Inert gas distribution system, aircraft fuel tank inerting system and inert gas flow method

Abstract

The present invention relates to an inert gas distribution system for a fuel tank. The fuel tank includes fuel and a gaseous space. The inert gas distribution system includes: a gas inlet port for introducing inert gas; a gas branch line that is fluidically connected to the gas inlet port and can be arranged within the fuel tank; the gas branch line includes a plurality of exhaust holes distributed along its length, at least one of the plurality of exhaust holes being submersible into the fuel within the fuel tank. Thus, as the fuel liquid level decreases, at least one exhaust hole is exposed to the gaseous space, allowing inert gas to flow therein, thereby regulating the flow rate of the inert gas distributed to the fuel tank. Thus, a simple structure can be used to resolve the mismatch between the inert gas flow distribution within the fuel tank and the volume of the gaseous space within the fuel tank, rapidly reducing the flammability of the fuel tank. The present invention also relates to an aircraft fuel tank inerting system and a method for regulating the flow rate of inert gas within the fuel tank.

Description

Technical Field

[0001] The present invention relates to an inert gas distribution system for a fuel tank, in particular an aircraft fuel tank. The present invention also relates to an aircraft fuel tank inerting system comprising such an inert gas distribution system. Furthermore, the present invention relates to a method for regulating the flow of inert gas in a fuel tank. Background Art

[0002] Currently, some aircraft, such as advanced wide-body aircraft, utilize composite fuel tanks to save structural weight. For example, the total fuel tank volume of the wide-body B787 is approximately six times that of the narrow-body B737. Because composite materials have significantly lower thermal conductivity than aluminum alloys, this results in insufficient heat dissipation from the tanks. Therefore, the aircraft's wings, such as the outer and center wings, must be inerted to meet the flammability requirements of the Transport Category Airplane Airworthiness Standards.

[0003] Aircraft-mounted nitrogen generation systems are widely used in aviation technology to inert aircraft, reducing the oxygen concentration within the aircraft to prevent combustion and explosion of combustible materials and oxygen. Many aircraft, including Airbus and Boeing, are equipped with inerting systems that produce gas with a high nitrogen content and inject it into the aircraft as an inert gas to protect aircraft systems and equipment from fire and explosion. Generally, the larger the vapor volume of a fuel tank, the greater the required inert gas flow rate. If the inerting gas flow rate could be adjusted based on the vapor volume (or fuel level) of each tank, the efficiency of the inerting system would be greatly improved, thereby reducing the oxygen concentration in the tank to below a safe level more quickly.

[0004] To this end, especially since the inerting volume of wide-body aircraft inerting systems is approximately 10 times greater than that of narrow-body aircraft, an inert gas distribution system is required. Its purpose is to quickly and evenly distribute the inert gas between the various compartments of the fuel tanks, ensuring that all tanks reach and maintain an inerted state as quickly as possible. However, due to the irregularity of the fuel tanks and the different fuel level change strategies of each tank, especially the larger fuel tanks of wide-body aircraft, uniform distribution of inert gas within the tanks is difficult to achieve.

[0005] It is known to use electronically controlled shut-off valves and exhaust lines within a fuel tank to distribute inert gas. However, given the complexity and variability of inert gas control, instead of providing a flow control valve within the fuel tank, an ejector pump is installed to enhance gas circulation, particularly in the most remote corners of the tank, thereby improving the uniform distribution of the inert gas.

[0006] In addition, it is known to use a buoyancy actuation device to change the gas flow in the oil tank, but this method requires a float actuation mechanism, which has a complex structure and can only change the gas flow within the range from the float contacting the oil surface to the float leaving the oil surface, so the adjustment range is very limited.

[0007] In addition, it is also known to provide a mechanical structure in the oil tank, and to change the gas flow area by providing a flow port on the rotating part of the mechanical structure to achieve the purpose of changing the flow rate. However, the mechanical structure needs to receive a signal to electrically control the aperture of the flow-limiting hole to change the gas flow rate. The control design is complex and the reliability is not high in the event of a fault.

