Fireproof sealed cargo hold and method of designing the same

Abstract

The application provides a fireproof sealed cargo cabin and a design method thereof, and belongs to the field of helicopter body structure function design. The method comprises the following steps: first, the interior decoration, the floor, the cargo cabin door, the front frame passage door and the rear frame passage door form a fireproof sealed boundary; second, the fireproof sealing design of the front frame passage door is performed and a fireproof and fire resistance test is completed; third, the fireproof sealing design of the rear frame passage door is performed and a fireproof and fire resistance test is completed; fourth, the fireproof sealing design of the cargo cabin door is performed and a fireproof and fire resistance test is completed; and fifth, the air convection passage design of the cargo cabin is performed. The cargo cabin has the fireproof sealing property, can contain the cabin fire, and makes the fire unable to reach the passenger cabin and the tail beam. During the flight of the airplane, under the action of the aerodynamic load, the cargo cabin door ensures the reliable sealing, does not make new oxygen enter the cargo cabin, and thus avoids increasing the fire burning time. The interior decoration and the structural parts in the cargo cabin are strictly tested according to the airworthiness clauses, and it is proved that the requirement of the fire resistance of 5 minutes is met, and the fireproof sealing property of the cargo cabin is ensured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of helicopter body structure function design, and particularly relates to a fireproof sealed cargo cabin and a design method thereof. BACKGROUND

[0002] The fireproof sealing property of the cargo cabin is crucial in the design of a helicopter. If a fire occurs in the cargo cabin, the fire in the cabin will spread to the passenger cabin, causing casualties, and will spread to the tail beam, causing equipment damage. During the flight of the aircraft, the pressure difference between the inside and outside of the cabin door and the cabin door sealing rubber strip causes deformation, which easily leads to poor sealing and causes oxygen to enter the cargo cabin. When the cargo cabin does not have fireproof sealing conditions, it is easily affected by a large amount of airflow, causing the fire to be larger or causing harmful smoke and other toxic gases to enter the passenger cabin.

[0003] Therefore, it is crucial to achieve the fireproof sealing property of the cargo cabin under the premise of ensuring the air convection path during the deformation of the cabin door during the flight of the aircraft. SUMMARY

[0004] The present application provides a fireproof sealed cargo cabin and a design method, which can contain the fire in the cabin, so that the fire cannot reach the passenger cabin and the tail beam. During the flight of the aircraft, the cargo cabin door is sealed reliably under the action of aerodynamic load, so that new oxygen does not enter the cargo cabin, thereby avoiding the increase of the fire burning time. The interior and structural parts in the cargo cabin are strictly tested according to the airworthiness provisions, and it has been proved that the requirement of fire resistance for 5 minutes is met, so as to ensure the fireproof sealing property of the cargo cabin. The technical solution is as follows:

[0005] In a first aspect, a design method of a fireproof sealed cargo cabin is provided, comprising:

[0006] Firstly, the interior, the floor, the cargo cabin door, the front frame passage door and the rear frame passage door form a fireproof sealed boundary;

[0007] Secondly, the fireproof sealing design of the front frame passage door is performed and the fireproof resistance test is completed;

[0008] Thirdly, the fireproof sealing design of the rear frame passage door is performed and the fireproof resistance test is completed;

[0009] Fourthly, the fireproof sealing design of the cargo cabin door is performed and the fireproof resistance test is completed;

[0010] Fifthly, the air convection path design of the cargo cabin is performed.

[0011] Optionally, the front frame passage door comprises a left detachable passage door, a middle detachable passage door and a right detachable passage door.

[0012] The upper part of the middle detachable passage door is connected with the inner decoration and the front frame web through a support; a ring-shaped fireproof sealing tooth-shaped rubber strip is arranged between the middle detachable passage door and the support; a flat rubber strip is arranged between the support and the inner decoration; and a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the support and the front frame web;

[0013] The lower part of the middle detachable passage door is connected with the floor and the front frame web through an aluminum alloy angle; a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the middle detachable passage door and the aluminum alloy angle; the floor adopts an aluminum panel aluminum honeycomb structure form; a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the left detachable passage door and the front frame web; and a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the middle detachable passage door and the left detachable passage door;

[0014] In the fire resistance test, the test piece is used for testing, the test piece is made according to the strength of different regions of the front frame passage door, the test piece is made of ECS2259.20 and ECS2042.20 two kinds of carbon cloth which are alternately laid, and the outer surface of the test piece is sprayed with polyurethane fireproof surface paint.

[0015] Optionally, the rear frame passage door comprises an upper detachable passage door and a lower detachable passage door;

[0016] The upper part of the upper detachable passage door is connected with the rear frame web through an aluminum alloy reinforcing piece; flat rubber strips are arranged between the upper detachable passage door, the inner decoration and the rear frame web and the aluminum alloy reinforcing piece;

[0017] The lower part of the upper detachable passage door is connected with the lower detachable passage door, and a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the two;

[0018] The upper detachable passage door, the inner decoration and the rear frame web are connected through an aluminum alloy reinforcing angle, and flat rubber strips are arranged between the upper detachable passage door, the inner decoration and the aluminum alloy reinforcing angle;

[0019] Flat rubber strips are arranged between the lower detachable passage door and the rear frame web;

[0020] In the fire resistance test, the test piece is used for testing, the test piece is made according to the strength of different regions of the rear frame passage door, the test piece is made of ECS0037, and the outer surface of the test piece is sprayed with polyurethane fireproof surface paint.

