Fire-resistant test piece and test method for wing integral fuel tank access cover

Abstract

The application provides a wing integral tank port cover fire resistance test piece and a test method, and belongs to the field of aircraft tank tests. The test piece comprises: a combined upper wall plate, which comprises an upper wall plate body provided with an opening and a first stringer, and the edge of the opening is provided with a second stringer, an opening area boss and a sunken feature area; a port cover assembly installed at the opening and fixedly connected with the upper wall plate; a flat plate structure lower wall plate provided with two oil discharge ports; a groove structure wing beam and wing rib, the upper and lower edges of the wing beam and the wing rib are provided with outwardly turned edge strips, and the wing beam and the wing rib are fixedly connected with the upper wall plate and the lower wall plate through the edge strips, and the upper wall plate, the tank rib, the tank beam and the lower wall plate are fixedly connected to form a closed box section structure. The application simplifies the structure form, the number of parts and the assembly relationship of the test piece, simplifies the part manufacturing and assembly process, and reduces the manufacturing cost.

Description

Technical Field

[0001] The present application relates to the field of aircraft fuel tank testing, and in particular to a fire resistance test piece and test method for an integral wing fuel tank cover. Background Art

[0002] The upper wall panel of the integral fuel tank area of ​​the wing box section of a certain type of aircraft is equipped with a large number of stress-bearing covers as maintenance channels, and the lower wall panel is also equipped with fuel vent covers. When a fire occurs outside the wing, if these covers cannot withstand the high temperature, fuel leakage will occur, leading to catastrophic consequences.

[0003] To meet the fire resistance requirements for wing-mounted fuel tank covers, they must undergo fire resistance testing for airworthiness compliance in a laboratory environment. This requires a test piece capable of assessing the fire resistance of wing-mounted fuel tank covers. This test piece should be a box-section structure with fuel storage capabilities and structural features suitable for assessing the fire resistance of wing-mounted fuel tank covers. Furthermore, since aircraft surfaces are generally curved, their structural parameters take into account strength and stiffness requirements. Using a test piece designed based on the actual aircraft's shape and structural parameters would result in complex and costly test piece fabrication.

[0004] Therefore, in order to simplify the test piece structure as much as possible while meeting the test purpose and to reduce the manufacturing cost, a wing integral fuel tank cover fire resistance test piece and test method are needed. Summary of the Invention

[0005] The purpose of the present application is to provide a fire resistance test piece and test method for an integral wing fuel tank cover, so as to solve or alleviate at least one problem in the background technology.

[0006] On the one hand, the technical solution of the present application is: a fire-resistant test piece for an integral wing fuel tank cover, comprising:

[0007] A combined upper wall panel, comprising an upper wall panel body, the upper wall panel body being provided with an opening and a first long stringer, the edge of the opening being provided with a second long stringer, an opening area boss, and a sunken characteristic area;

[0008] An opening cover assembly is installed at the opening and fixedly connected to the upper wall plate;

[0009] A lower wall plate of a flat structure, wherein two oil drain ports are provided on the lower wall plate;

[0010] The wing beams and wing ribs of the trough structure are provided with outward-flashed edge strips on the upper and lower edges of the wing beams and wing ribs. The wing beams and wing ribs are fixedly connected to the upper wall panel and the lower wall panel through the edge strips. The upper wall panel, the fuel tank ribs, the fuel tank beams and the lower wall panel are fixedly connected to form a closed box-section structure.

[0011] In an optional embodiment of the present application, the opening is runway-shaped.

[0012] In an optional embodiment of the present application, the first long stringer and the second long stringer are parallel to the wing beam.

[0013] In an optional embodiment of the present application, the first long girder and the second long girder are connected to the upper wall panel body through fasteners.