[0008] Therefore, there is always a need for an inert gas distribution system and method with simple structure, convenient control and high reliability in the inerting system. Summary of the Invention

[0009] The present invention relates to an inert gas distribution system for a fuel tank, wherein the fuel tank includes fuel and a gas phase space. The inert gas distribution system may include: a gas introduction port for introducing inert gas; a gas branch pipeline, which can be fluidically connected to the gas introduction port and can be arranged in the fuel tank; wherein the gas branch pipeline may include a plurality of exhaust holes distributed along its length, at least one of the plurality of exhaust holes can be immersed in the fuel in the fuel tank, so that as the fuel liquid level decreases, at least one exhaust hole can be exposed to the gas phase space to allow the inert gas to flow into it, thereby regulating the flow rate of the inert gas distributed to the fuel tank.

[0010] With the help of the inert gas distribution system of the present invention, the mismatch problem between the inert gas flow distribution in the fuel tank and the gas phase space volume of the fuel tank can be solved with a simple structure, the harsh working conditions during the fuel tank descent phase can be coped with, and the flammability of the fuel tank can be quickly reduced.

[0011] More specifically, as the fuel level drops, exhaust holes exposed to the gas phase space are added to the gas branch line to achieve the effect that the amount of discharged inert gas changes positively in real time with the gas phase space in the fuel tank. That is, the exhaust volume is automatically adjusted according to the size of the gas phase space of each fuel tank or fuel tank, thereby better inerting the fuel tank, especially the lower gas phase space closer to the fuel level, because the fuel vapor concentration here is the highest.

[0012] Preferably, the gas branch line may include a vertical portion extending in a direction substantially perpendicular to the fuel liquid level, and the at least one exhaust hole may be provided in the vertical portion.

[0013] By arranging the vent holes in the vertical section of the gas branch line, the fuel level can be more quickly responded to, and the amount of inert gas discharged can be automatically adjusted more quickly. In addition, the vertical arrangement of the gas branch line can also shorten its required overall length.

[0014] Advantageously, the inert gas distribution system may further include a gas distribution main pipe and a plurality of gas branch pipelines. The gas distribution main pipe may be in communication with the gas introduction port, and the plurality of gas branch pipelines may extend from the gas distribution main pipe.

[0015] The gas distribution manifold makes it easier to evenly distribute inert gas to each gas branch line. Furthermore, the gas distribution manifold can allow for more gas branch lines to be distributed across the width or length of the tank, for example, serving as a supporting beam for the gas branch lines.

[0016] In particular, the gas branch line may extend vertically downward from the gas distribution main pipe, and at least some of the plurality of gas exhaust holes may be immersed in the fuel in the fuel tank.

[0017] The branch gas lines extend vertically downward from the gas distribution manifold, allowing for automatic adjustment of the exhaust volume based on the fuel level with a simple structure. In particular, if multiple exhaust holes can be submerged in the fuel, the range of adjustable exhaust volume is wider as the fuel level drops, allowing for greater adaptability to the volume of the gas phase space.

[0018] Preferably, the multiple exhaust holes on the same gas branch pipeline can be distributed at different angles along the circumference of the gas branch pipeline.

[0019] Through reasonable circumferential distribution, the inert gas, such as nitrogen-rich gas, can be varied according to the volume of the fuel tank and the height of the fuel liquid level to ensure uniform distribution in space. For example, the problem of airflow unevenness caused by a single jet or the same circumferential angle can be avoided or alleviated.

[0020] In particular, the multiple exhaust holes on the same gas branch pipeline may have different apertures.

[0021] By flexibly setting different apertures, it is possible to effectively cope with situations such as different rates of liquid level drop at different fuel level heights caused by the irregular shape of the fuel tank itself, and different sizes of the gas phase space in different areas of the fuel tank.

