Aviation hydrogen fuel five-stage safety protection explosion suppression device

Abstract

The aviation hydrogen fuel five-stage safety protection explosion suppression device comprises a hydrogen storage tank part, a hydraulic buffer structure part, a distributed optical fiber hydrogen sensor part, a nitrogen inerting system, a pressure release valve system and a water mist explosion suppression system. According to the invention, hydrogen leakage rapid response and explosion suppression can be realized. The device is compact in structure, achieves quick response to leakage and full-process suppression of explosion risks, is suitable for hydrogen-powered aircrafts and hydrogen storage facilities, and remarkably improves the hydrogen energy application safety.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen energy safety, and particularly relates to a five-level safety protection and explosion suppression device for aviation hydrogen fuel. Background Art

[0002] Hydrogen fuel, with its high energy density and zero carbon emission characteristics, has become an important direction for the green transformation of aviation power systems, and the global hydrogen-powered aircraft market shows a rapid growth trend. However, hydrogen fuel still faces significant challenges in practical applications: its molecular characteristics lead to easy leakage, flammability, and explosiveness, and high-pressure hydrogen storage systems pose extremely high requirements for materials and safety protection. The current hydrogen fuel explosion suppression technology mainly focuses on single functions such as hydrogen storage tank sealing, leakage monitoring, and inerting and extinguishing. Although there have been preliminary progresses, the existing technologies still mainly consist of discrete modules and have not yet formed a full-process collaborative protection system covering leakage prevention, rapid response, and explosion suppression.

[0003] The existing technologies have significant limitations: 1. The protection mechanism is single. Traditional solutions rely on physical sealing or passive ventilation and are difficult to cope with complex dynamic working conditions. For example, NASA experiments have shown that the leakage rate of hydrogen storage tanks relying only on composite material sealing increases significantly under high-frequency vibration, and the efficiency of passive ventilation systems drops sharply when vertical takeoff and landing aircraft hover, leading to an increased risk of local hydrogen accumulation. 2. The response lag is serious. The detection delay of mainstream electrochemical sensors is relatively high, and the action time of pressure relief valves is too long. Research has shown that hydrogen can diffuse to the lower explosion limit (4% vol) within 3 seconds under standard conditions, while the response time of existing sensors and actuators generally exceeds 5 seconds, and the protection measures lag far behind the critical window of combustion and explosion. 3. The explosion suppression efficiency is insufficient. Traditional explosion suppression agents such as dry powder have too high a mass ratio, significantly increasing the load of the aircraft, and cannot interrupt the hydrogen chain combustion reaction. Industry research has shown that most aviation hydrogen safety accidents are due to the collaborative failure of the protection links. For example, the cascading risks caused by the mismatch of the response time sequence between sensors and inerting systems highlight the defect of the lack of systematicness in the existing technology system.

[0004] In view of the above problems, the present invention proposes a five-level safety protection and explosion suppression device, which realizes full-process protection from leakage source control to combustion and explosion chain reaction interruption for the first time through a multi-level collaborative mechanism of hydraulic buffering, real-time monitoring, inerting dilution, directional pressure relief, and fine water mist explosion suppression. Through modular integration and cross-dimensional linkage design, the device significantly improves the response speed and explosion suppression efficiency, providing key technical support for the high-safety commercial application of hydrogen-powered aircraft. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention aims to provide a five - level safety protection and explosion suppression device for aviation hydrogen fuel, which realizes rapid response to leakage and full - process suppression of explosion risk through the synergistic effects of hydraulic buffering, real - time monitoring, inerting dilution, directional relief and fine water mist explosion suppression. The present invention is realized through the following technical solutions.

[0006] The five - level safety protection and explosion suppression device for aviation hydrogen fuel includes a hydrogen storage tank part, a hydraulic buffering structure part, a distributed optical fiber hydrogen sensor part, a nitrogen inerting system, a pressure relief valve system, and a fine water mist explosion suppression system;

[0007] The hydrogen storage tank part includes a hydrogen storage tank, an integrated micro - Stirling refrigerator, a pipe flange, and a sealing ring. The hydrogen storage tank is composed of a carbon fiber winding layer and an inner aluminum alloy layer. The hydrogen storage tank is fixed on the flange chassis at the bottom of the tank body bracket. The pipe flange is connected to the rear - end pipe column of the pressure relief valve, and a sealing ring is provided at the connection to ensure the airtightness of the pipe connection. The low - temperature condition of the internal liquid hydrogen chamber of the hydrogen storage tank is maintained by the integrated micro - Stirling refrigerator, and the liquid hydrogen temperature is maintained at ≤ - 253°C. The cold head (low - temperature end) of the integrated micro - Stirling refrigerator is closely attached to the outer wall of the hydrogen storage tank through a high - thermal - conductivity copper alloy heat - conducting block, and the cold quantity is directly conducted to the liquid hydrogen in the chamber. The sealing ring is made of perfluoroelastomer, which is suitable for high - pressure environments and has excellent hydrogen gas permeability resistance.

[0008] The hydraulic buffer structure includes a hydraulic buffer device and a tank support; the hydraulic buffer device includes a spiral pipeline, a hydraulic buffer device body, a piston, a buffer rubber pad, a main oil chamber, a return spring, a micro-check valve, and a throttle hole; the hydraulic buffer device is installed and fixed on the inner wall grooves of the six vertical supports of the tank support, and each vertical support has four hydraulic buffer devices arranged continuously from top to bottom, with a total of 24, which provide buffering for the vibration of the hydrogen storage tank and make the liquid hydrogen inside the hydrogen storage tank more stable and safe, and the installation positions of the 24 hydraulic buffer devices all avoid the distributed optical fiber hydrogen sensor on the outer surface of the hydrogen storage tank; the spiral pipeline is installed inside the hydraulic buffer device body to provide a secondary chamber for the flow of oil when the piston is compressed during the hydraulic buffering process. The maximum oil storage capacity of the spiral pipeline is equal to the total oil capacity in the main oil chamber, and the spiral pipeline has two parallel The inlet is connected to the main oil chamber, and a throttling hole and a micro-check valve are respectively provided at the two inlets; the interior of the main oil chamber is filled with oil; the return spring is placed in the main oil chamber, one end of the return spring presses against the piston, and the other end presses against the wall of the main oil chamber; the throttling hole limits the oil flow rate in the compression stage, and through the throttling effect, the hydraulic buffer device has a better buffering effect; the micro-check valve only allows the oil in the spiral pipeline to flow into the main oil chamber, and in the reset stage, the return spring pushes the piston back, and the micro-check valve provides a low-resistance reflux channel to avoid damping resistance again when the oil passes through the throttling hole in the reverse direction, and provides an outlet for the oil to flow back to the main oil chamber; the throttling hole and the micro-check valve cooperate with each other, and the parallel pipelines control the oil in and out of the spiral pipeline in the compression stage and the reset stage, so as to achieve the purpose of vibration buffering of the hydrogen storage tank, and together constitute a hydraulic buffer system. When the oil in the main oil chamber is completely compressed, the elasticity of the return spring allows the piston to move back, and the pressure difference causes the oil in the spiral pipeline to return to the main oil chamber. At the same time, since the throttle hole and the micro-check valve are connected in parallel, the resistance of the throttle hole is relatively large, and most of the oil will choose to flow back to the mainstream chamber through the micro-check valve to avoid damping resistance again when the oil passes through the throttle hole in the opposite direction; the buffer rubber pad is in direct contact with the outer surface of the hydrogen storage tank to achieve a buffering effect, and is directly connected to the piston rod; the tank body bracket is installed and fixed in the fuselage fuel compartment of the aircraft.

