CN114458949A

CN114458949A - Liquid hydrogen aeroengine

Info

Publication number: CN114458949A
Application number: CN202210068455.1A
Authority: CN
Inventors: 袁宗立
Original assignee: Beijing Haishen Power Technology Co ltd
Current assignee: Beijing Haishen Power Technology Co ltd
Priority date: 2022-01-20
Filing date: 2022-01-20
Publication date: 2022-05-10

Abstract

The invention provides a liquid hydrogen aircraft engine, which comprises a liquid hydrogen tank, a fuel cell, a motor, a bypass shell, a fan and an anti-bird impact cone, wherein the liquid hydrogen is adopted for supplying energy, the fuel cell is used for generating electricity, the motor and the fan rotate in a power mode, compared with the power mode generated by burning fuel oil, a turbine, a gas compressor, a combustion chamber and a small bypass system are omitted, and the fuel cost and the weight of a fuel and power system can be greatly reduced; after the structure is cancelled, the noise can be greatly reduced by adopting the duct shell and the fan in the scheme; the specially designed motor is adopted, and the liquid hydrogen stored in the motor can be used for cooling, so that the magnetic force of the magnetic structure is improved, and the effects of improving the energy density and reducing the weight are achieved; the bird impact prevention cone is arranged in the scheme, so that the impact of big birds can be avoided; and moreover, the multilayer carbon fiber pure yarns are woven at the position of the blade root of the fan, so that the stress resistance of the position of the blade root can be greatly improved, and the structural strength of the fan is improved. This scheme has realized the environmental protection, has gone the noise and has practiced thrift the purpose of cost.

Description

Liquid hydrogen aeroengine

Technical Field

The invention relates to the technical field of aero-engines, in particular to a liquid hydrogen aero-engine.

Background

With the increasing global carbon emissions and global warming issues, the carbon neutralization and clean energy pace of various countries is accelerating, and we see that on land, various vehicles have begun to be replaced by electric motors (and fuel cells), and surface ships are just replacing and developing fuel cells, and the sky is no exception at all.

The noise problem of conventional fuel aircraft engines is very great, which causes a long troubling for the inhabitants in the vicinity of airports, mainly due to the acoustic vibrations caused by the combustion of the turbine and the combustion of the combustion chamber.

In the whole aviation field, civil aviation emission accounts for the majority, but the civil aviation engine is the most difficult to clean because the civil aviation engine has huge power and the flying time is often 10 hours. If the scheme of the energy storage battery is considered, the scheme of selecting the battery to be electrically operated does not have any exit according to the energy storage capacity of the battery (for example, the power of a single engine is often more than 20000KW, 666 tons of energy storage batteries are needed in a 10-hour voyage, 2666 tons of 4 engines are arranged in the whole aircraft, and the tonnage is 6.88 times of the total weight of the Boeing 747 matched with the tonnage, so that the market does not have the electric civil aviation engine and the electric civil aviation aircraft at present. We cannot use the mode of combustion of liquid hydrogen with air or liquid oxygen because the end result is clean and the emissions are water, but the energy consumption is large and the fuel costs far exceed those of fuel-powered engines.

In order to achieve the purposes of cleaning and protecting the environment, removing noise and saving cost of the aircraft engine, a new feasible scheme needs to be designed to replace the existing fuel aircraft engine.

Disclosure of Invention

The invention provides a liquid hydrogen aircraft engine, which is used for realizing the cleanness, environmental protection, noise reduction and cost saving of the aircraft engine.

In order to achieve the purpose, the invention provides a liquid hydrogen aircraft engine which comprises a liquid hydrogen tank, a fuel cell, a motor, a duct shell, a fan and an anti-bird impact cone, wherein the fan is arranged in a duct of the duct shell; the liquid hydrogen tank conveys liquid hydrogen to the liquid hydrogen cooling channel to cool the motor and gasify the liquid hydrogen, the gasified hydrogen is input into the fuel cell, the electric quantity generated by the fuel cell is conveyed to the motor, and the motor is in driving connection with the fan; the fan comprises a hub and a plurality of blades, wherein each blade comprises a blade root arranged on the hub and a plurality of layers of carbon fiber pure yarns woven on the blade root; the bird impact prevention cone is arranged on the air inlet side of the ducted shell and is of a conical structure with a plurality of hexagonal honeycomb-state air inlet holes.

Furthermore, the stator structure comprises a stator amorphous alloy core and a winding wound on the stator amorphous alloy core, a plurality of liquid hydrogen cooling channels are distributed on the stator amorphous alloy core in the circumferential direction, the inner wall of each liquid hydrogen cooling channel is made of aluminum-lithium alloy, and the winding is made of copper wires or superconducting composite wires.

Further, the rotor structure comprises a silicon steel rotor, a rotor shaft, a magnetism isolating material and a plurality of permanent magnets, wherein the rotor shaft penetrates through the silicon steel rotor, the magnetism isolating material is arranged around the rotor shaft, the permanent magnets are distributed in the silicon steel rotor, a liquid hydrogen cooling channel is arranged in each permanent magnet, the inner wall of each liquid hydrogen cooling channel is made of aluminum-lithium alloy, the permanent magnets are made of neodymium-iron-boron or superconducting materials, and the magnetism isolating material is polyimide added with silicon dioxide.

Furthermore, the liquid hydrogen aircraft engine also comprises a rectifier transformer, and the fuel cell, the rectifier transformer and the motor are electrically connected in sequence; the motor is a permanent magnet synchronous motor, the shell material of the motor is a silicon carbide composite material, the motor also comprises a speed change gear box, and a rotor shaft of the motor is in driving connection with a fan through the speed change gear box; the power of the motor is 4-29 MW, the energy-weight ratio of the motor is larger than 6kw/kg, and the output rotating speed of the motor is 2400-6000 rpm.

Furthermore, the liquid hydrogen aircraft engine also comprises a first bracket fixed in the bird-preventing impact cone, and the motor is positioned in the bird-preventing impact cone and is arranged on the first bracket; or the motor is arranged outside the bird impact prevention cone; on the outer surface of the bird-proof impact cone, the sum of the opening areas of the hexagonal honeycomb-shaped air inlets accounts for more than 90% of the conical surface area of the bird-proof impact cone, the bird-proof impact cone is made of a titanium alloy material, and the weight of the bird-proof impact cone is less than 110 kg.

Further, wheel hub is hollow structure, and wheel hub and a plurality of blade root are the integrative structure of forging by the aluminum alloy material finish, and the pure silk of carbon fiber sets up on the blade root through weaving and hot pressing, and the blade still includes carbon-fibre composite, and carbon-fibre composite is connected with the pure silk of carbon fiber on the blade root.