[0021] Optionally, an O-shaped fireproof sealing rubber strip is arranged between the cargo door and the door frame, and the inner decoration is screwed with the door frame; the O-shaped fireproof sealing rubber strip is cut at an angle of 45° in the middle part of the door to be divided into upper and lower parts, the upper part is bonded with the door frame, and the lower part is bonded with the cargo door body;

[0022] In the fire resistance test, the test piece is used for the test, the test piece is made according to the strength of different areas of the cargo door 4, the test piece is laid by ECS0017.108 and ECS2042.20, and the outer surface of the test piece is sprayed with a polyurethane fireproof finish.

[0023] Optionally, the fireproof sealing design process of the O-shaped fireproof sealing rubber strip under negative pressure is as follows:

[0024] Step 1, calculate the compression amount e1 of the O-shaped fireproof sealing rubber strip: the compression amount e1 = Hs-H1, wherein Hs is the height of the rubber strip, and H1 is the height of the rubber strip after compression;

[0025] Step 2, calculate the displacement dep2 of the cargo door under negative pressure and calculate the target displacement dep3: the displacement dep2 = (F2 / F1)*dep1, wherein F1 is the ultimate load, F2 = P2*S, P2 = (1 / 2)Cp*ρ*V2, Cp is the value given by the load manual of the cargo door under the maximum negative pressure P2, ρ is the air density, V is the air flow velocity, S is the surface area of the cargo door, and dep1 is the maximum displacement of the cargo door edge in the H1 direction; the target displacement dep3 = dep2+1;

[0026] Step 3, calculate the remaining compression amount e2 of the O-shaped fireproof sealing rubber strip under negative pressure: e2 = e1-dep2;

[0027] Step 4, under the condition of bearing the maximum negative pressure, when the remaining compression amount e2≥1-2mm, it is determined that the fireproof sealing of the O-shaped fireproof sealing rubber strip is effective.

[0028] Optionally, in the fifth step,

[0029] When there is an unsealed installation hole on the left and right floor inside the cargo compartment, the installation hole is used as an air convection hole; otherwise, an air convection hole is drilled on the floor inside the cargo compartment to ensure that there is a little air flow at the bottom of the helicopter.

[0030] In the second aspect, a fireproof sealing cargo compartment designed by using the method of any one of the first aspect is provided, comprising: a front frame access door, a rear frame access door, a cargo door, and an air convection hole on the floor inside the cargo compartment,

[0031] The front frame access door is located on the reinforced frame of the passenger cabin, the rear frame access door is located on the reinforced frame of the tail beam, and the cargo door is located on the cargo compartment skin.

[0032] Optionally, the front frame access door comprises a left detachable access door, a middle detachable access door, and a right detachable access door.

[0033] The upper part of the middle detachable passage door is connected with the interior decoration and the front frame web through a support; a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the middle detachable passage door and the support; a flat rubber strip is arranged between the support and the interior decoration; and a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the support and the front frame web;

[0034] The lower part of the middle detachable passage door is connected with the floor and the front frame web through an aluminum alloy angle; a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the middle detachable passage door and the aluminum alloy angle; the floor adopts an aluminum panel aluminum honeycomb structure form; a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the left detachable passage door and the front frame web; and a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the middle detachable passage door and the left detachable passage door.

[0035] Optionally, the rear frame passage door comprises an upper detachable passage door and a lower detachable passage door;

[0036] The upper part of the upper detachable passage door is connected with the rear frame web through an aluminum alloy reinforcing piece; flat rubber strips are arranged between the upper detachable passage door, the interior decoration and the rear frame web and the aluminum alloy reinforcing piece;

[0037] The lower part of the upper detachable passage door is connected with the lower detachable passage door, and a strip-shaped fireproof sealing tooth-shaped rubber strip is arranged between the two;

[0038] The upper detachable passage door, the interior decoration and the rear frame web are connected through an aluminum alloy reinforcing angle, and flat rubber strips are arranged between the upper detachable passage door, the interior decoration and the aluminum alloy reinforcing angle;

[0039] The lower detachable passage door and the rear frame web are arranged with flat rubber strips.

[0040] Optionally, an O-shaped fireproof sealing rubber strip is arranged between the cargo compartment door and the door frame, and the interior decoration is screwed with the door frame; the O-shaped fireproof sealing rubber strip is cut at an angle of 45° in the middle part of the compartment door, and is divided into upper and lower parts, the upper part is bonded with the door frame, and the lower part is bonded with the cargo compartment door body.

