A five-level safety protection explosion suppression device for aviation hydrogen fuel

Abstract

This invention discloses a five-level safety and explosion suppression device for aviation hydrogen fuel. The device comprises a hydrogen storage tank, a hydraulic buffer structure, a distributed fiber-optic hydrogen sensor, a nitrogen inerting system, a pressure relief valve, and a water mist explosion suppression system. This device enables rapid response to hydrogen leaks and explosion suppression. The compact structure ensures rapid leak response and full-process explosion risk suppression, making it suitable for hydrogen-powered aircraft and hydrogen storage facilities, significantly improving the safety of hydrogen energy applications.

Description

Technical Field

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

[0002] Hydrogen fuel, with its high energy density and zero-carbon emissions, has become a key driver of the green transformation of aviation propulsion systems, and the global hydrogen-powered aircraft market is experiencing rapid growth. However, hydrogen fuel still faces significant challenges in practical applications: its molecular properties make it prone to leakage and flammability, and high-pressure hydrogen storage systems place extremely high demands on materials and safety protection. Current hydrogen fuel explosion suppression technology primarily focuses on single functions such as hydrogen tank sealing, leak monitoring, and inerting fire extinguishing. While initial progress has been made, existing technologies are still primarily based on discrete modules, and a comprehensive, coordinated protection system encompassing leak prevention, rapid response, and explosion suppression has yet to be established.

[0003] Existing technologies have significant limitations: 1. A single protection mechanism. Traditional solutions rely on physical seals or passive ventilation, making them incapable of coping with complex dynamic operating conditions. For example, NASA experiments have shown that hydrogen storage tanks relying solely on composite seals experience a significant increase in leakage rate under high-frequency vibration, while passive ventilation systems experience a sharp decline in efficiency when hovering in vertical takeoff and landing (VTOL) aircraft, exacerbating the risk of localized hydrogen accumulation. 2. Response hysteresis is significant. Mainstream electrochemical sensors exhibit high detection delays, resulting in excessively long pressure relief valve activation times. Research has shown that under standard operating conditions, hydrogen can diffuse to its lower explosive limit (4% vol) within 3 seconds, while existing sensors and actuators typically respond in excess of 5 seconds, significantly lagging protective measures behind the critical combustion window. 3. Explosion suppression effectiveness is inadequate. Traditional explosion suppressants, such as dry powder, contain excessively high mass fractions, significantly increasing aircraft payloads and failing to interrupt hydrogen chain combustion reactions. Industry research indicates that most aviation hydrogen safety incidents stem from coordinated failures in protection components, such as cascading risks caused by mismatched response timing between sensors and inerting systems, highlighting the inadequate systematization of existing technologies.

[0004] To address these challenges, this paper proposes a five-level safety and explosion suppression device. Through a multi-stage coordinated mechanism of hydraulic buffering, real-time monitoring, inerting dilution, directional pressure relief, and water mist explosion suppression, this device, for the first time, achieves comprehensive protection from leak source control to interruption of the explosion chain reaction. Through modular integration and cross-dimensional linkage design, this device significantly improves 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] To address the shortcomings of existing technologies, the present invention aims to provide a five-level safety and explosion suppression device for aviation hydrogen fuel. Through the synergistic effects of hydraulic buffering, real-time monitoring, inerting dilution, directional release, and fine water mist explosion suppression, this device achieves rapid leak response and full-process explosion risk suppression. This invention is achieved through the following technical solutions.

[0006] The five-level safety protection explosion suppression device for aviation hydrogen fuel includes a hydrogen storage tank part, a hydraulic buffer 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 composite of a carbon fiber winding layer and an inner lining aluminum alloy layer. The hydrogen storage tank is fixed to the flange chassis at the bottom of the tank bracket. The pipe flange is connected to the rear end pipe column of the pressure relief valve. 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 an integrated micro Stirling refrigerator to maintain the liquid hydrogen temperature ≤-253°C. The cold head (low temperature end) of the integrated micro Stirling refrigerator is tightly fitted with the outer wall of the hydrogen storage tank through a high thermal conductivity copper alloy heat conducting block, and the cold energy is directly transferred to the liquid hydrogen in the chamber. The sealing ring is made of perfluororubber, which is suitable for high-pressure environments and has excellent resistance to hydrogen permeability.

