Hydrogen aircraft

Abstract

This hydrogen aircraft comprises: a fuselage; a hydrogen tank that is disposed inside the fuselage and stores liquid hydrogen; a cabin that is disposed inside the fuselage and accommodates occupants; and a supply pipe that connects the hydrogen tank and a supply destination of the liquid hydrogen and is disposed outside the cabin.

Description

Hydrogen aircraft

[0008] ,

[0001] The present disclosure relates to a hydrogen aircraft that flies using hydrogen as an energy source.

[0002] For example, a hydrogen aircraft that flies using hydrogen as an energy source, as shown in Patent Document 1, is known. In a hydrogen aircraft, it is necessary to mount a hydrogen fuel tank for storing liquid hydrogen on the aircraft body. In an aircraft using ordinary fuel, fuel tanks are arranged on the main wings of the aircraft body. In contrast, in a hydrogen aircraft, due to the requirements of the tank structure, the hydrogen fuel tank is often arranged inside the fuselage of the aircraft body. The hydrogen fuel tank inside the fuselage and the engine of the main wing are connected by a fuel supply pipe, and liquid hydrogen is supplied through the fuel supply pipe.

[0003] It is difficult to completely protect against all events so that damage or the like does not occur in the fuel supply pipe for transferring liquid hydrogen. Therefore, it is desirable to assume the leakage of liquid hydrogen from the fuel supply pipe. In the fuselage of a hydrogen aircraft where a hydrogen fuel tank is arranged, there is a cabin for accommodating passengers on the hydrogen aircraft, such as a passenger cabin and a cockpit. Even if leakage of liquid hydrogen occurs from the fuel supply pipe, a piping arrangement that does not affect the cabin as much as possible is desired.

[0004] Japanese Patent Application Laid-Open No. 2023-182235

[0005] An object of the present disclosure is to provide a hydrogen aircraft provided with a liquid hydrogen supply system capable of suppressing the influence on the cabin even when leakage of liquid hydrogen occurs.

[0006] A hydrogen aircraft according to an aspect of the present disclosure includes a fuselage, a hydrogen tank arranged inside the fuselage for storing liquid hydrogen, a cabin arranged inside the fuselage for accommodating passengers, and a supply pipe connecting the hydrogen tank and the supply destination of the liquid hydrogen, the supply pipe being arranged outside the cabin.

[0007] According to the present disclosure, it is possible to provide a hydrogen aircraft provided with a liquid hydrogen supply system capable of suppressing the influence on the cabin even when leakage of liquid hydrogen occurs.

[0008] Figure 1 is a perspective view showing a hydrogen aircraft according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view of the fuselage of a hydrogen aircraft according to the first embodiment, taken along the line II-II in Figure 3. Figure 3 is a schematic plan view of a hydrogen aircraft showing the piping route of the supply piping in the first embodiment. Figure 4 is a schematic side cross-sectional view along the line IV-IV in Figure 3. Figure 5 is a cross-sectional view of the fuselage of a hydrogen aircraft according to the second embodiment, taken along the line V-V in Figure 6. Figure 6 is a schematic plan view of a hydrogen aircraft showing the piping route of the supply piping in the second embodiment. Figure 7 is a schematic side cross-sectional view along the line VII-VII in Figure 6. Figure 8 is a cross-sectional view of the fuselage of a hydrogen aircraft according to the third embodiment, taken along the line VIII-VIII in Figure 9. Figure 9 is a schematic plan view of a hydrogen aircraft showing the piping route of the supply piping in the third embodiment. Figure 10 is a schematic side cross-sectional view along the line X-X in Figure 9. Figure 11 is a cross-sectional view showing various modifications of the hydrogen aircraft according to the second embodiment. Figure 12 is a perspective view showing an embodiment of a wall structure equipped with a ventilation system. Figure 13 is a diagram showing a modified example of the hydrogen aircraft of the third embodiment.

[0009] The following describes in detail various embodiments of the hydrogen aircraft relating to this disclosure. This disclosure includes an airframe comprising a fuselage and wings, and a propulsion system for flight, and is applicable to various aircraft in which the propulsion system uses liquid hydrogen as an energy source. The propulsion system is not limited insofar as it uses liquid hydrogen or vaporized hydrogen as an energy source. Examples of the propulsion system include a hydrogen combustion gas turbine engine, an electric propulsion system consisting of a combination of a fuel cell and an electric motor, or a hybrid propulsion system of the gas turbine engine and the electric propulsion system.

[0010] [Overview of Hydrogen Aircraft] Figure 1 is a perspective view showing a hydrogen aircraft 1 according to one embodiment of the present disclosure. The front, rear, left, and right direction indicators shown in Figure 1 are aligned with the direction when the hydrogen aircraft 1 is viewed from above and the nose side is defined as the front. The hydrogen aircraft 1 includes an airframe 10 and an engine 14, fuel supply piping 15, a hydrogen fuel tank 2 mounted at the rear of the fuselage 11 of the airframe 10, and a cabin 3 located inside the fuselage 11. Note that the mounting position of the hydrogen fuel tank 2 is not limited to the rear of the fuselage 11, and one or more may be placed at appropriate locations on the fuselage 11.

