Auxiliary fuel tank fuel reduction and bleed air pressurization subsystem and operation method thereof

Abstract

The present invention provides an auxiliary fuel tank fuel reduction and bleed air pressurization subsystem and an operation method thereof. The present invention realizes auxiliary fuel tank inerting and nitrogen-rich gas storage during the cruise phase by adding a nitrogen-rich gas branch at the outlet of the air separator and coordinating the corresponding bleed air and ventilation valve pipe network layout and control method, so that not only the flammability of the auxiliary fuel tank meets the airworthiness requirements during the hot weather ground phase, but also the nitrogen-rich gas is used as a backup gas source for auxiliary fuel tank fuel bleed air pressurization and transfer, thereby achieving weight reduction of the auxiliary fuel tank backup gas source engine bleed air regulation subsystem. Without affecting the flammability of the basic fuel tank, the existing inerting system engine bleed air regulation subsystem is shared to realize the auxiliary fuel tank bleed air pressurization and transfer function, thereby achieving weight reduction, and the existing main fuel tank inerting system is used to inert and pressurize the auxiliary fuel tank to store nitrogen-rich gas during the cruise phase, so that the flammability of the auxiliary fuel tank during the hot weather ground phase meets the quantitative requirements of the flammability clause of CCAR-25-R4 25.981.

Description

Technical Field

[0001] The present invention relates to the field of design of auxiliary fuel tank systems for civil aircraft, and in particular to an auxiliary fuel tank fuel reduction and bleed air pressurization subsystem and an operating method thereof. Background Art

[0002] Civil aircraft increase their fuel capacity and thus extend their range by adding auxiliary fuel tank systems to the original aircraft. Auxiliary fuel tank systems are generally designed, manufactured and installed after the original aircraft is designed and produced.

[0003] The main function of the auxiliary fuel tank system is to refill the wing tank with fuel. The fuel in the auxiliary tank is usually not directly supplied to the engine for consumption, but the fuel in the auxiliary tank is first transferred to the wing tank and supplied to the engine for consumption through the wing tank fuel pump. Therefore, it is necessary to control the start / stop of the auxiliary tank fuel transfer according to the fuel level of the wing tank. Otherwise, the original aircraft fuel tank structure may be over-pressurized due to excessive fuel transfer, or the oil level may be too high, causing fuel to overflow from the wing tank during flight. The main function of the auxiliary fuel control system is to realize the transfer control and refueling control of the auxiliary tank fuel.

[0004] In order to extend the range of civil aircraft derivative models, it is generally necessary to install an auxiliary fuel tank system (AFTS) in the cargo hold. The auxiliary fuel tank is a typical internal fuselage fuel tank, and its flammability needs to meet the quantitative requirements of the flammability clause of CCAR-25-R425.981. In order to comply with the clause, the fuel reduction measures that can be taken generally include fuel tank pressurization, cargo hold environment cooling, and onboard inerting. The above three measures are considered at the beginning of the model design and are all engineering practical, but for derivative models, substantial changes to other systems are required to complete the above fuel reduction measures, resulting in a high cost for installing auxiliary fuel tanks. For example, the flammability clause requires that the flammability requirement of the fuel tank in the fuselage during the hot weather ground stage and the hot weather climb stage should not exceed 1.8%. However, there is a refueling link during the ground stage, and the fuel tank needs to be ventilated to the environment to prevent overpressure. Therefore, it is difficult to pressurize the fuel tank on the ground. Generally, the cargo hold will not be equipped with air conditioning outlets, and the cargo hold cannot be temperature-regulated like the cabin, resulting in a high temperature in the cargo hold during the hot weather ground stage. The flammability index of the auxiliary fuel tank installed in the cargo hold is difficult to meet the requirements of the clause during the hot weather ground stage, and there is an airworthiness risk. For civil aircraft derivative models, only the design of auxiliary fuel tank combustion reduction using onboard inerting is practical. In addition, the auxiliary fuel tank often uses bleed air pressurization to realize fuel transfer, in order to avoid introducing ignition sources such as pumps and valves into the fuel tank. Civil aircraft generally use cabin bleed air as the main air source, and engine bleed air as the backup air source. When the cabin bleed air pressure is insufficient, the engine bleed air is activated. The engine bleed air is a high-temperature and high-pressure gas, and a special independent engine bleed air regulation subsystem needs to be specially designed to adjust the temperature and pressure of the bleed air before it can enter.

[0005] As mentioned above, the problems with the project of adding auxiliary fuel tank systems to derivative models of general civil aircraft are the airworthiness issues of ground flammability in hot weather and the high weight and cost of the engine bleed air regulation subsystem that serves as a backup air source.