[0041] The present application has at least the following beneficial effects:

[0042] The fireproof sealing cargo compartment of the present application can contain the flame in the compartment, so that the flame cannot reach the passenger compartment and the tail beam; during the flight of the aircraft, under the action of the aerodynamic load, the cargo compartment door ensures reliable sealing, so that new oxygen cannot enter the cargo compartment, thereby avoiding the increase of the flame burning time; the interior decoration and the structural members in the cargo compartment are strictly tested according to the airworthiness regulations, and it has been proved that the requirement of fire resistance for 5 minutes is met, thereby ensuring the fireproof sealing property of the cargo compartment. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Fig. 1 is a schematic view of the structure of the cargo compartment;

[0044] Figure 2 Figure 1 is a schematic view of a cargo hold fire seal boundary;

[0045] Figure 3 Figure 2 is a schematic view of a front frame and its access door structure;

[0046] Figure 4 Figure 3 is a schematic view of a front frame access door and perimeter structure A-A cross section;

[0047] Figure 5 Figure 4 is a schematic view of a fire seal tooth profile cross section;

[0048] Figure 6 Figure 5 is a schematic view of a front frame access door and perimeter structure B-B, C-C and D-D cross sections;

[0049] Figure 7 Figure 6 is a schematic view of a front frame access door typical fire resistant structure 1 ;

[0050] Figure 8 Figure 7 is a schematic view of a front frame access door typical fire resistant structure 2;

[0051] Figure 9 Figure 8 is a schematic view of a front frame access door typical fire resistant structure 3;

[0052] Figure 10 Figure 9 is a schematic view of a rear frame and its access door structure;

[0053] Figure 11 Figure 10 is a schematic view of a rear frame access door and perimeter structure A-A cross section;

[0054] Figure 12 Figure 11 is a schematic view of a rear frame access door and perimeter structure B-B cross section;

[0055] Figure 13 Figure 12 is a schematic view of a rear frame access door and perimeter structure C-C cross section;

[0056] Figure 14 Figure 13 is a schematic view of a rear frame access door and perimeter structure D-D cross section;

[0057] Figure 15 Figure 14 is a schematic view of a rear frame access door typical fire resistant structure;

[0058] Figure 16 Figure 15 is a schematic view of a rear frame access door upper and lower door typical connection structure 2;

[0059] Figure 17 Figure 16 is a schematic view of a rear frame access door upper and lower door typical layup structure 3 in test piece 2;

[0060] Figure 18 Figure 17 is a schematic view of a rear frame access door typical fire resistant structure 4;

[0061] Figure 19 Figure 18 is a schematic view of a cargo door fire seal structure;

[0062] Figure 20 This is a schematic diagram of the installation structure of the fireproof sealing strip for the cargo door;

[0063] Figure 21 This is a schematic diagram of the installation structure of the fireproof sealing strip for the cargo door;

[0064] Figure 22 Schematic diagram of the installation structure of the fireproof sealing strip for the cargo door.

[0065] Among them, 1- fuselage structure 2- interior 3- floor 4- cargo door 5- front frame access door 6- rear frame access door 7- fireproof sealing boundary 8- left removable access door 9- middle removable access door 10- right removable access door 11- front frame web 12- bracket 13- flat rubber strip 14- fireproof sealing toothed rubber strip 15- aluminum alloy reinforcement plate 16- blind nut 17- aluminum alloy angle 18- upper removable access door 19- lower removable access door 20- rear frame web 21- aluminum alloy reinforcement 22- aluminum alloy reinforcement angle 23- door frame 24- fireproof sealing strip 25- upper half of the fireproof sealing strip 26- lower half of the fireproof sealing strip. DETAILED DESCRIPTION

[0066] The present invention is further described in detail below through specific implementation methods and drawings.

[0067] This invention proposes a fireproof and sealed cargo hold structure and a fireproof and sealed design method for cargo hold door sealing strips. These structures can contain flames within the hold, preventing them from reaching the passenger cabin and tail boom. Under the action of aerodynamic loads during flight, the cargo hold door maintains a reliable seal, preventing new oxygen from entering the hold and thus increasing the duration of the flame. The interior trim and structural components within the cargo hold have been rigorously tested in accordance with airworthiness regulations and have been proven to meet the five-minute fire resistance requirement, thus ensuring the fireproof and sealed nature of the cargo hold. The specific implementation process includes the following steps:

[0068] The first step is to define the boundaries of the fireproof and sealed cargo hold:

[0069] like Figure 1 、 Figure 2 As shown, the cargo hold is located inside the fuselage structure 1, and its fireproof sealing area 8 is surrounded by the cabin interior 2, floor 3, cargo hold door 4, front frame passage door 5 and rear frame passage door 6 to form a fireproof sealing boundary 7.

[0070] The second step is the fireproof sealing design of the front frame passage door 5:

[0071] like Figure 3 As shown, in order to facilitate personnel to enter the cargo hold for maintenance, the front frame is designed with a left detachable access door 8, a middle detachable access door 9, and a right detachable access door 10.

[0072] likeFigure 4 As shown, the upper part of the middle detachable passage door 9 is connected to the interior 2 and the front frame web 11 through a bracket 12; a strip-shaped fireproof sealing toothed rubber strip 14 is arranged between the middle detachable passage door 9 and the bracket 12, and is connected by blind nuts 16 and bolts considering the limitations of the installation space. In order to meet the requirements of the blind nuts for the countersink thickness, an aluminum alloy reinforcement plate 15 is added; a flat rubber strip 13 is arranged between the bracket 12 and the interior 2, and is connected by support plate nuts and bolts; a strip-shaped fireproof sealing toothed rubber strip 14 is arranged between the bracket 12 and the front frame web 11, and is connected by support plate nuts and bolts.