[0014] In an optional embodiment of the present application, the mouth cover assembly includes a mouth cover body, a sealing gasket and a connecting strip plate. The mouth cover body is a reinforced structure with a cross-shaped reinforcement rib on the inner side. The mouth cover body is arranged on the outside of the opening of the upper wall plate, the sealing gasket is arranged between the mouth cover body and the upper wall plate, and the connecting strip plate is arranged on the inner side of the upper wall plate. The airtight support plate nut and the connecting strip plate are fixedly connected to the inner side of the upper wall plate 2 by rivets, and the connecting bolts pass through the mouth cover body, the sealing gasket, and the upper wall plate and cooperate with the airtight support plate nut, thereby fixing the mouth cover body, the sealing gasket, and the upper wall plate into an integral structure.

[0015] In an optional embodiment of the present application, the rivets and connecting bolts are both countersunk structures.

[0016] In an optional embodiment of the present application, the sealing gasket is an expanded polytetrafluoroethylene sealing gasket.

[0017] In an optional embodiment of the present application, the two oil drain ports are located on both sides of the diagonal line of the lower wall plate.

[0018] In an optional embodiment of the present application, the fitting surfaces, fillets, and fastener positions between the upper wall panel, the fuel tank ribs, the fuel tank beams, and the lower wall panel are sealed using sealants or gaskets.

[0019] In another aspect, the present application provides a method for conducting a fire resistance test using any of the above-described fire resistance test pieces for an integral wing fuel tank access cover, comprising:

[0020] 1) A fixture is used to fix one end of the test piece. During the test, the cover assembly is placed on the lower side of the test piece. A burner for performing a fire resistance test on the test piece is placed on the lower side of the test piece so that the flame generated by the burner can perform the fire resistance test on the test piece. A pressure sensor and a shut-off valve are connected to the oil drain port of the lower wall panel 5.

[0021] 2) Fill the test piece with a predetermined volume of fuel;

[0022] 3) Before the test, calibrate the flame temperature and heat flux density of the burner. Use thermocouples to measure the average temperature and heat flux of the burner to ensure that they meet the required values. If the heat flux or temperature generated by the burner is not within the required range, adjust the burner until its flame temperature and heat flux meet the requirements. After the burner flame meets the requirements, turn off the burner.

[0023] 4) Install the test piece on the test bracket, with the test piece and the burner at a predetermined distance so that the center of the burner flame should be directly opposite the center of the test piece;

[0024] 5) Turn on the burner and preheat for a predetermined time, then move the burner to the test position, conduct a fire resistance test on the test piece for a predetermined time, and record the test phenomena; during the test, observe and record the degree of deformation of the cover assembly and the leakage of fuel. If the cover assembly is burned through or visually leaks fuel, it indicates that the test piece fails; otherwise, the test passes.

[0025] In an optional embodiment of the present application, the predetermined volume is 2 / 3 of the volume of the test piece.

[0026] In an optional embodiment of the present application, the required value is that the average temperature reaches 1093±83°C and the heat flow is not less than 10.6W / cm2.

[0027] In an optional embodiment of the present application, the predetermined distance is 102 mm ± 3 mm.

[0028] In an optional implementation manner of the present application, the predetermined duration is 5 minutes.

[0029] The wing integral fuel tank cover fire resistance test piece provided in this application has a fuel storage function and has structural characteristics for assessing the fire resistance of the integral fuel tank cover. On the premise of meeting the test purpose, the test piece structure is simplified, the number of parts and assembly relationships are reduced, the parts manufacturing and assembly processes are simplified, and the manufacturing cost is reduced. The test method using the above-mentioned test piece simplifies the test scale, simplifies the test implementation, shortens the test cycle, reduces expenses, and can meet the airworthiness verification requirements. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0031] Figure 1 This is a schematic diagram of the assembled test piece of this application.

[0032] Figure 2 This is a schematic diagram of the test piece of this application after removing the cover assembly.

[0033] Figure 3This is a schematic diagram of the upper wall panel structure of this application.

[0034] Figure 4 This is a schematic diagram of the connection between the upper wall panel and the cover assembly of this application.