[0006] Existing patents on auxiliary fuel tanks mostly focus on auxiliary fuel tank architecture design, fuel tank body structure design, fuel tank installation design, fuel tank connection and pipe network design, auxiliary fuel tank system control architecture design, refueling / transfer / leakage drainage and other functional designs. In terms of auxiliary fuel tank combustion reduction, public documents only mention that pressurized transfer of fuel has the effect of reducing combustion. Usually, auxiliary fuel tank pressurization transfer only occurs in the air. The auxiliary fuel tank is connected to the atmosphere on the ground and usually maintains normal pressure. Fuel tank pressurization cannot be used to reduce combustion on the ground. Existing public technologies do not involve a discussion of combustion reduction design features that make the flammability of auxiliary fuel tanks meet the standards on the ground on hot days. In terms of the engine bleed air conditioning subsystem, most public documents mention the concept of using a heat exchanger to adjust the temperature of the bleed air, and the cold side uses an onboard cold source or ram air for cooling. They also do not involve specific auxiliary fuel tank engine bleed air conditioning subsystem integration implementation plans.

[0007] Figure 1 The schematic diagram of the architecture of the inerting system and auxiliary fuel tank system of a typical civil aircraft derivative model in the prior art is shown. As shown in the figure, in the prior art, the auxiliary fuel tank system and the inerting system are two independent systems and have no cross-linking relationship.

[0008] In view of the above technical problems, there are currently several solutions in the field of this technology:

[0009] For example, the closest existing document CN202010993986.2, its invention name is "Aircraft Fuel Tank Pressurization System and Method". This existing document uses engine bleed air pressurization to realize the fuel transfer from the auxiliary fuel tank to the base fuel tank, and at the same time plays a role in reducing the flammability of the auxiliary fuel tank, wherein the temperature regulation of the engine bleed air is achieved through heat exchanger and cooling air heat dissipation. However, the focus of this existing document is on the tank pressure control logic of bleed air transfer, but it does not mention the specific design and implementation path of engine bleed air heat dissipation, nor does it mention the flammability of the auxiliary fuel tank in the fuselage of civil aircraft on hot days on the ground in actual application scenarios. Therefore, it does not involve the integrated design method of the engine bleed air regulation subsystem and the fuel reduction design features that make the flammability of the auxiliary fuel tank on the ground meet the airworthiness requirements.

[0010] For another example, the existing document US14500988, whose invention name is "Method, system and device for aircraft auxiliary fuel tank". This existing document proposes an auxiliary fuel tank system architecture and corresponding embodiments, including a fuel tank structure, a fuel tank installation slide rail, a fuel transfer pipeline installation, a fuel tank self-sealing quick-release joint, etc. The auxiliary fuel tank system mentioned in this existing document is composed of a main fuel tank and a secondary fuel tank combined and connected. The main and secondary fuel tanks are both made of honeycomb sandwich wall panels. The shape of the fuel tank is compatible with the size of the cargo door, and both can enter the cargo hold through the cargo door. The conceptual structure of installing slide rails and brake blocks on the cargo hold floor can complete the transfer, installation or removal of the auxiliary fuel tank. The main fuel tank and the secondary fuel tank, and the secondary fuel tanks are connected by self-sealing quick-release joints, so the number of fuel tanks can be adjusted as needed according to the aircraft's range requirements. The auxiliary fuel tank system only has an interface between the main fuel tank and the basic fuel system. When transferring fuel, the fuel in the secondary tank first enters the main fuel tank, and the fuel in the main fuel tank is then transferred to the basic tank. However, the existing document focuses on providing a detailed design scheme and supporting devices for an auxiliary fuel tank system, and does not involve the integrated weight reduction design of the auxiliary fuel tank engine bleed air subsystem and the auxiliary fuel tank fuel reduction design features.

[0011] In addition, the existing document US12993039, whose invention name is "Auxiliary Fuel Tank System". This existing document proposes an auxiliary fuel tank system architecture based on neutral transfer fuel supply and induced fueling, which is suitable for business jets, including an empty structure and a pipe network system. By arranging the auxiliary fuel tanks higher in the cabin and cargo hold, the auxiliary fuel tanks can be transferred to the central wing under the action of gravity, and the auxiliary fuel tank refueling operation can be achieved by arranging an induced fuel pump on the central wing. However, this existing document does not involve the integrated weight reduction design of the auxiliary fuel tank engine bleed air subsystem and the auxiliary fuel tank fuel reduction design features.

[0012] In addition, the existing document US10768267, whose invention name is "Aircraft auxiliary fuel tank system and its manufacturing and use method". This existing document proposes an architecture, manufacturing and use method of an auxiliary fuel tank system suitable for civil aircraft. The fuel tank system mentioned in this existing document is mainly composed of a main fuel tank and an auxiliary fuel tank. The main and auxiliary fuel tanks can be installed in the cargo hold through the fuselage door. The number of fuel tanks is defined according to the aircraft requirements. The auxiliary fuel tank transfers fuel to the base tank through a built-in transfer pump. However, this existing document does not involve the integrated design method of the engine bleed air subsystem and the fuel reduction design features that make the flammability of the auxiliary fuel tank meet the airworthiness requirements during the ground phase.