Furthermore, carbon fiber pure yarns are woven on the hub, and in the multiple layers of carbon fiber pure yarns on the blade root, the weaving directions of two adjacent layers of carbon fiber pure yarns are different; wherein, on the cross section of the blade root, the thickness of the woven carbon fiber pure yarn is more than 2 times of the thickness of the blade root.

Further, the radius of the duct is R, the diameter of the duct is D, the maximum lip curvature radius of the duct is between 0.060R and 0.065R, the divergence angle of the duct is between 5.5 degrees and 7.5 degrees, and the height of the duct is between 0.2D and 0.3D; in the axial direction of the duct, the distance between the fan and the lip of the duct is 0.305R to 0.405R.

Furthermore, the liquid hydrogen aircraft engine also comprises a second bracket fixed in the bypass, and the fan is rotatably arranged on the second bracket; the radius of the duct is R, the clearance between the blade tip of the blade and the inner wall of the duct is less than 0.0056R, and the linear speed of the blade tip is 425-610 m/s; the number of the blades in the fan is 20-24, the outer diameter of the fan is 1.2-3.5 m, the weight of the fan is 50-400 kg, and the thrust of the fan is 50-450 KN.

Further, the energy density of the fuel cell is more than 1.3kw/kg, and the weight of the fuel cell is less than 25000 kg.

The technical scheme of the invention is applied, and the liquid hydrogen aircraft engine comprises a liquid hydrogen tank, a fuel cell, a motor, a duct shell, a fan and an anti-bird impact cone, wherein the fan is arranged in a duct of the duct shell, the motor comprises a stator structure and a rotor structure, the rotor structure is rotatably arranged in the stator structure, and both the stator structure and the rotor structure are provided with liquid hydrogen cooling channels; the liquid hydrogen tank conveys liquid hydrogen to the liquid hydrogen cooling channel to cool the motor and gasify the liquid hydrogen, the gasified hydrogen is input into the fuel cell, the electric quantity generated by the fuel cell is conveyed to the motor, and the motor is in driving connection with the fan; the fan comprises a hub and a plurality of blades, wherein each blade comprises a blade root arranged on the hub and a plurality of layers of carbon fiber pure yarns woven on the blade root; the bird impact prevention cone is arranged on the air inlet side of the ducted shell and is of a conical structure with a plurality of hexagonal honeycomb-state air inlet holes. The scheme adopts a power mode of liquid hydrogen energy supply, fuel cell power generation and motor and fan rotation, compared with the energy generated by fuel oil combustion, a turbine, a gas compressor, a combustion chamber and a small duct system are omitted, and the fuel cost and the weight of a fuel and power system can be greatly reduced; after the structure is cancelled, the ducted shell and the fan in the scheme are adopted, so that the noise can be greatly reduced; the specially designed motor is adopted, and the liquid hydrogen stored in the motor can be used for cooling, so that the magnetic force of the magnetic structure is improved, and the effects of improving the energy density and reducing the weight are achieved; the bird impact prevention cone is arranged in the scheme, so that the impact of big birds can be avoided; moreover, the multilayer carbon fiber pure yarns are woven at the position of the blade root of the fan, so that the stress resistance of the position of the blade root can be greatly improved, and the structural strength of the fan is improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic structural diagram of a liquid hydrogen aircraft engine provided by an embodiment of the invention;

FIG. 2 shows a schematic diagram of a portion of the structure of FIG. 1;

FIG. 3 shows a schematic view of a stator structure in an electric machine in the liquid hydrogen aircraft engine of FIG. 1;

FIG. 4 shows a schematic view of a rotor structure in an electric machine in the liquid hydrogen aircraft engine of FIG. 1;

FIG. 5 shows a schematic view of a fan in the liquid hydrogen aircraft engine of FIG. 1;

FIG. 6 shows a schematic view of a bypass casing in the liquid hydrogen aircraft engine of FIG. 1;

FIG. 7 shows a first schematic diagram of a fan-woven carbon fiber pure yarn in the liquid hydrogen aircraft engine in FIG. 1;

fig. 8 shows a second schematic diagram of the fan-woven carbon fiber pure yarn in the liquid hydrogen aircraft engine in fig. 1.

Wherein the figures include the following reference numerals:

10. a liquid hydrogen tank; 20. a fuel cell; 30. a motor; 31. a stator structure; 311. a stator amorphous alloy core; 312. a winding; 32. a rotor structure; 321. a silicon steel rotor; 322. a rotor shaft; 323. a magnetic barrier material; 324. a permanent magnet; 33. a liquid hydrogen cooling channel; 40. a ducted shell; 50. a fan; 51. a hub; 52. a blade; 521. a blade root; 522. pure carbon fiber filaments; 60. an anti-bird impact cone; 61. a hexagonal honeycomb-state air inlet hole; 70. a rectifier transformer; 81. a first bracket; 82. a second support.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 to 8, an embodiment of the present invention provides a liquid hydrogen aircraft engine, including a liquid hydrogen tank 10, a fuel cell 20, an electric machine 30, a bypass casing 40, a fan 50 and an anti-bird strike cone 60, wherein the fan 50 is disposed in the bypass of the bypass casing 40, the electric machine 30 includes a stator structure 31 and a rotor structure 32, the rotor structure 32 is rotatably disposed in the stator structure 31, and both the stator structure 31 and the rotor structure 32 have a liquid hydrogen cooling channel 33; the liquid hydrogen tank 10 delivers liquid hydrogen to the liquid hydrogen cooling channel 33 to cool the motor 30 and gasify the liquid hydrogen, the gasified hydrogen is input to the fuel cell 20, the electric quantity generated by the fuel cell 20 is delivered to the motor 30, and the motor 30 is in driving connection with the fan 50; the fan 50 comprises a hub 51 and a plurality of blades 52, wherein the blades 52 comprise a blade root 521 arranged on the hub 51 and a plurality of layers of carbon fiber pure yarns 522 woven on the blade root 521; the bird-proof impact cone 60 is arranged on the air inlet side of the ducted shell 40, and the bird-proof impact cone 60 is of a conical structure with a plurality of hexagonal honeycomb-shaped air inlet holes 61.

