The overall aerodynamic layout of a cryogenic fuel twin-hull swept-wing aircraft

Abstract

The present invention belongs to the field of aerospace technology, and relates to an overall aerodynamic layout of a cryogenic fuel twin-body swept-wing aircraft, comprising a barrel-shaped twin fuselage, a cylindrical cryogenic fuel storage tank, two symmetrically distributed V-shaped tails, a large aspect ratio swept wing, a wing-mounted gas fuel turbofan engine, etc.; the two symmetrically distributed V-shaped tails have a total of four inclined tails to provide horizontal and vertical stability and control functions, and can be firmly installed at the tail of the fuselage; the large aspect ratio swept wing can enable the aircraft to have a larger cruise lift-to-drag ratio, to a certain extent offsetting the reduced flight performance caused by the excessive resistance of the twin fuselage design, and does not contain a wing fuel tank inside, so the structural strength can be strengthened, and at the same time the twin fuselage design can unload the flight force of the wing; the wing-mounted gas fuel turbofan engine can use gaseous natural gas or hydrogen for combustion, and such an engine can also be replaced by a fuel cell plus an electric ducted fan.

Description

Technical Field

[0001] The invention belongs to the field of aerospace technology, and in particular relates to an overall aerodynamic layout of a cryogenic fuel twin-body swept-wing aircraft. Background Art

[0002] Cryogenic fuel refers to liquid fuels with extremely low temperatures, such as liquid natural gas and liquid hydrogen. They need to be stored in special insulated storage tanks. The low calorific value of cryogenic fuel is generally high, which leads to a significant reduction in the fuel consumption of the aircraft, so that the same weight of fuel can fly farther or longer; and for designs with fixed range or flight time, the required fuel weight is significantly reduced, and the saved weight can be used to increase the payload. Compared with traditional fuel aircraft, cryogenic fuel aircraft can have a longer range or flight time and a stronger payload capacity; because the density of cryogenic fuel is significantly lower than that of aviation kerosene, it requires a larger storage volume. At the same time, because it needs to maintain an extremely low temperature, the fuel tank cannot be designed in the wing, and only the fuselage tank can be used, resulting in an increase in the volume of the aircraft fuselage. The conventional single-fuselage layout needs to be designed as an extremely thick fuselage. At the same time, the aspect ratio of the wing cannot be too large, resulting in a reduction in the aircraft's cruising efficiency. Even so, it may result in insufficient payload space but excess payload weight, which greatly offsets the benefits of cryogenic fuel. The wing-body fusion layout can provide a larger internal volume and accommodate a larger cryogenic fuel tank. However, the wing-body fusion layout must be designed to a certain size so that its internal volume and cruising efficiency will have advantages over conventional layout aircraft. Otherwise, it will have no advantages over conventional layout aircraft due to increased flight control and manufacturing difficulties. The catamaran-type large aspect ratio swept-wing layout design can provide sufficient cryogenic tanks and commercial fuselage volume. The catamaran and wing-mounted engine design has a great unloading effect on the wing, so it can be designed with a larger aspect ratio, which can compensate for the defect of additional drag brought by the catamaran to a certain extent.

[0003] The Soviet Union's Tu-155 cryogenic fuel test aircraft (including LNG and liquid hydrogen), the European and American A-310 aircraft and the Do-328 liquid hydrogen test aircraft were tested between 1980 and 2005; cryogenic fuel aircraft, especially liquid hydrogen fuel aircraft, have received serious attention from major aircraft manufacturers. For example, Boeing has tested liquid hydrogen long-flight drones to explore the aviation application of hydrogen energy, and Airbus has come up with three liquid hydrogen aircraft concept designs, covering concepts from straight to mainline, propeller to turbofan, conventional layout to flying wing layout. Conventional turbofan power may be replaced by fuel cells plus electric ducted fans, but the current insufficient power density of fuel cells and electric motors limits their practical application on large aircraft. At present, they can only be used on some small aircraft. In the future, it is entirely possible to replace gas with electrification after the power density of fuel cells and electric motors is enhanced.