[0022] In some embodiments, the exhaust holes can be designed to have a smaller diameter in areas with smaller gas phase spaces. This smaller diameter allows the inert gas to be ejected over a greater distance while maintaining the same inert gas flow rate within the gas branch lines, thereby compensating for the inability to distribute more gas branch lines due to the smaller gas phase spaces.

[0023] Advantageously, a device to be cooled may be arranged in the oil tank, and the gas branch line may be positioned relative to the device to be cooled so that the inert gas flow flowing out of its exhaust hole can blow-cool the device to be cooled.

[0024] This makes it possible to provide additional or alternative cooling of devices to be cooled, such as a fuel pump, in order to reduce safety hazards caused by overheating of these devices.

[0025] The present invention also relates to an aircraft fuel tank inerting system, which may include the aforementioned inert gas distribution system.

[0026] The present invention also relates to a method for regulating the flow rate of inert gas in a fuel tank, the method comprising: introducing inert gas through a gas introduction port; fluidly connecting a gas branch line located in the fuel tank to the gas introduction port so that the inert gas can flow out through a plurality of exhaust holes distributed along the length of the gas branch line; immersing at least one of the plurality of exhaust holes in the fuel in the fuel tank, and exposing at least one exhaust hole to the gas phase space of the fuel tank as the fuel liquid level decreases, thereby regulating the flow rate of the inert gas distributed to the fuel tank.

[0027] With the help of the method of the present invention, it is possible to achieve the effect of automatically adjusting the inert gas flow rate according to the liquid level in a fuel tank or liquid hydrogen tank (for example, an aircraft), and as the fuel liquid level in the tank or fuel tank decreases, the exhaust volume gradually increases, that is, the exhaust flow rate is automatically adjusted dynamically according to the size of the gas phase space, the response time is short, and the inerting efficiency is improved, that is, the time it takes for the tank to enter the inerting state is reduced, thereby improving the safety of the tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure schematically shows a principle diagram of an inert gas distribution system according to one embodiment of the present invention.

[0029] List of reference numerals:

[0030] 100 Inert gas distribution system;

[0031] 110 gas introduction port;

[0032] 120 gas distribution main;

[0033] 130 gas branch pipeline;

[0034] 132 vent;

[0035] 140 one-way valve;

[0036] 200 fuel tanks;

[0037] 210 fuel level;

[0038] 220 bottom (of the fuel tank);

[0039] 230 oil string hole;

[0040] 300 fuel pump. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to specific embodiments and drawings, but this should not limit the scope of protection of the present invention. Figure 1 The reference numerals shown in the figure do not imply that these features must be the same as Figure 1 The features shown in are the same.

[0042] The present invention primarily relates to inerting systems for aircraft, particularly wide-body civilian aircraft. Aircraft inerting systems are used to fill fuel tanks with nitrogen to reduce the oxygen content in the fuel tank's vapor space, thereby preventing combustion or explosion. While the present invention primarily addresses the problem of simply, evenly, and efficiently distributing inert gas to the vapor space within aircraft fuel tanks, the inert gas distribution system for fuel tanks and the method for regulating the flow of inert gas within the tanks are clearly not limited to the aerospace field. For example, they can also be used in vessels, vehicles, operating machinery, and other applications where convenient, reliable, and even gas distribution is required.

[0043] The inert gas distribution system for a fuel tank of the present invention can be used as part of an aircraft inerting system to uniformly and efficiently distribute inert gas during the inerting of an aircraft fuel tank. However, it will be appreciated that the inert gas distribution system of the present invention can also be provided independently of the aircraft inerting system, for example, provided or sold separately.

