Hydrogen aircraft

Abstract

To provide a hydrogen aircraft which enables improvement of fuel consumption performance with a simple structure.SOLUTION: The hydrogen aircraft is provided with: a machine body; a hydrogen tank that stores liquid hydrogen; a propulsion device that generates propulsion force of the machine body using hydrogen as a fuel; a liquid hydrogen transfer device that transfers the liquid hydrogen from the hydrogen tank to the propulsion device; and a cooling device that includes a heat exchanger for exchanging heat between the liquid hydrogen and air inside the machine body to cool the air. The cooling device cools an inner surface of an outer plate of the machine body using the air cooled by the heat exchanger.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to hydrogen aircraft. [Background technology]

[0002] Patent Document 1 discloses an aircraft in which a duct for circulating a fluid is formed inside the skin of a wing, and the skin of the wing is cooled by circulating low-temperature fuel through the duct in order to improve fuel efficiency. Cooling the skin of the wing reduces air resistance on the surface of the skin, thereby improving the fuel efficiency of the aircraft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 4,807,831 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above configuration of Patent Document 1, fuel flows inside the outer plate of the wing, which means that fuel leakage from the wing and unexpected reactions of the fuel on the wing must be prevented, resulting in a problem of a complicated configuration.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has an object to provide a hydrogen aircraft that can improve fuel efficiency with a simple configuration. [Means for solving the problem]

[0006] A hydrogen aircraft according to one aspect of the present disclosure comprises an aircraft, a hydrogen tank for storing liquid hydrogen, a propulsion device that generates thrust for the aircraft using hydrogen as fuel, a liquid hydrogen transfer device that transfers liquid hydrogen from the hydrogen tank to the propulsion device, and a cooling device that includes a heat exchanger that exchanges heat between the liquid hydrogen and air inside the aircraft to cool the air, and that uses the air cooled by the heat exchanger to cool the inner surface of the exterior panel of the aircraft. Effect of the Invention

[0007] According to the present disclosure, fuel efficiency can be improved with a simple configuration in a hydrogen aircraft. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic bottom view of a hydrogen aircraft according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic plan view showing the internal structure of the main wing. [Diagram 3] FIG. 3 is a schematic perspective view showing the structure of the tip of a main wing. [Figure 4] FIG. 4 is a system diagram showing the propulsion system and the cooling system. [Diagram 5] FIG. 5 is a schematic perspective view showing the internal structure of a main wing in a hydrogen aircraft according to a second embodiment of the present disclosure. [Figure 6] FIG. 6 is a schematic plan view showing the structure of the tip of a main wing in a hydrogen aircraft according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Overall composition) 1 is a bottom view showing a schematic configuration of a hydrogen aircraft 1 according to a first embodiment of the present disclosure. The hydrogen aircraft 1 shown in this drawing includes an airframe 10, a hydrogen tank 30, a propulsion device 40, and a cooling device 70.

[0010] The hydrogen aircraft 1 is an aircraft that uses hydrogen as a propulsive energy source, and the propulsion device 40 uses hydrogen as fuel to generate propulsive force for the aircraft 10. Hereinafter, the propulsion direction of the hydrogen aircraft 1 will be simply referred to as the longitudinal direction, with the front side of the propulsion direction being referred to as the front and the opposite side being referred to as the rear. Additionally, the up-down direction of the parked hydrogen aircraft 1 will be simply referred to as the vertical direction, and the direction perpendicular to the longitudinal direction and the vertical direction will be referred to as the horizontal direction. The longitudinal direction coincides with the longitudinal direction of the fuselage 11, which will be described later.

[0011] The aircraft 10 includes a fuselage 11, a pair of left and right main wings 12, and a tail 13. The two main wings 12 have a symmetrical structure.

[0012] The fuselage 11 has a generally cylindrical shape extending in the front-rear direction. The fuselage 11 includes structural members such as a circular frame and stringers, and fuselage panels assembled into a cylindrical shape. The fuselage panels are outer plates of the fuselage 11. In other words, the fuselage panels are made of plate-like members and form the outer surface of the fuselage 11.

[0013] The pair of main wings 12 extend from the fuselage 11 to both outer sides in the left-right direction, that is, to both outer sides in the width direction of the fuselage 11. Fig. 2 is a schematic plan view showing the internal structure of the main wings 12. Fig. 3 is a schematic perspective view showing the structure of the ends of the main wings 12 in the left-right direction.

[0014] The main wing 12 includes a girder 21 extending in the left-right direction that constitutes its outer shape, and a plurality of ribs 22 arranged so as to intersect the girder 21 at right angles. The main wing 12 also includes a main wing panel 24 attached to the girder 21 and the rib 22. The main wing 12 also includes a plurality of stringers 23 that extend in the left-right direction to connect the ribs 22 to each other and reinforce the main wing 12. In the example of FIG. 2, the main wing 12 includes two girder 21, 21 arranged in the front-rear direction, a plurality of stringers 23 arranged in the front-rear direction along the upper inner surface of the main wing panel 24, and a plurality of stringers 23 arranged in the front-rear direction along the lower inner surface of the main wing panel 24. The girder 21, 21 is a main structure that bears the load during flight, and the stringer 23 is a reinforcing member that supports the main wing panel 24. The main wing panel 24 is an outer plate of the main wing 12. In other words, the main wing panel 24 is made of a plate-like member and constitutes the outer surface of the main wing 12. Although not shown in the drawings, flaps and ailerons may be further provided on the main wing 12. The position of the main wing 12 is not limited, but in this first embodiment, the main wing 12 is attached near the center of the fuselage 11 in the fore-and-aft direction.