[0004] Currently, heavy-duty trucks using LNG fuel are already mature industrial products. However, heavy-duty trucks using LH2 fuel have been launched successively by Daimler, Mercedes-Benz, BAIC, etc., with a range of 1,000 to 2,000 kilometers, in order to solve the problem that heavy-duty trucks produce 60% of carbon dioxide and pollution emissions while accounting for only 3% of the total number of motor vehicles.

[0005] Conventional jet fuel aircraft have the following disadvantages: (1) Conventional jet fuel aircraft do not meet the requirements of low-carbon and green environmental protection. It is extremely difficult to significantly improve its environmental protection performance from the aircraft design, and conventional jet fuel is a non-sustainable energy source; (2) The specific fuel consumption of conventional jet fuel aircraft is too high, and the growth of the cruise efficiency factor has reached its limit by improving the aircraft design alone; (3) Conventional jet fuel aircraft cannot use low-carbon and green low-temperature aviation fuel. The engine, especially the fuel tank, and even the cabin and wings need to be re-adapted to the low-temperature storage design. The reason for the disadvantages and problem 1 is that conventional jet fuel is refined from petroleum. Its production is limited and will eventually run out. During its refining and use, it releases a large amount of carbon dioxide and other harmful gases, liquids and solids, which harm the atmosphere, soil and water sources. Although the release of CO2 can be reduced from the aircraft design, and NOX compounds, but it cannot be eliminated fundamentally, and even compared with the refining process, even if the improvement is negligible; the reason for disadvantage and problem 2 is that, due to the physical and chemical properties of conventional aviation kerosene aircraft, although the aircraft's specific fuel consumption can be significantly reduced through large bypass ratio engine design or other overall aerodynamic layout design (such as wing-body fusion, boundary layer suction propulsion), it is currently approaching the limit or a major technical bottleneck, and there is limited room for improvement in the cruise efficiency factor; the reason for disadvantage and problem 3 is that cryogenic fuels need to be stored in cryogenic tanks, and the aircraft must be replaced with gas fuel turbofan engines. At the same time, due to the significant differences in the physical and chemical properties of the fuel, such as the huge differences in fuel volume or weight, the aircraft design based on aviation kerosene fuel cannot be used, and the overall aerodynamic design must be redesigned. For example, the internal storage volume is significantly different, and the tank must be designed to maintain extremely low temperatures.

[0006] There are currently no mature cryogenic fuel aircraft in service. Existing cryogenic fuel aircraft have the following shortcomings and problems: for example, the United States' "Canberra" bomber only has one side of its engine replaced with a liquid hydrogen fuel engine for use as a test model; the Soviet Union's Tu-155 aircraft was equipped with a liquid hydrogen engine NK88 to achieve commercial flight, but due to the extremely low density of liquid hydrogen, the cabin volume is seriously occupied by the liquid hydrogen cryogenic tank; the United States' P-3 maritime patrol aircraft has only been designed and discussed, and it was found that under the same range, the weight of the entire aircraft was reduced by 20%, but the cabin volume was only 35%, and the commercial space was seriously insufficient. Summary of the invention

[0007] The purpose of the present invention is to provide an overall aerodynamic layout of a cryogenic fuel twin-body swept-wing aircraft to solve the urgent pressure of low-carbon green environmental protection faced by existing conventional layout aircraft, such as the emission of CO2 and NOX pollutants, which even determines the market survival of commercial transport aircraft, and the unsustainable source of conventional aviation fuel; at the same time, the aircraft's range or flight time can be significantly improved, for example, a range of 20,000 to 30,000 kilometers can be achieved, and it can fly directly from Beijing to Argentina without transfer or aerial refueling; for fixed-range flights, the specific fuel consumption of cryogenic fuel is significantly reduced, the required fuel weight is significantly reduced, and thus the commercial load weight can be significantly increased.

