opening the remaining valves on the test gas transmission pipeline 20; starting the air tightness detection device 40 and causing it to operate for a predetermined duration (for example, half an hour) to test the air tightness of the aircraft fuel tank 10 and the entire system 100. The specific detection process has been explained in the above content of this disclosure and will not be repeated here. If the air tightness test fails (that is, the air tightness of the aircraft fuel tank 10 and the entire system 100 is poor), it is necessary to notify the technician to locate and repair the gas leak until the air tightness test passes. Those skilled in the art will understand that although the air tightness of the aircraft fuel tank and the test gas explosion verification device is described here, the air tightness test also includes the air tightness of the pipelines and valves associated with the aircraft fuel tank and the test gas explosion verification device.

[0097] Optionally, as shown in dashed box 555 , method 500 may further include, after the test gas explosion verification is completed, closing valve 55 and opening all other valves, using air tightness detection system 40 to fill the entire aircraft fuel tank 10 and system 100 with air, and exhausting the combustible gas (i.e., the test gas) that may be contained in the entire aircraft fuel tank 10 and system 100, to prevent the retained combustible gas from accidentally exploding and causing a safety risk.

[0098] As can be seen from the above disclosure, the aircraft fuel tank and the verification system and method for the aircraft fuel tank lightning protection design disclosed herein may have various advantages, such as:

[0099] 1) By adding a test gas explosion verification chamber, the risk of damage to the tested structure caused by the impact of combustible gas explosion can be greatly reduced, thereby effectively avoiding additional manufacturing costs and test costs;

[0100] 2) By installing inflation and exhaust nozzles in all fuel tank compartments of the aircraft fuel tank and setting up an air tightness detection system, the test gas inflation efficiency and ventilation effect can be effectively improved, ensuring the flammability of the gas environment in the fuel tank compartment. This can greatly reduce the number of invalid tests, avoid repeated tests, reduce test costs, and avoid extending the test cycle.

[0101] 3) Multiple fuel tank compartments within an aircraft fuel tank can be grouped and connected to enable flexible and targeted lightning ignition source detection testing without having to fill all fuel tank compartments with flammable gas. This can effectively reduce flammable gas usage and shorten filling and exhaust time, thereby effectively reducing test costs and improving test efficiency.

[0102] 4) The busbar connection form with flexible layout and convenient access nearby is adopted, which is conducive to multiple tested units to connect to the busbar nearby, can reduce the time of large-scale round-trip lifting and transportation, and is conducive to shortening the test cycle; multiple tested units can be interspersed with each other to carry out lightning tests, greatly improving the efficiency of test implementation.

[0103] The present disclosure is particularly suitable for lightning ignition source detection tests on large aircraft fuel tanks. Since the flammability of the test gas is verified in a test gas explosion verification chamber, after adopting the technical solution of the present disclosure, a large number of lightning protection design ignition source detection tests can be carried out on large aircraft fuel tanks without worrying about the impact of the test gas explosion impact on the aircraft fuel tank.

[0104] Furthermore, it should be noted that, although various embodiments of this application are described in conjunction with aircraft fuel tanks, the various embodiments of the present disclosure may also be applied to various other systems requiring lightning protection designs, such as fuel systems, hydraulic systems, inerting systems, EWIS systems, and fuel tank structures, as well as various aircraft, vehicles, and ships. It should also be understood that the terms "front, rear," "left, right," "up, down," and the like used in this disclosure to indicate directions are intended for illustrative purposes and, therefore, may be used interchangeably.

[0105] In addition, the references to “thunder” and “lightning” in this application specification are descriptions of the same physical discharge phenomenon, and the two can be used interchangeably.

[0106] The above detailed description includes references to the accompanying drawings, which form part of the detailed description. The accompanying drawings illustrate specific embodiments that can be put into practice by way of illustration. These embodiments are also referred to herein as "examples." Such examples may include elements other than those shown or described. However, examples that include the shown or described elements are also contemplated. In addition, examples using any combination or arrangement of those elements shown or described are also contemplated, or with reference to the specific examples (or one or more aspects thereof) shown or described herein, or with reference to other examples (or one or more aspects thereof) shown or described herein.

[0107] In the appended claims, the terms "including" and "comprising" are open-ended, that is, systems, apparatuses, articles, or processes that include elements in addition to those listed after such terms in a claim are considered to fall within the scope of that claim. Furthermore, in the appended claims, the terms "first," "second," and "third," etc. are used merely as labels and are not intended to indicate a numerical order to their objects.

[0108] In addition, the order of each operation explained in this specification is exemplary. In alternative embodiments, each operation can be performed in a different order than that shown in the drawings, and each operation can be combined into a single operation or split into more operations.

[0109] The above description is intended to be illustrative, not restrictive. For example, the examples described above (or one or more aspects thereof) may be used in conjunction with other embodiments. Other embodiments may be used, such as by a person of ordinary skill in the art after reviewing the above description. The abstract allows the reader to quickly determine the nature of the present disclosure. This abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the above specific embodiments, various features may be grouped together to make the disclosure smooth. However, the claims may not state every feature disclosed herein, as the embodiments may characterize a subset of the features. In addition, an embodiment may include fewer features than those disclosed in a particular example. Therefore, the appended claims are thereby incorporated into the specific embodiments, and a claim exists independently as a separate embodiment. The scope of the embodiments disclosed herein should be determined with reference to the appended claims and the full scope of equivalents to which such claims are entitled.

