Battery cooling system for hydrogen fuel cell ducted fan propulsion aircraft

Abstract

The application relates to the technical field of hydrogen energy fuel cells, in particular to a battery cooling system of a hydrogen energy fuel cell ducted fan propulsion aircraft, which comprises a hydrogen energy fuel cell and a fairing, the fairing is arranged on the inner side of the upper part of an aircraft body, the upper end of the fairing is open, the lower end of the fairing is provided with at least two exhaust air ducts, the lower end of the exhaust air ducts penetrates the lower end of the aircraft body, the hydrogen energy fuel cell is fixedly connected in the fairing, the fairing is provided with a heat dissipation flow channel, and the heat dissipation flow channel is in communication with the upper end of the fairing and the exhaust air ducts. Through the integrated design of the conical fairing and the exhaust air duct, the suction force of the exhaust air duct fan is utilized to realize forced convection heat dissipation of the hydrogen energy fuel cell, the exhaust air duct is integrated into the main propulsion channel of the aircraft, the heat dissipation system and the propulsion system are highly integrated, the power system structure of the hydrogen energy aircraft is greatly simplified, and the additional aerodynamic resistance is reduced.

Description

Technical Field

[0001] This invention relates to the field of hydrogen fuel cell technology, specifically to a battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft. Background Technology

[0002] Currently, most mainstream hydrogen fuel cell aircraft adopt a power architecture layout where the propulsion system and cooling system are independent. The propulsion system typically uses an electric motor to drive a propeller to generate lift or thrust, while the cooling system consists of an independent cooling fan combined with water-cooled or air-cooled components to remove the waste heat generated during the electrochemical reaction of the fuel cell stack. Although this independent design is simpler in terms of control logic, in the aviation field, which pursues weight reduction and long range, the hardware structure is seriously redundant. The weight of the independent cooling system usually accounts for 20%-30% of the total system weight, which significantly weakens the high energy density advantage of hydrogen fuel cells and limits the range of the aircraft. At the same time, the auxiliary fan used solely for cooling consumes an additional 5%-10% of the system's electrical energy, resulting in secondary energy being wasted on non-propulsion power consumption. Furthermore, traditional solutions often fail to provide stable and high-pressure forced convection airflow, leading to the formation of local hot spots inside the fuel cell stack, and the cooling efficiency is greatly affected by environmental conditions.

[0003] To address the aforementioned issues, existing technologies offer several solutions, such as optimizing the flow channel design of fuel cell bipolar plates to enhance natural heat transfer, or using high-performance composite materials to manufacture lightweight heat sinks to reduce weight. However, these improvements only alleviate heat dissipation pressure or reduce local weight to a certain extent, and cannot fundamentally eliminate the structural redundancy caused by the coexistence of propulsion and heat dissipation systems. For example, some designs attempt to utilize ram air for passive heat dissipation during flight, but this significantly reduces its effectiveness during takeoff, hovering, or low-speed flight due to insufficient intake dynamic pressure, failing to guarantee the thermal safety of the fuel cell stack throughout the entire flight envelope. Furthermore, adding independent auxiliary heat dissipation mechanisms not only increases the mechanical complexity of the system but also raises the failure rate and maintenance costs.

[0004] Therefore, there is an urgent need for a hydrogen fuel cell-driven integrated propulsion and heat dissipation system that can highly integrate heat dissipation functions while ensuring stable propulsion and lift, and achieve significant weight reduction and energy saving through simplified mechanical structure, so as to meet the stringent requirements of small electric aircraft for high power density, long endurance and high reliability. Summary of the Invention

[0005] The purpose of this invention is to provide a battery cooling system for hydrogen fuel cell ducted fan propulsion aircraft, in order to solve the problem of structural redundancy caused by the existing power architecture layout in hydrogen fuel cell aircraft, which adopts a power architecture layout in which the propulsion system and the heat dissipation system are independent.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft includes a hydrogen fuel cell and a fairing. The fairing is located on the upper inner side of the aircraft body, with its upper end open. At least two exhaust ducts are located at the lower end of the fairing, extending through the lower end of the aircraft body. The hydrogen fuel cell is fixedly connected inside the fairing. A heat dissipation channel is provided inside the fairing, connecting the upper end of the fairing to the exhaust ducts. The heat dissipation channel guides airflow through the hydrogen fuel cell. A brushless motor is coaxially connected inside the exhaust ducts, and an exhaust fan blade is coaxially fixedly connected to the lower end of the brushless motor. The exhaust fan blade generates downward-facing driving airflow when it rotates.