[0013] For another example, the existing document CN202010358954.5, whose invention name is "An aircraft fuel supply system and auxiliary fuel control method". This existing document can realize the auxiliary fuel tank system function without changing the basic fuel system control hardware and software through the special design of the auxiliary fuel tank refueling and fuel transfer control logic. However, this existing document focuses on the auxiliary fuel tank refueling and fuel transfer control logic design, and does not involve the engine bleed air subsystem integrated design method and the fuel reduction design features that make the auxiliary fuel tank's ground stage flammability meet the airworthiness requirements.

[0014] As can be seen from the above, the existing auxiliary fuel tank system technology basically does not involve the fuel reduction design features that make the auxiliary fuel tank meet the flammability standards during the hot weather ground stage, and there is no detailed discussion on the implementation path of the bleed air regulation of the engine bleed air boost and transfer, especially the integrated weight reduction design scheme of the engine bleed air regulation subsystem.

[0015] In view of the above, it can be known that there is currently no such auxiliary fuel tank fuel reduction and bleed air pressurization subsystem design in the technical field, which can share the existing inerting system engine bleed air regulation subsystem to realize the auxiliary fuel tank bleed air pressurization transfer function without affecting the flammability of the basic fuel tank, thereby achieving weight reduction, and utilize the existing main fuel tank inerting system to store nitrogen-rich gas for inerting and pressurization of the auxiliary fuel tank during the cruise phase, so that the flammability of the auxiliary fuel tank during the hot weather ground phase meets the quantitative requirements of the flammability clause of CCAR-25-R4 25.981. Summary of the invention

[0016] The present invention is made to solve the above-mentioned technical problems, and its main purpose is to provide an auxiliary fuel tank fuel reduction and bleed air pressurization subsystem that can share the existing inerting system engine bleed air regulation subsystem to realize the auxiliary fuel tank bleed air pressurization and transfer function to achieve weight reduction without affecting the flammability of the basic fuel tank, and can also use the existing main fuel tank inerting system to inert and pressurize the auxiliary fuel tank in the cruise stage to store nitrogen-rich gas so that the flammability of the auxiliary fuel tank in the hot weather ground stage meets the quantitative requirements of the flammability clause.

[0017] Another object of the present invention is to provide an operating method for the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem.

[0018] Another object of the present invention is to provide an aircraft including the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem.

[0019] In order to achieve the above-mentioned object of the invention, according to one aspect of the present invention, an auxiliary fuel tank fuel reduction and bleed air pressurization subsystem is provided, comprising:

[0020] an auxiliary fuel tank system, the auxiliary fuel tank system being controlled by an auxiliary fuel tank system controller;

[0021] An inerting system, wherein the inerting system is controlled by the inerting system controller;

[0022] An engine bleed air regulating subsystem, the engine bleed air regulating subsystem is located upstream of the inerting system and is used to adjust the temperature and filter the engine bleed air;

[0023] An air separator, after the temperature-adjusted bleed air enters the air separator, separates the bleed air into oxygen-rich gas and nitrogen-rich gas, and discharges the oxygen-rich gas to the outside, and the outlet of the air separator has two branches;

[0024] A base oil tank, which is located downstream of the air separator and connected to a branch at the outlet of the air separator, and is used to realize the fuel reduction function of the base oil tank;

[0025] An auxiliary oil tank, which is located downstream of the air separator and connected to another branch at the outlet of the air separator, and is used to realize the functions of bleed air transfer, backup air source and fuel reduction;

[0026] Multiple temperature sensors and multiple pressure sensors are used for over-temperature protection, over-pressure protection, boost transfer control and bleed air temperature regulation.

[0027] There is a fuel cross-linking and ventilation cross-linking relationship between the auxiliary fuel tank and the basic fuel tank.

[0028] Preferably, in the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention, the fuel in the auxiliary fuel tank enters the basic fuel tank through cabin bleed air or nitrogen-rich gas pressurization.

[0029] The auxiliary oil tank is provided with a venting pipeline and a pressure relief valve for overpressure protection.

[0030] The basic oil tank has a vent tank, and the auxiliary oil tank exchanges gas with the outside through the vent tank of the basic oil tank.

[0031] Preferably, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention further includes:

[0032] an auxiliary fuel tank system bleed air isolation valve, the auxiliary fuel tank system bleed air isolation valve is located on a branch from the air separator to the auxiliary fuel tank,

[0033] Among them, the auxiliary fuel tank system air bleed isolation valve is in a normally closed state, and is opened on demand when the backup air source is activated. After the cruise auxiliary fuel tank system is consumed, the auxiliary fuel tank system air bleed isolation valve is opened to inert the auxiliary fuel tank system. After the auxiliary fuel tank system is inerted and pressurized to the cabin pressure, the auxiliary fuel tank system air bleed isolation valve is closed.