Claims

1. A system for verifying the effectiveness of a lightning protection design for an aircraft fuel tank, the system comprising a lightning current waveform generator and a test gas explosion verification device for verifying the flammability of a test gas. The lightning current waveform generator is configured to output a lightning current waveform to the aircraft fuel tank to simulate the effects of actual lightning. The aircraft fuel tank comprises: one or more structural ribs within the interior of the aircraft fuel tank, the one or more structural ribs dividing the interior of the aircraft fuel tank into a plurality of compartments; For each compartment, this includes: an inflation nozzle provided on the first structural beam of the compartment for receiving the test gas into the compartment; an exhaust nozzle provided on the second structural beam of the compartment, for exhausting gas in the compartment; wherein the first structural beam is one of a front structural beam and a rear structural beam and the second structural beam is the other of the front structural beam and the rear structural beam, and the plurality of compartments are divided into a plurality of groups, and wherein the holes on the structural ribs between each group of compartments are sealed using a detachable non-conductive material so that each group of compartments is hermetically separated from each other.

2. The system according to claim 1, wherein: The lightning current waveform generating device comprises: Four generators for generating the four lightning current waveforms A, B, C, and D that meet the requirements of standard SAE ARP5412; a lightning current waveform output bus bar for converging the A-wave, B-wave, C-wave, and D-wave current components generated by the four generators; a first flat electrode electrically connected to the lightning current waveform output busbar; Lightning current ground return bus; A second flat electrode that is electrically bonded to the lightning current ground return busbar.

3. The system according to claim 2, characterized in that The first flat plate electrode and the second flat plate electrode are electrically bonded to the aircraft fuel tank using a plurality of groups of fasteners arranged at equal intervals.

4. The system according to claim 1, wherein: Also included is an air tightness detection device for detecting the air tightness of an aircraft fuel tank.

5. The system according to claim 4, characterized in that The air tightness detection device includes a booster fan for filling air into the multiple compartments of the aircraft fuel tank and a pressure differential gauge for monitoring the pressure difference between the aircraft fuel tank and the outside world.

6. The system according to claim 1, wherein: The test gas explosion verification device includes a test gas explosion verification cavity and a discharge electrode arranged inside the test gas explosion verification cavity. The discharge electrode is connected to an electric spark igniter outside the test gas explosion verification cavity through a wire.

7. The system according to claim 6, characterized in that The test gas explosion verification chamber is made of a transparent material and is provided with an inflation nozzle, an exhaust nozzle, an external pressure release damper and an internal air supply damper, wherein the inflation nozzle and the exhaust nozzle are arranged diagonally at the upper and lower end corners at both ends of the test gas explosion verification chamber, and the inflation nozzle is connected to the exhaust nozzle of each compartment of the multiple compartments of the aircraft fuel tank, and the external pressure release damper and the internal air supply damper are respectively arranged on the left and right sides, front and back sides or the top of the test gas explosion verification chamber.

8. The system according to claim 1, wherein: The invention also includes a test gas dispensing system for dispensing flammable test gas, wherein the test gas dispensing system fills each compartment of the plurality of compartments of the aircraft fuel tank with the test gas through a filling nozzle of each compartment.

9. A method for verifying the effectiveness of a lightning protection design of an aircraft fuel tank using the system according to any one of claims 1 to 8, the method comprising: selecting a group of compartments from the plurality of groups of compartments; Deliver the test gas to a selected group of compartments and the test gas combustion and explosion verification device; injecting lightning current into the aircraft fuel tank; confirming that no explosion has occurred in the selected group of compartments; and Verifying the flammability of the test gas by using the test gas explosion verification device; After the plurality of compartment groups have undergone the above operations, it is determined that the lightning protection design of the aircraft fuel tank is effective.

10. The method according to claim 9, characterized in that When claim 9 refers to claim 5, the method further comprises, before delivering the test gas into the selected group of compartments and the test gas combustion and explosion verification device, detecting the air tightness of the selected group of compartments and the test gas combustion and explosion verification device by the air tightness detection device, wherein detecting the air tightness comprises: Using the booster fan of the air tightness detection device to fill air into a selected group of compartments and the test gas explosion verification device, so that the pressure difference between the group of compartments and the test gas explosion verification device and the external atmosphere reaches a predetermined threshold; monitoring the pressure difference for a predetermined duration using the pressure differential gauge of the airtightness detection device; and During the predetermined duration, if the measured pressure difference remains within a predetermined percentage range of the predetermined threshold value, it is determined that the airtightness of the aircraft fuel tank and the test gas explosion verification device is good.

11. The method according to claim 9, characterized in that When claim 9 refers to claim 2 or 3, injecting lightning current into the aircraft fuel tank comprises: Use a lightning current waveform generator to generate a lightning current waveform that meets the requirements of standard SAE ARP5412; Converging the lightning current waveform to the lightning current waveform output bus bar; injecting the lightning current waveform from the lightning current waveform output bus into the aircraft fuel tank via the first flat electrode electrically bonded to the lightning current waveform output bus, and returning the lightning current waveform to the lightning current ground return bus via the second flat electrode electrically bonded to the lightning current ground return bus. The first flat electrode and the second flat electrode are electrically connected to the aircraft fuel tank using a plurality of groups of fasteners arranged at equal intervals.

12. The method according to claim 9, characterized in that Determining that the selected group of compartments has not exploded includes determining that the group of compartments has not exploded by detecting that the temperature and / or pressure in the group of compartments have not changed using a temperature sensor and / or a pressure sensor associated with the selected group of compartments.

13. The method according to claim 9, characterized in that When claim 9 refers to claim 6 or 7, verifying that the test gas is flammable includes generating electric sparks in the test gas explosion verification chamber thereof by the electric spark igniter to verify the flammability of the test gas.

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