[0007] By longitudinally arranging a fairing and exhaust duct inside the aircraft, the negative pressure suction generated by the high-speed rotation of the exhaust fan blades driven by a brushless motor forces cool outside air into the heat dissipation channel through the upper opening of the fairing and flows at high speed over the surface of the hydrogen fuel cell. This integrates propulsive lift output with forced convection cooling. While providing upward driving force for the aircraft, the exhaust fan blades actively extract waste heat generated during the hydrogen fuel cell reaction and expel it downwards with the high-speed airflow. This effectively solves the problem of a sharp drop in heat dissipation efficiency caused by insufficient intake dynamic pressure during takeoff, hovering, or low-speed flight in traditional passive cooling solutions, ensuring the thermal safety of the hydrogen fuel cell throughout the entire flight envelope and under various complex operating conditions.

[0008] Furthermore, since the heat dissipation function relies directly on the air pressure difference generated by the propulsion duct, the system does not need to be equipped with heavy liquid cooling components, circulation pumps or independent auxiliary cooling fans. This eliminates the hardware structural redundancy caused by the coexistence of propulsion and heat dissipation systems, which can significantly reduce the overall weight of the aircraft and effectively convert the saved energy consumption and payload space into range. This maximizes the advantages of the high energy density of hydrogen fuel cells and meets the needs of long-endurance flight.

[0009] Furthermore, the cooling channels inside the fairing can guide the airflow path to precisely cover the key heat-generating areas of the hydrogen fuel cell, providing a stable and high-pressure forced convection airflow, effectively eliminating local hot spots that are prone to occur inside the stack and extending the battery's lifespan; at the same time, by simplifying the mechanical structure, the complexity of the system and maintenance costs are reduced, making it suitable for the stringent requirements of small electric aircraft for high power density, long endurance, and high reliability.

[0010] Preferably, an adjusting duct is coaxially provided at the lower end of the exhaust duct, and a sliding rod is coaxially fixedly connected inside the adjusting duct. An electromagnet is slidably connected to the sliding rod, and multiple first connecting rods are hinged to the lower end of the sliding rod. Multiple second connecting rods are hinged to the outer wall of the electromagnet. The upper end of the first connecting rod is hinged to the middle of the second connecting rod. Canvas is provided on the outer wall of the multiple second connecting rods. When the electromagnet is at the upper dead point, the canvas is retracted to form a cone shape with the small end on the upper side.

[0011] By setting up a linkage mechanism driven by an electromagnet in the regulating duct, the axial displacement of the electromagnet on the slide bar drives the linkage structure composed of the first and second links to extend and retract. When the electromagnet moves to the top dead center position, the canvas retracts synchronously with the linkage mechanism and forms a tapered streamlined structure with the tip pointing upward, which allows the high-speed driving air discharged from the exhaust duct to be smoothly guided downward along the tapered surface, reducing the local resistance and turbulence loss of the airflow at the exhaust end, and ensuring that the aircraft has efficient thrust output and stable aerodynamic characteristics in propulsion mode.

[0012] Furthermore, through precise stroke control of the electromagnet, dynamic adjustment of the effective outlet area and exhaust direction of the exhaust duct is achieved. Under conditions requiring high-intensity heat dissipation without generating thrust, the electromagnet is driven to move downwards along the slide bar, causing the linkage mechanism to expand outwards and unfold the canvas. This blocks the vertically downward driving airflow and guides it into a horizontally overflowing diffuser. This physical vector conversion ensures that the exhaust fan blades can continuously generate sufficient negative pressure suction at high speeds to cool the hydrogen fuel cell, while effectively counteracting vertical lift and eliminating the risk of takeoff due to unexpected lift during ground standby or self-check phases.

[0013] Furthermore, the umbrella-shaped design combining canvas and multi-link has extremely high advantages in lightweighting and space utilization. Compared with heavy rigid guide vanes, the canvas structure can better adapt to the impact of high-pressure flow fields through flexible deformation, and occupies very little duct space in the fully retracted state. Through the coaxial guidance of the slide bar and the sleeve, the motion stability and structural self-locking capability during the electromagnetic regulation process are ensured. This not only improves the response speed of the thermal management system, but also enhances the system integration and operational reliability of the hydrogen-powered aircraft under complex working conditions.