[0034] Preferably, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention further includes:

[0035] an inerting system temperature isolation valve, wherein the inerting system temperature isolation valve is located on a branch from the air separator to the base oil tank,

[0036] Among them, the inerting system temperature isolation valve is opened when the inerting system is working, and is closed when the auxiliary fuel tank system activates the backup gas source. After the cruise auxiliary fuel tank system is consumed, the inerting system temperature isolation valve is closed when the auxiliary fuel tank system is inerted, and the inerting system temperature isolation valve is opened after the auxiliary fuel tank system is inerted and pressurized to the cabin pressure.

[0037] Preferably, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention further includes:

[0038] a vent isolation valve, the vent isolation valve being located on the passage between the auxiliary oil tank and the vent oil tank of the base oil tank,

[0039] The vent isolation valve is opened when the aircraft is on the ground, opened during the inertization phase of the cruise auxiliary fuel tank system, closed when the auxiliary fuel tank system is pressurized, and also closed during the remaining flight time.

[0040] Preferably, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention further includes:

[0041] a cabin bleed air valve, the cabin bleed air valve being located on a passage leading from the auxiliary fuel tank to the cabin bleed air,

[0042] The cabin air bleed valve is in a normally open state. When the auxiliary fuel tank system is consumed, the cabin air bleed valve is closed to inertate the auxiliary fuel tank system. After the auxiliary fuel tank inerting and pressurization are completed, the cabin air bleed valve is opened.

[0043] Preferably, in the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention, the multiple temperature sensors include: an engine bleed air regulation subsystem outlet temperature sensor, an air separator inlet temperature sensor; the multiple pressure sensors include: an air separator inlet pressure sensor, an auxiliary fuel tank pressure sensor.

[0044] According to another aspect of the present invention, there is provided an operating method of the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention, including an auxiliary fuel tank inerting process and an auxiliary fuel tank bleed air pressurization transfer process.

[0045] The auxiliary tank air bleed pressurized transfer process is to increase the pressure of the auxiliary tank by bleed air from an air source to form a pressure difference relative to the basic tank, thereby realizing the transfer of fuel from the auxiliary tank to the basic tank.

[0046] Preferably, in the above-mentioned operation method of the present invention, the auxiliary oil tank inerting process comprises the following steps:

[0047] a) the auxiliary fuel tank system and the inerting system controller detect that the auxiliary fuel tank system fuel has been consumed, triggering the auxiliary fuel tank system inerting function;

[0048] b) Open the ventilation isolation valve of the auxiliary fuel tank system, close the cabin bleed air valve, close the temperature isolation valve of the inerting system, and flush the inerting auxiliary fuel tank with nitrogen-rich gas for a period of time;

[0049] c) closing the ventilation isolation valve of the auxiliary fuel tank system, pressurizing the auxiliary fuel tank to the cabin pressure using nitrogen-rich gas and then stopping pressurization, thus completing the storage of nitrogen-rich gas;

[0050] d) Open the cabin bleed air valve, open the inerting system temperature isolation valve, close the auxiliary fuel tank system ventilation isolation valve, and restore the basic fuel tank inerting architecture.

[0051] Preferably, in the above-mentioned operation method of the present invention, the auxiliary oil tank inerting process comprises the following steps:

[0052] a) The auxiliary fuel tank system and the inerting system controller detect that the cabin is depressurized and the pressure difference between the auxiliary fuel tank and the basic fuel tank is lower than the threshold value △P1, and the backup gas source is activated;

[0053] b) closing the temperature isolation valve of the inerting system, opening the ventilation isolation valve of the auxiliary fuel tank system, and starting pressurization of the inerting system until the pressure difference between the auxiliary fuel tank and the base fuel tank reaches the upper limit △P2, and then stopping pressurization;

[0054] c) Open the temperature isolation valve of the inerting system, close the ventilation isolation valve of the auxiliary fuel tank system, restore the basic fuel tank inerting architecture, and wait for the next activation of the backup gas source.

[0055] According to yet another aspect of the present invention, an aircraft is provided. The aircraft includes the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention.

[0056] In view of the above, compared with the prior art, the core technology of the present invention lies in: the present invention realizes the inerting of the auxiliary fuel tank and the storage of nitrogen-rich gas in the cruising stage by adding a nitrogen-rich gas branch at the outlet of the air separator of the inerting system, and cooperates with the corresponding bleed air and ventilation valve control design, so that the flammability of the auxiliary fuel tank meets the airworthiness requirements in the hot weather ground stage, and at the same time, the nitrogen-rich gas is used as a backup air source for the auxiliary fuel tank fuel bleed air pressurization and transfer, so as to achieve the weight reduction of the auxiliary fuel tank system (AFTS) backup air source engine bleed air regulation subsystem.

[0057] Due to the above technical solution, compared with the prior art, the present invention can bring the following technical effects:

[0058] 1. Add a nitrogen-rich gas branch at the outlet of the air separator. During the cruise phase, nitrogen-rich gas is introduced into the auxiliary fuel tank for flushing, inerting and pressurizing to store the nitrogen-rich gas. During the descent phase, the nitrogen-rich gas at a certain pressure stored in the auxiliary fuel tank can resist the process of increasing external atmospheric pressure and prevent a large amount of external air from entering the auxiliary fuel tank. During landing, the auxiliary fuel tank can still remain in an inerted state, so that the auxiliary fuel tank is in an inerted state during the descent phase of the current sortie and the ground and climbing phases of subsequent sorties. The various flammability indicators of the auxiliary fuel tank meet the airworthiness requirements.