[0073] The bracket 12 is a composite laminated structure, and the material used is a bidirectional prepreg glass cloth ECS2259.20 with self-extinguishing function and high temperature resistance of 180°C. The surface of the part is sprayed with primer ECS2067 and then sprayed with polyurethane fire retardant topcoat ECS2066; Figure 5 As shown, the strip-shaped fireproof sealing toothed strip 14 has four tooth-shaped protrusions, and its material should be fire-resistant and self-extinguishing, with a compression ratio between 25% and 30% (sufficient elastic variation range can ensure that the web surface with slightly lower rigidity is sufficient to withstand the impact of flames without leaking harmful gases); the flat strip 13 is made of high-temperature resistant, glass fiber-coated neoprene ASNA4110.

[0074] like Figure 6 As shown, the lower part of the middle detachable passage door 9 is connected to the floor 3 and the front frame web 11 through an aluminum alloy angle 17; a strip-shaped fireproof sealing toothed rubber strip 14 is arranged between the middle detachable passage door 9 and the aluminum alloy angle 17; the floor 3 adopts an aluminum panel aluminum honeycomb structure; a strip-shaped fireproof sealing toothed rubber strip 14 is arranged between the left detachable passage door 8 and the front frame web 11, which is screwed together by bolts and support plate nuts; a strip-shaped fireproof sealing toothed rubber strip 14 is arranged between the middle detachable passage door 9 and the left detachable passage door 8, which is screwed together by bolts and support plate nuts.

[0075] Aisle doors are composite structures with laminated and honeycomb sandwich areas that meet strength requirements. Although all materials used are self-extinguishing, their typical structures must still undergo a 5-minute fire resistance test in accordance with the airworthiness requirements of CCAR 29-855. According to the airworthiness instructions, aluminum alloy metal materials meet the fire resistance requirements and do not require testing and verification.

[0076] The selection principle of typical structural test pieces is: taking into account both weak areas and typical areas; Figure 7 、 Figure 8 、 Figure 9 The typical structural forms shown in the figure have passed the 5-minute fire resistance verification test that meets airworthiness requirements.

[0077] In order to verify the fireproof sealing performance of the designed front frame channel door 5, the present invention manufactures multiple test pieces of the front frame channel door 5, namely test piece 1, test piece 2 and test piece 3. Test piece 1 is a test piece at the honeycomb position of the detachable channel door on the left and right parts of the front frame channel door 5, test piece 2 is a test piece at the lamination position of the detachable channel door on the left and right parts of the front frame channel door 5, and test piece 3 is a test piece at the position of the detachable channel door 9 in the middle part of the front frame channel door 5.

[0078] Test piece 1 is a test piece at the honeycomb position of the left and right detachable channel door of the front frame channel door 5, such as Figure 7 As shown, the size is 560mm*560mm; the honeycomb area ply is ECS2042.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(45°) / ECS2259.20(0°) / ECS2042.20(45°), and the laminated area ply is ECS2042.20(45°) / ECS2259.20(0°) / / ECS2259.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(45°) CS2259.20 (0°) / ECS2042.20 (45°); ECS2042.20 is a self-adhesive, self-extinguishing epoxy bidirectional glass cloth prepreg with a curing temperature of 180°C, an operating temperature of 120°C, a density of 284g / m2; ECS2259.20 is a self-adhesive, self-extinguishing epoxy bidirectional glass cloth prepreg with a curing temperature of 180°C, an operating temperature of 120°C, a density of 400g / m2; the honeycomb material is aramid paper honeycomb DHS251-135.15 with a thickness of 15mm and a density of 48kg / m^3; a layer of moisture-proof TELDAR film ECS0008.20 is applied to the inner surface of the honeycomb area; the surface of the part is sprayed with primer ECS2067, and then sprayed with polyurethane fire retardant topcoat ECS2066 that meets self-extinguishing standards.

[0079] Test piece 2 is a test piece at the lamination position of the left and right detachable channel doors of the front frame channel door 5, such as Figure 8As shown, the size is 560mm*560mm; the lay-up of the honeycomb area is ECS2042.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(45°) / ECS2259.20(0°) / ECS2042.20(45°), and the lay-up of the laminate area is ECS2042.20(45°) / ECS2259.20(0°) / / ECS2259.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(0°) / ECS2042.20(45°); wherein, ECS2042.20 is an epoxy bidirectional glass cloth prepreg with 180℃ curing, 120℃ using temperature, 284g / m2 density, self-adhesion and self-extinguishing; ECS2259.20 is an epoxy bidirectional glass cloth prepreg with 180℃ curing, 120℃ using temperature, 400g / m2 density, self-adhesion and self-extinguishing; the surface of the part is sprayed with primer ECS2067 and then sprayed with polyurethane fire-retardant topcoat ECS2066 meeting the self-extinguishing standard.