[0009] The distributed fiber optic hydrogen sensor part includes a distributed fiber optic hydrogen sensor and a demodulator. The distributed fiber optic hydrogen sensor includes a fiber Bragg grating, an optical fiber, a palladium nano-film, an optical fiber cladding, and a polyimide coating layer. The distributed fiber optic hydrogen sensor is spirally wound and laid along the outer surface of the hydrogen storage tank. One fiber Bragg grating, i.e., a sensing node, is arranged every 10 cm inside the distributed fiber optic hydrogen sensor. The optical fiber is protected by being wrapped with the optical fiber cladding, and the polyimide coating layer is coated on the surface of the optical fiber cladding. The fiber Bragg grating is a periodic refractive index modulation structure written in the optical fiber core by ultraviolet laser. The polyimide coating layer on the surface of the fiber Bragg grating area is removed, and a palladium nano-film is coated on the outer surface of the optical fiber cladding. Hydrogen adsorption causes the palladium lattice to expand, applying strain to the optical fiber and causing the grating wavelength to shift. The demodulator analyzes the shift amount in real time, calculates the hydrogen concentration, combines the data of multiple fiber Bragg grating nodes to locate the leakage point. The demodulator is integrated into the bottom flange chassis of the tank support, and is connected to the distributed fiber optic hydrogen sensor through an optical fiber. It can convert the optical signal into an electrical signal and transmit it to the main controller for further judgment. When the leakage concentration ≥ 1% LEL, an alarm is triggered. The distributed fiber optic hydrogen sensor is bonded to the tank surface with UV curing glue.

[0010] The nitrogen inerting system includes a pressure swing adsorption nitrogen generator, a 25L carbon fiber gas cylinder, and 12 copper nozzles. The pressure swing adsorption nitrogen generator is installed in the equipment compartment at the rear section of the fuselage. The pressure swing adsorption nitrogen generator separates and stores the nitrogen in the inhaled air in the 25L carbon fiber gas cylinder. The 25L carbon fiber gas cylinder is installed and fixed above the pressure swing adsorption nitrogen generator. The 25L carbon fiber gas cylinder is connected to 12 copper nozzles through an annular distribution pipe. The copper nozzles are installed at a downward inclination angle of 20° - 30°, and the spraying direction points to the tank surface. The annular distribution pipe is wound around the periphery of the central position in the vertical direction of the hydrogen storage tank. The 12 copper nozzles are evenly distributed on the annular distribution pipe. When leakage is confirmed, the copper nozzles on the annular distribution pipe release nitrogen at a flow rate of 50L / min to dilute the hydrogen concentration to a safe level.

[0011] The pressure relief valve system includes a pressure relief valve body, a high-torque motor part, a motor housing cover plate, a fan-shaped pressure relief port, and a pipe string at the rear end of the pressure relief valve. The pipe string at the rear end of the pressure relief valve is fixed to the pipe flange by screws, and a sealing ring is provided at the connection between the pipe string at the rear end of the pressure relief valve and the pipe flange to ensure the airtightness of the pipe connection. The pressure relief valve body includes an exhaust impeller, a servo motor, a key, a fixing ring 1, a fixing ring 2, a snap ring, a deep groove ball bearing, and a sealing ring; the servo motor is fixed in the motor housing on the outer shell of the pressure relief valve body by screws, the motor housing outer shell is matched with the motor housing by screws, the transmission rod of the servo motor in the housing is aligned and passed through the through hole provided in the motor housing, the sealing ring is stuck on the through hole on the inner wall of the motor housing to play a sealing role, the sealing ring is made of PTFE composite material, has a low friction coefficient and strong chemical corrosion resistance, and hardly adsorbs hydrogen; an exhaust impeller is assembled on the transmission rod of the servo motor, and a matching key is provided at the keyway of the transmission rod to ensure the circumferential fixation of the transmission rod and the exhaust impeller. Fixing rings 1 and 2 are respectively provided in front of and behind the exhaust impeller to ensure accurate axial positioning. The end of the transmission rod of the servo motor is fixed in cooperation with the groove on the inner surface of the pressure relief valve body through a matching snap ring and a deep groove ball bearing. The high-torque motor part includes a high-torque motor, a transmission shaft, pressure relief blades, a fixing member, and a high-torque motor fixing sleeve. The high-torque motor is fixed on the wall surface at the center of the fan-shaped pressure relief port through the high-torque motor fixing sleeve. The transmission shaft provided thereon passes through the through hole at the center of the fan-shaped pressure relief port and is matched with the transmission hole of the pressure relief blade. The pressure relief blade is axially fixed by the fixing member so that it fits on the inner surface of the fan-shaped pressure relief port. The key provided on the transmission shaft cooperates with the transmission groove provided on the pressure relief blade to ensure its circumferential fixation on the shaft. The radian of each blade in the pressure relief blade is 36°. Balance holes are provided to reduce the rotation resistance of the blade and ensure the reliable execution of the pressure relief action. The axis radian relationship of the two rows of balance holes provided on each blade surface is 30°, and there are six balance holes in each row; the radian of the external pressure relief hole is 24°. The surface of the pressure relief blade that is in close contact with the inner surface of the fan-shaped pressure relief port is sprayed with a PTFE coating to achieve low-friction sealing.