[0008] To solve this technical problem, the technical solution of the present invention is:

[0009] The invention discloses an overall aerodynamic layout of a cryogenic fuel twin-body swept-wing aircraft, which comprises a barrel-shaped twin-body fuselage, two cylindrical cryogenic fuel storage tanks, two symmetrically distributed V-shaped tails, a large aspect ratio swept wing, a wing-mounted gas fuel turbofan engine, etc. The cylindrical cryogenic fuel storage tanks are arranged in the middle and rear part of the fuselage, and each fuselage comprises a cylindrical cryogenic fuel storage tank.

[0010] The two cylindrical cryogenic fuel tanks account for 30% to 60% of the internal volume of the entire fuselage.

[0011] The cryogenic fuel refers to non-conventional aircraft fuels such as liquid natural gas and liquid hydrogen, which have a relatively high low calorific value but a very low density;

[0012] The wing leading edge sweep angle is 0 to 35 degrees;

[0013] The aspect ratio of a high aspect ratio swept wing is 7 to 15.

[0014] The tip-to-root ratio of the two V-tails (the ratio of the chord length of the wing tip to the chord length of the wing root) is 0.3-0.6, the aspect ratio is 3-6, and the V-tail dihedral angle is 30-60 degrees;

[0015] The fuselage aspect ratio is 10 to 15;

[0016] The relative span of the inner wing section accounts for 20% to 40%.

[0017] The relative thickness at the wing root is 15% to 20%, the relative thickness at the wing tip is 10% to 15%, and the relative thickness at the junction of the two sections is 13% to 18%.

[0018] The spanwise position of the wing-mounted gas fuel turbofan engine is installed at a relative half span (referring to the spanwise relative position) of 40% to 60%, and the number of engines is 2 to 6.

[0019] Preferably, the sweep angle of the leading edge of the wing is 5 to 20 degrees; the aspect ratio of the high aspect ratio swept wing is 11 to 15.

[0020] The V-tail dihedral angle is 45 to 55 degrees; the fuselage aspect ratio is 11 to 13; the relative span ratio of the inner wing section is 30% to 37%.

[0021] The cylindrical cryogenic fuel tank can also be divided into multiple sections. For example, a part of the tank can be decomposed and arranged near the head of the fuselage to adjust the center of gravity distribution of the whole machine.

[0022] The engine can also be replaced by a fuel cell plus an electric ducted fan.

[0023] The trailing edge of the inner wing section is not necessarily straight, and a certain degree of sweep or forward sweep is allowed.

[0024] The sweep angles of the leading edges of the inner and outer wing sections of the wing are allowed to be unequal, for example, the sweep angle of the inner wing section is larger while the sweep angle of the outer wing section is smaller.

[0025] The wing bridge between the two fuselages can be designed with a mounting device for carrying larger and heavier commercial cargo for long-distance transportation or aerial delivery.

[0026] The two V-shaped tails can also be designed as conventional vertical tails, T-shaped or cross-shaped vertical tails, or double cross tails connected together.

[0027] The outer wing section of the high aspect ratio swept wing can be designed as a foldable section. The foldable section can be 1 section or 2 sections. When parked on the ground, it can be folded upward and locked to reduce the wingspan in the parked state.

[0028] The overall aerodynamic layout of the twin-body swept-wing aircraft of the present invention can increase the internal volume by reducing the fuselage length and increasing the fuselage diameter.