The scheme adopts a power mode of liquid hydrogen energy supply, fuel cell 20 power generation and motor 30 and fan 50 rotation, compared with the energy generated by fuel oil combustion, the scheme omits a turbine, a gas compressor, a combustion chamber and a small duct system, and can greatly reduce the fuel cost and the weight of the fuel and power system; after the structure is cancelled, the bypass shell 40 and the fan 50 in the scheme are adopted, so that the noise can be greatly reduced; by adopting the specially designed motor 30, the liquid hydrogen stored in the system can be utilized to cool the motor 30 through the liquid hydrogen cooling channel 33, so that the magnetic force of a magnetic structure in the motor 30 is improved, and the effects of improving the energy density and reducing the weight are achieved; the bird impact prevention cone 60 is arranged in the scheme, so that the impact of big birds can be avoided; moreover, the multilayer carbon fiber pure yarn 522 is woven at the position of the blade root 521 of the fan 50, so that the stress resistance of the position of the blade root 521 can be greatly improved, and the structural strength and the reliability of the fan 50 are improved. Specifically, in the scheme, the weaving mode of the carbon fiber pure yarn 522 adopts a weaving and embroidering process.

Moreover, the appearance of the bird-preventing impact cone 60 is designed into a topological structure, and the honeycomb-shaped hexagon of the air inlet hole is used for replacing the round structure in the prior art, so that the air flow smoothness and the weight reduction are further increased on the basis of ensuring the impact stress, and the topological structure design basically exerts the unit weight stress of the material to the utmost extent.

As shown in fig. 3, the stator structure 31 includes a stator amorphous alloy core 311 and a winding 312 wound on the stator amorphous alloy core 311, wherein a plurality of liquid hydrogen cooling channels 33 are distributed on the stator amorphous alloy core 311 in the circumferential direction, the inner wall of the liquid hydrogen cooling channels 33 is made of an aluminum-lithium alloy, and the winding 312 is made of a copper wire or a superconducting composite wire. By distributing a plurality of liquid hydrogen cooling channels 33 in the circumferential direction of the stator amorphous alloy core 311, the cooling effect on the stator structure 31 can be improved, thereby improving the magnetic force of the structure. Moreover, the inner wall of the liquid hydrogen cooling channel 33 is made of aluminum lithium alloy, so that the hydrogen embrittlement problem of other materials is avoided, meanwhile, the heat conduction capacity of the aluminum lithium alloy is 3 times that of stainless steel which is another hydrogen embrittlement prevention material, and the capacity can quickly take away heat inside the magnetic pole of the motor. The winding 312 may be made of copper wire or superconductive composite wire, in which the copper wire is replaced by a very thin wire AC superconductive composite wire, and liquid hydrogen refrigeration environment consistent with the rotor structure is added to realize full superconductivity.

As shown in fig. 4, the rotor structure 32 includes a silicon steel rotor 321, a rotor shaft 322, a magnetic shielding material 323, and a plurality of permanent magnets 324, the rotor shaft 322 passes through the silicon steel rotor 321, the magnetic shielding material 323 is disposed around the rotor shaft 322, the plurality of permanent magnets 324 are distributed in the silicon steel rotor 321, each permanent magnet 324 has a liquid hydrogen cooling channel 33 therein, the inner wall material of the liquid hydrogen cooling channel 33 is an aluminum-lithium alloy, the permanent magnets 324 are made of neodymium-iron-boron or a superconducting material, and the magnetic shielding material 323 is polyimide with silica added. With the above arrangement, the liquid hydrogen can flow into the liquid hydrogen cooling passages 33 of the permanent magnets 324, thereby cooling the rotor structure 32. The permanent magnet 324 may be made of neodymium iron boron or a superconducting material, and when the superconducting material is used, a low temperature environment is realized through liquid hydrogen, so that the energy density can be greatly improved.

Further, the liquid hydrogen aircraft engine further comprises a rectifier transformer 70, the fuel cell 20, the rectifier transformer 70 and the motor 30 are electrically connected in sequence, the voltage output by the fuel cell 20 can be boosted through the rectifier transformer 70, and stable voltage output is realized and is transmitted to the motor 30. The motor 30 is a permanent magnet synchronous motor 30, and the shell material of the motor 30 is a silicon carbide composite material, so that the purpose of reducing weight can be achieved while the structural strength is ensured. The motor 30 further includes a speed change gearbox, and the rotor shaft 322 of the motor 30 is drivingly connected to the fan 50 through the speed change gearbox, so that the motor 30 has a suitable output speed, and the fan 50 is driven to rotate at a suitable speed.

Specifically, the power of the motor 30 is 4-29 MW, the energy-to-weight ratio of the motor 30 is larger than 6kw/kg, and the output rotating speed of the speed change gear box of the motor 30 is 2400-6000 rpm. Through the arrangement, compared with the existing aero-engine, the liquid hydrogen aero-engine has the advantages that the weight can be greatly reduced, sufficient thrust is guaranteed, and the liquid hydrogen aero-engine is suitable for civil aircrafts.

As shown in fig. 2, the liquid hydrogen aircraft engine further includes a first bracket 81 fixed in the bird strike prevention cone 60, and the motor 30 is located in the bird strike prevention cone 60 and mounted on the first bracket 81; on the outer surface of the bird strike prevention cone 60, the sum of the opening areas of the hexagonal honeycomb-shaped air inlet holes 61 accounts for more than 90% of the conical surface area of the bird strike prevention cone 60, the bird strike prevention cone 60 is made of a titanium alloy material, and the weight of the bird strike prevention cone 60 is less than 110 kg. The bird pick-up cone 60 utilizes a mesh structure to prevent the entry of birds, which is much larger and larger because only bird picks are needed to ensure adequate incoming air supply to the fan 50. Moreover, the motor 30 can be arranged inside the bird strike prevention cone, so that the motor 30 is opposite to the fan 50 to be driven in the simplest mode. Furthermore, the material and open area of the bird strike cone 60 allows the bird strike cone 60 to have a lower weight. Alternatively, the motor 30 may be mounted outside the bird impact cone 60 as desired.

As shown in fig. 7 and 8, the hub 51 is a hollow structure, the hub 51 and the plurality of blade roots 521 are an integral structure formed by precisely forging aluminum alloy material, the carbon fiber pure filaments 522 are arranged on the blade roots 521 through weaving and hot pressing, the blade 52 further comprises carbon fiber composite material, and the carbon fiber composite material is connected with the carbon fiber pure filaments 522 on the blade roots 521. With the above arrangement, the fan 50 can be reduced in weight and has high structural strength.

Further, the hub 51 is woven with carbon fiber pure yarns 522, and in the plurality of layers of carbon fiber pure yarns 522 on the blade root 521, the weaving directions of two adjacent layers of carbon fiber pure yarns 522 are different; in the cross section of the blade root 521, the thickness of the woven carbon fiber pure yarn 522 is more than 2 times of the thickness of the blade root 521. Through the arrangement, the blade 52 has stronger tensile strength in different directions of the blade root 521. The arrangement mode is that a metal embryo replaces a composite material substrate, the carbon fiber pure yarn 522 is woven and embroidered on the composite material substrate, the ultra-strong tensile stress (7000Mpa) of the carbon fiber pure yarn 522 is reduced, and the metal radial stress (874Mpa) is utilized to form a perfect combination.