[0014] Preferably, the lower end of the slide bar is located inside the regulating duct, the lower end of the regulating duct extends to the outside of the aircraft body, and multiple exhaust ports are evenly distributed around the outer side wall of the regulating duct extending to the outside of the aircraft. The multiple exhaust ports are horizontally arranged. When the electromagnet is at the lower dead point, the canvas is opened to fit against the inner wall of the regulating duct, and the lower end of the canvas is located between the upper and lower ends of the exhaust ports.

[0015] By opening horizontal exhaust vents on the wall of the adjustable duct extending outside the machine body, and coordinating with the fully unfolded canvas when the electromagnet reaches its bottom dead center, the physical blocking and forced reversal of the driving airflow path are achieved. When the electromagnet drives the linkage mechanism to open the canvas to fit against the inner wall of the duct, the canvas forms a guide umbrella surface for a closed vertical exhaust channel. Since the lower end of the canvas is precisely positioned within the opening area of ​​the horizontal exhaust vent, the driving air that was originally sprayed vertically downward is intercepted by the canvas and guided to the horizontal direction, and discharged outward through the circumferentially distributed exhaust vents. This momentum vector conversion design allows the system to cancel the vertical lift to zero without changing the speed of the exhaust fan blades, achieving a complete decoupling of propulsion power consumption and heat dissipation power consumption at the physical level.

[0016] Furthermore, during the standby, system self-check, or post-landing cooling phases of hydrogen-powered aircraft, the hydrogen fuel cell still requires high-intensity forced convection cooling. This solution allows the brushless motor to maintain high-speed operation to sustain the strong negative pressure suction force within the cooling channel, ensuring that the waste heat from the fuel cell stack is carried away in a timely manner. At the same time, since the airflow is changed to horizontal exhaust, vertical lift is avoided, ensuring that the aircraft can remain stably on the ground. This eliminates the risk of accidental low-altitude floating or strong airflow impact on the ground directly below, greatly improving the safety of ground operations.

[0017] Furthermore, the layout of the lower end of the canvas being highly matched with the exhaust vent ensures smooth flow during airflow reversal, reducing pressure buildup and energy loss at the bottom of the duct. The design of extending the duct to the outside of the aircraft not only facilitates the rapid diffusion of hot air to the outside atmosphere and prevents hot air from accumulating at the bottom of the fuselage, but also enhances the system's maintenance convenience. The overall mechanism can quickly switch between propulsion mode and static heat dissipation mode through simple control of the electromagnet's stroke, and has the advantages of fast response speed, simplified mechanical structure, and high reliability, fully meeting the stringent requirements of small UAVs for highly integrated thermal management systems.

[0018] Preferably, the outer wall of the slide rod is provided with a slide groove, the extension direction of the slide groove is coaxial with the slide rod, and the electromagnet is provided with a guide pin, which is slidably connected in the slide groove.

[0019] By setting a guide pin and a slide groove that cooperate with each other between the electromagnet and the slide rod, it is ensured that the electromagnet can strictly follow the preset straight trajectory when sliding along the axis of the slide rod. This effectively limits the circumferential rotation of the electromagnet during the adjustment process, thereby ensuring that the multiple linkage mechanisms are always in a stable spatial position and avoiding transmission failure or structural disorder caused by the mechanism's self-rotation during high-speed operation.

[0020] Furthermore, the coaxially arranged chute design provides precise rigid guidance for the unfolding and retraction of the canvas. Because the circumferential degree of freedom of the electromagnet is fully constrained, the multiple sets of first and second connecting rods and the canvas fixed to them can always maintain a high degree of circumferential symmetry during the extension and retraction process. This effectively prevents uneven force on the connecting rods or mechanical jamming caused by unexpected rotation of the electromagnet, and significantly improves the synchronization and smoothness of the umbrella-shaped adjustment mechanism under complex working conditions.

[0021] Furthermore, the cooperation between the guide pin and the slide groove effectively reduces the radial vibration amplitude of the electromagnet under the impact of high-speed airflow inside the duct. The stable sliding pair enhances the overall mechanical strength of the adjustment mechanism, ensuring that the canvas can maintain the preset geometric posture under the continuous action of the downward driving wind. This not only improves the accuracy of vector control during airflow reversal but also significantly enhances the structural reliability and service life of the adjustment mechanism under long-term high-frequency vibration environment.

[0022] Preferably, the inner wall of the fairing is provided with multiple rectifier grids, the outer wall of the hydrogen fuel cell is fitted with the multiple rectifier grids, and a rectifier channel is formed between the hydrogen fuel cell and the rectifier grids.

