Pipe for cryogenic fluid, pipe assembly, and aerospace system with pipe

Abstract

To provide an improved pipe and pipe assembly for conduction of a cryogenic fluid, and further provide an improved aerospace system employing a cryogenic fluid.SOLUTION: There is disclosed a pipe for conducting a cryogenic fluid. The pipe comprises a rigid outer tube at least partially made of a fibre-reinforced polymer, a gas-proof inner tube running within the outer tube, an insulation layer arranged between the inner tube and the outer tube, and at least one flange formed at a respective end of the inner tube. The at least one flange connects the inner tube with the outer tube. Further, there are disclosed a pipe assembly in which at least two such pipes are connected or configured to be connected at a respective flange thereof, and an aerospace system including at least one such pipe.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] In aerospace systems, liquids and gases are typically transported from, for example, their respective reservoirs to their respective points of use using rigid or flexible lines (pipes) consisting of one or more pipes. [Background technology]

[0002] Traditionally, these pipelines form part of so-called "secondary" structures, which are not used to support the structural load during operation, but are required to perform certain secondary functions. These pipes are usually made of a metal alloy and are attached by brackets to the adjacent load-bearing structure, the so-called "primary" structure.

[0003] New systems such as the FLINT system (Fluid Line Integrated Thrustframe) consistently integrate the secondary structure into the primary structure, resulting in mass reduction and utilizing existing mass for multiple functions. In particular, the use of intermediate struts allows rigid pipes to be combined into trusses and used as structural elements for load transfer.

[0004] However, when transporting a cryogenic medium such as liquid hydrogen, the pipes cool significantly during operation. This temperature change between the assembled state and the operating state results in a large change in length depending on the material. To reliably connect the pipes to the main structure of the aircraft or spacecraft, compensators are conventionally used to compensate for deformations between the respective attachment points.

[0005] Furthermore, when using cryogenic fluids, the piping must be insulated to limit heat transfer to the medium. Otherwise, excessive heat input can cause bubbles to form, which can lead to significant heat transfer problems. Various insulation options are available, including creating a vacuum in a double-walled pipe (vacuum insulation) or using insulating foam. Foam can be sprayed onto the pipe, attached as a half-shell to the outside, or wrapped around the pipe in the form of a flexible mat. Multilayer insulation (MLI) films can also be used to insulate the pipes. However, insulating each fixing point is difficult because of the inherent conductive connection between the holder and the pipe. Therefore, the maximum number of connections in a pipeline is limited by the maximum allowable heat flow rate at each connection.

[0006] As mentioned above, the dual use of pipes by integrating them into the primary system is a disadvantage for using structural elements to compensate for length changes. The structural use of pipes requires high stiffness and stability, which is contrary to the compensation function. Furthermore, this dual use involves an increase in connection points, which increases the heat flow into the pipes. Therefore, designing a structurally integrated system architecture using conventional pipes made of materials with high thermal expansion coefficients is a difficult challenge. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide improved pipes and pipe assemblies for conveying cryogenic fluids. It is a further object of the present invention to provide improved aerospace systems that use cryogenic fluids. [Means for solving the problem]

[0008] This object is achieved by a pipe according to claim 1, a pipe assembly according to claim 13 and an aerospace system according to claim 14. Advantageous embodiments are disclosed in the dependent claims, the description and the drawings.

[0009] The pipe according to the present invention is designed for the flow of cryogenic fluids, such as liquid hydrogen. The pipe comprises a rigid outer tube made at least in part of a fiber-reinforced polymer, where the reinforcing fibers may in particular comprise carbon and / or glass fibers. The pipe further comprises a gas-impermeable inner tube running through the outer tube, with a (thermal) insulating layer therebetween. The (preferably passive) insulating layer may in particular consist of, for example, a rigid foam and / or a multi-layer insulating material. At least one end of the inner tube is formed with a (respective) flange connecting the inner and outer tubes.

[0010] Due to its unique structure, the pipe according to the invention facilitates lightweight utilization as part of the primary structure of the respective system, in particular aerospace systems. In that respect, the outer tube serves to transfer the majority of the structural load, while the inner tube is configured to conduct the cryogenic fluid and ensure impermeability to gases. Since the insulating layer is inside the outer tube, its insulating properties are only slightly, if at all, affected by ambient gases such as helium. In particular, the pipe is thermally stabilized.

[0011] Furthermore, since the temperature change of the outer tube during use of the pipe (i.e. when a flow of cryogenic fluid is sent through the pipe) is efficiently reduced by the insulating layer, the outer tube can be attached or combined with a further structure (e.g. to at least one secondary structure) by means of fastening means, which can then be attached to the outer tube without significantly affecting the heat flow to the conducting fluid. Indeed, according to an advantageous embodiment, the tube comprises one or more fastening means for connecting the tube to a further structure. The fastening means may each be fixed to the outer tube or may be formed integrally (monolithically) with the outer tube.