[0080] Test piece 3 is a test piece at the position of the detachable passage door 9 in the middle of the front frame passage door 5, as shown in Figure 9 As shown, the size is 560mm*560mm; the lay-up of the honeycomb area is ECS2042.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(45°) / ECS2259.20(0°) / ECS2042.20(45°), and the lay-up of the laminate area is ECS2042.20(45°) / ECS2259.20(0°) / / ECS2259.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(45°) / ECS2259.20(0°) / ECS2259.20(45°) / ECS2259.20(0°) / ECS2042.20(45°); wherein, ECS2042.20 is an epoxy bidirectional glass cloth prepreg with 180℃ curing, 120℃ using temperature, 284g / m2 density, self-adhesion and self-extinguishing; ECS2259.20 is an epoxy bidirectional glass cloth prepreg with 180℃ curing, 120℃ using temperature, 400g / m2 density, self-adhesion and self-extinguishing; the honeycomb material is aramid paper honeycomb DHS251-142.20 with a thickness of 20mm and a density of 32kg / m3; a layer of moisture-proof TELDAR film ECS0008.20 is attached to the inner surface of the honeycomb area; the surface of the part is sprayed with primer ECS2067 and then sprayed with polyurethane fire-retardant topcoat ECS2066 meeting the self-extinguishing standard.

[0081] After the test piece 1, the test piece 2 and the test piece 3 are made, the fireproof and fire-resistant test is performed.

[0082] Third step, the fireproof sealing design of the rear frame passage door 6:

[0083] As shown in Figure 10 In order to facilitate personnel to enter the cargo compartment for maintenance, the front frame is designed with an upper detachable passage door 18 and a lower detachable passage door 19.

[0084] As shown in Figure 11 The upper detachable passage door 18 is connected between the upper part and the rear frame web plate 20 through an aluminum alloy reinforcing piece 21; flat rubber strips 13 are arranged between the upper detachable passage door 18, the interior 2, the rear frame web plate 20 and the aluminum alloy reinforcing piece 21, and are connected through a bracket nut and a bolt.

[0085] As shown in Figure 12 The lower part of the upper detachable passage door 18 is connected between the lower detachable passage door 19 through a bracket nut and a bolt, and a strip-shaped fireproof sealing tooth-shaped rubber strip 14 is arranged therebetween.

[0086] As shown in Figure 13 The upper detachable passage door 18, the interior 2 and the rear frame web plate 20 are connected through an aluminum alloy reinforcing angle 22, and flat rubber strips 13 are arranged between the upper detachable passage door 18, the interior 2 and the aluminum alloy reinforcing angle 22.

[0087] As shown in Figure 14 The lower detachable passage door 19 and the rear frame web plate 20 are connected through a bracket nut and a bolt, and flat rubber strips 13 are arranged therebetween.

[0088] In order to verify the fireproof sealing performance of the designed rear frame passage door 6, the present application produces a plurality of test pieces of the rear frame passage door 6, which are test piece 1, test piece 2 and test piece 3, respectively. The test piece 1 is a test piece at the honeycomb position of the rear frame passage door 6, the test piece 2 is a test piece at the connection position of the upper door and the lower door of the rear frame passage door 6, and the test piece 3 is a test piece at the lamination position of the rear frame passage door 6.

[0089] The test piece 1 is a test piece at the honeycomb position of the rear frame passage door 6, as shown in Figure 15The size is 510mm*510mm; the honeycomb area is ECS0037-255(0°) / ECS0037-256(0°) / ECS0037-256(0°) / ECS0037-255(0°), and the laminated area is ECS0037-255(0°) / ECS0037-256(45°) / ECS0037-256(0°) / ECS0037-256(45°) / ECS0037-256(0°) / ECS0037-255(45°); wherein, ECS0037-255 is a 130℃ curing, 70℃ using temperature, 210g / m^2 density, self-adhesive and self-extinguishing epoxy bidirectional glass cloth prepreg; ECS0037-256 is a 130℃ curing, 70℃ using temperature, 400g / m^2 density, self-adhesive and self-extinguishing epoxy bidirectional glass cloth prepreg; the honeycomb material is aramid paper honeycomb DHS251-142.08 with a thickness of 8mm and a density of 32kg / m^3; a moisture-proof TELDAR film ECS0008.20 is pasted on the inner surface of the honeycomb area; the surface of the part is sprayed with primer ECS2067, and then sprayed with polyurethane fireproof topcoat ECS2066 meeting the self-extinguishing standard.

[0090] Test piece 2 is a test piece at the connection position of the upper door and the lower door of the rear frame passage door 6, Figure 16 The titanium alloy bolt A0164TK050S018X is used as the connecting bolt, and the stainless steel nut 52358CB050N is used as the supporting plate nut. Figure 17 The titanium alloy bolt A0164TK050S018X is used as the connecting bolt, and the stainless steel nut 52358CB050N is used as the supporting plate nut. Figure 16The typical structure of the upper and lower honeycomb sandwich of the channel door 6 is shown in the figure. The size of the test piece is 560mm*560mm. The honeycomb area is ECS0037-255(0°) / ECS0037-256(0°) / ECS0037-256(0°) / ECS0037-255(0°), and the laminated area is ECS0037-255(0°) / ECS0037-256(45°) / ECS0037-256(0°) / ECS0037-256(45°) / ECS0037-256(0°) / ECS0037-255(45°). ECS0037-255 is a 130℃ cured, 70℃ used, 210g / m^2 density, self-adhesive, self-extinguishing epoxy bidirectional glass cloth prepreg. ECS0037-256 is a 130℃ cured, 70℃ used, 400g / m^2 density, self-adhesive, self-extinguishing epoxy bidirectional glass cloth prepreg. The honeycomb material is aramid paper honeycomb DHS251-142.08 with a thickness of 8mm and a density of 32kg / m^3. A moisture-proof TELDAR film ECS0008.20 is attached to the inner surface of the honeycomb area. After spraying primer ECS2067 on the surface of the part, a polyurethane fire-retardant topcoat ECS2066 meeting the self-extinguishing standard is sprayed.