[0015] The main wing 12 supports a nacelle 16, which is a cylindrical housing extending in the front-rear direction. Specifically, an engine pylon 17 extending in the front-rear direction is fixed to the lower surface of the main wing 12. The nacelle 16 is connected to the engine pylon 17 and is supported by the main wing 12 via the engine pylon 17. The nacelle 16 is supported by the main wing 12 in a position below the main wing 12 in the vertical direction and in a position protruding forward from the main wing 12 in a plan view. The nacelle 16 and the engine pylon 17 are provided for each of the two main wings 12. In other words, the hydrogen aircraft 1 has a pair of left and right nacelles 16 and a pair of left and right engine pylons 17.

[0016] A fuselage fairing 14 is attached to the underside of the fuselage 11. The fuselage fairing is a member for eliminating the step between the fuselage 11 and the main wings 12, and covers from below the roots of the main wings 12 and the underside of the fuselage 11 connected to the roots of the main wings 12. In this first embodiment, the fuselage fairing 14 extends in the left-right direction between the two main wings 12.

[0017] The tail 13 is provided at the rear end of the fuselage 11. The tail 13 includes a vertical tail extending upward from the upper surface of the rear end of the fuselage 11, and a pair of horizontal tails 13A extending in the left and right directions from the vertical tail.

[0018] The hydrogen tank 30 is a tank that stores hydrogen used as fuel. The hydrogen tank 30 has both thermal insulation and pressure resistance, and stores liquefied hydrogen, which is hydrogen that has been liquefied at an extremely low temperature of minus 253 degrees or less, inside while keeping it cold and pressurized. The hydrogen tank 30 is mounted inside the fuselage 11. In the illustrated example, the hydrogen tank 30 is mounted near the center of the fuselage 11 in the fore-and-aft direction.

[0019] (Propulsion System) Fig. 4 is a system diagram showing the schematic configuration of a propulsion system S1 including a propulsion unit 40 and a cooling unit 70 described below. The hydrogen aircraft 1 of the first embodiment includes a pair of left and right propulsion systems S1, each including a propulsion unit 40, and a pair of left and right cooling units 70. Fig. 4 shows one of the propulsion systems S1 and one of the cooling units 70. The two propulsion systems S1 are configured roughly symmetrically, and the following describes one of the propulsion systems S1.

[0020] The propulsion system S1 includes a propulsion unit 40 and a liquid hydrogen transfer unit 50 that extracts liquid hydrogen from the hydrogen tank 30 and transfers it to the propulsion unit 40. As described above, the hydrogen aircraft 1 has a pair of left and right propulsion systems S1, which include a pair of left and right propulsion units 40 and a pair of left and right liquid hydrogen transfer units 50.

[0021] The liquid hydrogen transfer device 50 includes a liquid hydrogen line 51, a downstream pump 52, and an upstream pump 53. The liquid hydrogen line 51 is a passage through which liquid hydrogen flows, and connects the hydrogen tank 30 and the propulsion device 40. The downstream pump 52 and the upstream pump 53 are provided midway along the liquid hydrogen line 51, and pump out the liquid hydrogen stored in the hydrogen tank 30 toward the propulsion device 40. With respect to the flow direction of the liquid hydrogen, the downstream pump 52 is provided downstream of the upstream pump 53, that is, closer to the propulsion device 40.

[0022] The propulsion system 40 includes a carburetor 41 and an engine 42. The engine 42 is housed inside the nacelle 16. The carburetor 41 is housed inside the engine pylon 17.

[0023] The vaporizer 41 is a device for vaporizing liquid hydrogen. The liquid hydrogen line 51 is connected to the vaporizer 41 of the propulsion device 40. The liquid hydrogen discharged from the hydrogen tank 30 is introduced into the vaporizer 41 and vaporized therein.

[0024] The engine 42 is a hydrogen gas turbofan engine including a combustor, a turbine, a compressor, and a fan. The carburetor 41 and the combustor are connected via an injection device, and hydrogen gas vaporized by the carburetor 41 is injected into the combustor. Air compressed by the compressor is introduced into the combustor. As a result, the hydrogen gas and the air react and burn in the combustor, generating combustion energy. The turbine receives the generated combustion energy and rotates to generate a jet stream, and also rotates the compressor and the fan. The engine 42 is disposed inside the nacelle 16 so that the jet stream generated by the turbine is ejected rearward and the fan blows air rearward, and the jet stream and the rearward flow of the air act on the aircraft 10 as a propulsive force that moves the aircraft 10 forward.

[0025] (cooling device) The two cooling devices 70 mounted on the hydrogen aircraft 1 are configured generally symmetrically, and one of the cooling devices 70 will be described below.

[0026] The cooling device 70 includes a heat exchanger 71, and is a device that cools the inner surface of the skin of the airframe 10 by using air cooled by the heat exchanger. In the first embodiment, the cooling device 70 cools the skin of the main wing 12, i.e., the inner surface 24A of the main wing panel 24. In addition to the heat exchanger 71, the cooling device 70 includes a cooled air line 72C and a pre-cooled air line 72B. The cooling device 70 also includes a first branch line 73B and a second branch line 73C.

[0027] The heat exchanger 71 is a device that exchanges heat between liquid hydrogen and air. The heat exchanger 71 is an indirect type heat exchanger that exchanges heat between two fluids without contact. Inside the heat exchanger 71, a first passage 72A and a second passage 73A are formed, through which the two fluids flow independently. As described below, air inside the aircraft body 10 is introduced into the first passage 72A, and liquid hydrogen is introduced into the second passage 73A. As described above, the liquid hydrogen is in an extremely low temperature state of minus 230 degrees or less, and the temperature of the liquid hydrogen is sufficiently lower than that of the air present inside the aircraft body 10. As a result, in the heat exchanger 71, the air is cooled by the liquid hydrogen.