[0012] The pipe may be particularly adapted to be attached to an aerospace system such as a launcher or launcher stage.

[0013] The inner tube preferably has a thermal expansion coefficient of at most 2.5 x 10 measured between 20°C and 90°C. -6 K -1 , or up to 2 × 10 -6 K -1 The inner tube can be made at least in part from a metal alloy, for example an iron alloy, in particular a nickel-iron alloy (such as FeNi36), or a composite material, for example a fiber-reinforced plastic (where the reinforcing fibers can in particular comprise carbon fibers). This minimizes changes in the length of the inner tube, i.e., no significant structural shrinkage occurs, and no compensators are required to adjust for such changes, as in the past. The (average) wall thickness of the inner tube is preferably, for example, at most 8 mm, or at most 5 mm.

[0014] The fiber-reinforced polymer laminate structure of the outer pipe may be different in the longitudinal center and at least one of the end portions connected to the at least one flange. This allows the central region to be adapted to the requirements regarding strength and / or efficient manufacturing of the outer pipe, while still achieving a particularly low coefficient of thermal expansion in the region where the outer pipe contacts the flanges and thus where cooling may occur when the cryogenic fluid is guided through the pipe. This results in a rigid mounting of the pipe and therefore an improved load-bearing capacity.

[0015] To facilitate connection with further pipes, the flange is preferably arranged with one or more through holes and / or threads.

[0016] At least one flange may be integrally formed with the inner pipe. Alternatively, the flange may be materially connected to the inner pipe (e.g., by gluing or welding) and / or fastened to the inner pipe with a form-fitting connection (e.g., by screwing). Additionally or alternatively, the at least one flange may be materially connected to the outer pipe (e.g., by gluing) and / or fastened to the inner pipe with a form-fitting connection. The material of the at least one flange and the material of the inner pipe preferably at least partially coincide. These embodiments facilitate particularly convenient manufacturing of the pipe. To improve the connection with the flange, the outer pipe may have a thickened portion in its material at one or both ends.

[0017] According to an advantageous embodiment, at least one flange comprises a segment (hereinafter also referred to as "bracket portion") surrounding the edge of the insulation layer. This increases the durability of the laminated structure and thus the durability of the pipe. Preferably, a circumferential channel is arranged between the bracket segment and the flat contact segment of at least one flange, which contact segment is configured to be connected to another pipe (in particular its flange). Such a channel advantageously provides access to the contact segment, thereby simplifying connection to another pipe, for example, by inserting a bolt into the respective through-hole and tightening with a nut. To further increase the durability of the pipe, the outer pipe can preferably at least partially cover the bracket segment.

[0018] According to an advantageous embodiment, at least one flange is formed with one or more grooves adapted to receive at least one segment of a respective sealing ring.

[0019] The pipe according to the invention may preferably comprise one or more insulating shells arranged to be placed on at least one flange or arranged to be placed on at least one flange when the latter is connected to another pipe, in particular to the flange, such shells further reducing the heat entering the pipe from the environment through the connection area of ​​the pipes.

[0020] A pipe assembly according to the invention comprises at least two pipes according to the invention (of the same or different embodiments), which are connected or adapted to be connected to each other at their respective flanges.

[0021] An aerospace system according to the invention comprises at least one pipe according to an embodiment of the invention, wherein the at least one pipe forms part of the primary structure of the aerospace system.

[0022] The aerospace system may be, in particular, a launcher or a stage of a multi-stage launcher. The system may include at least one engine configured to be powered by a cryogenic propellant, such as liquid hydrogen. In the system, at least one pipe may be configured to direct the cryogenic propellant to the engine.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which: It will be understood that the various elements and components are shown by way of example only and may be arbitrarily and / or combined in ways different from those shown, and reference numerals of related elements are used generically and are not necessarily redefined in each figure; [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a longitudinal cross-sectional view of a first embodiment of a pipe according to the present invention. [Figure 2a] FIG. 2 is a longitudinal cross-sectional view of an end segment of a second embodiment of a tube according to the present invention. [Figure 2b] FIG. 2b is a side view of the flange of the pipe of FIG. 2a. [Figure 3] 2b shows a pipe assembly comprising two tubes of the embodiment shown in FIG. 2a with an insulating shell placed at the joining flange. [Figure 4] 2 is a view of the tube shown in FIG. 1, further comprising a fixing means on the outer tube. DETAILED DESCRIPTION OF THE INVENTION

[0025] 1 shows a longitudinal section of a pipe 100 according to a first embodiment of the present invention. The pipe 100 comprises a rigid (i.e., hard) outer tube 10 made of a fiber-reinforced polymer (e.g., carbon fiber-reinforced polymer).