[0023] By setting a rectifier grid on the inner wall of the rectifier that fits against the outer wall of the hydrogen fuel cell, the open space inside the rectifier is divided into multiple parallel rectifier channels. Through the physical constraint of the rectifier grid, the cooling airflow entering from the top of the rectifier is forced to flow evenly along a preset axial path around the periphery of the hydrogen fuel cell. This effectively avoids turbulence, eddies, or uneven heating of the airflow on the surface of the fuel cell stack, ensuring that each hydrogen fuel cell module can obtain a stable and sufficient amount of cold air coverage, and significantly improving heat exchange efficiency.

[0024] Furthermore, the close fit design between the rectifier grille and the outer wall of the hydrogen fuel cell provides radial support and constraint for the hydrogen fuel cell. When the aircraft is performing high-maneuver flight or encountering turbulence and vibration, the multiple rectifier grilles can disperse and offset the inertial load on the hydrogen fuel cell, enhancing the installation stability of the hydrogen fuel cell within the fairing. At the same time, the narrow and deep rectifier channels formed by the grilles increase the contact pressure and residence time between the air and the surface of the hydrogen fuel cell, utilizing the boundary layer control effect to more thoroughly remove waste heat from the deeper layers of the stack.

[0025] Furthermore, the presence of the rectifier grille allows the cooling airflow to be initially smoothed before entering the exhaust duct below, reducing the turbulence intensity entering the brushless motor and exhaust fan blade area. This not only helps reduce the aerodynamic noise of the system but also reduces the load fluctuation of the exhaust fan blades, making the brushless motor run more smoothly. The overall structure achieves the dual purpose of flow field optimization and mechanical reinforcement through simple physical grids, fully meeting the stringent requirements of hydrogen-powered aircraft for high reliability and high temperature uniformity of the cooling system.

[0026] Preferably, a first magnet is provided at the lower end of the second connecting rod, and multiple second magnets are provided on the side wall of the adjusting duct. When the electromagnet is at the lower dead center, the first magnet and the second magnet are in contact.

[0027] By setting a first magnet and a second magnet at corresponding positions on the inner wall of the regulating duct at the end of the second connecting rod, magnetic attraction is used to achieve auxiliary positioning and locking of the umbrella-shaped regulating mechanism in the fully deployed state. When the electromagnet drives the connecting rod mechanism to the lower dead center, so that the canvas is completely attached to the inner wall of the regulating duct to block the vertical airflow, the instantaneous attachment of the first magnet and the second magnet provides additional holding force, thereby effectively offsetting the huge impact load generated by the high-speed driving wind on the canvas in the deployed state, preventing the connecting rod mechanism from fluttering or unexpected rebound in the extreme high-pressure flow field, and ensuring the physical stability of the airflow reversal path.

[0028] Furthermore, the magnetic locking structure provides significant energy savings for the electromagnet drive system. During the extended state, the static magnetic attraction between magnet one and magnet two can share part of the electromagnet's load, and even allow the central controller to reduce the electromagnet's holding current, thereby reducing the system's continuous power consumption. At the same time, this adsorption-type positioning method ensures that the lower end of the canvas can always accurately and tightly cover the preset flow guide position, eliminating air leakage caused by mechanical gaps and improving the thoroughness of thrust cancellation during vector switching.

[0029] Furthermore, the multi-point distributed second magnets guide the second connecting rod to automatically align with the preset position during deployment, compensating for the cumulative wear tolerances that may occur in the mechanical connecting rod due to long-term use. This magnetically assisted solution not only enhances the structural rigidity of the adjustment mechanism under severe vibrations in the aircraft, but also reduces the rigid collision between the connecting rod end and the inner wall of the duct through the damping effect of magnetic adsorption. This effectively reduces mechanical noise during mechanism operation and extends the service life of key hinge components, further meeting the dual requirements of high integration and high reliability of the UAV thermal management system.

[0030] Preferably, the inner side of the canvas is provided with a counterweight bar, which is located between two No. 2 connecting rods, and the two No. 2 connecting rods are symmetrical about the counterweight bar.

[0031] By setting symmetrically distributed counterweights on the inner side of the canvas between two adjacent No. 2 connecting rods, the dynamic shape of the flexible canvas in complex airflow environments is optimized. When the umbrella-shaped mechanism is in the retraction process or in a semi-expanded state, the counterweights can guide the canvas to remain flat in the high-speed pulsating airflow by virtue of their mass characteristics, effectively suppressing the violent shaking and slapping phenomena that are easily generated by the flexible fabric under the action of the high pressure difference in the duct. This symmetrical layout ensures that the center of force of the canvas coincides with the geometric center, improving the linearity of the mechanism's motion trajectory.