[0091] Test piece 3 is a test piece at the laminated position of the rear frame channel door 6, as shown in Figure 18 The size of the test piece is 560mm*560mm. The laminated area is ECS0037-255(45°) / ECS0037-256(0°) / ECS0037-256(0°) / ECS0037-256(45°) / ECS0037-256(0°) / ECS0037-255(45°). ECS0037-255 is a 130℃ cured, 70℃ used, 210g / m^2 density, self-adhesive, self-extinguishing epoxy bidirectional glass cloth prepreg. ECS0037-256 is a 130℃ cured, 70℃ used, 400g / m^2 density, self-adhesive, self-extinguishing epoxy bidirectional glass cloth prepreg. After spraying primer ECS2067 on the surface of the part, a polyurethane fire-retardant topcoat ECS2066 meeting the self-extinguishing standard is sprayed.

[0092] As shown in Figure 15 , Figure 16 , Figure 17 , Figure 18 , Figure 19 The typical structure shown in the figure has passed the verification test of fire resistance of 5min meeting airworthiness requirements;

[0093] Fourth step, fireproof sealing design of cargo door 4:

[0094] As shown in Figure 19As shown, the fireproof sealing function between the cargo door 4 and the door frame 23 is realized by the fireproof sealing rubber strip 24, and the interior decoration 2 is screwed with the door frame 23; the fireproof sealing rubber strip 24 is a hollow O-shaped ring structure, and considering the limitation of its forming process after adding fireproof cloth, it is cut at a 45° angle in the middle part of the left and right sides and is divided into two parts; as shown in Figure 20 As shown, the upper half of the fireproof sealing rubber strip 25 is bonded with the door frame 23 to better play a sealing effect (the sealing contact surface is away from the side of the door frame, avoiding the displacement of the rubber strip during the closing of the door), and the lower half of the fireproof sealing rubber strip 26 is bonded with the door body of the cargo door 4 to avoid wear of the rubber strip during the loading and transportation of goods; when assembling, the upper half of the fireproof sealing rubber strip 25 and the lower half of the fireproof sealing rubber strip 26 should be ensured to have no gap.

[0095] Step 5: Fireproof sealing design of the cargo door sealing rubber strip:

[0096] (1) As shown in Figure 21 , the huge deformation of the cargo door will not cause the connection between the sealing strip and the door to fail, thereby causing new oxygen to enter the cargo compartment and making the flame burn more fiercely; the pressure difference on both sides of the sealing strip will not cause the connection between the sealing strip and the door to fail, thereby causing new oxygen to enter the cargo compartment and making the flame burn more fiercely.

[0097] A. Compression (e1) of the cargo door sealing strip under normal conditions:

[0098] Assumption: There is no pressure difference on both sides of the sealing strip (P1=P2), and when the cargo door is closed, the compression amount of the sealing strip is:

[0099] e1=Hs-H1

[0100] Hs: height of the rubber strip; H1: height of the rubber strip after compression;

[0101] B. Displacement (dep2) of the cargo door under negative pressure conditions:

[0102] Assumption: Under negative pressure conditions, the cargo door edge reaches the maximum displacement value in the H1 direction

[0103] Referring to the strength calculation report, under the condition of bearing a certain limit load (F1), the finite element analysis will provide the maximum displacement value (dep1) of the cargo door edge in the H1 direction:

[0104] The maximum negative pressure value P2 of the door is (1 / 2)Cp*ρ*V2;

[0105] ρ is the air density; S is the surface area of the cargo door; V is the air flow velocity;

[0106] Therefore, when bearing the pressure P2, the limit load F2 on the cargo door is:

[0107] F2 = P2 * S,

[0108] At the maximum negative pressure, the edge displacement is the largest along the H1 direction, and the ratio dep2 is:

[0109] dep2 = (F2 / F1) * dep1,

[0110] Considering that the door and the structure are not completely fitted, the assembly error is 1mm:

[0111] dep3 = dep2 + 1,

[0112] C. The remaining compression amount (e2) of the cargo door seal under negative pressure:

[0113] Under negative pressure, the compression amount of the cargo door seal decreases due to the displacement of the door along the H1 direction:

[0114] e2 = e1 - dep2

[0115] Under the maximum negative pressure, the remaining compression amount e2 of the cargo door seal is ≥1-2mm, which can ensure effective sealing.