[0012] The fine water mist explosion suppression system includes a deionized water storage tank, a high-pressure water pump, a regular hexagonal stainless steel pipeline, an ultrasonic atomizing nozzle, a deionized water pipeline and a high-temperature infrared sensor. The deionized water storage tank is installed and fixed in the equipment compartment of the rear section of the fuselage. The deionized water storage tank is filled with deionized water. The high-pressure water pump is installed directly above the deionized water storage tank. The high-pressure water pump is connected to the regular hexagonal stainless steel pipeline through a deionized water pipeline. Twelve ultrasonic atomizing nozzles are arranged on the belly of the fuselage. The twelve ultrasonic atomizing nozzles are arranged on two regular hexagonal stainless steel pipelines. Six ultrasonic atomizing nozzles are installed on one regular hexagonal stainless steel pipeline. The regular hexagonal One stainless steel pipeline is wound around the periphery of the hydrogen storage tank at one quarter of its vertical height, and the other is wound around the periphery of the hydrogen storage tank at three quarters of its vertical height. The ultrasonic atomizing nozzle has a built-in heating wire to ensure normal spraying under extremely low temperatures. The high-temperature infrared sensor is installed on the outer wall of the vertical bracket of the tank bracket. The high-pressure water pump atomizes the deionized water in the deionized water storage tank into droplets with a particle size of ≤10μm, and forms a water mist curtain wall through the ultrasonic atomizing nozzle. The water mist suppresses the propagation of the hydrogen flame through the dual mechanisms of heat absorption cooling and free radical quenching. The free radical quenching reaction formula is: ·OH+H2→H2O, which blocks the chain combustion reaction and prevents hydrogen explosion. The triggering conditions are: when the high-temperature infrared sensor detects that the temperature is too high and the hydrogen concentration is ≥4% vol, the high-pressure water pump is started in conjunction with it, and the injection duration is ≥30 seconds. The "hydrogen concentration + flame / temperature rise" dual-condition trigger is used to reduce the probability of false triggering; the deionized water storage tank has a capacity of 40L, and antifreeze additive propylene glycol is added inside to ensure that it does not freeze at -40°C; the fine water mist explosion suppression system and the pressure relief valve system can be controlled in conjunction to remove hydrogen and reduce the concentration of combustible materials.

[0013] Compared with the prior art, the advantages of the present invention are: the five-level safety protection explosion suppression device for aviation hydrogen fuel controls the risk of hydrogen leakage in the embryonic stage through multi-dimensional linkage, and is particularly suitable for aviation scenarios with strict safety requirements. Its core innovations are: the hydraulic buffer device part plays a buffering role on the hydrogen storage tank, the high-precision positioning of the distributed optical fiber hydrogen sensor part greatly improves the positioning accuracy, the extremely fast action of the pressure relief valve system greatly improves the response speed, and the active inerting of nitrogen + fine water mist explosion suppression greatly reduces the possibility of hydrogen explosion. Through the five-level hydrogen fuel safety protection system, the risk of hydrogen leakage and explosion is significantly reduced.

[0014] Collaborative workflow (taking a leak incident as an example)

[0015] The first process: the aircraft was subjected to severe turbulence and the hydrogen tank was also shaken.

[0016] The second process: The first-stage hydraulic buffer structure plays a buffering role for the hydrogen storage tank (if the hydrogen storage tank is still broken, it will enter the next process).

[0017] The third process: The second - level distributed fiber optic hydrogen sensor detects a hydrogen concentration of 0.1% vol, locates the leakage point, and alarms the main controller.

[0018] The fourth process: The copper nozzles of the third - level annular distribution pipe spray nitrogen into the leakage area to dilute the hydrogen concentration.

[0019] The fifth process: If the concentration continuously rises to 4% vol, the fourth - level pressure relief valve system opens to vent hydrogen.

[0020] The sixth process: If the high - temperature infrared sensor detects a fire source, the fifth - level fine water mist explosion suppression system starts and extinguishes the flame within 30 seconds.

[0021] The present invention is particularly applicable to scenarios such as vertical take - off and landing (VTOL) aircraft, unmanned aerial vehicles, etc. Through modular mechanical design, the device realizes physical enclosure, directional venting, and combustion and explosion suppression of hydrogen leakage, significantly enhancing the safety of hydrogen - powered aircraft and hydrogen storage facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the overall schematic diagram of the present invention;

[0023] Figure 2 is the schematic diagram of the hydrogen storage tank part of the present invention;

[0024] Figure 3 is of the Figure 2 A enlarged schematic diagram of the present invention;

[0025] Figure 4 is the schematic diagram of the hydraulic buffer structure part of the present invention;

[0026] Figure 5 is the schematic diagram of the hydraulic buffer device of the present invention;

[0027] Figure 6 The Figure 5 B enlarged schematic diagram of the present invention;

[0028] Figure 7 is the schematic diagram of the distributed fiber optic hydrogen sensor of the present invention;

[0029] Figure 8 is the microscopic schematic diagram of the distributed fiber optic hydrogen sensor of the present invention;

[0030] Figure 9 is the schematic diagram of the nitrogen inerting system of the present invention;

[0031] Figure 10 is the schematic diagram of the pressure relief valve system of the present invention;

[0032] Figure 11 is of the Figure 10 C enlarged schematic diagram of the present invention;

[0033] Figure 12 Cross-sectional view of the pressure relief valve system of the present invention;

[0034] Figure 13 Of the present invention Figure 12 Schematic enlarged view of D;

[0035] Figure 14 Exploded view of the pressure relief valve system of the present invention;

[0036] Figure 15 Schematic diagram of the pressure relief vane of the present invention;

[0037] Figure 16 Front view of the pressure relief valve body of the present invention;

[0038] Figure 17 Schematic diagram of the fine water mist explosion suppression system of the present invention;

[0039] Figure 18 Combined diagram of the five-level safety protection explosion suppression device for aviation hydrogen fuel and the flying car of the present invention;

[0040] In the figure: 1. Hydrogen storage tank part, 2. Hydraulic buffer structure part, 3. Distributed optical fiber hydrogen sensor part, 4. Nitrogen inerting system, 5. Pressure relief valve system, 6. Fine water mist explosion suppression system;

[0041] 11. Hydrogen storage tank, 12. Integrated micro Stirling refrigerator, 13. Pipe flange, 14. Sealing ring;

[0042] 21. Hydraulic buffer device, 22. Tank body support;

[0043] 21-1. Spiral pipeline, 21-2. Main body of the hydraulic buffer device, 21-3. Piston, 21-4. Buffer rubber pad, 21-5. Main oil chamber, 21-6. Return spring, 21-7. Micro check valve, 21-8. Throttle hole;

[0044] 31. Distributed optical fiber hydrogen sensor, 32. Demodulator;

[0045] 31-1. Fiber Bragg grating, 31-2. Optical fiber, 31-3. Palladium nanometer film, 31-4. Optical fiber cladding, 31-5. Polyimide coating layer;

