Fire-resistant test piece and test method for wing integral fuel tank covering cap

Abstract

The invention provides a fire-resistant test piece and a fire-resistant test method for an integral wing fuel tank opening cap, and belongs to the field of aircraft fuel tank tests.The test piece comprises a combined upper wall plate, the upper wall plate comprises an upper wall plate body, the upper wall plate body is 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; the covering cap assembly is mounted at the opening and fixedly connected with the upper wall plate; the lower wall plate is of a flat plate structure, and two oil drainage openings are formed in the lower wall plate; the upper and lower edges of the wing beam and the wing rib are provided with edge strips which are turned outwards, 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 oil tank rib, the oil tank beam and the lower wall plate are fixedly connected to form a closed box section structure. The test piece structure form, the part number and the assembly relation are simplified, the part manufacturing and assembly procedures are simplified, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The present application belongs to the field of aircraft fuel tank testing, and in particular relates to a fire-resistant test piece and a test method for a wing integral 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 arranged with a large number of stress-bearing covers as maintenance channels, and the lower wall panel is also arranged with fuel vent covers. When a fire occurs outside the wing, these covers will not be able to withstand the high temperature and fuel leakage will occur, leading to catastrophic consequences.

[0003] In order to meet the fire resistance requirements of the integral fuel tank cover of the wing, the integral fuel tank cover of the wing needs to undergo a fire resistance test for airworthiness compliance verification in a laboratory environment. For this purpose, a test piece that can be used to assess the fire resistance of the integral fuel tank cover of the wing is required. This test piece should be a box-section structure and have a fuel storage function and structural features to assess the fire resistance of the integral fuel tank cover of the wing. In addition, since the aircraft's shape is a curved surface, the structural parameters all take into account the requirements of strength and stiffness. If the test piece is designed using the actual shape and structural parameters of the aircraft, the test piece structure processing will be complicated and costly.

[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 a 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 of a wing integral fuel tank cover, comprising:

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

[0008] A mouth cover assembly, which 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 groove structure are provided with outwardly turned edge strips at 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 a racetrack shape.

[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 via 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 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, 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, so as to fix the mouth cover body, the sealing gasket and the upper wall plate into an integral structure.

[0015] In an optional implementation manner 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 tank ribs, the tank beams, and the lower wall panel are sealed using sealants or sealing gaskets.

[0019] On the other hand, the present application provides a method for conducting a fire resistance test using any of the above-mentioned wing integral fuel tank cover fire resistance test pieces, 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 arranged on the lower side of the test piece so that the flame generated by the burner can perform a fire resistance test on the test piece. A pressure sensor and a stop valve are respectively connected to the oil drain port of the lower wall plate 5;

[0021] 2) The test piece is filled 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 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 predetermined distance between the test piece and the burner, so that the center of the burner flame should face the center of the test piece;

[0024] 5) Turn on the burner and preheat for a preset time, then move the burner to the test position, conduct a fire resistance test on the test piece for a preset 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 oil. If the cover assembly is burned through or there is visual oil leakage, 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 values ​​are that the average temperature reaches 1093±83°C and the heat flow is not less than 10.6W / cm2.

[0027] In an optional implementation manner 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 the present application has a fuel storage function and has structural features 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 solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present 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 the present 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 the present 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 of complex processing or high manufacturing cost of wing integral fuel tank cover in the prior art, the present application provides a wing integral fuel tank cover fire resistance test piece and a test method thereof.

[0038] like Figure 1 to Figure 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, and 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 wall panel 2 in the present application is a combined structure, and the upper wall panel 2 includes an upper wall panel body 21 and a first long stringer 22 and a second long stringer 23 fixedly mounted on the upper wall panel body 21, wherein the first long stringer 22 is arranged in parallel with the wing beam 4 to enhance the structural strength of the upper wall panel body 21. A runway-shaped opening (i.e., a rectangular middle portion and semicircular portions on both sides) is provided at the center of the upper wall panel body 21, and the second long stringer 23 is arranged near the edge of the runway-shaped opening to enhance the structural strength of the runway-shaped opening. In some embodiments of the present application, the first long stringer 22 and the second long stringer 23 can be connected to the upper wall panel body 21 by fasteners such as rivets or bolts.

[0040] Furthermore, an opening area boss 24 and a sunken feature area 25 are sequentially arranged outwardly from the semicircular periphery of the runway-shaped opening of the upper wall panel body 21, and the structural strength of the area near the opening can be further enhanced by the opening area boss 24 and the sunken feature area 25. The edge of the upper wall panel body 21 forms a connection area 26 connected to the wing beam 4 or the wing rib 3.