As shown in fig. 5 and 6, the radius of the duct is R, the diameter of the duct is D, the maximum lip radius of curvature of the duct is between 0.060R and 0.065R, the divergent angle of the duct is between 5.5 ° and 7.5 °, and the height of the duct is between 0.2D and 0.3D; in the axial direction of the duct, the distance between the fan 50 and the lip of the duct is 0.305R to 0.405R. Through the arrangement, the noise of gas flowing can be reduced, the gas is ensured to have larger flow, the thrust is improved, and the energy loss is reduced.

Further, the liquid hydrogen aircraft engine also includes a second bracket 82 secured within the duct, and the fan 50 is rotatably mounted on the second bracket 82, which facilitates the installation of the fan 50. Wherein, a bearing is arranged in the second bracket 82, and the rotating shaft passes through the bearing and is connected with the fan 50. The radius of the duct is R, the clearance between the blade tip of the blade 52 and the inner wall of the duct is less than 0.0056R, and the linear speed of the blade tip is 425-610 m/s; the number of the blades 52 in the fan 50 is 20 to 24, the outer diameter of the fan 50 is 1.2m to 3.5m, the weight of the fan 50 is 50 to 400kg, and the thrust of the fan 50 is 50 to 450 KN. This ensures that the fan 50 has sufficient thrust to be suitable for use in a civil aircraft.

In this embodiment, the energy density of the fuel cell 20 is greater than 1.3kw/kg and the weight of the fuel cell 20 is less than 25000 kg. Through the setting, compare in current fuel aeroengine, can reduce liquid hydrogen aeroengine's weight greatly to alleviate the weight of using this liquid hydrogen aeroengine's aircraft, and guaranteed to have sufficient duration, satisfied civil aviation user demand.

In order to more clearly understand the structure of the liquid hydrogen aircraft engine in the present solution and the advantages thereof over the existing aircraft engines, the following further description is provided.

The fuel cell engine is one of electric engines, and the electric motor and the electric power are used as driving means like the battery, the difference is that the fuel cell does not need to store energy, but the electric power generated by the cell stack instantly is used for supplying the electric motor in time, namely the energy storage mode of the fuel cell is fuel itself rather than the energy storage cell, the refocusing means that the power and the total weight of the fuel cell stack do not need to be increased no matter how many hours the flight is, the weight and the energy storage of the cell need to be increased along with the flight time, and the energy density of liquid hydrogen used as the energy storage is far higher than that of the energy storage cell (actually more than 60 times), so that the scheme of the fuel cell aeroengine becomes feasible.

The outer diameter of a hub of the liquid hydrogen aero-engine is 3.142m, the air flow rate is 1420kg/s, the latest fuel cell means is adopted, as shown in figures 1 and 2, the electrochemical reaction of liquid hydrogen and air in a fuel cell stack is used for generating electricity, a motor drives blades of the aero-engine to rotate until supersonic speed, acceleration is brought to incoming air, and theoretically, air pressure rise and fall and air temperature change are not involved (or the change is useless), only the air acceleration is simply given, and accordingly 389KN (39.7 tons) thrust is generated. The size, flow, thrust and application scenes of the liquid hydrogen aircraft engine are designed by taking the American general aircraft engine GE90 as a target and specifically replacing targets, and the liquid hydrogen aircraft engine is also suitable for civil aircraft engines such as Boeing 747 grade or other smaller grades after size change.

Compare traditional aeroengine, liquid hydrogen aeroengine has directly cancelled turbine, compressor unit and whole little duct structure, because those all need the burning fuel to be independable, in modern aeroengine, all realize energy-conservation through big duct ratio, the duct ratio has greatly all exceeded 8: 1, the large duct represented by the fan accounts for more than 78% of the total thrust and has the highest energy efficiency, so no small duct group exists whether the energy is saved or reduced, the small duct only plays a role of increasing the acceleration generated by the rest 22% of the thrust, and the acceleration is constructed on the basis that the efficiency is sharply reduced after the speed exceeds the sonic speed on the basis of the conventional theory that the rotational speed per second of the fan is rotated, however, the self-transmission supersonic speed of the modern fan is more than the self-transmission supersonic speed. Even though the fan of GE90 reaches 371m/s, the speed exceeds the sonic speed, and particularly after the invention of special supersonic speed blade profiles such as supersonic through-flow and the like, the existence of the small duct in the field of civil aviation engines loses the theoretical basis. This is because civil aircraft do not need to achieve transonic and supersonic flight, which can cause severe tone-barrier reactions that cause passenger discomfort. Thus in the subsonic regime, the fan is the best and most energy efficient propulsion mode. The subsonic civil aviation cruising speed is between 0.85 and 0.9 Mach, for one purpose, insufficient small power can be achieved only by increasing the rotating speed of a supersonic blade type fan, the blade tip peripheral speed of the fan is increased from 371m/s of GE90 to 425.46m/s, and the exhaust speed of a large bypass is increased from 235/m to 274/m.

The supersonic ducted fan is used as one of ducted fans, has quite silent characteristics, noise of the ducted fan is greatly reduced after noise of the ducted fan is reduced and directional, the fuel cell is quite quiet and almost has no noise, and cancelled small ducted noises such as a turbine, a gas compressor and a combustion chamber account for most of total noise, and finally, the aircraft noise can be controlled to be 60-70 decibels, compared with 100-140 decibels of a traditional civil aircraft, the difference is quite large, and because the decibel value difference is not an addition relation but an exponential relation:

the absolute value of 60 dB volume is 10^ (60/20) ^ 1 dB multiplied by 1,000;

70 dB volume absolute value 10^ (70/20) ^ 1 dB 3, 162;

110 dB volume absolute value 10^ (110/20) ^ 1 dB 316, 227;

the absolute value of 140 dB volume is 10^ (140/20) ^ 1 dB 10, 000, 000.