[0044] In the present invention, an inert gas may be, for example, nitrogen-rich gas. The term "nitrogen-rich gas" refers to a gas with a high nitrogen content, a type of inert gas, including but not limited to nitrogen. In the present invention, whether referring to an inert gas or specifically nitrogen-rich gas or nitrogen, it generally refers to chemically inert gases that can be used to prevent fires, explosions, and other conditions. Furthermore, in the present invention, the term "fuel tank" includes not only fuel tanks but also liquid hydrogen and liquid oxygen tanks, meaning that the specific energy source is not limited.

[0045] For example, current civilian airliners commonly use onboard inerting systems to produce nitrogen for aircraft protection. Inerting systems utilize air separation membranes to separate oxygen and nitrogen from the air. Due to the different permeability coefficients of the membranes for oxygen and nitrogen, more oxygen passes through the membranes, resulting in nitrogen-rich gas with a higher nitrogen concentration. When the nitrogen-rich gas is introduced into aircraft spaces, such as fuel tanks, it dilutes the oxygen concentration in the air or other liquids through diffusion or displacement. Once the oxygen concentration in the aircraft space is reduced to a certain level, combustion or explosion of combustible materials and oxygen within the space becomes impossible, thereby ensuring the safety of the aircraft and the aircraft.

[0046] In the present invention, the term "fuel tank" refers to a container for holding fuel, but its shape and form are not limited, for example, it is not limited to a box, a can, a bladder, etc. For example, the fuel tank may also refer to a large fuel tank on an aircraft, such as a center wing fuel tank, which includes multiple compartments.

[0047] In the present invention, the term "pipeline" refers to various tubular flow paths that contain fluids. Its cross-sectional shape is not limited, and its physical parameters, such as flow resistance, diameter, etc. are not limited, as long as it can achieve the specified function (for example, fluid transfer).

[0048] Furthermore, in the present invention, the term "pore" refers to an opening, and its shape and size are not limited unless a numerical range of a pore diameter or a shape of a pore is specifically indicated.

[0049] First, the present invention relates to an inert gas distribution system 100 for a fuel tank, which is used to distribute inert gas, such as nitrogen-enriched gas, into a fuel tank 200. The fuel tank 200 may be, but is not limited to, a fuel tank 200 on an aircraft. The fuel tank 200 may be a single fuel tank 200 or a fuel tank, or may be a plurality of interconnected fuel tanks 200 or fuel compartments. The fuel tank 200 of the present invention is used to hold fuel and comprises fuel and a gaseous phase. The gaseous phase refers to the space in the fuel tank 200 not covered by fuel, such as the area above the fuel liquid level 210.

[0050] The inert gas distribution system 100 includes a gas inlet port 110 through which inert gas can be introduced. There is preferably one gas inlet port 110, but this is not limited thereto. In some embodiments, the gas inlet port 110 can be located outside the fuel tank 200. The structure in which the inert gas flows into the gas inlet port 110 can be a pipeline or a device (e.g., an inert gas container, an inert gas generator, etc.), which will not be described in detail here.

[0051] The inert gas distribution system 100 includes a gas branch line 130. Although the term "branch" is used, the present invention may include only one gas branch line 130, but preferably includes multiple gas branch lines 130. The gas branch line 130 is disposed within the fuel tank 200. The gas branch line 130 can be in fluid communication with the gas introduction port 110, so that the inert gas can flow into and into the gas branch line 130 via the gas introduction port 110.

[0052] The gas branch line 130 comprises a length, along which a plurality of exhaust holes 132 are distributed. The gas branch line 130 of the present invention can extend in a straight line, but it can also extend in a non-straight manner, for example, including bends or curves. When the gas branch line 130 does not extend in a completely straight line, the plurality of exhaust holes 132 can be arranged at any suitable location on the gas branch line 130, such as on a bend or a straight portion.

