Rapid fuel draining device for aerial, space, land, naval or underwater vehicles, using cryogenic or gaseous fuel.

Abstract

The present invention relates to a device for the rapid emptying of cryogenic or gaseous fuel, whether these fuels are stored in liquid form, gaseous form, or as a liquid-gaseous mixture, for aircraft, spacecraft, land-based vehicles, naval vessels, or submarines, whether these vehicles are in motion or stationary. This system, specifically designed for aircraft using hydrogen but generalizable to other means of transport and other fuels, allows for the rapid and safe evacuation of all or part of the fuel stored in the aircraft, while attempting to counteract the thrust and drag generated by the purging operation, the ejection, and potentially the combustion of the fuel. Figure for the abstract: [Fig 3]

Description

Title of the invention: Rapid fuel draining device for aerial, space, land, naval or underwater vehicles, using cryogenic or gaseous fuel.

[0001] In the context of the search for a decarbonized transport industry, numerous projects using cryogenic or gaseous fuels are being studied. These fuels can be stored in liquid, gaseous, or liquid-gaseous form. When stored in gaseous form, these fuels require high-pressure tanks. When stored in liquid form, these fuels require the use of cryogenic technologies. The dangers of cryogenics are primarily caused by the large quantity of fluid in a liquid state at very low temperatures, which, once heated, can gasify and occupy a much larger volume, potentially producing a pressure increase leading to an explosion of the installation. This sequence can be particularly rapid, for example, in the case of accidental heat ingress.

[0002] Dihydrogen is certainly the most ambitious cryogenic or gaseous fuel design and undoubtedly has the greatest potential future. Therefore, we will use it as an example for the remainder of the description of the invention. Similarly, aeronautics certainly represents the most complex application. The first stage of hydrogen development will clearly consist of using hydrogen as a fuel for conventional propulsion systems. The second phase involves combining hydrogen with fuel cell technologies.

[0003] The hazards associated with hydrogen result primarily from:

[0004] - Risks of leaks arising from the small size of the hydrogen molecule.

[0005] - Risks of flammability caused by the small amount of energy required to set it on fire.

[0006] - Risks of explosions associated with its high instability.

[0007] Ultimately, the presence of such a quantity of dihydrogen on board an aircraft, whether in gaseous or liquid form, represents a significant increase in the severity of any malfunction, even if this malfunction is not necessarily caused by the hydrogen itself, or by its storage or distribution system. Therefore, it is essential to incorporate into this type of aircraft a mechanism for the rapid draining or purging of all or part of the hydrogen stored within it. This increased danger is particularly evident in the case of an aircraft that must enter the critical landing phase in the event of a failure. technical.

[0008] The purging process will take a different form depending on whether the vehicle is moving or stationary, or whether it is operating in air or water. Draining the hydrogen storage tank, even though the rapid combustion of a large quantity of hydrogen can generate some NOx, has the advantage of being relatively neutral from an environmental point of view, unlike, for example, the in-flight fuel dumping of an aircraft.

[0009] The present invention therefore relates to a device for the rapid emptying of all or part of the hydrogen, or another cryogenic or gaseous fuel, from aircraft, spacecraft, land vehicles, naval vessels, or submarines. The device comprises a rapid-release valve or rupture disc, allowing the supply of a rigid or flexible pipe, itself connected to a specific fixed or deployable nozzle. "Rapid" here refers to a system capable of emptying a hydrogen tank in a few minutes. This concept is therefore unrelated to venting mechanisms, the purpose of which is to evacuate evaporated hydrogen gases in order to regulate the pressure rise in the tank. The rapid-release device will be supplied with hydrogen either by gravity, by overpressure in the hydrogen tank, or via a pump or compressor system.

[0010] The specific nozzle has several functions, for example:

[0011] - Ensure the ejection of hydrogen from the device and dilute it in the medium by swirling, air or water.

[0012] - Initiate the combustion of hydrogen in the air, if the craft is moving in the atmosphere.

[0013] - Generate a drag that compensates for all or part of the thrust generated by the ejection and the possible combustion of hydrogen.

[0014] - To protect the device from fire or heat generated by combustion hydrogen.

[0015] - Stretch the drain line and move the purge area away from the apparatus structures.

[0016] As shown in [Fig. 1], this specific rapid drain nozzle is composed the following elements:

[0017] - A central channel (1) into which hydrogen is ejected and which may include a premixing part in the form of for example light (3) air supply and an ignition system (4).