Flying birds are killers of aircraft engines, and since 1988, a crash accident caused by bird strikes has caused more than 200 deaths, and especially for sensitive and fragile engines, 144 tons of destructive force can be generated when a seven-kilogram big bird strikes an aircraft engine blade at cruising speed, and the destructive force is equivalent to the energy of a bomb. In particular, the civil aircraft engine makes the area of the air inlet larger and larger in order to increase the proportion of the large duct (which is one of the cost of energy saving and is also the soft rib which is most considered by the liquid hydrogen aircraft engine because the liquid hydrogen aircraft engine already makes the area of the air inlet extremely large), and at present, no blade made of any material can resist the impact of a big bird, and particularly, the trend of the blade is to lighten the weight (to reduce the weight and the stress) rather than to lighten the weight. In order to resist the impact of big birds (the birds are good), a bird impact prevention cone similar to the punch head of a punching engine is designed, see fig. 2, the bird impact prevention cone can easily flick the big bird which comes from the front, so that the big bird can not enter the engine at any angle, the flicking process is also cone-shaped and linear, the big bird is either penetrated and decomposed by a cone tip or flicked linearly by a cone, and the coming force of the big bird is decomposed into a plurality of small blocks by the linear increase of the cone angle and is finally flicked. The bird-preventing bumping cone utilizes the net structure to prevent the entry of big birds, and the net structure has very large and numerous meshes to ensure enough incoming air supply fan as only big birds need to be prevented. The motor can be arranged inside the bird-proof cone, so that the motor is opposite to the fan and is driven in the simplest mode.

The liquid hydrogen aircraft engine will be specifically explained in the aspects of thrust implementation, energy consumption, modeling design, material selection, stress analysis and the like.

The thrust is realized:

first is the thrust equation: F-mV (minus the least effective part of the equation),

where F represents the unit of thrust N, m is the air flow per second in kg, and V represents the exhaust velocity per second in m/s.

As a substitute product, the consistency of the push force and the size of the substitute can be kept, and then the comparison can be carried out on the aspects of performance, quality, efficiency and the like.

We first obtained the parameters of the thrust formula, the known thrust of GE90 (reference model, for boeing 777B) is 389.2KN, which is a very large model inside aviation aircraft. We calculate by the thrust formula:

v is 389200 × 0.78 (large bypass push-weight ratio) ÷ 1268 (large bypass intake air flow rate at 8.4: 1 bypass ratio) ═ 239m/s,

u is 371m/s (U is tip peripheral speed, known),

V/U＝0.6442。

to achieve the same thrust we need to obtain the following parameters:

v2 (liquid hydrogen aircraft engine) 389200 ÷ 1420 (equivalent to GE90 total flow rate) 274 m/s.

U2 is 274/0.6442, and then two numbers 420 and 425.46m/s are obtained by power algorithm calculation, and the maximum value is 425.46m/s according to the unfavorable selection method.

This blade revolution has not exceeded fan blade revolution 478.4m/s of GE 90's competitor Ruida 800, and is therefore both engineering and theoretical suitable. In order to obtain larger margin, the tip peripheral speed of the liquid hydrogen aeroengine is designed to be between 425.46 (cruising) and 601m/s (takeoff, emergency, single engine mode and the like, and the highest rotating speed of 601 is matched to be the power multiplied by 2 of the single engine).

The following table compares the fan in this scenario to the fan in GE 90:

according to the table, the blade revolving speed of the fan is increased by 14.6%, so that a series of facilities such as a turbine, a compressor, a combustion chamber and a small duct on GE90 are eliminated, and weight reduction and environmental protection are achieved.

Power and energy consumption:

power of each liquid hydrogen aircraft engine: e is 1/2m U ^2 ^ 0.5 x 319.6 x 425.46^2 ^ 28, 926, 000w is 28, 926kw is power of the fan, unit w, m is weight unit kg of the fan, U is unit m/s of fan tip peripheral speed.

We thus obtain the required total weight of the fuel cell:

28, 926 ÷ 1.5 ÷ 19, 284kg × 2 (dual engine) ═ 38, 548 kg;

the latest aviation special fuel cell is adopted, and the energy density is 1.5 kw/kg.

We obtain the total weight of liquid hydrogen fuel required:

28926 × 2 (dual engine) × 10 (in 10 hours voyage as a unit of comparison) ÷ 18 (kg) ═ 32, 140 kg;

that is, the total fuel consumption of the twin engine after 10 hours of flight was 32140kg of liquid hydrogen.

Engine oil consumption and specific fuel consumption:

the oil consumption and cost per hour of the engine are 28926 ÷ 18 ÷ 1607kg liquid hydrogen x $ 4 $ 6.5 ═ 41, 782 yuan, compare 139, 145 yuan of GE90, save 70%!

The hydrogen consumption rate per kilogram of thrust per hour is 1607 ÷ (389200N ÷ 10) ═ 0.018kg/(AaN · h).

The average electricity generated by each kilogram of liquid hydrogen through the fuel cell is 18 kw.h, and the market price of each kilogram of liquid hydrogen is about $ 4 at present.

The GE90 fuel consumption rate is 0.324kg/(AaN · h), known; i.e. the fuel consumption per hour per kilogram of thrust is 0.324 kg.

The fuel consumption of GE90 engine per hour is 389200 ÷ 10 × 0.324 ═ 12610kg ═ 17383 liters × 8 yuan ═ 139, 145 yuan.

Aircraft using liquid hydrogen aircraft engines gross weight of fuel, fuel cell, electric motor and engine:

32, 140+38, 548+4, 821 (motor) × 2+750 (engine) × 2 ═ 81, 830kg, the weight loss compared to the traditional competitor is 69%!

Boeing 777B (GE90) total fuel and engine weight 252200 (10 hours for dual engine) +6, 619 × 2 265, 438 kg.

Therefore, the liquid hydrogen aircraft engine has overwhelming advantages in the aspects of energy conservation, weight reduction and emission reduction.

In addition, the hydrogen power industry is still in development, the market price cannot truly reflect the cost price due to relatively small demand, the cleanest and cheapest way for producing liquid hydrogen is to carry out photovoltaic liquid hydrogen complex production in desert, the cost can be reduced to below 1.5 dollars (100% cleanness, electricity consumption cost is close to 1 gross money, 50 degrees electricity can produce 1 kilogram of liquid hydrogen), the market price can enter a range below 2.5 dollars, and once the hydrogen fuel aviation industrialization era is reached, the energy saving advantage can be further expanded quickly.

And (3) stress analysis:

and (3) roughly calculating and analyzing the integral stress of the hub: integral centrifugal force of hub is 3+ V/8 multiplied by rho multiplied by U²＝3.3/8×1800×425，46²The number 134,000,000 pa 134Mpa is very low (because the rotation speed and density are not high).

V is Poisson's ratio of 0.3, and ρ is material density of 1800kg/m³U is the tip peripheral speed, m/s.

However, since the blade is too tall, the maximum stress concentration analysis of the blade itself is still required to confirm that the blade profile is usable, despite the weight reduction using carbon fiber material.