[0011] The aircraft 10 comprises a fuselage 11, a pair of left and right main wings 12, and a tail wing 13. The fuselage 11 is composed of fuselage panels 11W, as shown in Figure 2 below. The fuselage panels 11W include structural members such as circular frames and stringers, and a cylindrically assembled skin. The pair of main wings 12 include spars and flaps and extend laterally from the fuselage 11. The tail wing 13 is located at the end of the fuselage 11 and consists of a vertical stabilizer and a horizontal stabilizer. The engine 14 is, for example, a hydrogen combustion gas turbine engine that uses liquid hydrogen as fuel. The engine 14 is fixed to each of the pair of main wings 12. The engine 14 is an example of a liquid hydrogen supply destination in this disclosure. Note that an APU (Auxiliary Power Unit) may also be included as a liquid hydrogen supply destination.

[0012] The hydrogen fuel tank 2 is an example of a hydrogen tank according to this disclosure and stores liquid hydrogen LH, which is the fuel for the engine 14. The hydrogen fuel tank 2 is located inside the fuselage 11. As long as it is inside the fuselage 11, there are no restrictions on the location of the hydrogen fuel tank 2. In the example shown in Figure 1, the hydrogen fuel tank 2 is located in a storage compartment provided at the rear end of the fuselage 11. The storage area is a space outside the pressurized area, separated from the cabin 3 by a bulkhead. The hydrogen fuel tank 2 may also be located inside the pressurized area. There are no particular restrictions on the shape of the hydrogen fuel tank 2. In the example shown in Figure 1, the hydrogen fuel tank 2 has a cylindrical shape that is long in the front-rear direction of the fuselage 11. To maintain the coolness of the stored liquid hydrogen, it is desirable to use a hydrogen fuel tank 2 with a multi-shell structure. For example, as the hydrogen fuel tank 2, a tank with a double-shell structure comprising an inner tank and an outer tank, and a vacuum insulation layer between the inner tank and the outer tank can be used.

[0013] The fuel supply pipe 15 connects the hydrogen fuel tank 2 to the left and right engines 14. The fuel supply pipe 15 is an example of the supply pipe of this disclosure. As the fuel supply pipe 15, a pipe with an insulating structure such as a vacuum double pipe can be used to suppress the temperature rise of liquid hydrogen LH. To ensure redundancy, the fuel supply pipe 15 leading to each engine 14 may be doubled. A booster pump 16 that sends liquid hydrogen LH from the hydrogen fuel tank 2 is provided in the fuel supply pipe 15. The liquid hydrogen LH stored in the hydrogen fuel tank 2 is supplied to each of the engines 14 through the fuel supply pipe 15. The hydrogen tank of this disclosure may be a tank that stores liquefied hydrogen used for purposes other than as fuel for the engines 14. The supply pipe may also be a pipe for supplying liquid hydrogen to equipment other than the engines 14.

[0014] Cabin 3 is located within the fuselage 11. Cabin 3 is a pressurized space for accommodating passengers on the hydrogen aircraft 1. Passengers include crew and passengers. In other words, as used herein, Cabin 3 refers to spaces within the fuselage 11 where people are expected to enter and exit during the operation of the hydrogen aircraft 1, such as the passenger cabin, cockpit, and crew-only space.

[0015] The hydrogen fuel tank 2 is located within the fuselage 11, which encloses the cabin 3. On the other hand, the engine 14 is located on the main wing 12. In other words, at least a portion of the fuel supply piping 15 must be routed within the fuselage 11. For this reason, when designing the hydrogen aircraft 1, there is a high possibility that the area designated as the route for routing the fuel supply piping 15 within the fuselage 11 will overlap with the area of ​​the cabin 3, which is inherently located within the fuselage 11. The strength and structure of the fuel supply piping 15, including the pipe body and joints, are designed to withstand anticipated impacts and fluctuations in temperature and pressure. However, it is also desirable to anticipate leakage of liquid hydrogen LH from the fuel supply piping 15. If liquid hydrogen LH leaks, problems such as the scattering of liquid hydrogen with extremely low temperatures, the generation of liquefied air due to the cooling of air by the scattered liquid hydrogen, the embrittlement of surrounding materials by the scattered liquid hydrogen, and the creation of an environment where ignition can occur as the scattered liquid hydrogen vaporizes can occur. Therefore, in the hydrogen aircraft 1, it is desirable to have a piping configuration that can prevent liquid hydrogen LH from leaking into the cabin 3 even if it leaks from the fuel supply pipe 15, that is, a piping configuration that does not affect the passengers in the cabin 3. Specific examples of such piping configurations are listed below.