[0046] 41. Pressure swing adsorption nitrogen generator, 42. 25L carbon fiber gas cylinder, 43. Annular distribution pipe, 44. Copper nozzle;

[0047] 51. Pressure relief valve body, 52. High-torque motor part, 53. Motor casing cover plate, 54. Sector-shaped pressure relief port, 55. Pressure relief valve rear end pipe string;

[0048] 511. Exhaust impeller, 512. Servo motor, 513. Key, 514. Fixed ring 1, 515. Fixed ring 2, 516. Snap ring, 517. Deep groove ball bearing, 518. Sealing ring;

[0049] 521. High-torque motor, 522. Transmission shaft, 523. Pressure relief vane, 524. Fixing part, 525. High-torque motor fixing sleeve;

[0050] 523-1. Transmission groove, 523-2. Transmission hole, 523-3. Balance hole;

[0051] 61. Deionized water storage tank, 62. High-pressure water pump, 63. Regular hexagon stainless steel pipeline, 64. Ultrasonic atomizing nozzle, 65. Deionized water pipeline, 66. High-temperature infrared sensor. Specific implementation mode

[0052] An aviation hydrogen fuel five-level safety protection and explosion suppression device, including a hydrogen storage tank part 1, a hydraulic buffer structure part 2, a distributed optical fiber hydrogen sensor part 3, a nitrogen inerting system 4, a pressure relief valve system 5, and a fine water mist explosion suppression system 6;

[0053] The hydrogen storage tank part 1 includes a hydrogen storage tank 11, an integrated micro Stirling refrigerator 12, a pipe flange 13, and a sealing ring 14. The hydrogen storage tank 11 is composed of a carbon fiber winding layer and an inner aluminum alloy layer. The hydrogen storage tank 11 is fixed on the flange chassis at the bottom of the tank bracket 22. The pipe flange 13 is connected to the rear pipe column 55 of the pressure relief valve, and a sealing ring 14 is provided at the connection to ensure the airtightness of the pipe connection. The low-temperature condition of the internal liquid hydrogen chamber of the hydrogen storage tank 11 is maintained by the integrated micro Stirling refrigerator 12, and the liquid hydrogen temperature is maintained ≤ -253 °C. The cold head (low-temperature end) of the integrated micro Stirling refrigerator is closely attached to the outer wall of the hydrogen storage tank through a high-thermal conductivity copper alloy heat conduction block, and the cold quantity is directly conducted to the liquid hydrogen in the chamber. The sealing ring 14 is made of perfluoro rubber, suitable for high-pressure environments, and has excellent hydrogen gas permeability resistance.

[0054] The hydraulic buffer structure part 2 includes a hydraulic buffer device 21 and a tank support 22; the hydraulic buffer device 21 includes a spiral pipeline 21-1, a hydraulic buffer device main body 21-2, a piston 21-3, a buffer rubber pad 21-4, a main oil chamber 21-5, a return spring 21-6, a micro check valve 21-7, and a throttle orifice 21-8; the hydraulic buffer device 21 is installed and fixed on the inner wall grooves of the six vertical brackets of the tank support 22. Four hydraulic buffer devices 21 are arranged continuously from top to bottom on each vertical bracket, with a total of 24, providing buffering for the vibration of the hydrogen storage tank 11, making the liquid hydrogen inside the hydrogen storage tank 11 more stable and safe, and the installation positions of the 24 hydraulic buffer devices 21 avoid the distributed fiber optic hydrogen sensors 31 on the outer surface of the hydrogen storage tank 11; the spiral pipeline 21-1 is installed inside the hydraulic buffer device main body 21-2, providing a secondary chamber for the flow of oil when the piston 21-3 is compressed during the hydraulic buffering process. The maximum oil storage capacity of the spiral pipeline 21-1 is equal to the total oil volume in the main oil chamber 21-5. The spiral pipeline 21-1 has two parallel inlets connected to the main oil chamber 21-5, and a throttle orifice 21-8 and a micro check valve 21-7 are respectively arranged at the two inlets; the main oil chamber 21-5 is filled with oil; the return spring 21-6 is placed inside the main oil chamber 21-5, with one end of the return spring 21-6 against the piston 21-3 and the other end against the wall surface of the main oil chamber 21-5; the throttle orifice 21-8 restricts the oil flow rate during the compression stage, and through the throttling effect, makes the hydraulic buffer device 21 achieve a better buffering effect; the micro check valve 21-7 only allows the oil in the spiral pipeline 21-1 to flow into the main oil chamber 21-5. During the reset stage, the return spring 21-6 pushes the piston 21-3 to return, and the micro check valve 21-7 provides a low-resistance return channel, avoiding the generation of damping resistance again when the oil flows back through the throttle orifice 21-8, and providing an outlet for the oil to flow back into the main oil chamber 21-5; the throttle orifice 21-8 and the micro check valve 21-7 cooperate with each other and are parallel pipes to control the oil flow in and out of the spiral pipeline 21-1 during the compression stage and the reset stage, achieving the purpose of buffering the vibration of the hydrogen storage tank 11, and together constituting a hydraulic buffer system. After the oil in the main oil chamber 21-5 is compressed, the elasticity of the return spring 21-6 makes the piston 21-3 move back, and the pressure difference makes the oil in the spiral pipeline 21-1 return to the main oil chamber 21-5 again. At the same time, because the throttle orifice 21-8 and the micro check valve 21-7 are in parallel, and the resistance of the throttle orifice 21-8 is large, most of the oil will choose to flow back to the main chamber 21-5 through the micro check valve 21-7, avoiding the generation of damping resistance again when the oil flows back through the throttle orifice 21-8; the buffer rubber pad 21-4 is in direct contact with the outer surface of the hydrogen storage tank 11 to achieve a buffering effect and is directly connected to the piston rod; the tank support 22 is installed and fixed inside the fuel tank compartment of the aircraft fuselage.