[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 one-way 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 throttle hole and a micro one-way 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 throttle hole limits the oil flow rate during the compression stage, and through the throttling effect, the hydraulic buffer device has a better buffering effect; the micro one-way valve only allows the oil in the spiral pipeline to flow into the main oil chamber. During the reset stage, the return spring pushes the piston back, and the micro one-way valve provides a low-resistance reflux channel to avoid damping resistance again when the oil passes through the throttle hole in reverse, and provides an outlet for the oil to flow back to the main oil chamber; the throttle hole and the micro one-way valve cooperate with each other, and the parallel pipelines control the oil in and out of the spiral pipeline during the compression and reset stages, 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-one-way 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 main flow chamber through the micro-one-way valve, avoiding the damping resistance generated 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 optical fiber hydrogen sensor comprises a distributed optical fiber hydrogen sensor and a demodulator. The distributed optical fiber hydrogen sensor comprises an optical fiber Bragg grating, an optical fiber, a palladium nanofilm, an optical fiber cladding, and a polyimide coating. The distributed optical fiber hydrogen sensor is spirally wound and laid along the outer surface of the hydrogen storage tank. A optical fiber Bragg grating, i.e., a sensing node, is arranged every 10 cm inside the distributed optical fiber hydrogen sensor. The optical fiber is protected by the optical fiber cladding, and the polyimide coating is coated on the surface of the optical fiber cladding. The optical fiber Bragg grating is a periodic pattern written into the optical fiber core by an ultraviolet laser. The device features a refractive index modulation structure. The polyimide coating is removed from the fiber Bragg grating (FBG) region, and a palladium nanofilm is applied to the outer surface of the fiber cladding. Hydrogen adsorption causes the palladium lattice to expand, applying strain to the fiber and causing the grating wavelength to shift. The demodulator analyzes this shift in real time, calculates the hydrogen concentration, and uses data from multiple FBG nodes to locate the leak. The demodulator is integrated into the bottom flange chassis of the tank support and connected to the distributed fiber hydrogen sensor via optical fiber. It converts optical signals into electrical signals and transmits them to the main controller, which then makes the next step of the assessment. An alarm is triggered when the leakage concentration is ≥1% LEL. The distributed fiber hydrogen sensor is bonded to the tank surface with UV-curable adhesive.

[0010] The nitrogen inerting system includes a pressure swing adsorption nitrogen generator, a 25L carbon fiber cylinder and 12 copper nozzles. The pressure swing adsorption nitrogen generator is installed in the equipment compartment of the rear section of the fuselage. The pressure swing adsorption nitrogen generator separates the nitrogen from the inhaled air and stores it in a 25L carbon fiber cylinder. The 25L carbon fiber cylinder is fixed above the pressure swing adsorption nitrogen generator. The 25L carbon fiber cylinder is connected to 12 copper nozzles through an annular distribution pipe. The copper nozzle is installed at a downward angle of 20°-30°, and the spray direction points to the tank surface. The annular distribution pipe is wrapped around the periphery of the vertical center position of the hydrogen storage tank. The 12 copper nozzles are evenly distributed on the annular distribution pipe. When the leak is confirmed, the copper nozzle on the annular distribution pipe releases 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, a motor housing cover, a fan-shaped pressure relief port, and a pressure relief valve rear end pipe. The pressure relief valve rear end pipe is fixed to the pipeline flange with screws, and a sealing ring is installed at the connection between the pressure relief valve rear end pipe and the pipeline flange to ensure airtightness at the pipeline connection. The pressure relief valve body comprises an exhaust impeller, a servo motor, a key, a first retaining ring, a second retaining ring, a retaining ring, a deep groove ball bearing, and a sealing ring. The servo motor is screwed into the motor housing of the pressure relief valve body. The motor housing engages with the motor housing via screws. The servo motor's drive rod within the housing aligns with a through-hole within the motor housing. The sealing ring engages the through-hole in the inner wall of the motor housing, providing a seal. The sealing ring is made of PTFE composite material, which has a low friction coefficient, strong chemical resistance, and virtually no hydrogen adsorption. The exhaust impeller is mounted on the servo motor's drive rod, and matching keys are provided in the drive rod's keyway to ensure circumferential fixation between the drive rod and the exhaust impeller. Retaining rings 1 and 2 are provided at the front and rear of the exhaust impeller, respectively, to ensure accurate axial positioning. The end of the servo motor's drive rod is secured to a groove on the inner surface of the pressure relief valve body by a matching retaining ring and a deep groove ball bearing. The high-torque motor portion comprises a high-torque motor, a drive shaft, a pressure relief vane, a fixing member, and a high-torque motor fixing sleeve. The high-torque motor is fixed to the wall surface at the center of the fan-shaped pressure relief port via a high-torque motor fixing sleeve. The transmission shaft provided on the motor passes through the through hole at the center of the fan-shaped pressure relief port and cooperates with the transmission hole of the pressure relief vane. The pressure relief vane is axially fixed by a fixing member so that it fits the inner surface of the fan-shaped pressure relief port. The key provided on the transmission shaft and the transmission groove provided on the pressure relief vane cooperate with each other to ensure its circumferential fixation on the shaft. The curvature of each blade in the pressure relief vane is 36°. The balancing holes are used to reduce the rotational resistance of the blades and ensure the reliable execution of the pressure relief action. 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 curvature of the external pressure relief hole is 24°. The side of the pressure relief vane that is in close contact with the inner surface of the fan-shaped pressure relief port is sprayed with a PTFE coating to achieve a low-friction seal.