[0059] 2. Add an air bleed branch at the outlet of the inerting system heat exchanger, share the inerting system engine air bleed regulation subsystem, cancel the auxiliary fuel tank engine air bleed regulation subsystem temperature control equipment and high-temperature pipelines, and realize the integrated weight reduction design of the auxiliary fuel tank backup air source subsystem.

[0060] The above technical effects will not have a negative impact on the flammability of the existing basic fuel tanks. Specifically, the backup air source is only activated in the event of cabin depressurization, with a probability of less than 10%. -5 Even if a backup gas source is needed, nitrogen-rich gas can complete a single tank pressurization operation within 2 minutes to achieve fuel transfer, with little impact. The inerting and storage process of AFTS occurs during the cruise phase, when the main tank is fully inerted. Although the short-term interruption of nitrogen-rich gas supply to the base tank will cause the main tank to consume fuel and increase the gas phase space, and the introduction of outside air will slowly increase the oxygen concentration in the base tank, the interruption time of nitrogen-rich gas supply is short and will not damage the inerting state of the base tank.

[0061] Based on the common sense in this field, the above-mentioned preferred implementation modes can be combined arbitrarily to obtain the preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to better understand the above and other purposes, features, advantages and functions of the present invention, reference may be made to the preferred embodiments shown in the accompanying drawings. The same reference numerals in the accompanying drawings refer to the same components. It should be understood by those skilled in the art that the accompanying drawings are intended to schematically illustrate the preferred embodiments of the present invention and have no limiting effect on the scope of the present invention, and the components in the drawings are not drawn to scale.

[0063] - Figure 1 The schematic diagram of the structure of the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention is schematically shown.

[0064] List of reference numerals in the figures in the technical solutions and embodiments:

[0065] 1 Auxiliary fuel tank fuel reduction and bleed air pressurization subsystem

[0066] 10 Engine bleed air conditioning subsystem

[0067] 11 Air Separator (ASM)

[0068] 12 Basic fuel tank

[0069] 121 Breathing tank

[0070] 13 Auxiliary fuel tank

[0071] 14 Auxiliary fuel tank system controller

[0072] 15 Inerting system controller

[0073] 16 Auxiliary fuel tank system bleed air isolation valve

[0074] 17 Inerting system temperature isolation valve

[0075] 18 Ventilation isolation valve

[0076] 19 Cabin bleed air valve DETAILED DESCRIPTION

[0077] In order to make the purpose, technical solution and advantages of the implementation of the present invention clearer, the technical solution in the embodiment of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiment of the present invention.

[0078] In this regard, it should be pointed out that in the specific description of these embodiments, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual embodiments. It should be understood that in the actual implementation of any embodiment, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one embodiment to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the content disclosed by the present invention, some changes in design, manufacturing or production based on the technical content disclosed in this disclosure are just conventional technical means, and should not be understood as insufficient content of this disclosure.

[0079] In addition, it should be noted that, unless otherwise defined, the technical terms or scientific terms used in the claims and the specification should have the usual meanings understood by persons with ordinary skills in the technical field to which the invention belongs. "One" or "an" and other similar words do not indicate a quantitative limitation, but rather indicate the presence of at least one. "Include" or "comprises" and other similar words mean that the elements or objects appearing before "include" or "comprises" include the elements or objects listed after "include" or "comprises" and their equivalent elements, and do not exclude other elements or objects. "Connected" or "connected" and other similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0080] The following will be combined Figure 1 The present invention is described in detail so that the advantages and features of the present invention can be easily understood by those skilled in the art, thereby more clearly defining the scope of the present invention.

[0081] In general, if Figure 1 As shown, the figure schematically shows the schematic diagram of the structure of the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem 1 of the present invention. As shown in the figure, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem 1 includes: an auxiliary fuel tank system, an inerting system (FTIS), an engine bleed air regulation subsystem 10, an air separator (ASM) 11, a base fuel tank 12, an auxiliary fuel tank 13, a plurality of temperature sensors and a plurality of pressure sensors. Among them, the auxiliary fuel tank system is controlled by an auxiliary fuel tank system controller 14, and the inerting system is controlled by an inerting system controller 15.