[0028] In the first embodiment, the heat exchanger 71 is provided outside the hydrogen tank 30. Specifically, the heat exchanger 71 is mounted on the inside of the main wing 12, at a position close to the engine pylon 17.

[0029] The first branch line 73B and the second branch line 73C are passages through which liquid hydrogen flows. The first branch line 73B and the second branch line 73C each branch off from the liquid hydrogen line 51. In the flow direction of liquid hydrogen in the liquid hydrogen line 51, the branch point of the first branch line 73B to the liquid hydrogen line 51 is located upstream of the branch point of the second branch line 73C to the liquid hydrogen line 51. The first branch line 73B is connected to the heat exchanger 71 in a state of communication with one end of the second passage 73A of the heat exchanger 71, and connects the liquid hydrogen line 51 to the second passage 73A. The second branch line 73C is connected to the heat exchanger 71 in a state of communication with the other end of the second passage 73A of the heat exchanger 71, and connects the part of the liquid hydrogen line 51 downstream of the branch point of the first branch line 73B to the second passage 73A.

[0030] With the above-described configuration, a portion of the liquid hydrogen flowing inside liquid hydrogen line 51 and derived from hydrogen tank 30 is introduced into second passage 73A of heat exchanger 71 through first branch line 73B, and after passing through second passage 73A, i.e., heat exchanger 71, is returned to liquid hydrogen line 51 through second branch line 73C.

[0031] The first branch line 73B and the second branch line 73C branch off from a portion of the liquid hydrogen line 51 that is downstream of the downstream pump 52. In other words, one end of the first branch line 73B and the second branch line 73C that is opposite the heat exchanger 71 connects the pump 52 that is located furthest downstream in the flow direction of the liquid hydrogen among the multiple pumps provided in the liquid hydrogen line 51, and the portion between the propulsion device 40. The downstream pump 52 corresponds to the "pump" in this disclosure.

[0032] In the first embodiment, an opening / closing valve 74 for opening and closing the first branch line 73B is provided in the middle of the first branch line 73B. When the opening / closing valve 74 is closed, the inflow of liquid hydrogen into the heat exchanger 71 is stopped. The opening / closing valve 74 is opened and closed in response to a signal from a control device (not shown) mounted on the hydrogen aircraft 1. The opening / closing valve 74 is opened only when the hydrogen aircraft 1 is flying. For example, the opening / closing valve 74 is opened when the altitude detected by an altimeter mounted on the hydrogen aircraft 1 is higher than a preset reference altitude, and the opening / closing valve 74 is closed when the detected altitude is equal to or lower than the reference altitude.

[0033] The cooling air line 72C and the pre-cooling air line 72B are passages through which air flows. The pre-cooling air line 72B is connected to the heat exchanger 71 in a state where it communicates with one end of the first passage 72A of the heat exchanger 71. The cooling air line 72C is connected to the heat exchanger 71 in a state where it communicates with the other end of the first passage 72A of the heat exchanger 71.

[0034] The cooling device 70 has an air intake 72E that opens to the outside of the aircraft body 10 and takes in air from the outside of the aircraft body 10 into the pre-cooling air line 72B. In the first embodiment, the air intake 72E is formed in the fuselage fairing 14 and opens forward. As a result, mainly air that is a headwind passing below the aircraft body 10 and flows rearward relative to the aircraft body 10 below the aircraft body 10 is introduced into the pre-cooling air line 72B through the air intake 72E.

[0035] The air taken in from the air intake 72E into the pre-cooled air line 72B is introduced into the first passage 72A of the heat exchanger 71. In the first embodiment, a portion of the pre-cooled air line 72B is disposed inside the fuselage 11, and the remaining portion is disposed inside the main wing 12. As a result, the air taken in into the pre-cooled air line 72B through the air intake 72E passes through the inside of the fuselage 11 and the inside of the main wing 12 and is introduced into the first passage 72A of the heat exchanger 71.

[0036] The air introduced into the first passage 72A is cooled by heat exchange with liquid hydrogen in the heat exchanger 71. The air cooled in the heat exchanger 71 is led out from the first passage 72A to the cooling air line 72C and flows through the cooling air line 72C. In this manner, the air flows through the pre-cooling air line 72B, the first passage 72A, i.e., the heat exchanger 71, and the cooling air line 72C in this order. In other words, the pre-cooling air line 72B, the first passage 72A, i.e., the heat exchanger 71, and the cooling air line 72C are arranged in this order from the upstream side in the air flow direction. The air intake 72E is provided at the upstream end of the line including the pre-cooling air line 72B, the first passage 72A, i.e., the heat exchanger 71, and the cooling air line 72C in the air flow direction.

[0037] The cooling air line 72C is provided inside the main wing 12. The cooling air line 72C extends from near the engine pylon 17 where the heat exchanger 71 is disposed to near the outer end of the main wing 12 in the left-right direction.

[0038] The cooling air line 72C is branched into a plurality of air side branch lines 72C2 at its midpoint. The cooling air line 72C is composed of a plurality of air side branch lines 72C2, a pre-branch line 72C1 constituting the upstream portion from the branch point of the air side branch line 72C2, i.e., the upstream portion from the upstream end of the air side branch line 72C2 in the air flow direction, and a junction line 72C3 constituting the downstream portion from the junction point of the plurality of air side branch lines 72C2, i.e., the downstream portion from the downstream end of these. Each air side branch line 72C2 extends in the left-right direction along the outer plate of the main wing 12, i.e., the inner surface 24A of the main wing panel 24.