[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 the 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 a regular hexagonal stainless steel pipeline. The regular hexagonal One stainless steel pipe is wrapped around the periphery of the hydrogen storage tank at a quarter of its vertical height, and the other is wrapped around the periphery at a 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 body 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 the spray duration, 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 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 eliminate hydrogen and reduce the concentration of combustible materials.

[0013] Compared with existing technologies, the advantages of this invention are: through multi-dimensional linkage, the five-level safety protection explosion suppression device for aviation hydrogen fuel controls the risk of hydrogen leakage at an early stage, making it particularly suitable for aviation scenarios with stringent safety requirements. Its core innovations lie in: the hydraulic buffer device acts as a buffer for the hydrogen storage tank; the high-precision positioning of the distributed fiber optic hydrogen sensor greatly improves positioning accuracy; the extremely fast action of the pressure relief valve system greatly improves response speed; and the active nitrogen inerting and fine water mist explosion suppression greatly reduce the possibility of hydrogen explosion. Through this 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 strong turbulence and the hydrogen tank was also shaken.

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

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

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

[0019] The fifth process: If the concentration continues to rise to 4% vol, the fourth-stage pressure relief valve system opens to discharge hydrogen.

[0020] The sixth process: If the high-temperature infrared sensor detects a fire source, the fifth-level water mist explosion suppression system will be activated and the flames will be extinguished within 30 seconds.

[0021] The present invention is particularly suitable for scenarios such as vertical take-off and landing (VTOL) aircraft and drones. Through a modular mechanical design, the device achieves physical containment, directional release, and explosion suppression of hydrogen leaks, significantly improving the safety of hydrogen-powered aircraft and hydrogen storage facilities. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0024] Figure 3 For the present invention Figure 2 A magnified schematic diagram;

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

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

[0027] Figure 6 The present invention Figure 5 B is an enlarged schematic diagram;

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

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

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

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

[0032] Figure 11 For the present invention Figure 10 Schematic diagram of C enlargement;

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

[0034] Figure 13 For the present invention Figure 12 D enlarged schematic diagram;

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

[0036] Figure 15 It is a schematic diagram of the pressure relief blade of the present invention;

[0037] Figure 16 It is a front view of the main body of the pressure relief valve of the present invention;

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

[0039] Figure 18 This is a diagram of the combination 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, 2. Hydraulic buffer structure, 3. Distributed fiber optic hydrogen sensor, 4. Nitrogen inerting system, 5. Pressure relief valve system, 6. 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 support;

[0043] 21-1, spiral piping, 21-2, hydraulic buffer device body, 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 fiber optic hydrogen sensor, 32. Demodulator;