[0055] The distributed optical fiber hydrogen sensor section 3 includes a distributed optical fiber hydrogen sensor 31 and a demodulator 32. The distributed optical fiber hydrogen sensor 31 includes a fiber Bragg grating 31-1, an optical fiber 31-2, a palladium nano-film 31-3, an optical fiber cladding 31-4, and a polyimide coating layer 31-5. The distributed optical fiber hydrogen sensor 31 is spirally wound and laid along the outer surface of the hydrogen storage tank 11. One fiber Bragg grating 31-1, i.e., a sensing node, is arranged every 10 cm inside the distributed optical fiber hydrogen sensor 31. The optical fiber 31-2 is protected by being wrapped by the optical fiber cladding 31-4. The polyimide coating layer 31-5 is coated on the surface of the optical fiber cladding 31-4. The fiber Bragg grating 31-1 is a periodic refractive index modulation structure written in the core of the optical fiber 31-2 by ultraviolet laser. The polyimide coating layer 31-5 on the surface of the fiber Bragg grating 31-1 region is removed, and the palladium nano-film 31-3 is coated on the outer surface of the optical fiber cladding 31-4. Hydrogen adsorption causes the palladium lattice to expand, applying strain to the optical fiber 31-2 and causing the grating wavelength to shift. The demodulator analyzes the shift amount in real time, calculates the hydrogen concentration, and locates the leakage point by combining the data of multiple fiber Bragg grating 31-1 nodes. The demodulator 32 is integrated into the bottom flange chassis of the tank bracket 22 and is connected to the distributed optical fiber hydrogen sensor 31 through the optical fiber 31-2. It can convert the optical signal into an electrical signal and transmit it to the main controller for further judgment. An alarm is triggered when the leakage concentration ≥ 1% LEL. The distributed optical fiber hydrogen sensor 31 is bonded to the tank surface with UV curable glue.

[0056] The nitrogen inerting system 4 includes a pressure swing adsorption nitrogen generator 41, a 25L carbon fiber gas cylinder 42, and 12 copper nozzles 44. The pressure swing adsorption nitrogen generator 41 is installed in the equipment cabin at the rear section of the fuselage. The pressure swing adsorption nitrogen generator 41 separates and stores the nitrogen in the inhaled air in the 25L carbon fiber gas cylinder 42. The 25L carbon fiber gas cylinder 42 is installed and fixed above the pressure swing adsorption nitrogen generator 41. The 25L carbon fiber gas cylinder 42 is connected to 12 copper nozzles 44 through an annular distribution pipe 43. The copper nozzles 44 are installed at a downward inclination angle of 20°-30°, and the spraying direction points to the tank surface. The annular distribution pipe 43 is wound around the periphery of the central position in the vertical direction of the hydrogen storage tank 11. The 12 copper nozzles 44 are evenly distributed on the annular distribution pipe 43. After leakage is confirmed, the copper nozzles 44 on the annular distribution pipe 43 release nitrogen at a flow rate of 50L / min to dilute the hydrogen concentration to a safe level.

[0057] The pressure relief valve system 5 includes a pressure relief valve body 51, a high-torque motor part 52, a motor casing cover plate 53, a fan-shaped pressure relief port 54, and a pressure relief valve rear pipe string 55. The pressure relief valve rear pipe string 55 is fixed to the pipe flange 13 by screws, and a sealing ring 14 is provided at the connection between the pressure relief valve rear pipe string 55 and the pipe flange 13 to ensure the airtightness of the pipe connection. The pressure relief valve body 51 includes an exhaust impeller 511, a servo motor 512, a key 513, a fixing ring one 514, a fixing ring two 515, a snap ring 516, a deep groove ball bearing 517, and a sealing ring 518. The servo motor 512 is fixed in the motor casing on the outer shell of the pressure relief valve body 51 by screws. The motor casing cover plate 53 is matched with the motor casing by screws. The transmission rod of the servo motor 512 in the casing is aligned and passed through the through hole provided in the motor casing. The sealing ring 518 is stuck on the through hole on the inner wall of the motor casing to play a sealing role. The sealing ring 518 is made of PTFE composite material, with a low friction coefficient, strong chemical corrosion resistance, and hardly adsorbing hydrogen. The exhaust impeller 511 is assembled on the transmission rod of the servo motor 512, and a matching key 513 is provided at the keyway of the transmission rod to ensure the circumferential fixation of the transmission rod and the exhaust impeller 511. The fixing ring one 514 and the fixing ring two 515 are respectively provided in front of and behind the exhaust impeller 511 to ensure accurate axial positioning. The end of the transmission rod of the servo motor 512 is fixed in cooperation with the snap ring 516 and the deep groove ball bearing 517 and the groove on the inner surface of the pressure relief valve body 51. The high-torque motor part 52 includes a high-torque motor 521, a transmission shaft 522, a pressure relief vane 523, a fixing member 524, and a high-torque motor fixing sleeve 525. The high-torque motor 521 is fixed on the wall surface at the center position of the fan-shaped pressure relief port 54 by the high-torque motor fixing sleeve 525. The transmission shaft 522 provided thereon passes through the through hole at the center of the fan-shaped pressure relief port 54 and is matched with the transmission hole 523-2 of the pressure relief vane 523. The pressure relief vane 523 is axially fixed by the fixing member 524 to make it fit on the inner surface of the fan-shaped pressure relief port. The key provided on the transmission shaft 522 is matched with the transmission groove 523-1 provided on the pressure relief vane 523 to ensure its circumferential fixation on the shaft. The radian of each vane in the pressure relief vane 523 is 36°. The balance hole 523-3 can reduce the vane rotation resistance and ensure the reliable execution of the pressure relief action. The axis radian relationship of the two rows of balance holes provided on each vane surface is 30°, and there are six balance holes in each row. The radian of the external pressure relief hole is 24°. The surface of the pressure relief vane 523 that is in close contact with the inner surface of the fan-shaped pressure relief port is sprayed with a PTFE coating to achieve low-friction sealing.

[0058] The fine water mist explosion suppression system 6 includes a deionized water storage tank 61, a high-pressure water pump 62, a regular hexagonal stainless steel pipeline 63, an ultrasonic atomizing nozzle 64, a deionized water pipeline 65 and a high-temperature infrared sensor 66. The deionized water storage tank 61 is installed and fixed in the equipment compartment of the rear section of the fuselage. The deionized water storage tank 61 is filled with deionized water. The high-pressure water pump 62 is installed directly above the deionized water storage tank 61. The high-pressure water pump 62 is connected to the regular hexagonal stainless steel pipeline 63 through the deionized water pipeline 65. Twelve ultrasonic atomizing nozzles 64 are arranged on the belly of the fuselage. The twelve ultrasonic atomizing nozzles 64 are arranged on two regular hexagonal stainless steel pipelines 63. Six ultrasonic atomizing nozzles are installed on one regular hexagonal stainless steel pipeline 63. Head 64, one of the regular hexagonal stainless steel pipes 63 is wound around the periphery of the hydrogen storage tank 11 at a quarter of its height in the vertical direction, and the other is wound around the periphery of the hydrogen storage tank 11 at a three-quarter height in the vertical direction. The ultrasonic atomizing nozzle 64 has a built-in heating wire to ensure normal spraying under extremely low temperatures. The high-temperature infrared sensor 66 is installed on the outer wall of the vertical bracket of the tank bracket 22. The high-pressure water pump 62 atomizes the deionized water in the deionized water storage tank 61 into droplets with a particle size of ≤10μm, and forms a water mist curtain wall through the ultrasonic atomizing nozzle. The water mist suppresses the propagation of the hydrogen flame through the dual mechanisms of heat absorption cooling and free radical quenching. The free radical quenching reaction formula is: ·OH+H2→H2O, which blocks the chain combustion reaction and prevents hydrogen explosion. The triggering conditions are: when the high-temperature infrared sensor 66 detects that the temperature is too high and the hydrogen concentration is ≥4% vol, the high-pressure water pump 62 is started in conjunction with it, and the injection duration is ≥30 seconds. The "hydrogen concentration + flame / temperature rise" dual-condition trigger is adopted to reduce the probability of false triggering; the deionized water storage tank 61 has a capacity of 40L, and antifreeze additive propylene glycol is added inside to ensure that it does not freeze at -40°C; the fine water mist explosion suppression system 6 and the pressure relief valve system 5 can be controlled in conjunction to remove hydrogen and reduce the concentration of combustibles.