[0082] It is worth mentioning here that the present invention maintains the physical architecture of the existing inerting system, and the engine bleed air regulation subsystem 1 is located upstream of the inerting system, which realizes the functions of temperature control and filtration of the engine bleed air. After temperature control, the bleed air enters the air separator 11 (ASM), and the bleed air is separated into oxygen-rich gas (OEA) and nitrogen-rich gas (NEA). The oxygen-rich gas is directly discharged out of the machine, while the nitrogen-rich gas enters the downstream fuel tank. There are two branches at the outlet of the air separator 11, one branch leads to the base fuel tank 12, which is used to realize the fuel reduction function of the base fuel tank, and the other branch leads to the auxiliary fuel tank 13, which is used to realize the bleed air transfer backup gas source function and the fuel reduction function. Among them, the auxiliary fuel tank 13 and the base fuel tank 12 have a fuel cross-linking and ventilation cross-linking relationship. Specifically, the fuel in the auxiliary fuel tank 13 enters the basic fuel tank 12 through cabin bleed air or nitrogen-rich gas pressurization. The auxiliary fuel tank 13 is provided with a ventilation pipeline and a pressure relief valve for overpressure protection, and the auxiliary fuel tank 13 exchanges gas with the outside world through the ventilation tank 121 of the basic fuel tank 12.

[0083] In addition, the entire pipe network system is designed with multiple temperature sensors and pressure sensors for over-temperature protection, over-pressure protection, boost transfer control, bleed air temperature regulation, etc. Preferably, the multiple temperature sensors include the engine bleed air regulation subsystem outlet temperature sensor, the air separator inlet temperature sensor, etc., and the multiple pressure sensors include the air separator inlet pressure sensor, the auxiliary fuel tank pressure sensor, etc.

[0084] In addition, in a preferred embodiment, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem 1 of the present invention further includes an auxiliary fuel tank system bleed air isolation valve 16, which is located on the branch of the air separator 11 leading to the auxiliary fuel tank 13. The auxiliary fuel tank system bleed air isolation valve 16 is in a normally closed state, and is opened on demand when the backup air source is enabled. When the cruise auxiliary fuel tank system is consumed, the auxiliary fuel tank system bleed air isolation valve 16 is opened to inertify the auxiliary fuel tank system. After the auxiliary fuel tank system is inerted and pressurized to the cabin pressure, the auxiliary fuel tank system bleed air isolation valve 16 is closed.

[0085] In a preferred embodiment, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem 1 of the present invention further comprises an inerting system temperature isolation valve 17, which is located on the branch of the air separator 11 leading to the base fuel tank 12. The inerting system temperature isolation valve 17 is opened when the inerting system is working, and is closed when the auxiliary fuel tank system uses the backup air source. When the cruise auxiliary fuel tank system is consumed, the inerting system temperature isolation valve 17 is closed when the auxiliary fuel tank system is inerted, and the inerting system temperature isolation valve 17 is opened after the auxiliary fuel tank system is inerted and pressurized to the cabin pressure.

[0086] In a preferred embodiment, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem 1 of the present invention further comprises a vent isolation valve 18, which is located on the passage between the auxiliary fuel tank 13 and the vent tank of the base fuel tank 12. The vent isolation valve 18 is opened when the aircraft is on the ground, opened during the inert stage of the cruise auxiliary fuel tank system, closed when the auxiliary fuel tank system is pressurized, and also closed during the rest of the flight time.

[0087] In addition, in a preferred embodiment, the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem 1 of the present invention further includes a cabin bleed air valve 19, which is located on the passage from the auxiliary fuel tank 13 to the cabin bleed air. The cabin bleed air valve 19 is in a normally open state. When the auxiliary fuel tank system is consumed, the cabin bleed air valve 19 is closed to inertize the auxiliary fuel tank system until the auxiliary fuel tank inerting and pressurization are completed, and the cabin bleed air valve 19 is opened.

[0088] From the above, it can be seen that the present invention mainly realizes the inerting of the auxiliary fuel tank and the storage of nitrogen-rich gas in the cruising stage by adding a nitrogen-rich gas branch at the outlet of the air separator 11, and coordinating the corresponding bleed air and ventilation valve network layout and control method. Therefore, not only the flammability of the auxiliary fuel tank meets the airworthiness requirements in the hot weather ground stage, but also the nitrogen-rich gas is used as a backup air source for the auxiliary fuel tank fuel bleed air pressurization and transfer, thereby achieving the weight reduction of the AFTS backup air source engine engine bleed air regulation subsystem.

[0089] Next, an operation method of the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem of the present invention is introduced, which includes the following two processes: auxiliary fuel tank inerting process and auxiliary fuel tank bleed air pressurization transfer process. Among them, the auxiliary fuel tank bleed air pressurization transfer process is to increase the pressure of the auxiliary fuel tank by bleed air from the air source to form a pressure difference relative to the basic fuel tank, thereby realizing the transfer of fuel from the auxiliary fuel tank to the basic fuel tank.