[0045] 31-1, fiber Bragg grating, 31-2, optical fiber, 31-3, palladium nanofilm, 31-4, optical fiber cladding, 31-5, polyimide coating;

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

[0047] 51. Pressure relief valve body, 52. High torque motor part, 53. Motor box cover, 54. Fan-shaped pressure relief port, 55. Rear end pipe column of pressure relief valve;

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

[0049] 521. High-torque motor, 522. Drive shaft, 523. Pressure relief blade, 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 hexagonal stainless steel pipe, 64. Ultrasonic atomizing nozzle, 65. Deionized water pipeline, 66. High-temperature infrared sensor. DETAILED DESCRIPTION

[0052] A five-level safety protection explosion suppression device for aviation hydrogen fuel, comprising a hydrogen storage tank portion 1, a hydraulic buffer structure portion 2, a distributed optical fiber hydrogen sensor portion 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 composite of a carbon fiber winding layer and an inner lining aluminum alloy layer. The hydrogen storage tank 11 is fixed to the flange chassis at the bottom of the tank bracket 22. The pipe flange 13 is connected to the rear end pipe column 55 of the pressure relief valve. 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 to maintain the liquid hydrogen temperature ≤-253°C. The cold head (low temperature end) of the integrated micro Stirling refrigerator is tightly fitted with the outer wall of the hydrogen storage tank through a high thermal conductivity copper alloy heat conducting block, and the cold energy is directly transferred to the liquid hydrogen in the chamber. The sealing ring 14 is made of perfluororubber, which is suitable for high-pressure environments and has excellent resistance to hydrogen permeability.

[0054] The hydraulic buffer structure 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 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 hole 21-8; the hydraulic buffer device 21 is installed and fixed on the inner wall grooves of the six vertical supports of the tank support 22, and each vertical support is continuously arranged with four hydraulic buffer devices 21 from top to bottom, for a total of 24 The 24 hydraulic buffer devices 21 are installed in a position away from the distributed optical fiber hydrogen sensor 31 on the outer surface of the hydrogen storage tank 11; the spiral pipe 21-1 is installed in the hydraulic buffer device 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 pipe 21-1 is equal to the total oil capacity in the main oil chamber 21-5. The spiral pipe 21-1 has two parallel inlets connected to the main oil chamber 21-5. The main oil chamber 21-5 is connected, 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; the return spring 21-6 is placed in the main oil chamber 21-5, one end of the return spring 21-6 supports the piston 21-3, and the other end supports the wall of the main oil chamber 21-5; the throttle hole 21-8 limits the oil flow rate in the compression stage, and through the throttling effect, the hydraulic buffer device 21 has a better buffering effect; the micro-check valve 21-7 only allows the spiral pipe 21-1 to The oil flows into the main oil chamber 21-5. In the reset stage, the reset spring 21-6 pushes the piston 21-3 back, and the micro-check valve 21-7 provides a low-resistance reflux channel to prevent the oil from generating damping resistance again when it passes through the throttle hole 21-8 in the opposite direction, and provides an outlet for the oil to flow back to the main oil chamber 21-5; the throttle hole 21-8 and the micro-check valve 21-7 cooperate with each other, and the parallel pipelines control the oil in and out of the spiral pipeline 21-1 in the compression stage and the reset stage, so as to achieve the purpose of vibration buffering of the hydrogen storage tank 11, and together constitute a hydraulic buffer system. When the oil in the main oil chamber 21-5 is compressed, the elasticity of the return spring 21-6 allows the piston 21-3 to move back, and the pressure difference causes the oil in the spiral pipe 21-1 to return to the main oil chamber 21-5. At the same time, since the throttle hole 21-8 and the micro-one-way valve 21-7 are connected in parallel, the resistance of the throttle hole 21-8 is relatively large, and most of the oil will choose to flow back to the main flow chamber 21-5 through the micro-one-way valve 21-7, and the damping resistance will not be generated again when the oil passes through the throttle hole 21-8 in the opposite direction; 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 body bracket 22 is installed and fixed in the fuselage fuel compartment of the aircraft.