[0116] (2) As shown in Figure 22 , the pressure difference on both sides of the seal will not cause the connection between the seal and the door to fail: when the deformation of the cargo door at both ends reaches a certain value, it will not fail; the pressure difference on both sides of the seal causes the seal to twist and deform.

[0117] In order to demonstrate that the seal will not rotate around its axis, causing the seal to fail to connect with the door, a comparative analysis must be performed.

[0118] A. Due to the different pressures P2 / P1, the load on the seal is limited (Fdep):

[0119] Under the maximum negative pressure, considering that the cargo door is not equal to the structure, the distance H2 between the door and the structure is:

[0120] H2 = H1 + dep3,

[0121] Therefore, the limit load Fdep on the seal when P1 = 0 is:

[0122] Fdep = P2 * H2,

[0123] B. Due to the different pressures P2 / P1, the load on the seal is limited (Fdep):

[0124] In order to calculate the friction force Ffric of the rubber strip, the reaction force Fps acting on the sealing strip needs to be calculated; the Fps belongs to the mechanical inherent characteristics of the rubber strip, and is related to the material of the rubber strip and the deformation amount thereof, and the reaction force of the rubber strip is inquired according to the residual compression amount e2 of the sealing strip (the rubber strip manufacturer will give the reaction force-displacement curve of the rubber strip tested by a press):

[0125] Ffric=Fps*Cf,

[0126] Cf: friction coefficient;

[0127] The condition that the rubber strip is not failed in connection is that the maximum pressure difference is borne on the inner and outer sides of the rubber strip:

[0128] Ffric>Fdep,

[0129] Sixth step, air convection passage design inside the cargo compartment:

[0130] Two Φ6mm process holes on the left and right floor inside the cargo compartment are borrowed to ensure that a little air flow exists in the bottom of the helicopter, a small hole in the area ensures that a little air flow exists in the bottom of the helicopter, and the air flow is not sealed and will not affect the sealing performance of the cargo compartment;

[0131] Sealant should be used between all the assembled and bonded surfaces, rivets in non-electrically connected parts should be dipped in sealant and riveted, and the head or tail of the bolt should be sealed and sealed with sealant; fireproof sealing ring or fireproof sealing foam should be used for hole blocking at all system through holes; the composite parts are sprayed with fireproof paint; high-temperature-resistant elastic rubber is selected for the sealing strip; the door cover is installed and fixed by fireproof steel bolts.

[0132] The above only expresses the embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, a number of modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. In addition, the parts not described in detail in the present application are all conventional technologies.

Claims

1. A method of designing a fire sealed cargo hold, characterized in that, The application relates to a fireproof sealing design method for a cargo cabin door of a large aircraft. The first step is to form a fireproof sealing boundary by the interior, the floor, the cargo cabin door, the front frame passage door and the rear frame passage door; The second step is to design the fireproof sealing of the front frame passage door and complete the fireproof and fire resistance test; The third step is to design the fireproof sealing of the rear frame passage door and complete the fireproof and fire resistance test; The fourth step is to design the fireproof sealing of the cargo cabin door and complete the fireproof and fire resistance test; The fifth step is to design the air convection passage of the cargo cabin; The front frame passage door comprises a left detachable passage door, a middle detachable passage door and a right detachable passage door; The upper part of the middle detachable passage door is connected with the interior and the front frame web through a support; flat adhesive tape is arranged between the support and the interior; strip-shaped fireproof sealing tooth-shaped adhesive tape is arranged between the support and the front frame web; The lower part of the middle detachable passage door is connected with the floor and the front frame web through an aluminum alloy angle; strip-shaped fireproof sealing tooth-shaped adhesive tape is arranged between the middle detachable passage door and the aluminum alloy angle; the floor adopts an aluminum panel aluminum honeycomb structure; strip-shaped fireproof sealing tooth-shaped adhesive tape is arranged between the left detachable passage door and the front frame web; strip-shaped fireproof sealing tooth-shaped adhesive tape is arranged between the middle detachable passage door and the left detachable passage door; During the fireproof and fire resistance test, a test piece is used for the test; the test piece is made according to the strength of different regions of the front frame passage door; the test piece is made of ECS2259.20 and ECS2042.20 two kinds of carbon cloth which are alternately laid; and the outer surface of the test piece is sprayed with polyurethane fireproof surface paint; O-shaped fireproof sealing adhesive tape is arranged between the cargo cabin door and the door frame, and the interior is screwed with the door frame; the O-shaped fireproof sealing adhesive tape is cut at a 45-degree angle in the middle part of the cabin door, and is divided into upper and lower parts; the upper part is bonded with the door frame, and the lower part is bonded with the cabin door body; During the fireproof and fire resistance test, a test piece is used for the test; the test piece is made according to the strength of different regions of the cargo cabin door; the test piece is made of ECS0017.108 and ECS2042.20; and the outer surface of the test piece is sprayed with polyurethane fireproof surface paint; The fireproof sealing design process of the O-shaped fireproof sealing adhesive tape under negative pressure is as follows: Step 1, the compression amount e1 of the O-shaped fireproof sealing adhesive tape is calculated: the compression amount e1 = Hs-H1, wherein Hs is the height of the adhesive tape, and H1 is the height of the adhesive tape after compression; Step 2, calculate the displacement of the cargo door under negative pressure dep2 and calculate the target displacement dep3: displacement dep2 = (F2 / F1) * dep1, wherein F1 is the ultimate load, F2 = P2 * S, P2 = (1 / 2) Cp * p * V, Cp is the value given by the load manual of the cargo door under the maximum negative pressure value P2, p is the air density, V is the air flow velocity, S is the surface area of the cargo door, and dep1 is the maximum displacement of the cargo door edge in the H1 direction; target displacement dep3 = dep2 + 1. 2 , Cp is the value given by the load manual of the cargo door under the maximum negative pressure value P2, p is the air density, V is the air flow velocity, S is the surface area of the cargo door, and dep1 is the maximum displacement of the cargo door edge in the H1 direction; target displacement dep3 = dep2 + 1. Step 3, the residual compression amount e2 of the O-shaped fireproof sealing adhesive tape under negative pressure is calculated: e2 = e1-dep2; Step 4, under the condition of bearing the maximum negative pressure, when the residual compression amount e2 is greater than or equal to 1-2 mm, the fireproof sealing of the O-shaped fireproof sealing adhesive tape is determined to be effective.