[0039] In this first embodiment, the air side branch line 72C2 is formed by a part of the stringer 23 provided on the main wing 12 and the main wing panel 24. That is, in this first embodiment, the part of the multiple stringers 23 provided on the main wing 12 and the main wing panel 24 function as structural materials for the main wing 12 and as members that define the air side branch line 72C2.

[0040] 3 is a diagram showing a schematic cross-sectional structure of the main wing 12. Hereinafter, the stringers 23 provided on the main wing 12 and defining the air-side branch line 72C2 are referred to as cooling-line stringers 123. In the illustrated example, the four stringers 23 provided between the two spars 21, 21 of the main wing 12 and running along the upper inner surface 24A of the main wing panel 24 are each the cooling-line stringers 123.

[0041] The cooling-line stringers 123 have the same structure. The cooling-line stringers 123 are hollow members. Specifically, as shown in FIG. 3, a cross section of the cooling-line stringers 123 perpendicular to the left-right direction has a shape that bulges downward and opens upward. That is, the cooling-line stringers 123 are curved or bent so as to protrude downward, and the upper end portion of the cooling-line stringers 123 themselves is open. In the example of FIG. 3, the cooling-line stringers 123 are substantially U-shaped. That is, the cooling-line stringers 123 have a bottom wall extending in the left-right direction along a plane intersecting the up-down direction, and side walls extending upward from the front and rear edges of the bottom wall. The cooling line stringer 123 is disposed such that its upper end contacts the upper inner surface 24A of the main wing panel 24, and the inner surface 24A of the main wing panel 24 closes the upper opening of the cooling line stringer 123. As a result, a space extending in the left-right direction is defined between the cooling line stringer 123 and the inner surface 24A of the main wing panel 24, and an air-side branch line 72C2 through which air flows is defined inside. The above-mentioned cooling line stringer 123 corresponds to the "reinforcement member" in this disclosure.

[0042] The cooling device 70 has an air discharge section 72F that opens to the outside of the aircraft 10 and discharges the air inside the cooling air line 72C to the outside of the aircraft 10. In the first embodiment, the air discharge section 72F opens to the outside of the main wing 12 at the outer end of the main wing panel 24 in the left-right direction. The air discharge section 72F communicates with the downstream end of the cooling air line 72C. Specifically, the junction line 72C3 is provided at the outer end of the main wing panel 24 in the left-right direction, and the downstream end of the junction line 72C3 located at the outer end of the main wing panel 24 in the left-right direction communicates with the air discharge section 72F.

[0043] In the first embodiment, the air discharge section 72F is provided on the upper surface of the main wing panel 24. During the flight of the hydrogen aircraft 1, the pressure on the upper surface of the main wing panel 24 becomes low. Specifically, the pressure on the upper surface of the main wing panel 24 becomes lower than the pressure of the opening of the air intake section 72E that receives the headwind as described above. Thus, in the first embodiment, the air discharge section 72F is provided at a position where the pressure of the opening of the air discharge section 72F becomes lower than the pressure of the opening of the air intake section 72E during flight. With this configuration, in the first embodiment, the introduction of air into the path through which air flows from the air intake section 72E to the air discharge section 72F, that is, the path consisting of the pre-cooled air line 72B, the first passage 72A, and the cooled air line 72C, is promoted.

[0044] In the first embodiment, the air discharge section 72F is provided at the rear of the upper surface of the main wing panel 24, rearward of the center in the fore-aft direction of the main wing panel 24. As a result, the air in the cooling air line 72C is discharged from the rear of the upper surface of the outer end of the main wing panel 24 in the lateral direction to the outside of the main wing 12 and the aircraft 10.

[0045] As described above, in the first embodiment, the air is discharged from the rear of the main wing panel 24 to the outside of the fuselage 10, and thus the air layer is prevented from separating from the leading edge of the main wing panel 24 due to the discharged air. If the air layer were to separate from the leading edge of the main wing panel 24, the efficiency of the airplane may decrease due to a decrease in lift and an increase in air resistance. Therefore, according to the first embodiment, the air layer is prevented from separating from the leading edge of the main wing panel 24 as described above, and the air in the cooling air line 72C can be discharged to the outside of the main wing 12 and the fuselage 10 while ensuring the efficiency of the airplane. As shown in FIG. 5 and other figures, in the first embodiment, the rear of the main wing panel 24 extends diagonally downward and rearward, and the air discharge section 72F is provided on this inclined portion.

[0046] As described above, air cooled in the heat exchanger 71 is introduced into the cooling air line 72C. In addition, the air side branch line 72C2 of the cooling air line 72C extends in the left-right direction from near the engine pylon 17 to near the outer left-right end of the main wing 12. As a result, the air cooled in the heat exchanger 71 moves along the inner surface 24A of the main wing panel 24 from near the engine pylon 17 to near the outer left-right end of the main wing 12 while cooling the inner surface 24A, and then is discharged to the outside of the main wing 12 from the air discharge section 72F.

[0047] (action, etc.) As described above, in the hydrogen aircraft 1 according to the first embodiment, liquid hydrogen stored as fuel in the hydrogen tank 30 and carried inside the aircraft 10 and air taken into the interior of the aircraft 10 exchange heat in the heat exchanger 71, thereby cooling the air. The cooled air then flows along the inner surface 24A of the main wing panel 24 through the cooling air line 72C provided inside the main wing 12. Therefore, the inner surface 24A of the main wing panel 24 can be cooled by the air.