[0035] Figure 5 Schematic diagram of the fire resistance test of the test piece of this application. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0037] In order to overcome the problems in the prior art of complex processing or high manufacturing cost of wing integral fuel tank cover, the present application provides a wing integral fuel tank cover fire resistance test piece and a test method thereof.

[0038] like Figures 1 to 2 As shown, the wing integral fuel tank cover fire resistance test piece provided in the present application is a box-section structure as a whole. The test piece includes a cover assembly 1, an upper wall panel 2, a fuel tank rib 3 (usually arranged along the fuselage axial direction Y), a fuel tank beam 4 (usually arranged along the wingspan direction X) and a lower wall panel 5. The upper wall panel 2, the fuel tank rib 3, the fuel tank beam 4 and the lower wall panel 5 are fixedly connected by fasteners or welding to form a closed box-section structure, and the cover assembly 1 is installed on the upper wall panel 2.

[0039] like Figure 3 As shown, the upper panel 2 in the present application is a modular structure, comprising an upper panel body 21 and a first stringer 22 and a second stringer 23 fixedly mounted on the upper panel body 21. The first stringer 22 is arranged parallel to the wing beam 4 to enhance the structural strength of the upper panel body 21. A runway-shaped opening (i.e., a rectangular middle portion with semicircular sides) is provided at the center of the upper panel body 21. The second stringer 23 is arranged near the edge of the runway-shaped opening to enhance its structural strength. In some embodiments of the present application, the first stringer 22 and the second stringer 23 can be connected to the upper panel body 21 using fasteners such as rivets or bolts.

[0040] Furthermore, an opening area boss 24 and a recessed feature area 25 are sequentially provided outwardly from the semicircular perimeter of the runway-shaped opening of the upper panel body 21. These bosses 24 and recessed feature areas 25 further enhance the structural strength of the area near the opening. The edge of the upper panel body 21 forms a connection area 26 for connection to the wing spar 4 or wing rib 3.

[0041] Combine Figure 3 and Figure 4As shown, the flap assembly 1 includes a flap body 11, a sealing gasket 12 and a connecting strip 13. The flap body 11 is a reinforced structure, and its inner side is provided with cross-shaped reinforcing ribs. The flap body 11 is arranged on the outside of the runway-shaped opening of the upper wall panel 2, and the sealing gasket 12 is arranged between the flap body 11 and the upper wall panel 2. The compressibility of the sealing gasket 12 ensures the sealing of the fuel tank. The connecting strip 13 is arranged on the inner side of the upper wall panel 2, and the airtight support plate nut 15 and the connecting strip 13 are fixedly connected to the inner side of the upper wall panel 2 by countersunk rivets 16. The connecting bolt 14 passes through the flap body 11, the sealing gasket 12, and the upper wall panel 2 and cooperates with the airtight support plate nut 15, thereby fixing the flap body 11, the sealing gasket 12, and the upper wall panel 2 into an integral structure.

[0042] In some embodiments of the present application, the connecting bolts 14 are countersunk bolts to ensure the smoothness of the surface of the flap assembly 1. Furthermore, the sealing gasket 12 in the present application is an expanded polytetrafluoroethylene sealing gasket.

[0043] In the present application, the lower wall panel 5 is a flat plate structure, which may not have features such as long stringers, and is provided with two oil drain ports 51. In a preferred embodiment of the present application, the two oil drain ports 51 are located on both sides of the diagonal line of the lower wall panel 5.

[0044] In this application, the wing spar 3 and wing ribs 4 are integrally machined structures, with two wing spar 3 and two wing ribs 4 each. Both the wing spar 3 and the wing ribs 4 are channel-shaped structures, with reinforcing ribs provided on the outer webs of the channel structures. To simplify assembly, the wing spar 3 and the wing ribs 4 in this application are provided with flanges at their upper and lower edges. These flanges are flanged outwards for connection to the upper and lower wall panels 2 and 5 outside the wing box.