[0029] The beneficial effects of the present invention are:

[0030] The invention provides an overall aerodynamic layout of a low-temperature fuel catamaran swept-wing aircraft. The beneficial effect of the invention is to greatly solve the urgent low-carbon and green environmental protection pressure problems faced by existing conventional layout aircraft. For example, the emission of CO2 and NOX pollutants completely disappears or is greatly reduced, which greatly improves the market viability of commercial transport aircraft due to environmental constraints. There is no problem of unsustainability of conventional aviation fuel sources. Liquid hydrogen can be produced from solar energy, wind energy, hydropower, ocean energy or nuclear energy, and the source is unlimited; the potential for improving thermal efficiency is large because it can achieve lean combustion and has an extremely good cold source; hydrogen has excellent thermal conductivity and a high sound speed, about 7 times greater than air, and about 3 times the sound speed of air, which is conducive to combustion and mixing; at the same time, there are mature technologies for the aerospace industry and the automotive industry to use hydrogen energy Laying the groundwork; due to the high mass energy density of cryogenic fuels, such as liquid hydrogen aircraft, the range or flight time can be significantly improved, for example, an ultra-long range of 20,000 to 30,000 kilometers can be achieved, and it can fly directly from Beijing to Argentina without transferring or refueling in the air; for fixed-range flights, the specific fuel consumption of cryogenic fuels is significantly lower than that of conventional aviation kerosene, and the weight of fuel required for flight is significantly reduced, so the payload can be significantly increased. For example, when using liquid hydrogen fuel, the same range only requires 36% of the weight of aviation kerosene, and the 74% of the weight of aviation kerosene saved is the potential for increased payload.

[0031] The purpose of cryogenic fuel aircraft is to gradually replace conventional kerosene aircraft. There are currently no mature cryogenic fuel aircraft in service. Airbus, Boeing and others have recently proposed some conceptual plans for cryogenic fuel aircraft and extremely limited test models. Due to the huge gap in fuel density between cryogenic fuel aircraft and conventional aviation kerosene aircraft, the overall aerodynamic design must be redesigned rather than modifying existing models.

[0032] For example, in the history of cryogenic fuel aircraft, such as the US "Canberra" bomber, only one side of the engine was replaced with a liquid hydrogen fuel engine for use as a test model. Due to the insufficient capacity of the cabin to load liquid hydrogen, the range was very limited. The Soviet Tu-155 aircraft was replaced with a liquid hydrogen engine NK88 to achieve commercial flight, but due to the extremely low density of liquid hydrogen, the cabin volume was seriously occupied by the liquid hydrogen cryogenic storage tank. The US P-3 maritime patrol aircraft has only been designed and discussed, and it was found that under the same range, the weight of the entire aircraft was reduced by 20%, but the cabin volume was only 35%, and the commercial space was seriously insufficient.

[0033] In addition, even the source of LNG can be considered sustainable compared to oil. For example, the proven reserves of methane hydrate on the seabed and permafrost zones around the world can be used by humans for 1,000 years. It is also technically feasible to use CO2 and water to produce CH4 at the same time, but the current cost is too high. For example, SPACEX plans to use CO2 and water to produce CH4 on Mars to obtain fuel for the spacecraft to return to Earth.

[0034] Cryogenic fuel aircraft have lower specific fuel consumption. For example, the specific fuel consumption of liquid hydrogen fuel is close to 1 / 3 of that of conventional aviation kerosene. The range of the same weight of fuel can be increased by 2 times. Even the same weight of LNG fuel can increase the range by about 18%. At the same time, it has the great advantages of low carbon and green energy sources with sustainability. However, the density of cryogenic fuel is relatively low. For example, the density of liquid natural gas is only 0.43-0.47 tons / cubic meter, and the density of liquid hydrogen is even lower, only 0.071 tons / cubic meter, while the density of aviation kerosene is 0.8 tons / cubic meter, so conventional aircraft need to be significantly modified. The advantage of the catamaran swept wing layout over the wing-body fusion layout is that it does not need to be designed to be larger in size and can also have higher aerodynamic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions implemented in the present invention, the following is a brief explanation of the drawings required to be used in the examples of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is an overall schematic diagram of the layout structure of the present invention;

[0037] Figure 2 It is a front view of the present invention;

[0038] Figure 3 A top view of the present invention;

[0039] Figure 4 It is a left side view of the present invention;

[0040] Figure 5 Dimensions of the embodiment of the present invention when viewed from above;

[0041] Figure 6 is the left-view size of the embodiment of the present invention;