[0032] Furthermore, the counterweight strips act as lateral reinforcing ribs on the inner side of the canvas, improving the overall tear resistance of the flexible material. In the aircraft propulsion mode, the counterweight strips retract with the canvas and adhere to the periphery of the slide bar. Their own mass helps maintain the centrifugal stability of the umbrella-shaped structure and prevents the mechanism from swaying during high-speed vibrations, forming a composite structure of flexible coverage and rigid weighting. This not only solves the technical problem of lightweight canvas being prone to instability in strong wind fields, but also optimizes the dynamic response of the adjustment mechanism through physical balancing, further improving the thermal management control accuracy of the system under different flight attitudes.

[0033] Preferably, a preset gap is maintained between the maximum rotation diameter of the exhaust fan blade and the inner wall of the exhaust duct, and the preset gap ranges from 0.5mm to 1.5mm.

[0034] By setting a preset gap between the exhaust fan blade tip and the inner wall of the exhaust duct, and controlling the preset gap to be between 0.5mm and 1.5mm, the leakage loss at the blade tip and the generation of blade tip vortices are suppressed. From an aerodynamic perspective, the preset gap can effectively prevent the high-pressure side airflow from flowing back to the low-pressure side through the gap, significantly enhancing the static negative pressure generated at the air inlet of the duct when the exhaust fan blade rotates. This enhances the suction capacity of the heat dissipation channel inside the fairing, ensuring that cold air can pass through the surface of the hydrogen fuel cell at a higher flow rate, and greatly optimizing the forced convection heat transfer efficiency of the system.

[0035] Furthermore, this preset gap range effectively balances the conflict between aerodynamic performance and structural safety. The lower limit of 0.5mm ensures that even when the exhaust fan blades experience thermal expansion due to heat dissipation from the hydrogen fuel cell inside the duct, or when the aircraft undergoes minor structural deformation during high-maneuver flight, the exhaust fan blades will not rigidly collide or rub against the inner wall of the duct, thus guaranteeing the operational reliability of the propulsion system. The upper limit of 1.5mm ensures that energy conversion efficiency does not significantly decrease due to excessive gap size, avoiding the waste of secondary energy in unnecessary leakage losses, thereby guaranteeing the aircraft's power output.

[0036] Furthermore, the preset gap effectively improves the acoustic characteristics inside the exhaust duct, reduces high-frequency aerodynamic noise caused by blade tip turbulence, and enhances the environmental performance of the aircraft. By controlling the size requirements of the preset gap, the system improves the negative pressure heat dissipation level while also optimizing the momentum conversion efficiency of the propeller, enabling the system to achieve the dual optimal solution of heat dissipation performance and endurance under the limited energy conditions of small UAVs.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention integrates a conical fairing with an exhaust duct, which utilizes the suction force of the exhaust duct fan to achieve forced convection cooling of the hydrogen fuel cell and integrates the exhaust duct into the main propulsion channel of the aircraft. This achieves a high degree of integration between the cooling system and the propulsion system, greatly simplifies the power system structure of the hydrogen-powered aircraft, and reduces additional aerodynamic drag.

[0038] 2. This invention achieves rapid switching between propulsion mode and static heat dissipation mode through an adjustable umbrella-shaped canvas airflow guiding mechanism. While ensuring the heat dissipation requirements during the ground standby phase, it offsets the vertical lift, improves the safety of ground operations, and achieves physical decoupling of propulsion power consumption and heat dissipation power consumption, avoiding unnecessary energy waste.

[0039] 3. This invention divides the cooling airflow into multiple uniform rectifier channels through a rectifier grille, which not only achieves uniform heat dissipation of the hydrogen fuel cell and avoids local overheating, but also provides radial support and reinforcement for the fuel cell stack. At the same time, it optimizes the flow field quality entering the exhaust fan blades, reduces aerodynamic noise and load fluctuations, and achieves the dual effects of flow field optimization and structural reinforcement.