2. The method of claim 1, wherein, The rear frame passage door comprises an upper detachable passage door and a lower detachable passage door; The upper part of the upper detachable passage door is connected with the rear frame web through an aluminum alloy reinforcing piece; flat adhesive tape is arranged between the upper detachable passage door, the interior, the rear frame web and the aluminum alloy reinforcing piece; The lower part of the upper detachable passage door is connected with the lower detachable passage door, and strip-shaped fireproof sealing tooth-shaped adhesive tape is arranged between the two. The upper detachable passage door, the interior decoration and the rear frame web plate are connected through aluminum alloy reinforcing angle bars, and flat rubber strips are arranged between the upper detachable passage door, the interior decoration and the aluminum alloy reinforcing angle bars; Flat rubber strips are arranged between the lower detachable passage door and the rear frame web plate; In the fire resistance test, the test piece is used for the test, the test piece is made according to the strength of different regions of the rear frame passage door, the test piece is laid by ECS0037, and the outer surface of the test piece is sprayed with polyurethane fireproof finish.

3. The method of claim 1, wherein, In the fifth step, When there is an unblocked installation hole on the left and right sides of the floor inside the cargo compartment, the installation hole is used as an air convection hole; otherwise, an air convection hole is drilled on the floor inside the cargo compartment to ensure that there is a little air flow at the bottom of the helicopter.

4. A fire sealed cargo hold designed by the method according to any one of claims 1 to 3, characterized in that, Comprise: The front frame passage door, the rear frame passage door, the cargo compartment door and the air convection hole on the floor inside the cargo compartment, The front frame passage door is located on the reinforced frame of the passenger cabin, the rear frame passage door is located on the reinforced frame of the tail beam, and the cargo compartment door is located on the cargo compartment skin.

5. A fire sealed cargo hold according to claim 4, c h a r a c t e r i s e d in that The front frame passage door comprises a left detachable passage door, a middle detachable passage door and a right detachable passage door; The upper part of the middle detachable passage door is connected with the interior decoration and the front frame web plate through a support, flat rubber strips are arranged between the support and the interior decoration, and strip-shaped fireproof sealing tooth-shaped rubber strips are arranged between the support and the front frame web plate; The lower part of the middle detachable passage door is connected with the floor and the front frame web plate through an aluminum alloy angle bar, strip-shaped fireproof sealing tooth-shaped rubber strips are arranged between the middle detachable passage door and the aluminum alloy angle bar, the floor adopts an aluminum panel aluminum honeycomb structure form, strip-shaped fireproof sealing tooth-shaped rubber strips are arranged between the left detachable passage door and the front frame web plate, and strip-shaped fireproof sealing tooth-shaped rubber strips are arranged between the middle detachable passage door and the left detachable passage door.

6. The fire protected sealed cargo hold of claim 4, wherein, The rear frame passage door comprises an upper detachable passage door and a lower detachable passage door; The upper part of the upper detachable passage door is connected with the rear frame web plate through an aluminum alloy reinforcing piece, flat rubber strips are arranged between the upper detachable passage door, the interior decoration and the rear frame web plate and the aluminum alloy reinforcing piece; The lower part of the upper detachable passage door is connected with the lower detachable passage door, and strip-shaped fireproof sealing tooth-shaped rubber strips are arranged between the two; The upper detachable passage door, the interior decoration and the rear frame web plate are connected through aluminum alloy reinforcing angle bars, and flat rubber strips are arranged between the upper detachable passage door, the interior decoration and the aluminum alloy reinforcing angle bars; Flat rubber strips are arranged between the lower detachable passage door and the rear frame web plate.

7. The fire protected sealed cargo hold according to claim 4, characterized in that O-shaped fireproof sealing rubber strips are arranged between the cargo compartment door and the door frame, the interior decoration is screwed with the door frame; the O-shaped fireproof sealing rubber strips are cut at an angle of 45° in the middle part of the door and are divided into upper and lower parts, the upper part is bonded with the door frame, and the lower part is bonded with the door body of the cargo compartment door.

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