[0053] According to the present invention, inert gas can flow out of the gas branch line 130 through the multiple vent holes 132 of the gas branch line 130, for example, into the gas phase of the fuel tank 200. At least one of the multiple vent holes 132 can be submerged in the fuel in the fuel tank 200, that is, located below the fuel liquid level 210. Here, the term "submerged" means that the at least one vent hole 132 will be submerged in the fuel when fuel is present in the fuel tank 200. It does not mean that the at least one vent hole 132 must always be submerged in the fuel, but rather that it can be submerged in the fuel at some point. Furthermore, the term "submerged in the fuel" means that the at least one vent hole 132 is covered by the fuel and does not touch the gas phase within the fuel tank 200.

[0054] To automatically adjust the flow rate of inert gas, such as nitrogen-rich gas, the at least one vent hole 132 of the gas branch line 130 of the present invention, and preferably at least some of the vent holes 132 in the gas branch line 130, can be exposed to the gas phase as the fuel level 210 decreases, allowing inert gas to flow into the gas phase through the at least one vent hole 132. The decrease in the fuel level 210 can be due to a decrease in fuel volume caused by continuous fuel consumption, but it can also be due to a change in the position of the fuel tank 200, such as aircraft turbulence or a certain aircraft attitude. In the present invention, the at least one vent hole 132 can be submerged in fuel again when the fuel level 210 rises again, such as due to refueling of the fuel tank 200 or a new change in the position of the fuel tank 200, such as aircraft turbulence or a return to a previous certain aircraft attitude.

[0055] When at least one vent hole 132, and preferably several vent holes 132, are submerged in the fuel, inert gas remains within the gas branch line 130. However, since at least one vent hole 132 is covered by the fuel, the inert gas cannot flow into the gas phase. To reduce the possibility of bubble formation, the flow rate of inert gas flowing into the gas branch line 130 must be kept low. The diameter of the vent holes 132 will be further explained below.

[0056] The present invention may also relate to a method for regulating the flow of inert gas within a fuel tank 200. The method includes introducing an inert gas through a gas introduction port 110. The method may also include fluidly connecting a branch gas line 130 within the fuel tank 200 to the gas introduction port 110, allowing the inert gas to flow out through a plurality of vent holes 132 distributed along the length of the branch gas line 130. To automatically regulate the flow of the inert gas based on the fuel level 210, the method includes submerging at least one of the plurality of vent holes 132 in the branch gas line 130 into the fuel within the fuel tank 200, and exposing the at least one vent hole 132 to the gas phase of the fuel tank 200 as the fuel level 210 decreases.

[0057] Although the foregoing description of the inert gas distribution system 100 of the present invention may also be applied to executing the method for regulating the flow of inert gas in the fuel tank 200, for example, the structures of various preferred embodiments may be used to execute the method, it should be understood that the execution of the method of the present invention does not depend on the aforementioned inert gas distribution system 100 having the same structure.

[0058] Preferably, the gas branch line 130 may include a vertical portion extending approximately perpendicular to the fuel level 210, with the at least one vent 132, and preferably a plurality of vents 132, disposed on this vertical portion. Typically, during normal navigation or taxiing without significant fluctuations, the fuel level 210 is approximately horizontal, and the vertical portion of the gas branch line 130 may extend approximately vertically. It will be appreciated that the bottom 220 of the fuel tank 200 may not be flat, for example, including a slope or various geometric shapes (depending on the aircraft space constraints in which the fuel tank 200 is installed). Therefore, the vertical portion of the gas branch line 130 may be positioned relative to the fuel level 210.

[0059] In some embodiments, the bottom of the fuel tank 200 includes a substantially flat area that occupies a larger area of ​​the bottom. Therefore, the gas branch line 130 can also be oriented relative to the flat bottom area of ​​the fuel tank 200. For example, the gas branch line 130 may include a vertical portion extending in a direction approximately perpendicular to the flat bottom of the fuel tank 200.