[0016] [First Embodiment] Figure 2 is a left-right cross-sectional view of the fuselage 11 of the hydrogen aircraft 1A according to the first embodiment. Figure 3 is a schematic plan view of the hydrogen aircraft 1A showing the piping route of the fuel supply piping 15 in the first embodiment. Figure 2 is a cross-sectional view taken along line II-II in Figure 3. Figure 4 is a schematic side cross-sectional view taken along line IV-IV in Figure 3. The left-right direction indications in Figures 2 to 4 and the subsequent figures correspond to the direction indications in Figure 1. The up-down direction indications are based on the direction when the hydrogen aircraft 1A is on the ground. In the first embodiment and the second embodiment described below, examples are shown in which the fuel supply piping 15 is arranged inside the fuselage 11.

[0017] The upper part of the fuselage 11 is the cabin 3, and the lower part is the cargo compartment 4. The cargo compartment 4 is a space located inside the fuselage 11 for storing passenger luggage and cargo. The cabin 3 is partitioned by a floor 31, sides 32, and ceiling 33. The floor 31 is a plane that extends horizontally, located slightly below the vertical center of the fuselage 11. When the hydrogen aircraft 1A is on the ground, the floor 31 is generally a horizontal plane. Multiple seats 34 for passengers are mounted on the floor 31. Figure 2 shows an example in which three sets of three-seat rows 34 are arranged on either side of an aisle.

[0018] The side surfaces 32 are walls located to the left and right of the floor surface 31. The ceiling surface 33 is a wall located above the floor surface 31. A central luggage compartment 35 is located in the central area of ​​the ceiling surface 33 in the left-right direction. Side luggage compartments 36 are located to the left and right of the area where the central luggage compartment 35 is located on the ceiling surface 33. The central luggage compartment 35 and the side luggage compartments 36 include a space for storing passengers' luggage. The central luggage compartment 35 is opened and closed by operating the central hatch 351. The left and right side luggage compartments 36 are opened and closed by operating their respective side hatches 361. There is a back wall 352 at the rear of the central luggage compartment 35. The back wall 352 separates the luggage storage space of the central luggage compartment 35 from the space above it. There is also a back wall 362 at the rear of each side luggage compartment 36. The rear wall 362 separates the space for storing luggage in the side luggage box 36 from the space above that space. Because the rear walls 352 and 362 separate the respective spaces, the cabin 3 can maintain a closed space even when the central hatch 351 or the side hatch 361 is opened.

[0019] The cargo compartment 4 is installed using the space within the fuselage 11 located below the floor surface 31. The cargo compartment 4 is equipped with stanchions 41 that extend vertically and a cargo compartment floor 42 that is a flat surface extending horizontally. The stanchions 41 are columnar support members that support the floor surface 31 from below. Luggage and cargo brought into the cargo compartment 4 are placed on the cargo compartment floor 42.

[0020] The fuel supply pipe 15 is located inside the fuselage 11 and outside the cabin 3. In the first embodiment, the fuel supply pipe 15 is located below the floor surface 31. More specifically, the fuel supply pipe 15 is located below the floor surface 31 near the right or left side surface 32, in the lateral direction inward of the fuselage panel 11W and outward of the lateral direction outward of the stanchion 41. In other words, the fuel supply pipe 15 passes through a first space R1 partitioned by the floor surface 31, the stanchion 41 and the fuselage panel 11W of the side surface 32. Figure 2 shows an example in which the fuel supply pipe 15 is located in the first space R1 set outside the left stanchion 41. The fuel supply pipe 15 may also be located in the space outside the right stanchion 41, or in the space outside both the left and right stanchions 41.

[0021] Referring to Figures 3 and 4, the hydrogen aircraft 1A of the first embodiment includes a first hydrogen fuel tank 2A ​​and a second hydrogen fuel tank 2B as tanks corresponding to the hydrogen fuel tank 2 in Figure 1. The hydrogen aircraft 1A also includes a first supply pipe 15A and a second supply pipe 15B as piping corresponding to the fuel supply pipe 15 in Figure 1. The first hydrogen fuel tank 2A ​​is located in the rear region of the fuselage 11. The second hydrogen fuel tank 2B is located in the front region of the fuselage 11. Liquid hydrogen is supplied as fuel from the first hydrogen fuel tank 2A ​​and the second hydrogen fuel tank 2B to a pair of left and right engines 14 through the first supply pipe 15A and the second supply pipe 15B.

[0022] The first supply pipe 15A connects the first hydrogen fuel tank 2A ​​to the left and right pair of engines 14. The first supply pipe 15A includes a front and rear piping section 151 that is arranged along the front and rear of the fuselage 11. The front and rear piping section 151 extends linearly in the front-rear direction on the left side of the fuselage 11. Figure 2 shows a cross-section of the front and rear piping section 151 of the first supply pipe 15A. The second supply pipe 15B connects the second hydrogen fuel tank 2B to the left and right pair of engines 14. The second supply pipe 15B also includes a front and rear piping section 152 that is arranged along the front and rear of the fuselage 11. The front and rear piping section 152 extends linearly in the front-rear direction on the right side of the fuselage 11. The front and rear piping section 152 of the second supply pipe 15B passes through the space partitioned by the right-side stanchion 41, the floor surface 31, and the fuselage panel 11W.