[0040] 4. This invention achieves auxiliary locking of the canvas in the unfolded state through a magnetically coupled positioning structure, which counteracts the impact load of high-speed airflow on the canvas, reduces the holding power consumption of the electromagnet, compensates for mechanical wear tolerances, reduces collision damage during mechanism operation, and improves the overall reliability of the adjustment mechanism. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the overall structure of the hydrogen fuel cell-based ducted fan propulsion aircraft in this invention. Figure 2 This is a top view of the hydrogen fuel cell-based ducted fan propulsion aircraft of the present invention; Figure 3 for Figure 2 Full sectional view at point AA; Figure 4 for Figure 2 A magnified view of a section at point B in the middle; Figure 5This is a schematic diagram of the battery cooling system of the hydrogen fuel cell ducted fan propulsion aircraft of the present invention; Figure 6 for Figure 5 Full sectional view at point BB; Figure 7 for Figure 6 A magnified view of a section at point C; Figure 8 This is a schematic diagram of the fully deployed canvas in the battery cooling system of the hydrogen fuel cell ducted fan propulsion aircraft of the present invention.

[0042] In the diagram: 1. Aircraft body; 2. Outriggers; 3. Hydrogen cylinder; 4. Air compressor; 5. Hydrogen fuel cell; 6. Fairing; 601. Heat dissipation channel; 602. Rectifying grille; 603. Rectifying channel; 7. Exhaust duct; 8. Brushless motor; 9. Exhaust fan blade; 901. Preset gap; 10. Adjustable duct; 1001. Exhaust vent; 11. Sliding rod; 1101. Slide groove; 12. Electromagnet; 13. Link 1; 14. Link 2; 15. Canvas; 16. Guide pin; 17. Magnet 1; 18. Magnet 2; 19. Counterweight bar. Detailed Implementation

[0043] Please see Figures 1 to 8 This invention provides a battery cooling system for a hydrogen fuel cell ducted fan propulsion aircraft, the technical solution of which is as follows: Please refer to the battery cooling system for hydrogen fuel cell ducted fan propulsion aircraft. Figures 1 to 4The system includes a hydrogen fuel cell 5 and a fairing 6. The fairing 6 is located on the upper inner side of the aircraft body 1. The upper end of the fairing 6 is open, and the lower end of the fairing 6 is provided with at least two exhaust ducts 7. The lower end of the exhaust ducts 7 penetrates the lower end of the aircraft body 1. The hydrogen fuel cell 5 is fixedly connected inside the fairing 6. The fairing 6 is provided with a heat dissipation channel 601, which connects the upper end of the fairing 6 with the exhaust ducts 7. The heat dissipation channel 601 is used to guide airflow through the hydrogen fuel cell 5. The inner sidewall of the fairing 6 is provided with multiple rectifier grilles 602. The outer sidewall of the hydrogen fuel cell 5 is attached to the multiple rectifier grilles 602, and a rectification channel 603 is formed between the hydrogen fuel cell 5 and the rectifier grilles 602. A brushless motor 8 is coaxially connected inside the exhaust duct 7. An exhaust fan blade 9 is coaxially fixed to the lower end of the brushless motor 8. When the exhaust fan blade 9 rotates, it generates downward-facing driving air. A preset gap 901 (1mm) is maintained between the maximum rotation diameter of the exhaust fan blade 9 and the inner wall of the exhaust duct 7. It should be noted that two support legs 2 are located on the lower side of the aircraft body 1. The support legs 2 provide support when the aircraft body 1 is not in takeoff mode. Each support leg 2 is equipped with a hydrogen cylinder 3, which is connected to the hydrogen inlet of the hydrogen fuel cell 5. An air compressor 4 is located at the front of the aircraft body 1. The air compressor 4 provides oxygen to the hydrogen fuel cell 5. The air inlet of the air compressor 4 faces the front of the aircraft, and the air outlet of the air compressor 4 is connected to the oxygen inlet of the hydrogen fuel cell 5.

[0044] For further details, please refer to Figures 5 to 8An adjusting duct 10 is coaxially provided at the lower end of the exhaust duct 7. A slide rod 11 is coaxially fixedly connected inside the adjusting duct 10. An electromagnet 12 is coaxially slidably connected to the slide rod 11. A strong magnet is coaxially fixedly connected to the lower end of the slide rod 11. The strong magnet is used to generate magnetic force between itself and the electromagnet 12. A groove 1101 is provided on the outer wall of the slide rod 11. The extension direction of the groove 1101 is coaxial with the slide rod 11. A guide pin 16 is provided on the electromagnet 12. The guide pin 16 is slidably connected inside the groove 1101. The lower end of the slide rod 11 is hinged to multiple first connecting rods 13, and the outer wall of the electromagnet 12 is hinged to multiple second connecting rods 14. The upper end of the first connecting rod 13 is hinged to the middle of the second connecting rod 14. Canvas 15 is provided on the outer wall of the multiple second connecting rods 14, and a counterweight bar 19 is provided on the inner side of the canvas 15. The counterweight bar 19 is located between two second connecting rods 14, and the two second connecting rods 14 are symmetrical about the counterweight bar 19. When the electromagnet 12 is at the top dead center, the canvas 15 retracts to a cone shape with the small end on the upper side. The lower end of the slide rod 11 is located inside the adjusting duct 10. The lower end of 10 extends to the outside of the aircraft body 1. The regulating duct 10 extends to the outer side wall of the aircraft and has multiple exhaust ports 1001 evenly distributed around its circumference. The multiple exhaust ports 1001 are horizontally arranged. When the electromagnet 12 is at the lower dead point, the canvas 15 is opened to fit against the inner wall of the regulating duct 10, and the lower end of the canvas 15 is located between the upper and lower ends of the exhaust ports 1001. The lower end of the second connecting rod 14 is provided with a first magnet 17. Multiple second magnets 18 are provided on the side wall of the regulating duct 10. When the electromagnet 12 is at the lower dead point, the first magnet 17 and the second magnet 18 are in contact.