[0026] The pipe 100 further comprises a gas-impermeable inner pipe 20 running through the outer pipe 10 and a thermal insulating layer 30 therebetween. The inner pipe 20 may in particular be made at least in part of a metal alloy, for example an iron alloy, in particular a nickel-iron alloy such as FeNi36, or a composite material.

[0027] The (preferably passive) insulating layer 30 is advantageously made from at least partially cured (and therefore rigid) foam.

[0028] At both ends, the pipe 100 includes respective flanges 40, 402 which connect the inner pipe 20 and the outer pipe 10. Both flanges 40, 402 are of identical shape and their respective details are shown in Fig. 1 for flange 40 with a contact segment 41. This contact segment 41 is configured to be connected to another pipe, not shown in Fig. 1, in particular its corresponding flange, by means of bolts (not shown) which pass through through holes H in the contact segment 41, the positions of these bolts being indicated by dashed lines.

[0029] 1, the respective contact segment 41 of each flange 40, 402 is integrally (and therefore monolithically) formed with the inner pipe. According to alternative embodiments, the respective flange may be materially connected (e.g., welded or glued) and / or form-fit (i.e., fastened in a form-fit connection) to the inner pipe 20, for example, by being threaded onto the inner pipe 20.

[0030] 1 are materially connected (e.g., glued) at the thickened end segment 11 of the outer pipe 10, which thickened portion serves to improve the stability of the connection. According to an alternative embodiment, the respective flanges may (additionally or alternatively) be joined to the outer pipe (not shown) by a form-fit connection.

[0031] 2a shows in cross section an end segment of a pipe 100' according to a further embodiment of the invention. The opposite end of the pipe 100', not shown, can preferably be designed similarly to the end shown.

[0032] The pipe 100' comprises a rigid (and therefore stiff) outer pipe 10' made of a fiber-reinforced polymer (e.g., carbon fiber-reinforced polymer) and a gas-impermeable inner pipe 20' passing through the outer pipe 10', with a thermal insulating layer 30' interposed therebetween. The inner pipe 20' may in particular be made at least in part from a metal alloy, for example an iron alloy, in particular a nickel-iron alloy such as FeNi36, or a composite material, in particular a fiber-reinforced plastic, more particularly a carbon fiber-reinforced plastic.

[0033] A flange 40' connects the inner pipe 20' and the outer pipe 10'. Figure 2b shows only the flange 40' of the pipe 100' in side view.

[0034] 2a and 2b, flange 40' comprises a flat contact segment 41' configured to be connected to another pipe (not shown in those figures), in particular to its corresponding flange. An annular groove G formed in contact segment 41' serves to receive at least a part of a sealing ring (not shown) to ensure an airtight connection between pipe 100' and the other pipe.

[0035] The flange 40' further comprises a bracket segment 42' that surrounds the edge 31' of the insulation layer 30'. The bracket segment 42' is separated from the contact segment 41' by a circumferential channel C and is covered by an end segment of the outer pipe 10' that extends into the channel C.

[0036] At the end of the pipe 100', the stack of the insulating layer 30', the bracket segment 42' and the outer pipe 10' thus established ensures a particularly high durability of the pipe 100'. Furthermore, the channel C provides access to the through-holes H of the contact segment 41'. As a result, the pipe 100', in its finished state, can be easily connected to another pipe by means of bolts (not shown) inserted into the through-holes H, as shown by the respective dashed lines in Fig. 2a.

[0037] Figure 3 shows a segment of a pipe assembly 1000 according to the present invention, consisting of the pipe 100' depicted in Figure 2a and connected to another pipe 1002' of the same shape. The top of Figure 3 shows a side view of the connection, and the bottom of Figure 3 shows a cross-sectional view, showing the respective inner pipes 20', 202' and insulation layers 30', 302', as well as the sealing rings 50' inserted in the respective grooves G in the mating flanges 40', 402'.

[0038] Additionally, an insulating shell 60' is disposed over the connected flanges 40', 402'. Preferably, the insulating shell 60' is combined with at least one additional insulating shell (not shown) to completely surround the connecting ends of the pipes 100', 1002', thereby further reducing heat flow from the environment to the fluid (not shown) flowing through the connected pipes 100', 1002'.

[0039] 4 depicts an end segment of the pipe 100 shown in FIG. 1 with fastening means 70, 702 secured to the outer pipe 10. The fastening means may serve to attach the pipe 100 to a respective structure (not shown), such as an aerospace system, and / or to secure a secondary structure (not shown) to the pipe 100.