[0023] In the hydrogen aircraft 1A of the first embodiment, the fuel supply piping 15, including the first supply pipe 15A and the second supply pipe 15B, is located inside the fuselage 11. Therefore, it is not necessary to provide radial protrusions on the outer circumference of the fuselage 11 to accommodate the fuel supply piping 15. In other words, it is unnecessary to provide protrusions on the surface of the fuselage 11 that would worsen the aerodynamic performance of the hydrogen aircraft 1A in order to supply fuel.

[0024] Furthermore, according to the hydrogen aircraft 1A of the first embodiment, the fuel supply piping 15 can be installed by effectively utilizing the dead space within the fuselage 11. Normally, the cross-section of the fuselage 11 is circular due to structural strength and aerodynamic requirements. In contrast, the floor surface 31 of the cabin 3 is generally a substantially horizontal plane. In other words, a floor material that extends horizontally and has a substantially horizontal surface on its upper surface that becomes the floor surface 31 is placed inside the fuselage 11, which is a structure with a circular cross-section. For this reason, dead space tends to occur below the floor surface 31. In the first embodiment, the fuel supply piping 15 is installed by utilizing the first space R1 to the side of the stanchion 41. The first space R1 is a narrow space near the corner below the floor surface 31 and is particularly prone to becoming dead space. In the first embodiment, by installing the fuel supply piping 15 in the first space R1, the dead space can be effectively utilized. The lower surface of the floor material is the surface that partitions the cargo compartment 4 and is a flat surface or an uneven surface to which equipment is attached.

[0025] Furthermore, since the fuel supply piping 15 is located below the floor 31, even if liquid hydrogen leaks from the fuel supply piping 15, the impact on the cabin 3, especially on the passengers, can be minimized. If the fuel supply piping 15 is damaged, the liquid hydrogen inside the fuel supply piping 15 may leak to the outside, and as a byproduct, gaseous hydrogen or liquefied air may be generated. Even in this case, since the fuel supply piping 15 is located below the cabin 3, the possibility of the leaked liquid hydrogen or liquefied air entering the cabin 3 due to gravity is low. In addition, by not only enclosing the cabin 3 with the floor 31, sides 32 and ceiling 33, but also by strengthening the airtightness of the cabin 3, it is possible to suppress the entry of gaseous hydrogen into the cabin 3.

[0026] [Second Embodiment] Figure 5 is a left-right cross-sectional view of the fuselage 11 of the hydrogen aircraft 1B according to the second embodiment. Figure 6 is a schematic plan view of the hydrogen aircraft 1B showing the piping route of the fuel supply piping 15 in the second embodiment. Figure 5 is a cross-sectional view taken along line V-V in Figure 6. Figure 7 is a schematic side cross-sectional view taken along line VII-VII in Figure 6.

[0027] The cabin 3 and cargo compartment 4 are located inside the fuselage 11. The cross-sectional structure of the fuselage 11 is the same as that of the first embodiment shown in Figure 2, so a detailed explanation is omitted here. In the second embodiment as well, the fuel supply piping 15 is located inside the fuselage 11 and outside the cabin 3. In the second embodiment, the fuel supply piping 15 is located above the ceiling surface 33. More specifically, the fuel supply piping 15 is located approximately in the left-right center of the fuselage 11, between the rear wall 352 of the central cargo box 35 and the vertically inward side of the fuselage panel 11W. In other words, the fuel supply piping 15 passes through the second space R2 partitioned by the ceiling surface 33, the rear walls 352 and 362, and the upper shell of the fuselage panel 11W.

[0028] Figure 5 shows an example in which the fuel supply piping 15 is positioned directly above the central luggage box 35 in the second space R2. Alternatively, the fuel supply piping 15 may be positioned above the left side luggage box 36, above the ceiling surface 33 between the left or right rear wall 362 and the central rear wall 352, or above the right side luggage box 36.

[0029] Referring to Figures 6 and 7, the hydrogen aircraft 1B, similar to the first embodiment, includes a first hydrogen fuel tank 2A ​​and a second hydrogen fuel tank 2B, and a first supply pipe 15A and a second supply pipe 15B as fuel supply piping 15. Liquid hydrogen is supplied as fuel from the first hydrogen fuel tank 2A ​​and the second hydrogen fuel tank 2B to a pair of left and right engines 14 through the first supply pipe 15A and the second supply pipe 15B.

[0030] The first supply pipe 15A connects the first hydrogen fuel tank 2A ​​to the left and right pair of engines 14. The first supply pipe 15A includes a front and rear piping section 151 that is arranged along the front and rear of the fuselage 11. The front and rear piping section 151 extends linearly in the front-rear direction near the upper end of the left-right center of the fuselage 11. Figure 5 shows a cross-section of the front and rear piping section 151 of the first supply pipe 15A. The second supply pipe 15B connects the second hydrogen fuel tank 2B to the left and right pair of engines 14. The second supply pipe 15B also includes a front and rear piping section 152 that is arranged along the front and rear near the upper end of the left-right center of the fuselage 11.