[0045] It should be noted that the fitting surfaces, fillets, fasteners and other locations between the components in this application can be sealed with sealants or gaskets for fuel storage and testing.

[0046] In this application, the cover assembly 1 and the upper wall panel 2 of the test piece are the assessment areas of the wing integral fuel tank. Except that the shape is simplified into a plane, the rest of the structural form, materials and parameters are consistent with the actual structural form and parameters of the aircraft, so as to achieve the purpose of verifying the actual structural fire resistance of the aircraft.

[0047] In some embodiments of the present application, except for the sealing gasket and fasteners, the materials of the components such as the cover assembly 1, the upper wall panel 2, the fuel tank rib 3, the fuel tank beam 4 and the lower wall panel 5 are all aluminum alloy metal structures.

[0048] Based on the above-mentioned wing integral fuel tank cover fire resistance test piece, this application also provides a test method, such as Figure 5 Said test method comprises the following steps:

[0049] 1) A fixture is used to secure one end of the test piece. During the test, the cover assembly 1 is placed on the lower side of the test piece. A burner 101 for performing a fire resistance test on the test piece is located on the lower side of the test piece so that the flame generated by the burner 101 can perform the fire resistance test on the test piece. A pressure sensor 103 and a shut-off valve 102 are connected to the oil drain port 51 of the lower wall panel 5, respectively.

[0050] 2) The test specimen is filled with fuel, with the amount or volume of fuel injected being approximately 2 / 3 of the test specimen volume. The fuel should be the same grade as that normally used in the wing tanks, for example, RP-3.

[0051] 3) Before the test, calibrate the flame temperature and heat flux density of burner 101. Measure the average temperature of burner 101 using a thermocouple to ensure it reaches 1093±83°C, and the heat flux must reach at least 10.6W / cm2. If the heat flux or temperature generated by burner 101 is not within the required range, adjust burner 101 until its flame temperature and heat flux meet the requirements. Once the flame meets the requirements, turn off the burner.

[0052] 4) Install the test piece on the test bracket, with the distance between the test piece and the burner 101 being approximately 102 mm ± 3 mm, so that the center of the flame of the burner 101 is facing the center of the test piece;

[0053] 5) Turn on the burner 101 and preheat for 5 minutes, then move the burner 101 to the test position and perform a 5-minute fire resistance test on the test piece, recording the test phenomena; during the test, observe and record the degree of deformation of the cover assembly 1 and the leakage of fuel. If the cover assembly 1 burns through or visually leaks fuel, it indicates that the test piece fails; otherwise, the test passes.

[0054] The wing integral fuel tank cover fire resistance test piece provided in this application has a fuel storage function and has structural characteristics for assessing the fire resistance of the integral fuel tank cover. On the premise of meeting the test purpose, the test piece structure is simplified, the number of parts and assembly relationships are reduced, the parts manufacturing and assembly processes are simplified, and the manufacturing cost is reduced. The test method using the above-mentioned test piece simplifies the test scale, simplifies the test implementation, shortens the test cycle, reduces expenses, and can meet the airworthiness verification requirements.

[0055] The fire resistance test piece and test method of the wing integral fuel tank cover of the present application have been applied to the fire resistance test of the integral fuel tank cover of a certain type of aircraft.

[0056] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A fire-resistant test piece for an integral wing fuel tank cover, characterized in that: include: A combined upper wall panel, comprising an upper wall panel body, the upper wall panel body being provided with an opening and a first long stringer, the edge of the opening being provided with a second long stringer, an opening area boss, and a sunken characteristic area; An opening cover assembly is installed at the opening and fixedly connected to the upper wall plate; A lower wall plate of a flat structure, wherein two oil drain ports are provided on the lower wall plate; The wing beams and wing ribs of the trough structure are provided with outward-flashed edge strips on the upper and lower edges of the wing beams and wing ribs. The wing beams and wing ribs are fixedly connected to the upper wall panel and the lower wall panel through the edge strips. The upper wall panel, the fuel tank ribs, the fuel tank beams and the lower wall panel are fixedly connected to form a closed box-section structure.