[0040] Disclosed is a pipe 100, 100', 1002' for transporting a cryogenic fluid. The pipe comprises a rigid outer tube 10, 10', 102' made at least in part of a fiber-reinforced polymer, a gas-impermeable inner tube 20, 20', 202' running through the outer tube 10, 10', 102', a thermal insulation layer 30, 30', 302' disposed between the inner tube 20, 20', 202' and the outer tube, and at least one flange 40, 40', 402' formed at each end of the inner tube 20, 20', 202'. The at least one flange 40, 40', 402' connects the inner tube 20, 20', 202' to the outer tube 10, 10', 102'.

[0041] Further disclosed is a pipe assembly 1000 including at least two pipes 100, 100', 1002' connected or configured to be connected at respective flanges 40, 40', 402', and an aerospace system including at least one such pipe 100, 100', 1002'. [Explanation of symbols]

[0042] 10,10',102' outer tube 20,20',202' inner tube 30,30',302' insulation layer 31' Edge of insulation layer 40, 40', 402' flange 41,41' flange contact segments 42' Flange Bracket Segment 50' Seal Ring 60' Insulated Shell 100,100',1002' pipe 1000 Pipe Assembly C channel G groove H through hole

Claims

1. Pipes (100, 100', 100) for conveying cryogenic fluids ２ ') and The pipe is - a rigid outer tube (10, 10', 10) made at least partly of fiber-reinforced polymer ２ '), - the outer tube (10, 10', 10 ２ A gas-impermeable inner tube (20, 20', 20') passes through the ２ '), - the inner tube (20, 20', 20 ２ ') and the outer tube (10, 10', 10 ２ The insulating layers (30, 30', 30') are arranged between the insulating layers (30, 30', 30'). ２ '), and - the inner tube (20, 20', 20 ２ At least one flange (40, 40', 40') formed at each end of the ２ '), and the inner tube (20, 20', 20 ２ ') to the outer tube (10, 10', 10 ２ said at least one flange (40, 40', 40') connecting to said ２ ') equipped with a pipe.

2. The at least one flange (40, 40') - being integrally formed with said inner tube (20) or being materially connected to said inner tube (20') and / or being form-fittingly connected to said inner tube; and / or A pipe according to claim 1, which is materially connected to said outer pipe (10, 10') and / or form-fittingly connected to said outer pipe.

3. 3. A pipe according to claim 1 or 2, wherein the material of said at least one flange (40, 40') and the material of said inner pipe (20, 20') at least partially coincide.

4. The inner tube (20, 20') - the wall thickness is at most 8 mm or at most 5 mm, The thermal expansion coefficient measured between -20°C and 90°C is a maximum of 2.5 x 10 －６ K －１ Or a maximum of 2 x 10 －６ K －１ and / or A pipe according to any one of claims 1 to 3, made at least partly from a metal alloy, for example an iron alloy, in particular a nickel-iron alloy, or a composite material, in particular a carbon-fiber-reinforced plastic.

5. A pipe according to any one of the preceding claims, wherein the at least one flange (40, 40') comprises a bracket segment (42') surrounding an edge (31') of the insulation layer (30').

6. The bracket segment (42') is separated from a flat contact segment (41') of the at least one flange (40') by a circumferential channel (C), the contact segment (41') being connected to another pipe (100 ２ 6. The pipe of claim 5, adapted to be connected to a casing.

7. A pipe according to claim 5 or 6, wherein the outer pipe (10') covers at least a portion of the bracket segment (42').

8. A pipe according to any one of the preceding claims, wherein the insulating layer (30, 30') consists at least partly of rigid foam.

9. The at least one flange (40, 40') is connected to another pipe (100 ２ 9. A pipe according to any one of claims 1 to 8, which is provided with at least one through hole (H) and / or at least one thread for connection to a pipe with a tubular member (1').

10. 10. A pipe according to any one of the preceding claims, wherein said at least one flange (40') is formed with one or more grooves (G) adapted to receive at least a portion of a respective sealing ring (50').

11. Another pipe (100 ２ 11. A pipe according to any one of claims 1 to 10, further comprising one or more insulating shells (60') disposed or configured to be disposed on said at least one flange (40, 40') when said pipe is connected to said at least one flange (40, 40').

12. One or more fastening means (70, 70) for joining the pipe to another structure. ２ 12. A pipe according to any one of the preceding claims, further comprising a fixing means (100) fixed to the outer pipe (100) or integrally formed therewith.

13. At least two pipes (100', 100') according to any one of claims 1 to 12 ２ These pipes are provided with respective flanges (40', 40'). ２ 10. A pipe assembly (1000) connected or configured to be connected by a

14. At least one pipe (100, 100', 100) according to any one of claims 1 to 12 ２ '), wherein the pipe forms part of the primary structure of the aerospace system.

15. 15. The aerospace system of claim 14, wherein the aerospace system is a launcher or a stage of a multi-stage launcher and comprises at least one engine configured to be powered by cryogenic propellant supplied through the at least one pipe.

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