[0031] According to the hydrogen aircraft 1B of the second embodiment, the fuel supply piping 15 can be installed by effectively utilizing the dead space above the ceiling surface 33 of the cabin 3. The space below the floor surface 31 of the cabin 3 is often used as a cargo compartment. The space next to the stanchion 41, which was utilized in the first embodiment, may also be used as part of the cargo compartment or as a place to install equipment. According to the second embodiment, for example, if space for piping cannot be secured below the floor surface 31, the fuel supply piping 15 can be installed by utilizing the space above the ceiling surface 33.

[0032] [Third Embodiment] Figure 8 is a left-right cross-sectional view of the fuselage 11 of the hydrogen aircraft 1C according to the third embodiment. Figure 9 is a schematic plan view of the hydrogen aircraft 1C showing the piping route of the fuel supply piping 15 in the third embodiment. Figure 8 is a cross-sectional view taken along line VIII-VIII in Figure 9. Figure 9 is a schematic side cross-sectional view taken along line X-X in Figure 8. In the third embodiment, an example is shown in which the fuel supply piping 15 is located outside the fuselage 11.

[0033] The cross-sectional structure of the fuselage 11 is the same as that of the first embodiment shown in Figure 2, so a detailed explanation is omitted here. In the third embodiment, unlike the first and second embodiments, the fuel supply pipe 15 is located outside the cabin 3 and outside the fuselage 11. More specifically, the fuel supply pipe 15 is located outside the side surface 32 of the fuselage 11 and below the floor surface 31 of the cabin 3. The area around the fuel supply pipe 15 is covered by a fairing 37. By arranging the fuel supply pipe 15 outside the fuselage 11, a protrusion is formed on the surface of the fuselage 11, but the aerodynamic shape can be maintained by attaching the fairing 37.

[0034] Figure 8 shows an example where the fuel supply pipe 15 is located on the outside of the left side surface 32 of the fuselage 11. There are no particular restrictions on the location of the fuel supply pipe 15 on the outer circumferential surface of the fuselage 11. The fuel supply pipe 15 may be located on the outside of the top surface 33 of the fuselage 11, on the outside of the right side surface 32, or on the outside of the bottom surface, etc. Furthermore, there may be multiple fuel supply pipes 15 located on the outer circumferential surface of the fuselage 11, as long as the degree of aerodynamic influence due to the shape of the fuselage 11 is not excessive.

[0035] Referring to Figures 9 and 10, the hydrogen aircraft 1C, similar to the first embodiment, includes a first hydrogen fuel tank 2A ​​and a second hydrogen fuel tank 2B, and a first supply pipe 15A and a second supply pipe 15B as fuel supply piping 15. Liquid hydrogen is supplied as fuel from the first hydrogen fuel tank 2A ​​and the second hydrogen fuel tank 2B to a pair of left and right engines 14 through the first supply pipe 15A and the second supply pipe 15B.

[0036] The first supply pipe 15A connects the first hydrogen fuel tank 2A ​​to a pair of left and right engines 14. The first supply pipe 15A includes a front and rear piping section 151 that is arranged along the front and rear of the fuselage 11. The front and rear piping section 151 extends linearly in the front-rear direction on the outside of the left side of the fuselage 11. Figure 8 shows a cross-section of the front and rear piping section 151 of the first supply pipe 15A. The second supply pipe 15B connects the second hydrogen fuel tank 2B to a pair of left and right engines 14. The second supply pipe 15B includes a front and rear piping section 152 that is arranged along the front and rear on the outside of the right side of the fuselage 11.

[0037] In the third embodiment of the hydrogen aircraft 1C, the fuel supply piping 15 is located outside the fuselage 11. Therefore, even if liquid hydrogen leaks from the fuel supply piping 15, at least the fuselage panel 11W of the fuselage 11 is present between the fuel supply piping 15 and the cabin 3. Thus, the entry of liquid or gaseous hydrogen into the cabin 3 can be suppressed.

[0038] [Modification 1] Figure 11 is a cross-sectional view showing various modifications of the hydrogen aircraft 1B of the second embodiment. In the hydrogen aircraft 1B, the fuel supply pipe 15 is located in a predetermined piping area PA in the second space R2 located above the ceiling surface 33 of the cabin 3. In the event that liquefied hydrogen leaks from the fuel supply pipe 15, it is assumed that liquid hydrogen will enter the cabin 3 through gaps in the ceiling surface 33, etc. In view of this, it is desirable to place a liquid receiver 51 between the fuel supply pipe 15 and the ceiling surface 33 to receive the liquid leaking from the fuel supply pipe 15.

[0039] The liquid receiver 51 has a trough-shaped cross-section with an open top. The liquid receiver 51 extends below the fuel supply pipe 15, along the direction in which the fuel supply pipe 15 extends. Even if liquid hydrogen leaks from the fuel supply pipe 15, the liquid receiver 51 will receive the leaked liquid hydrogen. Therefore, the scattering of liquid hydrogen and its entry into the cabin 3 can be suppressed. Furthermore, even if the heat insulation structure of the fuel supply pipe 15 is damaged and liquefied air is generated around the fuel supply pipe 15, the liquid receiver 51 will also receive this liquefied air. Therefore, the scattering of liquefied air and its entry into the cabin 3 can also be suppressed. There are no restrictions on the shape of the liquid receiver 51 as long as it can receive and store the liquid hydrogen falling from the fuel supply pipe 15. However, it is desirable that the liquid receiver 51 be made of a material that does not become brittle upon contact with liquid hydrogen.