[0042] Figure 7 is the front view size of the embodiment of the present invention;

[0043] In the picture, 1 is a barrel-shaped double fuselage, 2 is an outer wing section of a large aspect ratio swept wing, 3 is an inner wing section of a large aspect ratio swept wing, 4 is two symmetrically distributed V-shaped tail fins, 5 is a cylindrical cryogenic fuel tank, 6 is a wing-mounted gas-fuel turbofan engine, etc. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. The features of various aspects of the embodiments of the present invention will be described in detail below. In the various drawings and the following description, well-known structures and technologies are not shown to avoid unnecessary ambiguity of the present invention. Figures 2 to 4 The figure shows a schematic diagram of the aircraft layout structure of the present invention, wherein: Figure 5 Figure 6 Figure 7 : is an aircraft layout of a specific embodiment, wherein the numerical unit is m.

[0045] The cryogenic fuel tank has a capacity of 1,600 cubic meters and is divided into two parts, located in the middle and rear of the fuselage, each with a capacity of 800 cubic meters. There are 6 engines, which are arranged in a wing-mounted layout, located at 36.4%, 49.1%, and 61.8% of the half-span, respectively. The fuel is liquid hydrogen. The leading edge of the wing has a sweep angle of 35 degrees; the aspect ratio of the high aspect ratio swept wing is 11; and the length-to-diameter ratio is 13.6. For details, see Figures 5 to 7 .

[0046] In the V-tail layout, the root-to-tip ratio of the two V-tails is 0.3, the aspect ratio is 5, and the V-tail dihedral angle is 45 degrees. The fuselage aspect ratio is 13.6; the relative span of the inner wing section accounts for 20%. The relative thickness at the wing root is 17%, the relative thickness at the wing tip is 10%, and the relative thickness at the junction of the two sections is 15%;

[0047] During the landing phase, the outer wing sections of the cryogenic fuel catamaran swept-wing aircraft are folded and locked after stopping on the airport runway to facilitate the movement and parking of the large aspect ratio wing aircraft; during the take-off phase, the aircraft is filled with sufficient cryogenic fuel through a special fuel filling vehicle or other device, the outer wing sections are unfolded and locked, and then it takes off on the runway like a conventional aircraft.

[0048] The twin-fuselage design provides ample cabin volume, which can accommodate the huge volume caused by the extremely low density of liquid hydrogen and have sufficient commercial space left, without the need to design additional external cryogenic fuel tanks, which would significantly reduce the aircraft's aerodynamic performance. For example, an external cryogenic tank may result in the lift-to-drag ratio of the entire aircraft to only 11 to 12, while the twin-fuselage design can achieve a lift-to-drag ratio of 16.

[0049] The barrel-shaped double-fuselage design is mainly to increase the internal storage volume of the fuselage, because cryogenic fuels such as LNG or LH2 fuel have a low density, require a larger storage volume, and need to maintain an extremely low temperature and cannot be stored inside the wing, so only the fuselage volume can be used; two cylindrical cryogenic fuel tanks are arranged in the middle and rear part of the fuselage, and each fuselage contains a cylindrical cryogenic fuel tank; the cryogenic fuel tank can also be decomposed into multiple sections, for example, a part of the tank can be decomposed and arranged near the head of the fuselage to adjust the center of gravity distribution of the whole machine.

[0050] The two symmetrically distributed V-shaped tails produce the functions of a vertical tail and a horizontal tail when in flight, which to a certain extent reduces the wetted area of ​​a conventional vertical horizontal tail and helps reduce the frictional resistance of the aircraft. The V-tail is directly installed on the fuselage, with better structural strength, firmness and safety. The two V-shaped tails can also be designed as conventional vertical horizontal tails, T-shaped or cross-shaped vertical horizontal tails, or double cross tails connected together.

[0051] The high aspect ratio swept wing can be designed with higher structural strength because it does not have an in-wing fuel tank. Through the twin-fuselage layout design and the engine arrangement to unload the force when the wing is in flight, its aspect ratio can be greater than that of ordinary conventional civil aircraft.