[0048] Here, when a fluid flows along a certain wall surface, the lower the wall surface temperature, the larger the range of the laminar boundary layer formed on the wall surface, specifically, the distance in the direction of the fluid flow, and the smaller the range of the turbulent boundary layer is. Also, the friction resistance of the fluid in the laminar boundary layer is smaller than the friction resistance of the fluid in the turbulent boundary layer. Therefore, according to the hydrogen aircraft 1 according to the first embodiment, the main wing panel 24 is cooled, so that the friction resistance, i.e., the air resistance, generated on the main wing 12 during flight can be reduced, and the fuel efficiency can be improved. In particular, in the hydrogen aircraft 1 according to the first embodiment, the main wing panel 24 of the outer plate of the aircraft 10 is cooled, and the air resistance on the main wing 12 is reduced. Therefore, the propulsive force can be effectively increased, and the fuel efficiency can be reliably improved.

[0049] Moreover, in the hydrogen aircraft 1 according to the first embodiment, air cooled by liquid hydrogen, rather than liquid hydrogen itself, flows through the cooling air line 72C. Therefore, there is no need to configure the cooling air line 72C to handle liquid hydrogen. For example, there is no need to increase the airtightness of the passage to avoid leakage of liquid hydrogen, or to manage the temperature inside the passage to avoid unexpected reactions of liquid hydrogen. Therefore, the fuel efficiency of the hydrogen aircraft 1 can be improved with a simple configuration.

[0050] Furthermore, in the hydrogen aircraft 1 according to the first embodiment described above, the heat exchanger 71 is provided outside the hydrogen tank 30, and the liquid hydrogen discharged from the hydrogen tank 30 exchanges heat with the air in the heat exchanger 71. Therefore, fluctuations in the temperature and therefore the pressure of the liquid hydrogen in the hydrogen tank 30, i.e., pressure fluctuations in the hydrogen tank 30, can be suppressed compared to when the heat exchanger 71 is provided inside the hydrogen tank 30 and heat is exchanged between the liquid hydrogen and air inside the hydrogen tank 30.

[0051] Furthermore, in the hydrogen aircraft 1 according to the first embodiment, the first branch line 73B branches off from a portion of the liquid hydrogen line 51 downstream of the downstream pump 52, and the liquid hydrogen flowing through the liquid hydrogen line 51 downstream of the downstream pump 52 is introduced into the heat exchanger 71 and exchanged with air. In other words, the liquid hydrogen flowing through a portion of the liquid hydrogen line 51 close to the vaporizer 41 of the propulsion device 40 exchanges heat with air. Therefore, the liquid hydrogen that has been heated by heat exchange with the air can be introduced into the vaporizer 41 at an early stage, and the liquid hydrogen can be prevented from vaporizing unexpectedly before it is introduced into the vaporizer 41.

[0052] Furthermore, in the hydrogen aircraft 1 according to the first embodiment described above, the main wing panel 24 is provided with an air discharge section 72F that opens to the outside of the main wing 12 and discharges air that flows inside the cooling air line 72C and is used to cool the inner surface 24A of the main wing panel 24 to the outside of the main wing 12. Therefore, there is no need to provide a passage, pump, or the like for returning the air after cooling the main wing 12 back to the inside of the aircraft 10. Therefore, the above-mentioned effects can be obtained while avoiding an increase in the weight of the hydrogen aircraft 1.

[0053] Furthermore, in the hydrogen aircraft 1 according to the first embodiment, the air discharge section 72F provided on the main wing 12 is provided at the rear of the main wing panel 24, so that air can be discharged rearward from the air discharge section 72F as described above. This makes it possible to prevent the air layer formed at the leading edge of the main wing panel 24 during flight from peeling off due to the air discharged from the air discharge section 72F. Therefore, the main wing panel 24 can be cooled while ensuring the lift generated by the main wing panel 24 and preventing an increase in air resistance.

[0054] In addition, in the hydrogen aircraft 1 according to the first embodiment, the air discharge section 72F provided on the main wing 12 is provided on the upper surface of the main wing panel 24, so that during flight, the pressure at the opening of the air intake section 72E is higher than the pressure at the opening of the air discharge section 72F, and the pressure at the upstream end of the line formed by the pre-cooling air line 72B, the first passage 72A, and the cooling air line 72C is higher than the pressure at the downstream end of the line. Therefore, air can be reliably introduced and circulated in the line formed by the pre-cooling air line 72B, the first passage 72A, and the cooling air line 72C, and the main wing 12 can be reliably cooled by the air. In addition, pumps and the like for introducing and circulating air in the above-mentioned lines can be omitted, so that the above-mentioned effects can be obtained while avoiding an increase in the weight of the hydrogen aircraft 1.

[0055] Furthermore, in the hydrogen aircraft 1 according to the first embodiment, the air-side branch line 72C2 and thus a portion of the cooling air line 72C are partitioned by the inner surface 24A of the main wing panel 24, and a portion of the cooling air line 72C extends along the inner surface 24A of the main wing panel 24 while being in contact with the inner surface 24A of the main wing panel 24. Therefore, the main wing panel 24 can be directly cooled by the air flowing inside the cooling air line 72C, and the temperature of the main wing panel 24 can be reliably lowered.