[0040] Figure 11 shows four specific configuration examples of a piping area PA equipped with a liquid hydrogen receiving function, namely the first configuration example PA1 to the fourth configuration example PA4. In the first configuration example PA1, a flat tray 51A, which serves as a liquid receiver, is positioned below the fuel supply piping 15. The flat tray 51A includes a bottom piece 511 and side pieces 512. The bottom piece 511 is a flat plate located directly below the fuel supply piping 15. The side pieces 512 rise diagonally upward from both sides of the bottom piece 511.

[0041] The height of the upper end of the side piece 512 is set such that even if the hydrogen aircraft 1B tilts within the allowable tilt range, the liquid hydrogen stored in the flat tray 51A will not leak out. Let L1 be a horizontal line passing through the axis of the fuel supply pipe 15, L2 be a line connecting the upper end of the side piece 512 and the circumferential surface of the fuel supply pipe 15, and L3 be a line perpendicular to line L2 and passing through the axis. The angle between lines L1 and L3 is set to the tilt range angle AN, for example, 60 degrees, which is defined for the bank attitude of the hydrogen aircraft 1B.

[0042] The second configuration example PA2 is an example in which a U-shaped tray 52, which serves as a liquid receiver, is positioned below the fuel supply pipe 15. The bottom portion of the U-shaped tray 52 facing the fuel supply pipe 15 is a curved surface that is convex downwards. A pair of side pieces 521 of the U-shaped tray 52 sandwich the fuel supply pipe 15. The height of the upper end of the side pieces 521 is higher than the upper end of the fuel supply pipe 15.

[0043] The third configuration example PA3 is an example of a wall structure 6 that covers at least a portion of the outer circumference in the longitudinal direction of the fuel supply pipe 15. The wall structure 6 has a duct-like structure with a rectangular cross-section and forms a substantially sealed internal space R3. The fuel supply pipe 15 is housed in the internal space R3. Even if liquid hydrogen leaks from the fuel supply pipe 15, the leaked liquid hydrogen can be received at the bottom of the wall structure 6. Furthermore, even if the leaked liquid hydrogen vaporizes and gaseous hydrogen is generated, the diffusion of the gaseous hydrogen can be suppressed because the area around the fuel supply pipe 15 is surrounded by the wall structure 6.

[0044] The fourth configuration example PA4 is an example of filling the periphery of the fuel supply pipe 15 with an inert gas. In the fourth configuration example PA4, the hydrogen aircraft 1B includes an inert gas supply source 63. The periphery of the fuel supply pipe 15 is covered by a wall structure 6A. The wall structure 6A is provided with an air inlet 61 and an exhaust port 62. An inert gas such as nitrogen gas or helium gas is supplied from the inert gas supply source 63 into the interior of the wall structure 6A through the air inlet 61. By this supply, the internal space R4, which is the space between the inner surface of the wall structure 6A and the outer peripheral surface of the fuel supply pipe 15, is filled with an inert gas. A part of the inert gas filled in the internal space R4 is discharged from the internal space R4 through the exhaust port 62. When the airtightness of the wall structure 6A is high, after filling the internal space R4 with an inert gas, the air inlet 61 and the exhaust port 62 may be closed. When the internal space R4 is filled with an inert gas and the air inlet 61 and the exhaust port 62 are closed, it is not essential to permanently install the inert gas supply source 63 in the hydrogen aircraft 1B.

[0045] According to the fourth configuration example PA4, even if leakage of liquid hydrogen occurs from the fuel supply pipe 15, the leaked liquid hydrogen can be received at the bottom of the wall structure 6A. Further, since the leakage destination of the liquid hydrogen is the internal space R4 where oxygen does not exist or oxygen is dilute, even if gaseous hydrogen is generated, ignition can be suppressed. Note that any one of the above-described first configuration example PA1 to fourth configuration example PA4 may be applied to the location where the fuel supply pipe 15 is disposed in the first embodiment. In this case, instead of the stand 41, a wall member that makes the first space R1 a substantially sealed space may be attached to form a wall structure.

[0046] [Modification Example 2] FIG. 12 is a perspective view showing a modification example in which a ventilation device is attached to a wall structure covering the fuel supply pipe 15. The fuel supply pipe 15 includes a portion accommodated in an internal space R5 of a cylindrical wall structure 6B. An intake duct 64 is disposed at one end of the wall structure 6B, and an exhaust duct 65 is disposed at the other end. The intake duct 64 and the exhaust duct 65 are openings that communicate the internal space R of the wall structure 6B with the outside.

[0047] As a ventilation device, an intake fan 71 is assembled to the intake duct 64, and an exhaust fan 72 is assembled to the exhaust duct 65, respectively. By driving the intake fan 71, external air is taken into the internal space R5 of the wall structure 6B. By driving the exhaust fan 72, the exhaust of the gas from the internal space R5 is promoted. That is, by the operation of the intake fan 71 and the exhaust fan 72, the space between the inner surface of the wall structure 6B and the outer peripheral surface of the fuel supply pipe 15 is ventilated.