[0055] The distributed optical fiber hydrogen sensor part 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 nanofilm 31-3, an optical fiber cladding 31-4, and a polyimide coating 31-5. The distributed optical fiber hydrogen sensor 31 is spirally wound and laid along the outer surface of the hydrogen storage tank 11. A 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 the optical fiber cladding 31-4, and the polyimide coating 31-5 is coated on the surface of the optical fiber cladding 31-4. The fiber Bragg grating 31-1 is generated by ultraviolet laser. A periodic refractive index modulation structure is embedded within the core of optical fiber 31-2. The polyimide coating 31-5 is removed from the surface of the fiber Bragg grating 31-1. A palladium nanofilm 31-3 is applied to the outer surface of the fiber cladding 31-4. Hydrogen adsorption causes the palladium lattice to expand, applying strain to optical fiber 31-2 and causing the grating wavelength to shift. The demodulator analyzes this shift in real time, calculates the hydrogen concentration, and uses data from multiple fiber Bragg grating 31-1 nodes to locate the leak. The demodulator 32 is integrated into the bottom flange chassis of the tank support 22 and connects to the distributed fiber hydrogen sensor 31 via optical fiber 31-2. It converts optical signals into electrical signals and transmits them to the main controller, which then determines the next step. An alarm is triggered when the leakage concentration is ≥1% LEL. The distributed fiber hydrogen sensor 31 is bonded to the tank surface with UV-curable adhesive.

[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 compartment of the rear section of the fuselage. The pressure swing adsorption nitrogen generator 41 separates the nitrogen from the inhaled air and stores it in the 25L carbon fiber gas cylinder 42. The 25L carbon fiber gas cylinder 42 is 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 downward at a certain angle of 20°-30°, and the injection direction is directed to the tank surface. The annular distribution pipe 43 is wrapped around the periphery of the vertical center position of the hydrogen storage tank 11. The 12 copper nozzles 44 are evenly distributed on the annular distribution pipe 43. When a leak 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 box cover 53, 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 the pipe 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 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 1 514, a fixing ring 2 515, a retaining ring 516, a deep groove ball bearing 517, and a sealing ring 518; the servo motor 512 is fixed to the motor box on the outer shell of the pressure relief valve body 51 by screws, and the motor box cover 53 is matched with the motor box by screws. The transmission rod of the servo motor 512 in the box is aligned with the through hole provided in the motor box and passes through. The sealing ring 518 is stuck on the through hole on the inner wall of the motor box to play a sealing role. The sealing ring 518 adopts PTFE composite material has a low coefficient of friction and strong chemical resistance, and absorbs almost no hydrogen. The servo motor 512's drive rod is equipped with an exhaust impeller 511. A key 513 is provided in the drive rod's keyway to ensure circumferential fixation between the drive rod and the exhaust impeller 511. The exhaust impeller 511 is respectively equipped with a first retaining ring 514 and a second retaining ring 515 to ensure accurate axial positioning. The end of the servo motor 512's drive rod is secured to a groove on the inner surface of the pressure relief valve body 51 via a matching retaining ring 516 and a deep groove ball bearing 517. The high-torque motor portion 52 includes a high-torque motor 521, a drive 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 secured to the wall at the center of the fan-shaped pressure relief vent 54 via a high-torque motor fixing sleeve 525. A drive shaft 522 extends through the central through-hole of the fan-shaped pressure relief vent 54 and engages with the drive hole 523-2 of the pressure relief vane 523. The pressure relief vane 523 is axially secured by a fixing member 524, allowing it to adhere to the inner surface of the fan-shaped pressure relief vent. A key on the drive shaft 522 engages with a drive groove 523-1 provided on the pressure relief vane 523, ensuring circumferential fixation on the shaft. Each blade in the pressure relief vane 523 has a 36° arc. The balancing holes 523-3 reduce blade rotational resistance and ensure reliable pressure relief. The two rows of balancing holes on each blade have a 30° axial arc relationship, with six balancing holes in each row. The external pressure relief holes have a 24° arc. The side of the pressure relief vane 523 that abuts the inner surface of the fan-shaped pressure relief vent is sprayed with a PTFE coating to achieve a low-friction seal.