[0060] However, it should be understood that the gas branch line 130 may not include a vertical portion extending substantially perpendicular to the fuel level 210, but rather include an inclined portion that is inclined relative to the fuel level 210. Whether or not the gas branch line 130 is vertically positioned does not actually affect the functionality of the present invention. However, a vertical portion of the gas branch line 130 is preferred because it allows for a predetermined number of vent holes 132 to be distributed within the shortest length of the gas branch line 130, and allows for rapid and automatic adjustment of the flow rate of inert gas, such as nitrogen-enriched gas, as the fuel level 210 changes.

[0061] Preferably, the gas branch line 130 can extend completely in a straight line and in a direction substantially perpendicular to the fuel level 210, such as Figure 1 However, when the gas branch line 130 extends in a straight line, it can also extend obliquely from the top to the bottom of the fuel tank 200. This does not mean that the gas branch line 130 must be placed close to the top or bottom of the fuel tank 200, although it is preferred that the lower end of the gas branch line 130 be close to the bottom of the fuel tank 200.

[0062] It is particularly preferred that at least some of the plurality of vent holes 132, and in particular most of the vent holes 132, can be submerged in the fuel in the fuel tank 200. Figure 1 As shown in . Therefore, when the height of the fuel level 210, or the amount of fuel in the fuel tank 200, varies within a wide range, the gas branch line 130 can promptly adjust the flow rate of the inert gas to accommodate this wide range of changes. For example, when the multiple vent holes 132 are widely distributed along the gas branch line 130, the inert gas can gradually flow into the gas phase within the fuel tank 200 through these vent holes 132 as the fuel in the fuel tank 200 transitions from being relatively full to nearly empty. In other words, the multiple vent holes 132 are gradually exposed to the gas phase, thereby gradually increasing the exhaust flow rate.

[0063] The inert gas distribution system 100 of the present invention may further include a gas distribution main pipe 120 and a plurality of gas branch pipes 130. The gas distribution main pipe 120 is typically a single pipe and is connected to the gas inlet port 110. The plurality of gas branch pipes 130 extend from the gas distribution main pipe 120, for example, downward (but not limited to extending vertically downward). The inert gas first flows from the gas inlet port 110 into the gas distribution main pipe 120, then flows through the gas distribution main pipe 120 into the gas branch pipes 130, and finally flows from the exhaust holes 132 of the gas branch pipes 130 into the gas phase space of the fuel tank 200.

[0064] Advantageously, the gas branch lines 130 can extend vertically directly from the gas distribution manifold 120. At least some, and preferably most, of the plurality of vent holes 132 can be submerged in the fuel within the fuel tank 200, thereby providing structural provision for regulating the flow of inert gas when the fuel level 210 subsequently decreases. The gas distribution manifold 120 preferably extends generally horizontally (i.e., parallel to the direction of the fuel level 210), but may also be inclined relative to the horizontal plane. The gas distribution manifold 120 is preferably long enough to allow multiple gas branch lines 130 to extend therefrom, with these gas branch lines 130 spaced appropriately apart from each other. This allows for the discharge and flow regulation of inert gas throughout substantially the entire area of ​​the fuel tank 200.

[0065] Advantageously, as Figure 1 As shown in FIG, a one-way valve 140 may be arranged between the gas introduction port 110 and the pipeline (either the gas distribution main pipe 120 or the gas branch pipeline 130) to allow the inert gas to flow into the gas branch pipeline 130 in only one direction.

[0066] Regarding the arrangement of the exhaust holes 132, the multiple exhaust holes 132 on the same gas branch line 130 can be distributed at different angles along the circumference of the gas branch line 130. For example, adjacent exhaust holes 132 can be staggered at a circumferential angle. The circumferential angles at which different adjacent exhaust holes 132 are staggered can be the same, but can also be different. Some of the multiple exhaust holes 132 on the same gas branch line 130 can also have the same circumferential angle, but it is preferred that at least some of the exhaust holes 132 have different circumferential angles, because one gas branch line 130 can be used to spray inert gas in different directions, so that the inert gas in the gas phase space produces a better flow effect, thereby achieving a more uniform distribution of the inert gas. By distributing the multiple exhaust holes 132 on the gas branch line 130 along the circumference, which varies according to the volume size and liquid level of the oil tank 200, it is possible to ensure that the inert gas is evenly distributed in the space, thereby avoiding the problem of unevenness of a single jet.