[0048] By performing the above ventilation, air can be continuously sent into the internal space R5 constantly or in an emergency. Therefore, even if leakage of liquid hydrogen occurs from the fuel supply pipe 15, it is possible to prevent the occurrence of a state where hydrogen and oxygen are in a specific ratio that ignites. The intake fan 71 and the exhaust fan 72 may be applied to the supply and exhaust of inert gas in the fourth configuration example PA4 shown in FIG. 11.

[0049] [Modification 3] FIG. 13 is a diagram showing a modification of the hydrogen aircraft 1C of the third embodiment. In the hydrogen aircraft 1C, the fuel supply pipe 15 includes a portion piped outside the fuselage 11. For example, the front and rear piping portions 151 of the first supply pipe 15A are disposed on the outer peripheral surface of the fuselage 11. In Modification 3, an example is shown in which an air intake opening 371 and an air outlet opening 372 are provided in a fairing 37A that covers the front and rear piping portions 151. The air intake opening 371 is an opening for taking in air in the fairing 37A. The air outlet opening 372 is an opening for discharging air in the fairing 37A. The longitudinal direction of the fairing 37A is along the longitudinal direction of the fuselage 11. The air intake opening 371 is provided on one side in the longitudinal direction of the fairing 37A, and the air outlet opening 372 is provided on the other side.

[0050] The intake opening 371 is an opening at the front end of the fairing 37A. The exhaust opening 372 is an opening at the rear end of the fairing 37A. By having an opening in the fairing 37A, the internal space R6 of the fairing 37A can be ventilated automatically during the flight of the hydrogen aircraft 1C. That is, as indicated by arrow Ar1, air enters the internal space R6 from the intake opening 371. As indicated by arrow Ar2, air is discharged from the internal space R6 from the exhaust opening 372. Therefore, air is constantly supplied to the internal space R6 during flight, and the internal space R6 is ventilated. For this reason, even if liquid hydrogen leaks from the fuel supply pipe 15, ignition can be suppressed.

[0051] [Summary of this disclosure] The specific embodiments described above include disclosures having the following configurations.

[0052] A hydrogen aircraft according to one aspect of the present disclosure comprises a fuselage, a hydrogen tank located inside the fuselage for storing liquid hydrogen, a cabin located inside the fuselage for accommodating passengers, and a supply pipe connecting the hydrogen tank to a source of the liquid hydrogen, the supply pipe located outside the cabin.

[0053] According to the first embodiment, even if liquid hydrogen leaks from the supply pipe, since the supply pipe is located outside the cabin, it is possible to prevent liquid hydrogen or vaporized hydrogen from entering the cabin where the passengers are located. Therefore, it is possible to prevent damage to the cabin from the cryogenic coldness of the leaked liquid hydrogen and the liquefied air generated by that coldness, thereby protecting the passengers.

[0054] In the second embodiment of the hydrogen aircraft, the supply piping is located inside the fuselage, in the hydrogen aircraft of the first embodiment.

[0055] According to the second embodiment, it is not necessary to provide radial protrusions on the outer circumference of the fuselage to accommodate the supply piping. In other words, it is not necessary to provide protrusions on the fuselage surface that would worsen the aerodynamic performance of the hydrogen aircraft.

[0056] A hydrogen aircraft according to a third embodiment is a hydrogen aircraft according to the first or second embodiment, wherein the cabin is partitioned by a floor, sides and ceiling, and the supply piping is located below the floor.

[0057] Typically, the fuselage cross-section of an aircraft is circular due to structural strength and aerodynamic requirements. In contrast, the cabin floor is horizontal. Because a planar member extending horizontally is placed inside a circular cross-section structure, dead space tends to be created below the floor. According to the third embodiment, the dead space below the cabin can be utilized to install supply piping. Furthermore, the possibility of leaked liquid hydrogen entering the cabin through the supply piping can be eliminated.

[0058] A hydrogen aircraft according to the fourth embodiment further comprises a cargo compartment located within the fuselage, wherein the hydrogen aircraft according to any of the first to third embodiments is further comprising a cargo compartment located within the fuselage, the cabin being partitioned by a floor, sides, and ceiling, the cargo compartment being located below the floor, and the supply piping being located above the ceiling.

[0059] According to the fourth embodiment, even when the dead space below the cabin floor is used as a cargo area, the dead space above the ceiling can be effectively utilized to install the supply piping.

[0060] A hydrogen aircraft according to the fifth embodiment further comprises a liquid receiver located between the supply piping and the ceiling surface, which is provided for receiving liquid leaking from the supply piping, in addition to the hydrogen aircraft according to any of the first to fourth embodiments.

[0061] According to the fifth embodiment, even if liquid hydrogen leaks from the supply pipe, the leaked liquid hydrogen can be received by the liquid receiver. Therefore, the scattering of liquid hydrogen can be suppressed. Furthermore, even if the insulation structure of the supply pipe is damaged and liquefied air is generated around the supply pipe, this liquefied air can also be received by the liquid receiver, thus suppressing its scattering as well.