The maximum centrifugal stress of the hub is mainly concentrated at the blade root, and the calculation equation is (American system):

Set＝0.00548×1/g×ρb×hb×dm×N²×[1－(1－at÷ar)/2×(1+hb/3dm)]，

the blade root centrifugal stress is 381910psi 2633 Mpa.

Bending stress on blade root section due to aerodynamic loads:

bending stress is total bending moment Mg/cross-sectional area of blade root is 284560 in.1 b/10.8276in²＝26256psi＝181Mpa。

Bending moment Mg ═ hb × Wt × (Ft)²+Fa²)0.5 power/2 zb is 284560in 1 b.

Ft＝(C1×cosα1+C2×cosα2)/g，

Fa＝(C1×sinα1－V2×sinβ2)/g。

g, acceleration of gravity, 32.2ft,

ρ b, density of blade material, 0.0651 b/in³(1800÷27679)，

hb, blade height, 47.99in,

dm, hub diameter, 123in,

n, rotating speed, 2600r/min,

ar, blade root cross-sectional area, 10.8376in²，

at, blade tip cross-sectional area, 8.2522in²，

Wt, flow rate, 3130.51 b/S,

zb, the number of blades 22,

ft, the tangential force acting on the blade, 831 b/(1b/S),

fa axial thrust on the blade, 7.541 b/(1 b/S).

The total stress at the blade root is 2633+181 2814 Mpa.

The overall stress of the hub is greatly different from the stress of the blade root, which shows that the phenomenon of huge stress concentration exists because the blade profile is too high and is concentrated at the position of the blade root.

The tensile strength of a carbon fiber reinforced matrix Composite (CFRP) used for the hub is 4283Mpa (carbon fiber T1100+ carbonized reinforcing matrix), and the allowable strength coefficient of the carbon fiber composite is 0.6, so that the potential safety hazard of stress exists at the blade root (2569Mpa is smaller than 2814Mpa), and the following method is adopted for solving the problems:

the hollow hub and the blade root embryo are made by using aluminum alloy 7Y69, precision forging and the yield strength of 874Mpa (the total actual density of the hub hollowing is 2700 kg/m)³4 divided by 3), hot-pressing/weaving and embroidering the carbon fiber T1100 pure yarn (with the tensile strength of 7000Mpa) on the pure yarn, and then butting the pure yarn with a carbon fiber reinforced matrix Composite (CFRP) on the blade root, wherein the operation ensures that the total weight of the hub does not exceed 319.6kg, and can greatly improve the stress at the blade root. This designThe cruise speed can be easily and infinitely coped with and can be confronted with any speed of 601m/s and below the maximum design peripheral speed of the engine in the design time.

The thickness of the carbon fiber pure silk weaving embroidery of the blade root is as follows: the cross section is 2 times of that of the aluminum alloy,

the ratio of the annular weaving and embroidering layer to the radial weaving and embroidering layer is as follows: greater than 7: 3,

the maximum hoop stress is 874 multiplied by 1/3+7000 multiplied by 2/3 multiplied by 0.7 is 3557Mpa,

higher than 2814MPa and has enough margin.

The method uses metal embryo to replace composite material matrix, and weaves and embroiders the carbon fiber pure silk on the composite material matrix, and restores the super tensile stress of the carbon fiber pure silk and forms perfect combination by utilizing the radial stress of metal.

Designing a duct and a fan:

number of blades: 22

Leaf type: supersonic flow grid (first choice); SAV16 and 21, ARL-SL19, PAV-1.5 (candidates);

maximum lip radius of curvature: 0.0626R;

duct spread angle: 6.64 degrees;

blade tip culvert clearance: less than 0.0056R;

the position of the fan is as follows: 0.3156R (axial distance of fan to lip);

the height of the duct is as follows: 0.2528D;

linear velocity: 425.46-610 m/s;

rotating speed: 2600 to 3673 r/min;

wherein R is the radius of the duct, D is the diameter of the duct, and R is the number of turns of rotation.

Designing a liquid hydrogen regeneration cooling motor:

motor power: 28.926 MW;

voltage: greater than 3000V;

the motor type is as follows: a permanent magnet synchronous motor.

Energy-to-weight ratio:

the first period is 7 kw/kg;

the second stage is 15 kw/kg.

Designing the total weight of the motor:

first stage 4132 kg;

second stage 1928 kg.

A stator core: amorphous alloy (Fe-based amorphous) with density of 7800kg/m³The maximum working magnetic induction intensity is 1.55T;

insulating material: polyimide with silicon dioxide; the temperature resistance level is 280 ℃;

a rotor: high-strength silicon steel with density of 7810kg/m³Tensile strength is 600 MPa;

rotating speed: the system outputs a rotating speed of 2600-3673 r/min, and a speed change gear box is used.

The liquid hydrogen regeneration cooling motor has the innovation points that:

the weight reduction method comprises two methods, one is to increase the magnetic force of the magnetic structure of the motor with the same weight to achieve the weight reduction purpose, and the other is to directly reduce the weight by reducing the material density, and the motor needs to use the first weight reduction mode except the shell material. Temperature control has absolute advantages in the aspect of increasing magnetic efficiency, two magnetic pole cooling modes are available in the market at present, one mode is air cooling, namely the air quantity of a motor fan is increased but the efficiency is poor, and the motor is placed at the position of the wind direction of the engine fan, so that only a small amount of magnetic efficiency can be increased, but the air duct output of the engine can be directly influenced due to the large size of the motor; the second method is to design a high-temperature superconducting material using a liquid nitrogen environment, but the temperature of the liquid nitrogen environment is about 77k, and the magnetic force of the high-temperature superconducting material cannot be exerted to an optimal level.

The aero-engine adopts liquid hydrogen as fuel, so that a very practical liquid hydrogen regeneration cooling function is designed, in the first stage, the liquid hydrogen is introduced into the motor before entering the fuel cell for gasification to form a regeneration cycle, the magnetic pole temperature of a stator and a rotor is greatly reduced, the magnetic energy is improved, and the design directly increases the energy-weight ratio of the motor to 7 kw/kg. The channel is made of an aluminum lithium alloy main body, so that the hydrogen embrittlement problem of other materials is avoided, meanwhile, the heat conduction capacity of the aluminum lithium alloy is 3 times that of another hydrogen embrittlement prevention material stainless steel, and the capacity can quickly take away heat inside a magnetic pole of a motor.