[0059] Collaborative workflow (taking a leak incident as an example)

[0060] The first process: the aircraft was subjected to severe turbulence and the hydrogen tank was also shaken.

[0061] The second process: The first-stage hydraulic buffer structure plays a buffering role for the hydrogen storage tank (if the hydrogen storage tank is still broken, it will enter the next process).

[0062] The third process: The second-level distributed optical fiber hydrogen sensor part detects the 0.1% vol hydrogen concentration, locates the leakage point, and alarms the main controller.

[0063] The fourth process: The copper nozzle of the third-stage annular distribution pipe sprays nitrogen into the leakage area to dilute the hydrogen concentration.

[0064] The fifth process: If the concentration continues to rise to 4% vol, the fourth-stage pressure relief valve system opens to discharge hydrogen.

[0065] How it works

[0066] The specific process of its working principle is as follows: the hydraulic buffer device is installed and fixed on the inner wall grooves of the six vertical brackets of the tank body bracket. Each vertical bracket has four hydraulic buffer devices arranged continuously from top to bottom, with a total of 24, which provide buffering for the vibration of the hydrogen storage tank, making the liquid hydrogen inside the hydrogen storage tank more stable and safe, and the installation positions of the 24 hydraulic buffer devices are all avoided from the distributed fiber optic hydrogen sensors on the outer shell of the hydrogen storage tank. In the compression stage, the throttle hole limits the oil flow rate, and the hydraulic buffer device has a better buffering effect through the throttling effect; while the micro-check valve only allows the oil in the spiral pipeline to flow into the main oil chamber. In the reset stage, the reset spring pushes the piston back, and the micro-check valve provides a low-resistance reflux channel to avoid the damping resistance generated again when the oil passes through the throttle hole in the reverse direction, and provides an outlet for the oil to flow back to the main oil chamber. Because the resistance of the throttle hole is large, most of the oil will choose to flow back to the mainstream chamber through the micro-check valve to avoid the damping resistance generated again when the oil passes through the throttle hole in the reverse direction. The throttle hole and the micro-check valve cooperate with each other, and the parallel pipeline controls the oil in and out of the spiral pipeline in the compression stage and the reset stage, so as to achieve the purpose of vibration buffering of the hydrogen storage tank, and together constitute a hydraulic buffer system. The buffer rubber pad is in direct contact with the outer surface of the hydrogen storage tank to achieve a buffering effect. The hydraulic buffer device part significantly improves the impact resistance and service life of the hydrogen storage system through dynamic energy dissipation and displacement control.

[0067] The distributed optical fiber hydrogen sensor part monitors the surface status of the hydrogen storage tank in real time, accurately locates the leakage point and triggers the subsequent protection level. It uses the expansion characteristics of palladium absorbing hydrogen to convert the hydrogen concentration into a grating strain signal, causing the grating wavelength to shift. The demodulator analyzes the offset in real time. The hydrogen concentration is calculated by reverse calculation, and the leakage point is located by combining the data of multiple fiber Bragg grating nodes. The demodulator transmits the electrical signal to the main controller, and the main controller makes the next analysis and judgment. Its warning logic: the first-level warning (greater than 0.1% vol hydrogen concentration) triggers the nitrogen inerting system; the second-level alarm (greater than 0.4% vol hydrogen concentration) starts the pressure relief valve system and links the fine water mist explosion suppression system.

[0068] Palladium nanofilm expands by absorbing hydrogen: After palladium (Pd) absorbs hydrogen (H2), hydrogen atoms diffuse into the gaps in the palladium lattice to form palladium hydride (PdH x ), resulting in the volume expansion of the palladium film. The expansion (ΔV) is related to the hydrogen concentration Proportional to:

[0069] Where: k is the hydrogen-induced expansion coefficient of palladium (the experimental value is about 2.5×10-3 ppm -1 ); is the hydrogen concentration (ppm).

[0070] Fiber Bragg grating (FBG) wavelength shift: The Bragg wavelength (λ B ) of the FBG is determined by the grating period (Λ) and the effective refractive index (n eff ): λ B = 2n eff Λ

[0071] When palladium expands to generate axial strain , the grating period and refractive index change, resulting in a wavelength shift (λ B ):

[0072] Δλ B = λ B ·(1 - p e )·ε

[0073] (p e ≈ 0.22 is the photoelastic coefficient of the optical fiber)

[0074] Linear relationship between hydrogen concentration and wavelength shift

[0075] The palladium expansion strain (ε) is related to the hydrogen concentration as follows:

[0076] Substituting into the wavelength shift formula, we get:

[0077] Sensitivity coefficient (S):

[0078] (For example: when λ B = 1550 nm, S ≈ 0.1 nm / ppm)

[0079] The nitrogen inerting system dilutes the hydrogen concentration in the leakage area by actively injecting high-purity nitrogen to block the formation of combustion and explosion conditions. The pressure swing adsorption nitrogen generator separates and stores the nitrogen in the inhaled air in 25L carbon fiber cylinders. The 25L carbon fiber cylinders are connected to 12 copper nozzles through a ring distribution pipe. The copper nozzles are installed at a downward inclination of 20° - 30°, and the spraying direction points to the surface of the tank. The ring distribution pipe is wound around the periphery of the central position of the vertical direction of the hydrogen storage tank. The 12 copper nozzles are evenly distributed on the ring distribution pipe. When a leakage is confirmed, the copper nozzles on the ring distribution pipe release nitrogen at a flow rate of 50L / min to dilute the hydrogen concentration to a safe level.