[0062] A hydrogen aircraft according to the sixth embodiment further comprises a wall structure covering at least a portion of the outer circumference in the longitudinal direction of the supply piping, in addition to the hydrogen aircraft according to any of the first to fifth embodiments.

[0063] According to the sixth embodiment, even if liquid hydrogen leaks from the supply pipe, at least in the portion of the supply pipe enclosed by the wall structure in the longitudinal direction, the leaked liquid hydrogen can be received at the bottom of the wall structure. Furthermore, even if the leaked liquid hydrogen vaporizes and gaseous hydrogen is generated, the diffusion of the gaseous hydrogen can be suppressed because it is enclosed by the wall structure.

[0064] A hydrogen aircraft according to the seventh embodiment further comprises an inert gas that fills the space between the inner surface of the wall structure and the outer surface of the supply piping, in addition to the hydrogen aircraft according to any of the first to sixth embodiments.

[0065] According to the seventh embodiment, even if liquid hydrogen leaks from the supply piping, filling with an inert gas makes it possible to avoid the hydrogen and oxygen reaching a specific ratio that would cause ignition.

[0066] The hydrogen aircraft according to the eighth embodiment further comprises a ventilation device for ventilating the space between the inner surface of the wall structure and the outer surface of the supply piping, in addition to the hydrogen aircraft according to any of the first to seventh embodiments.

[0067] According to the eighth aspect, even if liquid hydrogen leaks from the supply piping, the ventilation operation of the ventilation device makes it possible to avoid the hydrogen and oxygen reaching a specific ratio that would cause ignition.

[0068] In the ninth embodiment, the hydrogen aircraft is one of the first to eighth embodiments, wherein the supply piping is located outside the fuselage.

[0069] According to the ninth embodiment, even if liquid hydrogen leaks from the supply piping, the fuselage is present between it and the cabin. Therefore, the entry of liquid hydrogen into the cabin can be suppressed.

[0070] A hydrogen aircraft according to the tenth embodiment further comprises a fairing covering the area around the supply piping, wherein the hydrogen aircraft according to any of the first to ninth embodiments further comprises a fairing, the fairing having openings on one longitudinal side and the other side of the fuselage.

[0071] According to the tenth embodiment, by covering the supply piping with a fairing, the aerodynamic shape can be maintained even if the supply piping is placed outside the fuselage. In addition, by providing openings, ventilation inside the fairing can be performed automatically during the flight of the hydrogen aircraft.

[0072] 1 Hydrogen Aircraft 10 Airframe 11 Fuselage 14 Engine (liquid hydrogen supply destination) 15 Fuel supply piping (supply piping) 15A First supply piping (supply piping) 15B Second supply piping (supply piping) 2 Hydrogen fuel tanks (hydrogen tanks) 2A, 2B First hydrogen fuel tank, second hydrogen fuel tank (hydrogen tank) 3 Cabin 31 Floor 32 Side 33 Ceiling 37, 37A Fairing 371, 372 Intake opening, exhaust opening (opening) 4 Luggage compartment 51 Tray (liquid receptacle) 52 U-shaped tray (liquid receptacle) 6, 6A, 6B Wall structure 71 Intake fan (ventilation device) 72 Exhaust fan (ventilation device) LH Liquid hydrogen

Claims

1. A hydrogen aircraft comprising: a fuselage; a hydrogen tank located inside the fuselage for storing liquid hydrogen; a cabin located inside the fuselage for accommodating passengers; and a supply pipe connecting the hydrogen tank to a source of liquid hydrogen, the supply pipe located outside the cabin.

2. A hydrogen aircraft according to claim 1, wherein the supply piping is located inside the fuselage.

3. A hydrogen aircraft according to claim 2, wherein the cabin is partitioned by a floor, side and ceiling, and the supply piping is located below the floor.

4. A hydrogen aircraft according to claim 2, further comprising a cargo compartment located within the fuselage, wherein the cabin is partitioned by a floor, sides and a ceiling, the cargo compartment is located below the floor, and the supply piping is located above the ceiling.

5. A hydrogen aircraft according to claim 4, further comprising a liquid receiver disposed between the supply pipe and the ceiling surface for receiving liquid leaking from the supply pipe.

6. A hydrogen aircraft according to any one of claims 1 to 4, further comprising a wall structure covering at least a portion of the outer circumference in the longitudinal direction of the supply piping.

7. A hydrogen aircraft according to claim 6, further comprising an inert gas filled in the space between the inner surface of the wall structure and the outer surface of the supply piping.

8. A hydrogen aircraft according to claim 6, further comprising a ventilation device for ventilating the space between the inner surface of the wall structure and the outer surface of the supply piping.

9. A hydrogen aircraft according to claim 1, wherein the supply piping is located outside the fuselage.

10. A hydrogen aircraft according to claim 9, further comprising a fairing covering the periphery of the supply piping, wherein the fairing has openings on one longitudinal side and the other side of the fuselage.

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