In the second phase, the rotor and the stator are designed to be completely in the high-temperature superconducting material and liquid hydrogen environment, and because the high-temperature superconductors of the motor developed at present are developed on the basis of the liquid nitrogen environment or are high-temperature superconductors of the single rotor, the energy-to-weight ratio of the motor made of the common superconducting material is not higher than that of a copper wire material optimized through liquid hydrogen cooling, and even possibly lower. Liquid nitrogen is changed into liquid hydrogen, and a stator and a rotor are integrated into an ultralow temperature space; the system is convenient to use/regenerate and circulate, the low-temperature environment can be reduced from 77k to 20k, the temperature is close to the actual space temperature, the magnetic energy of the superconducting material is approximately optimally released by the temperature, the copper loss is reduced to the minimum, the flux density of the high-temperature superconductor in the stator/rotor synchronous ultralow-temperature environment can be 7-10T, the flux density is 4.66-6.66 times of that of a silicon steel sheet (1.2-1.5T), and the energy-weight ratio of the secondary motor is set to be larger than 15 kw/kg.

Rotor permanent magnet:

in the first stage: Nd-Fe-B with tensile strength of 80MPa and density of 7600kg/m³Adding a liquid hydrogen regeneration type liquid hydrogen cooling channel, wherein the channel is made of aluminum lithium alloy; the maximum magnetic energy product was raised to 64MGOe (25 ℃) to 80MGOe (0 ℃ or lower) by liquid hydrogen cooling.

And a second stage: the high-temperature superconducting material Bi2223 is used, a liquid hydrogen ultralow-temperature environment (20k) is used for replacing a liquid nitrogen environment (more than 77k), the irreversible field of the Bi2223 material is greatly improved, the energy-weight ratio of 15kw/kg is realized, and the weight of a motor is reduced to 1928 kg.

Stator winding:

in the first stage: a copper wire is used, a liquid hydrogen regeneration type liquid hydrogen cooling channel is added, the channel is made of aluminum lithium alloy, and the maximum magnetic force and the minimum copper loss are obtained by cooling liquid hydrogen instead of ventilation cooling; the energy-weight ratio of 7kw/kg is realized by matching with the cooling function of the rotor permanent magnet, and the weight of the motor is reduced to 4, 132 kg.

And a second stage: the ultra-thin wire AC superconducting composite wire is used for replacing a copper wire, and a liquid hydrogen refrigeration environment consistent with that of the rotor is added, so that the full superconducting capacity is realized.

End cover (casing) weight reduction: the C/Sic composite material is used for replacing metal and has the density of 1600kg/m³The heat-resisting stress is increased and the weight is reduced by more than half.

The hub and blade root manufacturing process comprises the following steps:

(1) the hollow hub and the blade root embryo are manufactured by using an aluminum alloy 7Y69 precision forging process (yield strength 874 Mpa);

(2) carrying out one-layer annular pressure embroidery on the hub and the metal blade root by using a carbon fiber T1100 pure yarn;

(3) carrying out one-layer pressure radial weaving embroidery on the metal blade root by using carbon fiber T1100 pure wires;

(4) carrying out annular and radial overlapping pressure weaving and embroidering on the blade root for multiple times by using a carbon fiber T1100 pure yarn; the ratio of the circumferential layer to the radial layer is greater than 7: 3;

(5) after hot pressing, the Carbon Fiber Reinforced Polymer (CFRP) is butted with the blade root which is embroidered by the carbon fiber pure silk, and the weaving or manufacturing of the blade is carried out;

(6) the total actual density for ensuring the hollowing of the hub is 2700kg/m³4, division by 3; ensuring that the cross section ratio of the T1100 pure wire to the aluminum alloy blade root embryo is more than 2: 1, ensuring that the quantity ratio of the circumferential layer to the radial layer of the blade root pure wire is greater than 7: 3;

(7) the process method comprises the steps of replacing a composite material substrate with a metal embryo, weaving and embroidering the carbon fiber pure yarn on the composite material substrate, reducing the ultra-strong tensile stress (7000Mpa) of the carbon fiber pure yarn, and forming a perfect combination by utilizing the radial stress (874Mpa) of metal.

The starting process of the liquid hydrogen aircraft engine is described as follows:

1, starting an engine, and conveying about 20k of liquid hydrogen from a liquid hydrogen tank to a liquid hydrogen regeneration cooling motor;

2, carrying out internal regenerative cooling on a stator copper wire (second-stage is a superconducting wire) winding by liquid hydrogen through an aluminum-lithium alloy channel of the motor stator structure, so that the stator copper wire meets the requirement of designed magnetic force or superconducting magnetic force, and copper loss (or line loss) is reduced to the maximum extent;

3, the liquid hydrogen simultaneously carries out internal regenerative cooling on the rotor permanent magnet (the second-stage is a high-temperature metamaterial) through an aluminum-lithium alloy channel of the motor rotor structure, so that the magnetic force or superconducting magnetic force requirements are designed compositely, and the iron loss or superconducting loss is reduced to the maximum extent;

4, the liquid hydrogen takes away heat after passing through a regenerative cooling motor to generate temperature rise, and the gasification is completed through a special pipeline;

5 gas hydrogen (liquid hydrogen) is about 234K (-40 ℃) and enters the fuel cell together with the incoming air;

6, extracting oxygen in the air by the fuel cell, and generating electric power through the electrochemical reaction of the hydrogen and the oxygen;

7 hydrogen hydrate-water produced by the fuel cell is discharged from the fuel cell through a pipe for use by aircraft passengers;

8, supplying power to the rectifier transformer by the fuel cell;

the 9 rectification booster is used for rectifying and boosting the current into stable current and voltage which are larger than 3000V and inputting the stable current and voltage to the liquid hydrogen regeneration cooling motor;

the stator winding, the stator alloy core, the rotor permanent magnet and the silicon steel rotor in the 10 liquid hydrogen regenerative cooling motor are held by regenerative cooling to generate magnetic force 4.6-6.6 times more than that of a common permanent magnet synchronous motor, so as to drive the motor rotor to start rotating;

11 generally, the rotating speed of a large permanent magnet motor cannot be directly connected with the rotating speed of an engine, and the liquid hydrogen regeneration cooling motor transmits power to the speed change gear box;

12 the change speed gearbox adjusts the rotating speed to be as follows through the synchronous operation of a plurality of gears with different diameters: 2600r/min (line speed 425.46 m/s);

the 13 speed change gear box transmits power to an engine shaft according to 2600 r/min;

the 14 shaft drives the hub and the fan to rotate, so that incoming flow is sucked and air acceleration is given;

15, the bearing and the second bracket ensure the stability of the rotation of the fan;

16 due to the increase of the rotating speed and the height of the blades, the root of the fan blade of the engine entering the cruising speed can generate huge hoop stress, and the stress level of the fan blade far exceeds that of the fan blade of a common aeroengine;