[0052] Wing-mounted gas-fuel turbofan engines use gaseous fuel, such as liquid CH4 or H2. This type of fuel is stored in liquid form, but when it is sent into the engine, it can cool the parts of the engine that need cooling. It is an extremely excellent cold source. Due to its good cooling effect, it can improve the thermal efficiency of the engine. At the same time, the liquid fuel is vaporized after being heated and sent into the combustion chamber in gaseous form. Due to its high mass energy density, the mass of gas material required to produce equal energy is less, so lean combustion can be achieved, which improves the thermal efficiency of the engine and is more environmentally friendly. This type of engine can also be replaced by a fuel cell plus an electric ducted fan, which is more economical and environmentally friendly.

[0053] Finally, it should be noted that in order to avoid interfering with the parking and movement of other aircraft at the airport due to the excessive wingspan of the aircraft, the outer wing section of the large aspect ratio wing can be designed as a two-section foldable mechanism. The outer wing section is folded and locked when moving and parking at the airport, and the outer wing section of the wing is unfolded and locked when preparing for takeoff on the runway, and then the takeoff is carried out.

Claims

1. An overall aerodynamic layout of a cryogenic fuel twin-body swept-wing aircraft, characterized in that: The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft includes a barrel-shaped twin-body fuselage, two cylindrical cryogenic fuel storage tanks, two symmetrically distributed V-shaped tail wings, a large aspect ratio swept wing, and a wing-mounted gas fuel turbofan engine; the cylindrical cryogenic fuel storage tank is arranged in the middle and rear part of the fuselage, and each fuselage includes a cylindrical cryogenic fuel storage tank; The two cylindrical cryogenic fuel tanks account for 30% to 60% of the internal volume of the entire fuselage. The cryogenic fuel refers to liquid natural gas or liquid hydrogen; The fuselage aspect ratio is 10~15; the wing leading edge sweep angle is 0~35 degrees; the aspect ratio of the high aspect ratio swept wing is 7~15; The relative span of the inner wing section is 20%~40%, the relative thickness at the wing root is 15%~20%, the relative thickness at the wing tip is 10%~15%, and the relative thickness at the junction of the two sections is 13%~18%; The tip-to-root ratio of the two V-tails is 0.3~0.6, the aspect ratio is 3~6, ​​and the V-tail dihedral angle is 30~60 degrees; The spanwise position of the wing-mounted gas-fuel turbofan engine is 40% to 60% relative to the half-span, and the number of engines is 2 to 6.

2. The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft according to claim 1, characterized in that: The fuselage aspect ratio is 11~13; the wing leading edge sweep angle is 5~20 degrees; the aspect ratio of the high aspect ratio swept wing is 11~15; the relative span ratio of the inner wing section is 30%~37%; the V-tail dihedral angle is 45~55 degrees.

3. The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft according to claim 1, characterized in that: The cylindrical cryogenic fuel tank is divided into multiple sections.

4. The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft according to claim 1, characterized in that: The engine is replaced with a fuel cell and an electric ducted fan.

5. The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft according to claim 1, characterized in that: The trailing edge of the inner wing section is swept back or forward.

6. The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft according to claim 1, characterized in that: The leading edge sweep angles of the inner and outer wing sections are not equal.

7. The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft according to claim 1, characterized in that: The wing bridge between the two fuselages is designed with a mounting device for mounting commercial cargo for long-distance transportation or aerial delivery.

8. The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft according to claim 1, characterized in that: The two V-shaped tail fins are designed as a T-shaped or cross-shaped vertical tail, or as a double cross-tail fin connected together.

9. The overall aerodynamic layout of the cryogenic fuel twin-body swept-wing aircraft according to claim 1, characterized in that: The outer wing section of the high aspect ratio swept wing is designed with a foldable section, which is one section or two sections and can be folded upward and locked when parked on the ground.

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