[0018] - An external funnel (2) centered and fixed on the central channel (1), capable of channeling an airflow joining the hydrogen jet and serving both to supply oxygen to the hydrogen combustion, to carry the hydrogen away from the aircraft by viscosity and to create around the hydrogen jet and the combustion a protective sheath in the form of a flow of fresh air and dilution of the temperature.

[0019] The initiation of a rapid draining sequence may include a system that initiates inerting of the drain line before the valve or purge disc is opened. Similarly, at the end of the hydrogen draining sequence, another inerting sequence may safely complete the operation.

[0020] When hydrogen burns in air, the phenomenon is complex and rapid. In the case of a free-jet flame, above a certain jet velocity, the flame is most often of the "lifted flame" type. This type of detached flame generally comprises three zones of longitudinal development. First, an extinction zone induced by the steep velocity gradient and the excessively high fuel concentration. This is followed by a combustion development phase, which occurs particularly at the outer surface of the fuel jet at the confluence of the two streams of oxygen and fuel. Finally, there is a dilution zone, where the jet slows down and combustion is extinguished due to a lack of fuel.

[0021] In this configuration, depending on the speed of the primary hydrogen jet and that of the secondary air flow generated via the external funnel (2) by the device's speed, temporary or permanent accidental combustion extinctions are possible. In some cases, an alternating, pulsating, and potentially explosive flow pattern may develop. To counter this situation, the central channel may be equipped with a premixing system, for example in the form of a light (3), allowing the air to mix with the hydrogen before exiting the central channel (1), and an ignition device (4) to ensure the initiation of combustion and / or its reignition in the event of extinction.

[0022] However, depending on flight conditions (altitude, speed, temperature, aircraft attitude, weather, environment, etc.), the choice between initiating combustion of the hydrogen / air mixture or opting for a non-combustion fuel drain with hydrogen dilution in the air may differ. Indeed, the high diffusion rate of gaseous hydrogen in the air and its rapid dilution in the atmosphere constitutes a safety advantage, without necessarily requiring combustion initiation. When fuel diffusion in the air is insufficient for rapid dilution or stabilized combustion, the present invention may be supplemented by mixer-type systems positioned at the end of the central channel and characterized by alternating internal and external undulations distributed around its circumference.

[0023] For example, in the context of an aircraft, when the rapid drainage device is deployed, the central channel and the outer funnel can retract to move away from the aircraft structure and out of the aircraft's boundary layer, while the outer funnel opens to assume its final position, as illustrated in [Fig. 2]. The shape of the funnel may, depending on the circumstances, resemble a cone, a The funnel is a hemisphere or a parabolic shape, streamlined and truncated at the top. Its degree of opening can be fixed or variable depending on the aircraft's configuration. The part can be made of a rigid material, metallic or composite, or of a flexible material, elastomer or textile. The role of the external funnel is multifaceted, depending on the purge configuration.

[0024] In flight or when the aircraft is in motion, the outer funnel channels a flow of fresh air onto the outer ejection zone of the central channel. It generates a kind of fresh air duct that encloses and carries the flow of hydrogen, which contains the combustion as it occurs, and then dilutes the hydrogen or its combustion product, in order to quickly restore safe conditions. It also creates a drag force that more or less counteracts the thrust force caused by the ejection of hydrogen through the central channel, with or without combustion. This drag force also helps to maintain the device in its rearward position. Furthermore, the outer surface at the rear of the funnel acts as a thermal shield, protecting the aircraft's airframe from thermal loads and potential flashbacks related to instabilities or detonation phenomena.If the specific rapid drainage nozzle is supplied by all or part of a flexible hose, the external funnel also acts as a stabilizer for the device, for example via a fin system.

[0025] On the ground and stationary, two scenarios may occur during a hydrogen purge of an aircraft:

[0026] - Either the aircraft parking area is equipped with specific infrastructure that allows for draining and / or recovering the dihydrogen. In this case, the present device provides a specific connection system to this infrastructure and the principle of the specific draining nozzle is rendered inoperative.

[0027] - Either the aircraft parking area is not equipped with this specific infrastructure. In In this case, purging will be carried out via the specific rapid drain nozzle. If the aircraft is not moving, there will be no airflow in the external funnel. To provide the protective and sheathing effect that fresh air would have when the aircraft was moving, the device can be connected to a fire hydrant and spray, via a circular nozzle (5) located on the rear of the external funnel (2), a protective sheath in the form of a water film surrounding the hydrogen jet. This water jet also helps to visualize the hydrogen jet and its often barely visible combustion, to protect the aircraft structures from heat in the event of combustion and flashback, and to keep the area of ​​hydrogen dilution or combustion away from the aircraft.Another option for purging on the ground or at low speed is to integrate into the external funnel a fan-type fan (6), which will be able to generate an airflow similar to that naturally present when the aircraft is in motion. This fan can be driven by an electric motor.