[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. One regular hexagonal stainless steel pipeline 63 is installed with six ultrasonic atomizing nozzles. Head 64, one of the regular hexagonal stainless steel pipes 63 is wrapped around the periphery at a quarter of the height of the hydrogen storage tank 11 in the vertical direction, and the other is wrapped around the periphery at a three-quarter height of the height of the hydrogen storage tank 11 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 body 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 the injection duration ≥30 seconds, and the "hydrogen concentration + flame / temperature rise" dual-condition trigger is used to reduce the probability of false triggering; the deionized water storage tank 61 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 6 and the pressure relief valve system 5 can be controlled in conjunction to remove hydrogen and reduce the concentration of combustible materials.

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

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

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

[0062] The third process: The second-level distributed optical fiber hydrogen sensor detects a hydrogen concentration of 0.1% vol, locates the leak point, and alerts 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 avoid the distributed fiber optic hydrogen sensors on the outer shell of the hydrogen storage tank. During the compression phase, the orifice restricts the oil flow rate, enhancing the hydraulic buffer's effectiveness through the throttling effect. The micro-check valve only allows oil in the spiral piping to flow into the main oil chamber. During the reset phase, the return spring pushes the piston back, and the micro-check valve provides a low-resistance return path, preventing the oil from re-inducing damping resistance when it reverses through the orifice and providing an outlet for the oil to flow back into the main oil chamber. Because the orifice presents greater resistance, most of the oil will flow through the micro-check valve back into the main flow chamber, avoiding the re-inducing damping resistance when it reverses through the orifice. The orifice and micro-check valve work together as parallel pipelines, controlling the flow of oil into and out of the spiral piping during both the compression and reset phases, achieving the purpose of absorbing vibrations in the hydrogen storage tank and forming a hydraulic buffer system. The rubber cushion directly contacts the outer surface of the hydrogen storage tank to achieve its cushioning effect. The hydraulic buffer system, in part, significantly improves the shock resistance and service life of the hydrogen storage system through dynamic energy dissipation and displacement control.

[0067] The distributed optical fiber hydrogen sensor 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 and The hydrogen concentration is calculated by reverse engineering and combined with data from multiple fiber Bragg grating nodes to locate the leak point. The demodulator transmits the electrical signal to the main controller, which then makes the next analysis and judgment. The early warning logic is as follows: Level 1 (hydrogen concentration greater than 0.1% vol) triggers the nitrogen inerting system; Level 2 (hydrogen concentration greater than 0.4% vol) activates the pressure relief valve system and activates the water mist explosion suppression system.

[0068] Palladium nanofilm absorbs hydrogen and expands: 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 of FBG (λ B ) is determined by the grating period (Λ) and the effective refractive index (n eff ) determines: B =2n eff Λ

[0071] When palladium expands, it produces axial strain When the grating period and refractive index change, the wavelength shift (λ B ):

[0072] Δλ B =λ B ·(1-p e )·ε

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

[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: B =1550nm, S≈0.1nm / ppm)

[0079] The nitrogen inerting system actively injects high-purity nitrogen to dilute the hydrogen concentration in the leak area and prevent the formation of explosive conditions. The pressure swing adsorption nitrogen generator separates nitrogen from the inhaled air and stores it in 25L carbon fiber cylinders. These cylinders are connected to 12 copper nozzles via a circular distribution pipe. The copper nozzles are installed at a downward angle of 20°-30°, with the spray direction directed toward the tank surface. The circular distribution pipe surrounds the vertical center of the hydrogen storage tank, and the 12 copper nozzles are evenly distributed on the ring distribution pipe. Once a leak 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 a set threshold, the main controller receives a signal, triggering the protection system to rapidly open the pressure relief valve system, releasing excess hydrogen and preventing the tank from rupturing. Alternatively, the pressure relief valve system opens when the distributed fiber-optic hydrogen sensor detects a hydrogen concentration on the surface of the hydrogen storage tank exceeding 4% vol. Once the pressure relief valve system is opened, a high-torque motor rotates the pressure relief vane. Once the balancing hole in the pressure relief vane is exposed, hydrogen is immediately discharged through the balancing hole. This causes a sudden drop in pressure within the pressure relief valve system, reducing the blade's rotational resistance and ensuring reliable pressure relief. A servo motor then rotates the exhaust impeller, accelerating the discharge of hydrogen. The pressure relief valve's fan-shaped relief port is designed for directional injection, with a dedicated hydrogen discharge conduit that directs the discharge away from the aircraft fuselage or sensitive areas of the hydrogen storage facility to prevent hydrogen accumulation in the equipment compartment. 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 hydrogen concentration will eventually show a downward trend.