[0041] Combination 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 a cross-shaped reinforcing rib is arranged on its inner side. The flap body 11 is arranged on the outer side of the runway-shaped opening of the upper wall plate 2, and the sealing gasket 12 is arranged between the flap body 11 and the upper wall plate 2, and the sealing of the fuel tank is ensured by the compressibility of the sealing gasket 12. The connecting strip 13 is arranged on the inner side of the upper wall plate 2, and the airtight support plate nut 15 and the connecting strip 13 are fixedly connected to the inner side of the upper wall plate 2 by countersunk rivets 16. The connecting bolt 14 passes through the flap body 11, the sealing gasket 12, and the upper wall plate 2 and cooperates with the airtight support plate nut 15, so that the flap body 11, the sealing gasket 12, and the upper wall plate 2 are fixedly connected as 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 mouth cover 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 plate 5 is a flat plate structure, which may not have features such as long beams, and two oil drain ports 51 are provided on the lower wall plate 5. 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 plate 5.

[0044] In the present application, the wing beam 3 and the wing rib 4 are integrally machined structures, and there are two wing beams 3 and two wing ribs 4. Both the wing beam 3 and the wing rib 4 are groove structures, and the outer web of the groove structure is provided with reinforcing ribs. In order to simplify assembly, the upper and lower edges of the wing beam 3 and the wing rib 4 in the present application are provided with edge strips, which are turned outward and used to connect with the upper wall panel 2 and the lower wall panel 5 outside the wing box.

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

[0046] In the present application, the cover assembly 1 and the upper wall panel 2 of the test piece are the assessment areas of the integral fuel tank of the wing. Except that the shape is simplified into a plane, the other structural forms, materials and parameters are consistent with the actual structural forms and parameters of the aircraft, so as to achieve the purpose of verifying the real 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, the present application also provides a test method, such as Figure 5 Said test method comprises the following steps:

[0049] 1) A fixture is used to fix one end of the test piece. During the test, the cover assembly 1 is placed on the lower side of the test piece. The burner 101 used for performing a fire resistance test on the test piece is arranged on the lower side of the test piece, so that the flame generated by the burner 101 can perform a fire resistance test on the test piece. The oil drain port 51 of the lower wall plate 5 is respectively connected with a pressure sensor 103 and a stop valve 102;

[0050] 2) The test piece is filled with fuel, the amount or volume of fuel injected is about 2 / 3 of the volume of the test piece, and the fuel is of the same grade as that normally used in the wing tank, for example, the fuel grade is RP-3;

[0051] 3) Before the test, the flame temperature and heat flux density of the burner 101 are calibrated. The average temperature of the burner 101 measured by the thermocouple reaches 1093±83℃, and the heat flux must reach at least 10.6W / cm2. If the heat flux or temperature generated by the burner 101 is not within the required range, adjust the burner 101 until its flame temperature and heat flux meet the requirements. After 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 flame center of the burner 101 should face 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, conduct a 5-minute fire resistance test on the test piece, and record the test phenomenon; during the test, observe and record the deformation degree of the cover assembly 1 and the leakage of fuel. If the cover assembly 1 is burned 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 the present application has a fuel storage function and has structural features 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 wing integral fuel tank cover fire resistance test piece and test method 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 is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A fire-resistant test piece for a wing integral fuel tank cover, characterized in that: include: A combined upper wall plate, the upper wall plate comprising an upper wall plate body, the upper wall plate body being provided with an opening and a first long stringer, the edge of the opening being provided with a second long stringer and an opening area boss and a sunken characteristic area; A mouth cover assembly, which 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 groove structure are provided with outwardly turned edge strips at 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-resistant test piece for the integral wing fuel tank cover according to claim 1, characterized in that: The opening is of a racetrack type.

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

5. The fire-resistant 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 outer side 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, so that the mouth cover body, the sealing gasket, and the upper wall plate are fixedly connected into an integral structure.

6. The fire resistance test piece of 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-resistant 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-resistant 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-resistant 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 oil tank ribs, the oil tank beams and the lower wall plate are sealed by using 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) 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 arranged on the lower side of the test piece so that the flame generated by the burner can perform a fire resistance test on the test piece. A pressure sensor and a stop valve are respectively connected to the oil drain port of the lower wall plate 5; 2) The test piece is filled 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 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 predetermined distance between the test piece and the burner, so that the center of the burner flame should face the center of the test piece; 5) Turn on the burner and preheat for a preset time, then move the burner to the test position, conduct a fire resistance test on the test piece for a preset 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 oil. If the cover assembly is burned through or there is visual oil leakage, it indicates that the test piece fails; otherwise, the test passes.

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

12. The method according to claim 10, characterized in that 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, characterized in that The predetermined distance is 102 mm±3 mm.

14. The method according to claim 10, characterized in that The predetermined duration is 5 minutes.

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