[0056] Moreover, in the hydrogen aircraft 1 according to the above embodiment, the air side branch line 72C2, i.e., a part of the cooling air line 72C, is defined by the stringer 123 which also serves as a cooling line and reinforces the main wing panel 24. This makes it possible to provide the air side branch line 72C2 in the main wing 12 while avoiding an increase in the weight of the hydrogen aircraft 1, compared to the case where a member for defining the air side branch line 72C2 is provided separately from the stringer 23.

[0057] Second embodiment Fig. 5 is a schematic perspective view showing the internal structure of the main wing 12 in the hydrogen aircraft 1 according to the second embodiment of the present disclosure. Fig. 6 is a schematic plan view showing the structure of the end of the main wing 12 in the hydrogen aircraft 1 according to the second embodiment of the present disclosure.

[0058] The hydrogen aircraft 1 according to the second embodiment differs from the hydrogen aircraft 1 according to the first embodiment only in the structure of the cooling air line 72C. Therefore, only the cooling air line 72C of the hydrogen aircraft 1 according to the second embodiment will be described below. Note that in the following description of the hydrogen aircraft 1 according to the second embodiment and in Figures 5 and 6, the same reference numerals are used for the same elements as in the first embodiment.

[0059] In the second embodiment, as in the first embodiment, the cooling air line 72C is defined by the cooling line stringer 223 and the upper inner surface 24A of the main wing panel 24. Specifically, the cooling line stringer 223 has a shape that bulges downward and opens upward. The cooling line stringer 223 is disposed such that its upper end is in contact with the upper inner surface 24A of the main wing panel 24, and the inner surface 24A of the main wing panel 24 closes the upper opening of the cooling line stringer 223. As a result, in the second embodiment, as in the first embodiment, a space extending in the left-right direction and allowing air to flow is defined between the cooling line stringer 223 and the main wing panel 24.

[0060] On the other hand, in the second embodiment, the cooling air line 72C does not branch midway, and only one of the stringers 23 of the main wing 12 functions as the cooling line double-use stringer 223 and the cooling air line 72C. Also, in the second embodiment, the dimension in the front-rear direction of the cooling line double-use stringer 223 is set to be longer than the other stringers 23. For example, the dimension in the front-rear direction of the cooling line double-use stringer 223 is set to be three times or more the dimension of the other stringers 223.

[0061] In the second embodiment, the cooling air line 72C is configured so that its flow passage area becomes smaller toward the downstream side. Specifically, the height dimension of the cooling line / stringer 223 is substantially constant in the left-right direction, i.e., in the air flow direction. Meanwhile, the front-rear dimension of the cooling line / stringer 223 becomes smaller toward the outside in the left-right direction, i.e., toward the downstream side in the air flow direction. As a result, the cross-sectional area of ​​the flow passage of the cooling air line 72C becomes smaller toward the downstream side.

[0062] (action, etc.) In the second embodiment, the cooling air line 72C does not branch midway, which simplifies the configuration of the cooling air line 72C.

[0063] In addition, the temperature of the air flowing through the downstream portion of the cooling air line 72C in the air flow direction is higher than the temperature of the air flowing through the upstream portion due to heat reception from the main wing panel 24. In contrast, in the second embodiment, the flow passage area of ​​the cooling air line 72C is smaller toward the downstream side, so that the flow velocity of the air flowing through the cooling air line 72C can be increased toward the downstream side. Therefore, even in the portion of the main wing panel 24 that is cooled by the air flowing downstream of the cooling air line 72C, the temperature can be reliably reduced by the air flowing through the cooling air line 72C. Specifically, in a configuration in which the cooling air line 72C extends from the vicinity of the engine pylon 17 toward the outer end of the main wing panel 24 in the left-right direction, as described above, the temperature of the outer portion of the main wing panel 24 in the left-right direction can also be reliably reduced.

[0064] As described above, the configuration other than the cooling air line 72C is the same between the first and second embodiments, and the second embodiment can provide the same effects as the first embodiment.

[0065] (Other variations) In the above first embodiment, the case where the number of the air side branch lines 72C2 is four has been described, but the number of the air side branch lines 72C2 is not limited to this. The specific shape of the air side branch line 72C2 is not limited to the above. The air side branch line 72C2 may be omitted. That is, the cooling air line 72C may be configured with one line. The air side branch line 72C according to the above first embodiment may be configured so that the flow path area becomes smaller toward the downstream side, as in the above second embodiment.

[0066] In the above first and second embodiments, the air side branch line 72C2 is defined by the stringer 23 and the main wing panel 24. However, the air side branch line 72C2 may be defined only by the stringer 23. The air side branch line 72C2 may be defined by a member other than the stringer 23.

[0067] Furthermore, the positions of the air intake portion 72E and the air discharge portion 72F are not limited to those described above.

[0068] Further, the position of the heat exchanger 71 is not limited to the above. For example, the heat exchanger 71 may be disposed inside the engine pylon 17 or inside the nacelle 16.

[0069] Furthermore, the position of the carburetor 41 is not limited to the above. However, the carburetor 41 is preferably disposed near the engine 42. Therefore, the carburetor 41 is preferably disposed inside the engine pylon 17 or inside the nacelle 16, as described above.

[0070] Furthermore, the number of hydrogen tanks 30 is not limited to one, and multiple hydrogen tanks 30 may be mounted on the aircraft 10. Furthermore, the location of the hydrogen tank 30 is not limited to inside the fuselage 11, and it may be disposed on the outside of the fuselage 11 or the main wing 12.