[0067] Furthermore, the multiple vent holes 132 on the same gas branch line 130 can have different apertures. The aperture design can take into account flow control requirements, such as the overall shape of the fuel tank 200 (or the rate at which the fuel level 210 drops), the amount of inert gas required in the gas phase, and so on. For example, the closer the vent hole 132 on the gas branch line 130 is to the bottom of the fuel tank 200, the larger the aperture can be.

[0068] In addition, the gas branch lines 130 located in different areas within the fuel tank 200 can have exhaust holes 132 with different apertures, so that they can be adaptively designed according to the amount, flow rate, uniformity, coverage, and other conditions of the inert gas required in different areas (for example, when the gas branch line 130 is located in an area with a small gas phase space in the fuel tank 200, exhaust holes with different apertures can be designed specifically).

[0069] In some embodiments, a high-temperature device, such as a fuel pump 300, is also provided in the fuel tank 200. Such high-temperature device usually needs to be cooled to prevent safety hazards caused by excessive temperature. Therefore, the high-temperature device can also be referred to as a device to be cooled. When the high-temperature device is in the fuel, the fuel can cool it. In other words, when the device to be cooled is submerged in the fuel, no other device is required to cool it. However, when the fuel liquid level 210 drops, the device to be cooled is exposed to the gas phase space, so liquid cooling cannot be achieved. Preferably, the gas branch line 130 of the inert gas distribution system 100 can be positioned relative to the device to be cooled so that the airflow of the inert gas flowing out of its exhaust hole 132 can blow-cool the device to be cooled, such as Figure 1 In other words, the device to be cooled can be located within the inert gas ejection range of the exhaust hole 132 of the gas branch line 130. When the device to be cooled is exposed above the fuel liquid level 210 and lacks cooling fuel, it can be provided with additional cooling fluid to reduce the temperature of, for example, the fuel pump 300 and protect the safety of the fuel tank 200. When the device to be cooled is submerged in fuel, no cooling gas is consumed.

[0070] The present invention also relates to an aircraft inerting system. In addition to the inert gas distribution system 100, the inerting system may also include other devices or components such as an inert gas generating device, which will not be described in detail here.

[0071] In summary, the inert gas distribution system and the method for regulating the inert gas flow rate in a fuel tank according to the present invention can achieve the effect of automatically regulating the inert gas flow rate according to the height of the liquid level in the fuel tank (for example, an aircraft), and as the fuel level in the fuel tank or fuel tank decreases, the exhaust volume gradually increases, that is, the exhaust flow rate is automatically adjusted dynamically according to the size of the gas phase space, the response time is short, and the inerting efficiency is improved, that is, the time it takes for the fuel tank to enter the inerting state is reduced, thereby improving the safety of the fuel tank.

[0072] In addition, the inert gas distribution system according to the present invention can automatically adjust the exhaust volume according to the size of the gas phase space without the need for software control, additional valve actuation, and fuel quantity calculation. It does not require any actuation mechanism, has high reliability, and does not consume any electrical energy or mechanical energy.

[0073] In particular, when the aircraft continuously circles or pitches, this can lead to significant asymmetric fuel distribution (for example, fuel may flow from the right wing fuel compartment to the left wing fuel compartment via the fuel duct). In such situations, the inert gas distribution system of the present invention can better adjust the flow distribution of the inert gas (for example, nitrogen-enriched gas), thereby achieving a better protection effect.

[0074] In addition, the inert gas distribution system 100 of the present invention has a simple and reliable structure. Since it has no moving parts, there is no risk of ignition source in the event of lightning, which further improves the safety of the fuel tank.