17 the carbon fiber T1100 pure yarn finished according to the special weaving and embroidering and hot pressing plays a decisive role, the allowable hoop stress of the carbon fiber pure yarn reduced by the special method is 2.77 times of that of the carbon fiber composite material with the same yarn, the stress is rapidly reduced after passing through the blade root, and the carbon fiber composite material is used for butt joint with the carbon fiber composite material;

the 18 fan blades generate 39.71 tons of thrust after the rotation speed of 2600r/min is finished, the ultrahigh thrust belongs to the field of aviation, but the carbon emission is 0, and the fuel cost is saved by 70%.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid hydrogen aircraft engine, characterized by comprising a liquid hydrogen tank (10), a fuel cell (20), an electric motor (30), a bypass casing (40), a fan (50) and an anti-bird strike cone (60), wherein the fan (50) is arranged in the bypass of the bypass casing (40), the electric motor (30) comprises a stator structure (31) and a rotor structure (32), the rotor structure (32) is rotatably arranged in the stator structure (31), and the stator structure (31) and the rotor structure (32) are both provided with a liquid hydrogen cooling channel (33); the liquid hydrogen tank (10) is used for delivering liquid hydrogen to the liquid hydrogen cooling channel (33) to cool the motor (30) and gasify the liquid hydrogen, the gasified hydrogen is input into the fuel cell (20), the electric quantity generated by the fuel cell (20) is delivered to the motor (30), and the motor (30) is in driving connection with the fan (50); the fan (50) comprises a hub (51) and a plurality of blades (52), wherein each blade (52) comprises a blade root (521) arranged on the hub (51) and a plurality of layers of carbon fiber pure yarns (522) woven on the blade root (521); the bird impact prevention cone (60) is arranged on the air inlet side of the ducted shell (40), and the bird impact prevention cone (60) is of a conical structure with a plurality of hexagonal honeycomb-shaped air inlet holes (61).

2. The liquid hydrogen aircraft engine according to claim 1, wherein the stator structure (31) comprises a stator amorphous alloy core (311) and a winding (312) wound on the stator amorphous alloy core (311), the stator amorphous alloy core (311) is circumferentially distributed with a plurality of liquid hydrogen cooling channels (33), the inner wall material of the liquid hydrogen cooling channels (33) is aluminum lithium alloy, and the winding (312) is made of copper wire or superconductive composite wire.

3. The liquid hydrogen aircraft engine of claim 1, characterized in that rotor structure (32) includes silicon steel rotor (321), rotor shaft (322), magnetism isolating material (323) and a plurality of permanent magnet (324), rotor shaft (322) pass the silicon steel rotor (321), magnetism isolating material (323) centers on rotor shaft (322) sets up, and is a plurality of permanent magnet (324) distributes in the silicon steel rotor (321), each have one in the permanent magnet (324) liquid hydrogen cooling channel (33), the inner wall material of liquid hydrogen cooling channel (33) is the aluminium lithium alloy, the material of permanent magnet (324) is neodymium iron boron or superconductive material, magnetism isolating material (323) is the polyimide that adds silicon dioxide.

4. The liquid hydrogen aircraft engine of claim 1,

the liquid hydrogen aircraft engine also comprises a rectifier transformer (70), and the fuel cell (20), the rectifier transformer (70) and the motor (30) are electrically connected in sequence;

the motor (30) is a permanent magnet synchronous motor (30), the shell material of the motor (30) is a silicon carbide composite material, the motor (30) further comprises a speed change gear box, and a rotor shaft (322) of the motor (30) is in driving connection with the fan (50) through the speed change gear box;

the power of the motor (30) is 4-29 MW, the energy-to-weight ratio of the motor (30) is larger than 6kw/kg, and the output rotating speed of a speed change gear box of the motor (30) is 2400-6000 rpm.

5. The liquid hydrogen aircraft engine of claim 1,

the liquid hydrogen aircraft engine also comprises a first bracket (81) fixed in the bird impact prevention cone (60), and the motor (30) is positioned in the bird impact prevention cone (60) and is installed on the first bracket (81); or the motor (30) is arranged outside the bird impact prevention cone (60);

on the outer surface of the bird-proof impact cone (60), the sum of the opening areas of the hexagonal honeycomb-shaped air inlet holes (61) accounts for more than 90% of the conical surface area of the bird-proof impact cone (60), the bird-proof impact cone (60) is made of a titanium alloy material, and the weight of the bird-proof impact cone (60) is less than 110 kg.

6. The liquid hydrogen aircraft engine of claim 1, characterized in that the hub (51) is a hollow structure, the hub (51) and the plurality of blade roots (521) are a unitary structure formed by precision forging of an aluminum alloy material, the carbon fiber filaments (522) are arranged on the blade roots (521) by weaving and hot pressing, and the blade (52) further comprises a carbon fiber composite material, and the carbon fiber composite material is connected with the carbon fiber filaments (522) on the blade roots (521).

7. The liquid hydrogen aircraft engine according to claim 6, characterized in that the hub (51) is woven with the carbon fiber pure yarns (522), and in the plurality of layers of the carbon fiber pure yarns (522) on the blade root (521), the weaving directions of two adjacent layers of the carbon fiber pure yarns (522) are different; wherein, on the cross section of the blade root (521), the thickness of the woven carbon fiber pure yarn (522) is more than 2 times of the thickness of the blade root (521).

8. The liquid hydrogen aircraft engine of claim 1, wherein the radius of the duct is R, the diameter of the duct is D, the maximum lip radius of curvature of the duct is between 0.060R and 0.065R, the divergent angle of the duct is 5.5 ° to 7.5 °, the height of the duct is 0.2D to 0.3D; the distance between the fan (50) and the lip of the duct is 0.305R to 0.405R in the axial direction of the duct.

9. The liquid hydrogen aircraft engine of claim 1, further comprising a second bracket (82) fixed within the duct, the fan (50) being rotatably mounted on the second bracket (82); the radius of the duct is R, the clearance between the blade tip of the blade (52) and the inner wall of the duct is less than 0.0056R, and the linear speed of the blade tip is 425-610 m/s; the number of the blades (52) in the fan (50) is 20-24, the outer diameter of the fan (50) is 1.2-3.5 m, the weight of the fan (50) is 50-400 kg, and the thrust of the fan (50) is 50-450 KN.

10. The liquid hydrogen aircraft engine of claim 1, characterized in that the energy density of the fuel cell (20) is greater than 1.3kw/kg and the weight of the fuel cell (20) is less than 25000 kg.