[0090] Specifically, the auxiliary fuel tank inerting process includes the following steps:

[0091] a) The auxiliary fuel tank system controller and the inerting system controller detect that the auxiliary fuel tank system fuel has been consumed, triggering the auxiliary fuel tank system inerting function;

[0092] b) Open the ventilation isolation valve of the auxiliary fuel tank system, close the cabin bleed air valve, close the temperature isolation valve of the inerting system, and flush the inerting auxiliary fuel tank with nitrogen-rich gas for a period of time;

[0093] c) Close the ventilation isolation valve of the auxiliary fuel tank system, pressurize the auxiliary fuel tank to the cabin pressure with nitrogen-rich gas, and then stop pressurizing, thus completing the storage of nitrogen-rich gas;

[0094] d) Open the cabin bleed air valve, open the inerting system temperature isolation valve, close the auxiliary fuel tank system ventilation isolation valve, and restore the basic fuel tank inerting architecture.

[0095] The nitrogen-rich gas stored in the auxiliary fuel tank system can make the auxiliary fuel tank in an inerting state during the descent, post-flight ground, pre-flight ground for the next flight, and climb phases, thereby achieving the purpose of reducing fuel.

[0096] In addition, the bleed air pressurization and transfer process of the auxiliary fuel tank is to increase the pressure of the auxiliary fuel tank by bleed air from the air source (cabin bleed air or engine bleed air), forming a pressure difference relative to the basic fuel tank, and realizing the process of transferring fuel from the auxiliary fuel tank to the basic fuel tank. This process includes:

[0097] a) The auxiliary fuel tank system and inerting system controller detects cabin depressurization and the pressure difference between the auxiliary fuel tank and the basic fuel tank is lower than the threshold △P1, and activates the backup gas source;

[0098] b) Close the temperature isolation valve of the inerting system, open the ventilation isolation valve of the auxiliary fuel tank system, and start pressurizing the inerting system until the pressure difference between the auxiliary fuel tank and the basic fuel tank reaches the upper limit △P2, and then stop pressurizing;

[0099] c) Open the temperature isolation valve of the inerting system, close the ventilation isolation valve of the auxiliary fuel tank system, restore the basic fuel tank inerting architecture, and wait for the next activation of the backup gas source.

[0100] The bleed air pressurization and transfer function does not require a high pressure difference, that is, the gas source flow requirement is low, and the nitrogen-rich gas flow can meet the requirement. During the cruise phase, the basic fuel tank has been fully inerted, and the nitrogen-rich gas flow is abundant. By adding a nitrogen-rich gas branch at the air separator outlet and utilizing the high-pressure and low-temperature characteristics of the nitrogen-rich gas in the inerting system, a backup gas source is provided for the auxiliary fuel tank pressurization and transfer. That is, the auxiliary fuel tank system and the inerting system share the engine bleed air regulating subsystem, and the auxiliary tank engine bleed air regulating subsystem temperature control equipment and high-temperature pipelines are eliminated, thereby realizing the integrated weight reduction design of the auxiliary fuel tank backup gas source subsystem.

[0101] The preferred embodiments of the present invention have been described in detail above, but it should be understood that after reading the above teachings of the present invention, those skilled in the art will easily think of other advantages and modifications. Therefore, in its broader aspects, the present invention is not limited to the specific details and representative embodiments shown and described herein. Therefore, those skilled in the art can reasonably combine or modify the elements of the above embodiments so as to make various modifications without departing from the spirit or scope of the general inventive concept of the present invention as defined by the attached claims and their equivalents.

Claims

1. An auxiliary fuel tank fuel reduction and bleed air pressurization subsystem, comprising: an auxiliary fuel tank system, the auxiliary fuel tank system being controlled by an auxiliary fuel tank system controller; An inerting system, wherein the inerting system is controlled by the inerting system controller; An engine bleed air regulating subsystem, the engine bleed air regulating subsystem is located upstream of the inerting system and is used to adjust the temperature and filter the engine bleed air; An air separator, after the temperature-adjusted bleed air enters the air separator, separates the bleed air into oxygen-rich gas and nitrogen-rich gas, and discharges the oxygen-rich gas to the outside, and the outlet of the air separator has two branches; A base oil tank, which is located downstream of the air separator and connected to a branch at the outlet of the air separator, and is used to realize the fuel reduction function of the base oil tank; An auxiliary oil tank, which is located downstream of the air separator and connected to another branch at the outlet of the air separator, and is used to realize the functions of bleed air transfer, backup air source and fuel reduction; Multiple temperature sensors and multiple pressure sensors are used for over-temperature protection, over-pressure protection, boost transfer control and bleed air temperature regulation. There is a fuel cross-linking and ventilation cross-linking relationship between the auxiliary fuel tank and the basic fuel tank.

2. The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to claim 1, characterized in that: The fuel in the auxiliary tank enters the basic tank through cabin bleed air or nitrogen-enriched gas pressurization. The auxiliary oil tank is provided with a venting pipeline and a pressure relief valve for overpressure protection. The basic oil tank has a vent tank, and the auxiliary oil tank exchanges gas with the outside through the vent tank of the basic oil tank.