[0045] It should also be noted that the aircraft body 1 is equipped with a central controller, which is used to control the rotation speed of multiple drive motors of the aircraft body 1, the magnetic force of electromagnet 12, the rotation speed of brushless motor 8 and the output power of hydrogen fuel cell 5; when electromagnet 12 is at the top dead center, there is mutual repulsion between electromagnet 12 and strong magnet.

[0046] Working principle: Please refer to Figures 1 to 8 During aircraft startup and flight, the brushless motor 8 drives the exhaust fan blades 9 to rotate at high speed within the exhaust duct 7. The strong negative pressure generated by the rotation of the exhaust fan blades 9 forces cool outside air into the interior of the fairing 6 through the upper opening. After entering the fairing 6, the airflow is separated by multiple rectifier grilles 602 and guided into parallel rectifier channels 603, flowing evenly along the axial path across the peripheral surface of the hydrogen fuel cell 5. During this process, the cooling airflow carries away the waste heat generated by the hydrogen fuel cell 5 through forced convection. Subsequently, the heat-absorbing airflow converges into the lower exhaust duct 7 and, under the action of the exhaust fan blades 9, is discharged at high speed downwards from the aircraft, providing upward lift for the aircraft while simultaneously completing the heat dissipation cycle of the fuel cell stack.

[0047] When the aircraft is in a propulsion mode requiring maximum thrust, such as level flight or takeoff, the central controller drives the electromagnet 12 to slide upwards to its top dead center. At this time, the electromagnet 12, through the linkage of the second link 14 and the first link 13, drives the canvas 15 to synchronously retract towards the central slide bar 11. The canvas 15 ultimately forms a streamlined conical structure with its tip pointing upwards, tightly adhering to the slide bar 11. The high-speed driving air discharged from the exhaust duct 7 is smoothly sprayed downwards along this conical surface, minimizing airflow resistance and turbulence losses, ensuring the aircraft achieves optimal propulsion efficiency. At this time, the precisely preset gap 901 maintained between the blade tip of the exhaust fan 9 and the inner wall of the duct effectively prevents airflow backflow, enhances negative pressure suction, and maintains a highly efficient cooling effect.

[0048] When the aircraft is in a zero-thrust cooling mode, such as ground standby, system self-check, or post-landing cooling, the central controller drives the electromagnet 12 to slide downwards along the slide bar 11 to the lower stop. The electromagnet 12, through the umbrella-shaped linkage mechanism composed of the first link 13 and the second link 14, spreads the canvas 15 outwards until the outer side of the canvas 15 is completely in contact with the inner wall of the regulating duct 10. At this time, the canvas 15 forms a guide plane with a closed vertical exhaust path at the bottom of the duct. The originally vertically downward driving airflow is intercepted by the canvas 15, and the momentum direction is forcibly reversed, becoming a horizontally overflowing diffuser. The airflow is finally discharged from the aircraft through multiple horizontal exhaust ports 1001 on the outer wall of the regulating duct 10. In this mode, the brushless motor 8 can maintain high speed operation to provide high-intensity cooling negative pressure, and because the vertical thrust is physically canceled out, the aircraft can remain stably on the ground, achieving physical decoupling of propulsion power consumption and cooling power consumption.