[0028] As mentioned above, [Fig. 3] shows a rapid purge device which may include a supply line in the form of a flexible hose. This flexible hose device (7) may be unrollable, rerollable, or even jettisonable. The advantage of combining the flexible hose with a rigid pole (8) is that it allows the specific nozzle to move slightly to the right without the device falling downwards when the rapid purge is performed on the ground while stationary. For in-flight purges, the hose (pole + flexible section) can be fully unrolled and hang behind the aircraft, thus ensuring a greater distance from the purge area. To relieve tension in the flexible hose, a controllable cable system (9) can maintain the specific rapid purge nozzle in position and under tension.

[0029] In aircraft, purge devices can be located, depending on the position of the hydrogen tanks and the technologies used, directly on the wings, on external auxiliary tanks (cans), at the rear of the engines, on a pod (engine + tank assembly), at the rear or underneath the aircraft. These devices can be fixed or deployable, reusable or disposable, depending on their position and technology.

[0030] Naturally, for viability and to ensure the continuity of flight of the aircraft, the device can be coupled with a technology of the type of safe hydrogen reserve, pre-filled or associated with a transfer and filling system from the main tank(s).

[0031] By extending the principles stated above for aircraft, and depending on the environment surrounding the installations, this rapid emptying device can be adapted to all vehicles—airborne, spaceborne, land-based, naval, or underwater—using hydrogen as fuel. For land vehicles or boats, part of the piping supplying the specific nozzle can be directed upwards, thus limiting the risks of fire, burns, and / or explosions upon contact with other equipment or infrastructure. For naval or underwater vehicles, emptying, following the same principles, can be carried out directly in the water.

[0032] Similarly, by analogy, the descriptions developed above in the context of di-hydrogen can be extended to all cryogenic or gaseous fuels.

Claims

Demands

1. Rapid discharge device for cryogenic or gaseous fuel, characterized in that it is equipped with a rapid valve or rupture disc, allowing to supply a rigid or flexible pipe, itself connected to a specific nozzle composed of a central channel (1) in which the cryogenic or gaseous fuel flows and an external funnel (2) centered and fixed on the central channel (1), and capable of channeling a secondary flow towards the fuel to carry it and dilute it in the surrounding environment.

2. Device according to claim 1, characterized in that the specific discharge nozzle is fixed or deployable, enabling the generation of drag which compensates for all or part of the thrust generated by the ejection and possible combustion of the fuel and the tensioning of the discharge line to move the purge zone away from the structures of the device.

3. Device according to claims 1 and / or 2, characterized in that the central channel (1) has a pre-mixing zone in the form of feed lights (3), allowing air to mix with cryogenic or gaseous fuel before exiting the central channel (1).

4. Device according to one or more of claims 1 to 3, characterized in that the central channel (1) includes an ignition system (4) capable of initiating the combustion of cryogenic or gaseous fuel in air.

5. Device according to one or more of claims 1 to 4, characterized in that the central channel (1) has at its end a mixer materialized by the alternation of internal and external undulations distributed over the circumference.

6. Device according to one or more of claims 1 to 5, characterized in that the device provides a specific system for connecting to an external fuel recovery infrastructure and rendering the specific drain nozzle inoperative.

7. Device according to one or more of claims 1 to 6, characterized in that the device can be connected to a fire hydrant and spray water through nozzles (5).

8. Device according to one or more of claims 1 to 7, characterized in that the outer funnel includes a fan (6) capable of generating an airflow even when the machine supporting the device is stopped.

9. Device according to one or more of claims 1 to 8, characterized in that the device comprises a flexible piping portion (7).

10. Device according to claim 9, characterized in that the device is unrollable and rerollable.

11. Device according to one or more of claims 1 to 10, characterized in that the device comprises a rigid pole (8).

12. Device according to one or more of claims 9 to 11, characterized in that the device includes a load-bearing cable (9) to relieve tension in the flexible hose.

13. Device according to one or more of claims 1 to 12, characterized in that all or part of the device is jettisonable.

14. Device according to one or more of claims 1 to 13, characterized in that the emptying sequence is preceded and / or followed by a device inerting sequence.

15. Device according to one or more of claims 1 to 14, characterized in that said rapid drainage devices are used in the context of aerial, space, land, naval or underwater vehicles.

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