[0071] In the above first and second embodiments, the case has been described where the inner surface 24A of the main wing panel 24 is cooled by air cooled by liquid hydrogen in the heat exchanger 71, but the object to be cooled may be any inner surface of the outer plate of the airframe 10 and is not limited to the inner surface 24A of the main wing panel 24. For example, the inner surface of a fuselage panel, which is the outer plate of the fuselage 11, may be cooled by air. Even in this case, the air resistance generated on the fuselage panel can be reduced, and fuel efficiency can be improved.

[0072] In the above first and second embodiments, the propulsion device includes the carburetor 41 and the engine 42, and the engine 42 is a hydrogen gas turbofan engine that uses hydrogen as fuel and includes a combustor, a turbine, a compressor, and a fan. However, the propulsion device that uses hydrogen as fuel to generate the propulsion force of the vehicle 10 is not limited to this. For example, a device including a carburetor, an engine that burns hydrogen to generate combustion energy as in the above embodiments but does not have a turbine unlike the above embodiments, and an electric motor driven by the engine may be mounted on the vehicle 10 as the propulsion device, and the electric motor may be used to rotate the turbine to obtain the propulsion force of the vehicle 10.

[0073] (summary) The above-described embodiment and its modifications include the following disclosures.

[0074] A hydrogen aircraft according to a first aspect of the present disclosure comprises an aircraft body, a hydrogen tank for storing liquid hydrogen, a propulsion device that generates thrust for the aircraft using hydrogen as fuel, a liquid hydrogen transfer device that transfers liquid hydrogen from the hydrogen tank to the propulsion device, and a cooling device that includes a heat exchanger that exchanges heat between the liquid hydrogen and the air inside the aircraft to cool the air, and that uses the air cooled by the heat exchanger to cool the inner surface of the exterior panel of the aircraft.

[0075] According to this first aspect, the inner surface of the skin of the aircraft can be cooled by air cooled by liquid hydrogen. This makes it possible to reduce frictional resistance, i.e., air resistance, that occurs on the skin of the aircraft during flight, and improves fuel efficiency. Moreover, in this aspect, air cooled by liquid hydrogen, rather than liquid hydrogen itself, flows through the cooling air line to cool the skin. This eliminates the need to configure the cooling air line to accommodate liquid hydrogen, and the fuel efficiency of the hydrogen aircraft can be improved with a simple configuration.

[0076] A hydrogen aircraft according to a second aspect is the hydrogen aircraft of the first aspect, wherein the heat exchanger exchanges heat between the liquid hydrogen drawn out from the hydrogen tank by the liquid hydrogen transfer device and air.

[0077] According to the second aspect, the air can be cooled by the liquid hydrogen while suppressing pressure fluctuations in the hydrogen tank.

[0078] A third aspect of the hydrogen aircraft is the same as that of the second aspect, in which the propulsion device includes a vaporizer that vaporizes liquid hydrogen, the liquid hydrogen transfer device includes a liquid hydrogen line that connects the hydrogen tank and the vaporizer and through which liquid hydrogen flows, and a pump provided midway along the liquid hydrogen line, and the heat exchanger exchanges heat between the liquid hydrogen flowing through the liquid hydrogen line downstream of the pump and air.

[0079] According to the third aspect, the liquid hydrogen heated by heat exchange with the air can be introduced into the vaporizer at an early stage, thereby preventing the liquid hydrogen from unexpectedly vaporizing before it is introduced into the vaporizer.

[0080] A hydrogen aircraft according to a fourth aspect is any one of the first to third aspects, wherein the cooling device includes a cooling air line through which air flows to cool the inner surface of the outer panel of the aircraft, and an air discharge section that opens to the outside of the aircraft and discharges air that has passed through the cooling air line to the outside of the aircraft.

[0081] According to the fourth aspect, the air that has passed through the cooling air line is discharged to the outside of the aircraft via the air discharge section. Therefore, there is no need to provide a passage or pump for returning the air that has cooled the aircraft back inside the aircraft. Therefore, it is possible to improve fuel efficiency with a simple configuration while avoiding an increase in the weight of the hydrogen aircraft.

[0082] A fifth aspect of the hydrogen aircraft is the fourth aspect, wherein the cooling device includes a pre-cooled air line through which air flowing into the heat exchanger flows, and an air intake section that opens to the outside of the aircraft and takes in air from outside the aircraft into the pre-cooled air line, and the air intake section is located at a position where the pressure at the opening of the air intake section is higher than the pressure at the opening of the air discharge section while the aircraft is in flight.

[0083] According to the fifth aspect, air can be introduced and circulated into the line by utilizing the pressure difference between the air intake section provided at the upstream end of the line, which is composed of the uncooled air line, the heat exchanger, and the cooled air line and through which air flows, and the air discharge section provided at the downstream end of the line. Therefore, a pump or the like for introducing and circulating air into the line can be omitted, and the above effect can be obtained while avoiding an increase in the weight of the hydrogen aircraft.

[0084] A hydrogen aircraft of a sixth aspect is the fifth aspect, wherein the aircraft comprises a fuselage and a main wing extending from the fuselage outward in the width direction of the fuselage, the cooling air line is provided along the inner surface of the outer plate of the main wing, and the air discharge section is provided at the rear of the outer plate of the main wing.

[0085] According to the sixth aspect, the cooling air line is provided along the inner surface of the outer plate of the main wing, so that the main wing can be cooled by air. Also, the air discharge section is provided at the rear of the outer plate of the main wing, so that the air discharged from the air discharge section is prevented from blocking the rearward air flow formed around the main wing during flight. In other words, it is possible to prevent the separation of the air layer formed around the leading edge of the main wing panel 24 during flight due to the air discharged from the air discharge section. Therefore, the main wing panel 24 can be cooled while ensuring the lift generated around the main wing panel 24 and preventing an increase in air resistance.