[0081] The water mist explosion suppression system serves as the ultimate line of defense, extinguishing flames and blocking the spread of explosions through a dual mechanism of physical cooling and chemical quenching. The ultrasonic atomizing nozzle has a built-in heating wire to ensure normal spraying even at extremely low temperatures. The high-pressure water pump atomizes deionized water from the deionized water storage tank into droplets ≤10μm in size. The ultrasonic atomizing nozzle forms a water mist curtain wall. The water mist suppresses the propagation of hydrogen flames through a dual mechanism of heat absorption cooling and free radical quenching. The free radical quenching reaction is: OH + H2 → H2O, interrupting the chain combustion reaction and preventing 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, it transmits the signal 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 combustible materials.

[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 portion (1) includes a hydrogen storage tank (11), an integrated micro Stirling refrigerator (12), and a pipe flange (13), wherein the pipe flange (13) is arranged on the hydrogen storage tank (11), the pipe 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 conducting 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) includes 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 the six vertical support inner wall grooves of the tank support (22). The hydraulic buffer device (21) includes 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 capacity 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 interior of 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), with one end of the return spring (21-6) supporting the piston (21-3) and the other end supporting the wall of the main oil chamber (21-5); The distributed optical fiber hydrogen sensor part (3) includes 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 bracket (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) includes 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, and the 25L carbon fiber gas cylinder (42) is fixed on the pressure swing adsorption nitrogen generator (41). The pressure swing adsorption nitrogen generator (41) separates the nitrogen in 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), and the copper nozzles (44) are installed at a downward tilt of 20°-30°, with the spray direction pointing to the tank surface. 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 the 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 housing of the pressure relief valve body (51); the exhaust impeller (511) is assembled 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 member (524), a high-torque motor fixing sleeve (525), the high-torque motor (521) is fixed to the wall surface at the center of the fan-shaped pressure relief port (54) through the high-torque motor fixing sleeve (525), a transmission shaft (522) provided on the high-torque motor (521) passes through the through hole at the center of the fan-shaped pressure relief port (54), and cooperates with the transmission hole (523-2) of the pressure relief blade (523), the pressure relief blade (523) is axially fixed by the fixed member (524) so ​​as to be attached to the 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 the hydrogen discharge pipeline; 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 pipe (63), an ultrasonic atomizing nozzle (64), a deionized water pipe (65) and a high-temperature infrared sensor (66). The deionized water storage tank (61) is 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 connected to the deionized water storage tank (61). The deionized water pipeline (65) is connected to the regular hexagonal stainless steel pipeline (63), and twelve ultrasonic atomizing nozzles (64) are arranged on the 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 installed 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 arranged 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 (31-5). A 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 (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 (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 this 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) uses the hydrogen absorption expansion characteristics of palladium to convert the hydrogen concentration into a grating strain signal, causing the grating wavelength to shift. The demodulator (32) analyzes the offset in real time and calculates the value according to the The hydrogen concentration is calculated by reverse calculation and the leak point is located by combining the multi-fiber Bragg grating node data. The demodulator (32) transmits the electrical signal to the main controller, which makes the next 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 and 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 radian of each blade in the pressure relief blade (523) is 36°. The pressure relief blade (523) is provided with a balancing hole (523-3). The balancing hole (523-3) can reduce the rotational resistance of the blade. The axial radian 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) pressurizes the deionized water and delivers it to the ultrasonic atomizing nozzle (64), which atomizes the deionized water into droplets with a particle size of ≤ 10 μm. The ultrasonic atomizing nozzle (64) forms a water mist curtain wall, and the water mist suppresses the propagation of the hydrogen flame through the dual mechanisms of heat absorption cooling and free radical quenching. 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 conjunction.

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