2. The fire resistance test piece for the integral wing fuel tank cover according to claim 1, characterized in that: The opening is racetrack-shaped.

3. The fire resistance test piece for the integral wing fuel tank cover according to claim 2, characterized in that: The first long stringer and the second long stringer are parallel to the wing beam.

4. The fire resistance test piece for the integral wing fuel tank cover according to claim 3, characterized in that: The first long girder and the second long girder are connected to the upper wall panel body through fasteners.

5. The fire resistance test piece for the integral wing fuel tank cover according to claim 1, characterized in that: The mouth cover assembly includes a mouth cover body, a sealing gasket and a connecting strip plate. The mouth cover body is a reinforced structure with a cross-shaped reinforcing rib on the inner side. The mouth cover body is arranged on the outside of the opening of the upper wall plate. The sealing gasket is arranged between the mouth cover body and the upper wall plate. The connecting strip plate is arranged on the inner side of the upper wall plate. The airtight support plate nut and the connecting strip plate are fixedly connected to the inner side of the upper wall plate by rivets. The connecting bolt passes through the mouth cover body, the sealing gasket and the upper wall plate and cooperates with the airtight support plate nut, thereby fixing the mouth cover body, the sealing gasket and the upper wall plate into an integral structure.

6. The fire resistance test piece for the integral wing fuel tank cover according to claim 5, characterized in that: The rivets and connecting bolts are both countersunk structures.

7. The fire resistance test piece for the integral wing fuel tank cover according to claim 5, characterized in that: The sealing gasket is an expanded polytetrafluoroethylene sealing gasket.

8. The fire resistance test piece for the integral wing fuel tank cover according to claim 1, characterized in that: The two oil drain ports are located on both sides of the diagonal line of the lower wall plate.

9. The fire resistance test piece for the integral wing fuel tank cover according to claim 1, characterized in that: The fitting surfaces, fillets and fastener positions between the upper wall plate, the fuel tank ribs, the fuel tank beams and the lower wall plate are sealed with sealants or sealing gaskets.

10. A method for conducting a fire resistance test using the fire resistance test piece of the integral wing fuel tank cover according to any one of claims 1 to 9, characterized in that: include: 1) Fix one end of the test piece with a fixture. During the test, place the cover assembly on the lower side of the test piece. A burner for conducting a fire resistance test on the test piece is placed on the lower side of the test piece so that the flame generated by the burner can conduct the fire resistance test on the test piece. A pressure sensor and a shut-off valve are connected to the oil drain port of the lower wall panel. 2) Fill the test piece with a predetermined volume of fuel; 3) Before the test, calibrate the flame temperature and heat flux density of the burner. Use thermocouples to measure the average temperature and heat flux of the burner to ensure that they meet the required values. If the heat flux or temperature generated by the burner is not within the required range, adjust the burner until its flame temperature and heat flux meet the requirements. After the burner flame meets the requirements, turn off the burner. 4) Install the test piece on the test bracket, with the test piece and the burner at a predetermined distance so that the center of the burner flame should be directly opposite the center of the test piece; 5) Turn on the burner and preheat for a predetermined time, then move the burner to the test position, conduct a fire resistance test on the test piece for a predetermined time, and record the test phenomena; during the test, observe and record the degree of deformation of the cover assembly and the leakage of fuel. If the cover assembly is burned through or visually leaks fuel, it indicates that the test piece fails; otherwise, the test passes.

11. The method according to claim 10, wherein The predetermined volume is 2 / 3 of the volume of the test piece.

12. The method according to claim 10, wherein The required values ​​are that the average temperature reaches 1093±83°C and the heat flow is not less than 10.6W / cm2.

13. The method according to claim 10, wherein The predetermined distance is 102 mm ± 3 mm.

14. The method according to claim 10, wherein The predetermined duration is 5 minutes.

Images