[0075] Although various embodiments of the present invention are described with reference to aircraft fuel tanks in the accompanying drawings, it should be understood that embodiments within the scope of the present invention may be applied to other safety-critical applications having similar structures and / or functions, such as ships, vehicles, work machines, and liquid hydrogen and liquid oxygen tanks.

[0076] The foregoing description has presented numerous features and advantages, including various alternative embodiments, and details of the structure and function of apparatus and methods. This description is intended to be illustrative and not exhaustive or limiting.

[0077] It will be apparent to those skilled in the art that various modifications may be made within the full scope indicated by the broad general meaning of the terms expressed in the appended claims, especially in terms of structure, materials, elements, components, shapes, sizes and arrangements of components, including combinations of these aspects within the scope of the principles described herein. To the extent that these various modifications do not depart from the spirit and scope of the appended claims, they are intended to be included therein.

Claims

1. An inert gas distribution system for a fuel tank, wherein the fuel tank comprises fuel and a gas phase space, characterized in that: The inert gas distribution system comprises: A gas introduction port for introducing inert gas; a gas branch line, the gas branch line being in fluid communication with the gas introduction port and disposed within the oil tank; The gas branch line includes a plurality of exhaust holes distributed along its length, and at least one of the plurality of exhaust holes can be submerged in the fuel in the fuel tank. Thus, as the fuel liquid level decreases, the at least one exhaust hole can be exposed to the gas phase space to allow the inert gas to flow therein, thereby adjusting the flow rate of the inert gas distributed to the fuel tank. The gas branch pipeline includes a vertical portion extending in a direction substantially perpendicular to the fuel liquid level, and the at least one exhaust hole is arranged in the vertical portion.

2. The inert gas distribution system according to claim 1, wherein: It also includes a gas distribution main pipe and a plurality of gas branch pipelines. The gas distribution main pipe is communicated with the gas introduction port, and the plurality of gas branch pipelines extend from the gas distribution main pipe.

3. The inert gas distribution system according to claim 2, wherein: The gas branch pipeline extends vertically downward from the gas distribution main pipe, and at least some of the multiple exhaust holes can be immersed in the fuel in the fuel tank.

4. The inert gas distribution system according to claim 1, wherein: The multiple exhaust holes on the same gas branch pipeline can be distributed at different angles along the circumference of the gas branch pipeline.

5. The inert gas distribution system according to claim 1, wherein: The multiple exhaust holes on the same gas branch pipeline have the same aperture.

6. The inert gas distribution system according to claim 1, wherein: The multiple exhaust holes on the same gas branch pipeline have different apertures.

7. The inert gas distribution system according to claim 6, wherein: The exhaust holes are designed to have a smaller diameter in the area where the gas phase space is small.

8. The inert gas distribution system according to claim 1, wherein: A device to be cooled is also arranged in the oil tank. The gas branch pipeline is positioned relative to the device to be cooled so that the air flow of the inert gas flowing out of the exhaust hole can blow-cool the device to be cooled.

9. An aircraft fuel tank inerting system, characterized in that: The aircraft fuel tank inerting system comprises the inert gas distribution system according to any one of claims 1-8.

10. A method for regulating the flow of inert gas in a fuel tank, characterized in that: The method comprises: Introducing an inert gas through a gas introduction port; placing a gas branch line located within the fuel tank in fluid communication with the gas introduction port so that the inert gas can flow out through a plurality of exhaust holes distributed along the length of the gas branch line; At least one of the plurality of exhaust holes is immersed in the fuel in the fuel tank, and as the fuel liquid level decreases, the at least one exhaust hole is exposed to the gas phase space of the fuel tank, thereby adjusting the flow rate of the inert gas distributed to the fuel tank, wherein the gas branch pipeline includes a vertical portion extending in a direction approximately perpendicular to the fuel liquid level, and the at least one exhaust hole is arranged in the vertical portion.

Images