3. The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to claim 1 or 2, characterized in that: Also includes: an auxiliary fuel tank system bleed air isolation valve, the auxiliary fuel tank system bleed air isolation valve is located on a branch from the air separator to the auxiliary fuel tank, Among them, the auxiliary fuel tank system air bleed isolation valve is in a normally closed state, and is opened on demand when the backup air source is activated. After the cruise auxiliary fuel tank system is consumed, the auxiliary fuel tank system air bleed isolation valve is opened to inert the auxiliary fuel tank system. After the auxiliary fuel tank system is inerted and pressurized to the cabin pressure, the auxiliary fuel tank system air bleed isolation valve is closed.

4. The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to claim 1 or 2, characterized in that: Also includes: an inerting system temperature isolation valve, wherein the inerting system temperature isolation valve is located on a branch from the air separator to the base oil tank, Among them, the inerting system temperature isolation valve is opened when the inerting system is working, and is closed when the auxiliary fuel tank system activates the backup gas source. After the cruise auxiliary fuel tank system is consumed, the inerting system temperature isolation valve is closed when the auxiliary fuel tank system is inerted, and the inerting system temperature isolation valve is opened after the auxiliary fuel tank system is inerted and pressurized to the cabin pressure.

5. The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to claim 1 or 2, characterized in that: Also includes: a vent isolation valve, the vent isolation valve being located on the passage between the auxiliary oil tank and the vent oil tank of the base oil tank, The vent isolation valve is opened when the aircraft is on the ground, opened during the inertization phase of the cruise auxiliary fuel tank system, closed when the auxiliary fuel tank system is pressurized, and also closed during the remaining flight time.

6. The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to claim 1 or 2, characterized in that: Also includes: a cabin bleed air valve, the cabin bleed air valve being located on a passage leading from the auxiliary fuel tank to the cabin bleed air, The cabin air bleed valve is in a normally open state. When the auxiliary fuel tank system is consumed, the cabin air bleed valve is closed to inertate the auxiliary fuel tank system. After the auxiliary fuel tank is inerted and pressurized, the cabin air bleed valve is opened.

7. The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to claim 1 or 2, characterized in that: The multiple temperature sensors include: an engine bleed air conditioning subsystem outlet temperature sensor and an air separator inlet temperature sensor.

8. The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to claim 1 or 2, characterized in that: The multiple pressure sensors include: an air separator inlet pressure sensor and an auxiliary fuel tank pressure sensor.

9. An operating method of the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to any one of claims 1 to 3, comprising an auxiliary fuel tank inerting process and an auxiliary fuel tank bleed air pressurization transfer process, in, The auxiliary tank air bleed pressurized transfer process is to increase the pressure of the auxiliary tank by bleed air from an air source to form a pressure difference relative to the basic tank, thereby realizing the transfer of fuel from the auxiliary tank to the basic tank.

10. The operating method according to claim 9, characterized in that: The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem is provided with an inerting system temperature isolation valve located on a branch from the air separator to the base fuel tank, a ventilation isolation valve located on a passage between the auxiliary fuel tank and the ventilation tank of the base fuel tank, and a cabin bleed air valve located on a passage from the auxiliary fuel tank to the cabin bleed air, wherein the auxiliary fuel tank inerting process comprises the following steps: a) The auxiliary fuel tank system controller and the inerting system controller detect that the auxiliary fuel tank system fuel has been consumed, triggering the auxiliary fuel tank system inerting function; b) opening the ventilation isolation valve, closing the cabin bleed air valve, closing the inerting system temperature isolation valve, and flushing the inerting auxiliary oil tank with nitrogen-rich gas for a period of time; c) closing the ventilation isolation valve, pressurizing the auxiliary fuel tank to the cabin pressure using the nitrogen-rich gas and then stopping pressurization, thus completing the storage of the nitrogen-rich gas; d) Open the cabin bleed air valve, open the inerting system temperature isolation valve, close the ventilation isolation valve, and restore the basic fuel tank inerting architecture.

11. The operating method according to claim 9, characterized in that: The auxiliary fuel tank fuel reduction and bleed air pressurization subsystem is provided with an inerting system temperature isolation valve located on a branch from the air separator to the base fuel tank, a ventilation isolation valve located on a passage between the auxiliary fuel tank and the ventilation tank of the base fuel tank, and a cabin bleed air valve located on a passage from the auxiliary fuel tank to the cabin bleed air, wherein the auxiliary fuel tank inerting process comprises the following steps: a) The auxiliary fuel tank system and the inerting system controller detect that the cabin is depressurized and the pressure difference between the auxiliary fuel tank and the basic fuel tank is lower than the threshold value △P1, and the backup gas source is activated; b) closing the temperature isolation valve of the inerting system, opening the ventilation isolation valve, and starting pressurization of the inerting system until the pressure difference between the auxiliary oil tank and the basic oil tank reaches an upper limit ΔP2, and then stopping pressurization; c) Open the temperature isolation valve of the inerting system, close the ventilation isolation valve, restore the basic tank inerting architecture, and wait for the next activation of the backup gas source.

12. An aircraft, characterized in that: The aircraft comprises the auxiliary fuel tank fuel reduction and bleed air pressurization subsystem according to any one of claims 1 to 8.

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