[0086] A hydrogen aircraft according to a seventh aspect is the sixth aspect, wherein the air discharge portion is provided on an upper surface of an outer plate of the main wing.

[0087] The pressure generated on the upper surface of the main wing during flight is kept relatively low. Therefore, according to the seventh aspect, the pressure in the air intake section can be reliably made higher than the pressure in the air discharge section during flight.

[0088] A hydrogen aircraft according to an eighth aspect is any one of the first to seventh aspects, wherein the cooling device includes a cooling air line that extends along and is in contact with the inner surface of the skin of the aircraft, and through which air flows inside to cool the inner surface of the skin of the aircraft.

[0089] According to the eighth aspect, heat can be efficiently exchanged between the air flowing inside the cooling air line and the inner surface of the skin of the airframe, thereby efficiently cooling the skin.

[0090] A ninth aspect of the hydrogen aircraft is any one of the first to eighth aspects, wherein the cooling device includes a cooling air line through which air flows to cool the inner surface of the skin of the aircraft, and the aircraft includes a hollow reinforcing member that reinforces the skin of the aircraft and defines at least a portion of the cooling air line.

[0091] According to this ninth aspect, the weight of the hydrogen aircraft can be kept small compared to a case in which a member for partitioning the cooling air line through which air flows to cool the inner surface of the aircraft's skin is provided separately from a member for reinforcing the aircraft's skin.

[0092] A hydrogen aircraft according to a tenth aspect is any one of the first to ninth aspects, wherein the cooling device includes a cooling air line through which air flows to cool the inner surface of the outer panel of the aircraft, and the cooling air line has a shape in which the flow path area becomes smaller toward the downstream side.

[0093] According to the tenth aspect, in a cooling air line through which air flows to cool the inner surface of the skin of an airframe, the flow velocity of the air can be increased toward the downstream side of the cooling air line, so that the skin of the airframe can be reliably cooled by air at a higher temperature downstream of the cooling air line than upstream. [Explanation of symbols]

[0094] 10 Aircraft 11. Torso 12 Wing 30 Hydrogen Tank 40 Propulsion device 41 Carburetor 50 Liquid hydrogen transfer device 51 Liquid Hydrogen Line 52 Pump 70 Cooling device 71 Heat exchanger 72B Pre-cooling air line 72C Cooling Air Line 72E Air Intake 72F Air release section 123 Cooling line / stringer (reinforcement member)

Claims

1. The aircraft and A hydrogen tank for storing liquid hydrogen; A propulsion device that uses hydrogen as fuel to generate thrust for the vehicle; a liquid hydrogen transfer device that transfers liquid hydrogen from the hydrogen tank to the propulsion device; A hydrogen aircraft comprising a heat exchanger that cools the air by exchanging heat between liquid hydrogen and the air inside the aircraft, and a cooling device that cools the inner surface of the outer plate of the aircraft using the air cooled by the heat exchanger.

2. 2. The hydrogen aircraft according to claim 1, A hydrogen aircraft, wherein the heat exchanger exchanges heat between the liquid hydrogen drawn out from the hydrogen tank by the liquid hydrogen transfer device and air.

3. The hydrogen aircraft according to claim 2, the propulsion device includes a vaporizer for vaporizing liquid hydrogen; the liquid hydrogen transfer device includes a liquid hydrogen line connecting the hydrogen tank and the vaporizer and through which liquid hydrogen flows, and a pump provided in the liquid hydrogen line, The heat exchanger exchanges heat between the liquid hydrogen flowing through the liquid hydrogen line downstream of the pump and air.

4. 2. The hydrogen aircraft according to claim 1, The cooling device includes a cooling air line through which air flows to cool the inner surface of the outer panel of the aircraft, and an air discharge section that opens to the outside of the aircraft and discharges the air that has passed through the cooling air line to the outside of the aircraft.

5. The hydrogen aircraft according to claim 4, The cooling device includes a pre-cooling air line through which air flowing into the heat exchanger flows, and an air intake section that opens to the outside of the aircraft and takes in air from the outside of the aircraft into the pre-cooling air line, A hydrogen aircraft, wherein the air intake section is provided at a position where the pressure at an opening of the air intake section is higher than the pressure at an opening of the air discharge section during flight of the aircraft.

6. The hydrogen aircraft according to claim 5, The aircraft includes a fuselage and a main wing extending from the fuselage to an outer side in a width direction of the fuselage, The cooling air line is provided along an inner surface of an outer casing of the main wing, A hydrogen aircraft, wherein the air discharge portion is provided at the rear of the outer plate of the main wing.

7. The hydrogen aircraft according to claim 5, A hydrogen aircraft, wherein the air discharge portion is provided on an upper surface of the outer plate of the main wing.

8. 2. The hydrogen aircraft according to claim 1, A hydrogen aircraft, wherein the cooling device includes a cooling air line extending along an inner surface of the skin of the aircraft in contact with the inner surface, and through which air flows to cool the inner surface of the skin of the aircraft.

9. The hydrogen aircraft according to any one of claims 1 to 8, the cooling device includes a cooling air line through which air flows to cool an inner surface of an outer panel of the airframe; The airframe includes a hollow reinforcing member that reinforces an outer skin of the airframe and defines at least a portion of the cooling air line.

10. 2. The hydrogen aircraft according to claim 1, the cooling device includes a cooling air line through which air flows to cool an inner surface of an outer panel of the airframe; A hydrogen aircraft, wherein the cooling air line has a shape in which the flow passage area becomes smaller toward the downstream side.

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