[0049] When the adjustment mechanism reaches its lower limit, the first magnet 17 at the end of the second connecting rod 14 automatically engages with the second magnet 18 on the side wall of the adjustment duct 10. The magnetic attraction force firmly locks the canvas 15 in the unfolded position, effectively counteracting the impact load generated by the high-speed airflow on the canvas 15, preventing mechanism flutter, and allowing the electromagnet 12 to reduce its holding current to save energy. The counterweight 19, located between the two second connecting rods 14 on the inner side of the canvas 15, guides the canvas 15 to remain flat during extension and retraction through its own inertia, suppressing the shaking and slapping of the flexible fabric in the pulsating airflow. When switching back to the propulsion mode, the central controller drives the electromagnet 12 to move in the opposite direction, overcoming the magnetic attraction force and causing the connecting rod mechanism to retract. The counterweight 19 then assists the canvas 15 to quickly adhere to the side of the slide rod 11, completing the mechanism's closure.

[0050] The specific embodiment of the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the embodiments described above. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and ideas of the present invention should still fall within the protection scope of the present invention.

Claims

1. A battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft, characterized in that, The system includes a hydrogen fuel cell (5) and a fairing (6). The fairing (6) is located on the upper inner side of the aircraft body (1). The upper end of the fairing (6) is open. The lower end of the fairing (6) is provided with at least two exhaust ducts (7). The lower end of the exhaust ducts (7) penetrates the lower end of the aircraft body (1). The hydrogen fuel cell (5) is fixedly connected inside the fairing (6). The fairing (6) is provided with a heat dissipation channel (601). The heat dissipation channel (601) connects the upper end of the fairing (6) with the exhaust ducts (7). The heat dissipation channel (601) is used to guide airflow through the hydrogen fuel cell (5). A brushless motor (8) is coaxially connected inside the exhaust duct (7). The lower end of the brushless motor (8) is coaxially fixedly connected with an exhaust fan blade (9). When the exhaust fan blade (9) rotates, it generates downward driving wind.

2. The battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft according to claim 1, characterized in that, The lower end of the exhaust duct (7) is coaxially provided with an adjustment duct (10). A slide rod (11) is coaxially fixedly connected inside the adjustment duct (10). An electromagnet (12) is coaxially slidably connected to the slide rod (11). Multiple first connecting rods (13) are hinged to the lower end of the slide rod (11). Multiple second connecting rods (14) are hinged to the outer wall of the electromagnet (12). The upper end of the first connecting rod (13) is hinged to the middle of the second connecting rod (14). Canvas (15) is provided on the outer wall of the multiple second connecting rods (14). When the electromagnet (12) is at the upper dead point, the canvas (15) is retracted to a cone shape with the small end on the upper side.

3. The battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft according to claim 2, characterized in that, The lower end of the slide bar (11) is located inside the regulating duct (10). The lower end of the regulating duct (10) extends to the outside of the aircraft body (1). Multiple exhaust ports (1001) are evenly distributed on the outer side wall of the regulating duct (10) extending to the outside of the aircraft. The multiple exhaust ports (1001) are horizontally arranged. When the electromagnet (12) is at the lower dead point, the canvas (15) is opened to fit against the inner wall of the regulating duct (10), and the lower end of the canvas (15) is located between the upper and lower ends of the exhaust ports (1001).

4. The battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft according to claim 2, characterized in that, A groove (1101) is provided on the outer wall of the slide rod (11). The extension direction of the groove (1101) is coaxial with that of the slide rod (11). A guide pin (16) is provided on the electromagnet (12). The guide pin (16) is slidably connected in the groove (1101).

5. The battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft according to claim 1, characterized in that, The inner wall of the fairing (6) is provided with multiple rectifier grids (602), the outer wall of the hydrogen fuel cell (5) is attached to the multiple rectifier grids (602), and a rectifier channel (603) is formed between the hydrogen fuel cell (5) and the rectifier grids (602).

6. The battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft according to claim 3, characterized in that, The lower end of the second connecting rod (14) is provided with a first magnet (17), and the side wall of the regulating duct (10) is provided with multiple second magnets (18). When the electromagnet (12) is at the lower dead point, the first magnet (17) and the second magnet (18) are in contact.

7. The battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft according to claim 3, characterized in that, The inner side of the canvas (15) is provided with a counterweight strip (19), which is located between two No. 2 connecting rods (14) and the two No. 2 connecting rods (14) are symmetrical about the counterweight strip (19).

8. The battery cooling system for a hydrogen fuel cell-based ducted fan propulsion aircraft according to claim 1, characterized in that, The maximum slewing diameter of the exhaust fan blade (9) and the inner wall of the exhaust duct (7) are maintained at a preset gap (901), the preset gap (901) being in the range of 0.5mm to 1.5mm.

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