[0080] The pressure relief valve system is equipped with a pressure sensor. When the internal pressure of the hydrogen storage tank exceeds the set threshold, the main controller receives a signal, and the protection system triggers the pressure relief valve system to open quickly, releasing excess hydrogen to prevent the tank from rupturing; or when the distributed optical fiber hydrogen sensor detects that the hydrogen concentration on the surface of the hydrogen storage tank has risen to 4% vol, the pressure relief valve system is opened. After the pressure relief valve system is turned on, the high-torque motor drives the pressure relief blade to rotate. When the balance hole on the pressure relief blade is exposed, hydrogen is immediately discharged from the balance hole. At this time, the internal air pressure of the pressure relief valve system will drop sharply, reducing the resistance to blade rotation and ensuring reliable execution of the pressure relief action. Then the servo motor drives the exhaust impeller to rotate to speed up the discharge of hydrogen. The fan-shaped pressure relief port of the pressure relief valve is designed for directional injection, with a specific hydrogen discharge pipeline, and the discharge direction is away from the aircraft fuselage or sensitive areas of the hydrogen storage facility to avoid hydrogen accumulation in the equipment cabin. The core of the pressure relief valve system is to quickly reduce the internal pressure of the hydrogen storage tank to prevent the tank from rupturing due to overpressure. The hydrogen storage tank may also cause a sudden increase in pressure due to leakage or abnormal temperature. After the pressure relief valve is opened, a relatively long-term concentration control can be achieved. After the pressure relief valve is opened, the internal pressure of the hydrogen storage tank is reduced, and the leakage rate of the compartment where the hydrogen storage tank is located is slowed down. At the same time, the nitrogen inerting system is started: the nitrogen is continuously diluted, and the final hydrogen concentration will show a downward trend.

[0081] As the ultimate line of defense, the fine water mist explosion suppression system extinguishes the flame and blocks the explosion propagation through the dual mechanisms of physical cooling and chemical quenching. The ultrasonic atomizing nozzle has a built-in heating wire to ensure normal spraying at extremely low temperatures. The high-pressure water pump atomizes the deionized water in the deionized water storage tank into droplets with a particle size of ≤10μm, and forms a water mist curtain wall through the ultrasonic atomizing nozzle. The water mist suppresses the propagation of hydrogen flames through the dual mechanisms of heat absorption cooling and free radical quenching. The free radical quenching reaction formula is: OH+H2→H2O, which blocks the chain combustion reaction and prevents hydrogen explosion. The trigger conditions are: when the high-temperature infrared sensor detects that the temperature is too high and the hydrogen concentration is ≥4% vol, the signal is transmitted to the main controller. The main controller sends a signal to the solenoid valve of the high-pressure water pump, the full flow is opened, and the ultrasonic atomizing nozzle sprays deionized water. The spray duration is ≥30 seconds. The "hydrogen concentration + flame / temperature rise" dual condition trigger is used to reduce the probability of false triggering; the deionized water storage tank has a capacity of 40L, and the antifreeze additive propylene glycol is added inside to ensure that it does not freeze at -40°C; the fine water mist explosion suppression system and the pressure relief valve system can be controlled in conjunction to exclude hydrogen and reduce the concentration of combustibles.

[0082] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A five-level safety protection explosion suppression device for aviation hydrogen fuel, characterized in that: It includes a hydrogen storage tank part (1), a hydraulic buffer structure part (2), a distributed optical fiber hydrogen sensor part (3), a nitrogen inerting system (4), a pressure relief valve system (5), and a fine water mist explosion suppression system (6); The hydrogen storage tank part (1) comprises a hydrogen storage tank (11), an integrated micro Stirling refrigerator (12), and a pipeline flange (13); the pipeline flange (13) is arranged on the hydrogen storage tank (11); the pipeline flange (13) is connected to the pressure relief valve system (5); the cold head of the integrated micro Stirling refrigerator (12) is tightly fitted to the outer wall of the hydrogen storage tank (11) through a high thermal conductivity copper alloy heat conduction block; and the low temperature condition of the internal liquid hydrogen chamber of the hydrogen storage tank (11) is maintained by the integrated micro Stirling refrigerator (12); The hydraulic buffer structure part (2) comprises a hydraulic buffer device (21) and a tank support (22); the hydrogen storage tank (11) is fixed to a flange chassis at the bottom of the tank support (22); the tank support (22) is installed and fixed in the fuselage fuel compartment of the aircraft; the hydraulic buffer device (21) is installed and fixed on six vertical support inner wall grooves of the tank support (22); the hydraulic buffer device (21) comprises a spiral pipeline (21-1), a hydraulic buffer device body (21-2), a piston (21-3), a buffer rubber pad (21-4), a main oil chamber (21-5), a return spring (21-6), a micro one-way valve (21-7), and a throttle hole (21-8); the spiral pipeline (21-1) and the main oil chamber (21-5) are arranged in the hydraulic buffer device body (21-2); the piston (21-3) is arranged In the main oil chamber (21-5), a buffer rubber pad (21-4) is arranged on the piston rod of the piston (21-3), and the buffer rubber pad (21-4) contacts the outer surface of the hydrogen storage tank (11). The spiral pipeline (21-1) provides a secondary chamber for the flow of oil when the piston (21-3) is compressed during the hydraulic buffering process. The maximum oil storage capacity of the spiral pipeline (21-1) is equal to the total oil volume in the main oil chamber (21-5). The spiral pipeline (21-1) has two parallel inlets connected to the main oil chamber (21-5), and the two inlets are respectively provided with a throttle hole (21-8) and a micro check valve (21-7); the main oil chamber (21-5) is filled with oil, and the return spring (21-6) is placed in the main oil chamber (21-5), and one end of the return spring (21-6) is against the piston (21-3), and the other end is against the wall of the main oil chamber (21-5); The distributed optical fiber hydrogen sensor part (3) comprises a distributed optical fiber hydrogen sensor (31) and a demodulator (32). The distributed optical fiber hydrogen sensor (31) is spirally wound and laid along the outer surface of the hydrogen storage tank (11). The demodulator (32) is integrated into the bottom flange chassis of the tank support (22). The demodulator (32) is connected to the distributed optical fiber hydrogen sensor (31) through an optical fiber (31-2). The distributed optical fiber hydrogen sensor (31) and the hydraulic buffer device (21) avoid each other. The nitrogen inerting system (4) comprises a pressure swing adsorption nitrogen generator (41), a 25L carbon fiber gas cylinder (42) and 12 copper nozzles (44), wherein the pressure swing adsorption nitrogen generator (41) is installed in the equipment cabin of the rear section of the fuselage, the 25L carbon fiber gas cylinder (42) is fixedly installed on the pressure swing adsorption nitrogen generator (41), the pressure swing adsorption nitrogen generator (41) separates nitrogen from the inhaled air and stores it in the 25L carbon fiber gas cylinder (42), the 25L carbon fiber gas cylinder (42) is connected to the 12 copper nozzles (44) through an annular distribution pipe (43), the copper nozzles (44) are installed at a downward tilt of a certain angle of 20°-30°, and the spray direction points to the surface of the tank body, the annular distribution pipe (43) is wound around the periphery of the vertical center position of the hydrogen storage tank (11), and the 12 copper nozzles (44) are evenly distributed on the annular distribution pipe (43); The pressure relief valve system (5) comprises a pressure relief valve body (51), a high torque motor part (52), a fan-shaped pressure relief port (54), and a pressure relief valve rear end pipe column (55); the pressure relief valve rear end pipe column (55) is fixed to a pipeline flange (13) by screws, and a sealing ring (14) is provided at the connection between the pressure relief valve rear end pipe column (55) and the pipeline flange (13); the pressure relief valve body (51) comprises an exhaust impeller (511) and a servo motor (512); the servo motor (512) is fixed in a motor box on the outer shell of the pressure relief valve body (51); the exhaust impeller (511) is mounted on the transmission rod of the servo motor (512); the high torque motor part (52) comprises a high torque motor (521), a transmission shaft (522), a pressure relief blade (523), a fixed A fixed piece (524) and a high-torque motor fixing sleeve (525), wherein the high-torque motor (521) is fixed to a wall surface at a central position of the fan-shaped pressure relief port (54) through the high-torque motor fixing sleeve (525), a transmission shaft (522) arranged on the high-torque motor (521) passes through a through hole at the center of the fan-shaped pressure relief port (54), and cooperates with a transmission hole (523-2) of a pressure relief blade (523), the pressure relief blade (523) is axially fixed by the fixed piece (524) so ​​as to be attached to an inner surface of the fan-shaped pressure relief port (54), the high-torque motor (521) drives the pressure relief blade (523) to rotate through the transmission shaft (522) so that the pressure relief blade (523) opens or closes the fan-shaped pressure relief port (54), and the fan-shaped pressure relief port (54) is connected to a hydrogen discharge pipeline; The fine water mist explosion suppression system (6) comprises a deionized water storage tank (61), a high-pressure water pump (62), a regular hexagonal stainless steel pipeline (63), an ultrasonic atomizing nozzle (64), a deionized water pipeline (65) and a high-temperature infrared sensor (66). The deionized water storage tank (61) is installed and fixed in the equipment cabin of the rear section of the fuselage. The deionized water storage tank (61) is filled with deionized water. The high-pressure water pump (62) is installed above the deionized water storage tank (61). The high-pressure water pump (62) is installed through The deionized water pipeline (65) is connected to the regular hexagonal stainless steel pipeline (63), and twelve ultrasonic atomizing nozzles (64) are arranged on two regular hexagonal stainless steel pipelines (63). One of the two regular hexagonal stainless steel pipelines (63) is wound around the periphery of the hydrogen storage tank (11) at a position of one quarter of its height in the vertical direction, and the other is wound around the periphery of the hydrogen storage tank (11) at a position of three quarters of its height in the vertical direction. The high-temperature infrared sensor (66) is mounted on the outer wall of the vertical support of the tank support (22).

2. The five-level safety protection explosion suppression device for aviation hydrogen fuel according to claim 1 is characterized in that: Each vertical support of the tank support (22) is continuously provided with four hydraulic buffer devices (21) from top to bottom, with a total of 24 hydraulic buffer devices (21) to provide buffering for the vibration of the hydrogen storage tank (11).

3. The five-level safety protection explosion suppression device for aviation hydrogen fuel according to claim 1 is characterized in that: The distributed optical fiber hydrogen sensor (31) comprises an optical fiber Bragg grating (31-1), an optical fiber (31-2), a palladium nanofilm (31-3), an optical fiber cladding (31-4), and a polyimide coating layer (31-5). An optical fiber Bragg grating (31-1) is arranged every 10 cm inside the distributed optical fiber hydrogen sensor (31). The optical fiber (31-2) is protected by the optical fiber cladding (31-4). The polyimide coating layer (31-5) is coated on the surface of the optical fiber cladding (31-4). The optical fiber Bragg grating (31-1) is a periodic refractive index modulation structure written into the core of the optical fiber (31-2) by ultraviolet laser. The polyimide coating layer (31-5) is removed from the surface of the optical fiber Bragg grating (31-1) region, and the palladium nanofilm (31-3) is coated on the outer surface of the optical fiber cladding (31-4) in the region.

4. The five-level safety protection explosion suppression device for aviation hydrogen fuel according to claim 3 is characterized in that: The distributed optical fiber hydrogen sensor part (3) utilizes the expansion property of palladium absorbing hydrogen to convert the hydrogen concentration into a grating strain signal, causing the grating wavelength to shift. The demodulator (32) analyzes the shift in real time. The hydrogen concentration is calculated by reverse calculation, and the leakage point is located by combining the multi-fiber Bragg grating node data. The demodulator (32) transmits the electrical signal to the main controller, and the main controller makes the next step of analysis and judgment; when the leakage is greater than 0.1% vol hydrogen concentration, the first-level warning is triggered and the nitrogen inerting system (4) is started; when the leakage is greater than 0.4% vol hydrogen concentration, the second-level warning is triggered, the pressure relief valve system (5) is started and the fine water mist explosion suppression system (6) is linked.

5. The five-level safety protection explosion suppression device for aviation hydrogen fuel according to claim 1 is characterized in that: The curvature of each blade in the pressure relief blade (523) is 36°. The pressure relief blade (523) is provided with a balancing hole (523-3), and the balancing hole (523-3) can reduce the rotation resistance of the blade. The axial curvature relationship of the two rows of balancing holes provided on the surface of each blade is 30°, and each row has six balancing holes. The side of the pressure relief blade (523) that is in close contact with the inner surface of the fan-shaped pressure relief port is sprayed with a PTFE coating.

6. The five-level safety protection explosion suppression device for aviation hydrogen fuel according to claim 1 is characterized in that: The high-pressure water pump (62) atomizes the deionized water in the deionized water storage tank (61) into droplets with a particle size of ≤10 μm, and forms a water mist curtain wall through an ultrasonic atomizing nozzle (64). The water mist suppresses the propagation of the hydrogen flame through the dual mechanisms of heat absorption cooling and free radical quenching. The free radical quenching reaction formula is: OH+H2→H2O. The triggering condition of the high-pressure water pump (62) is: when the high-temperature infrared sensor (66) detects that the temperature is too high and the hydrogen concentration is ≥4% vol, the high-pressure water pump (62) is started in a linked manner.

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