Leak detection for pressurized fluid systems

In accordance with at least one aspect of this disclosure, a fluid system of an aircraft includes a primary fluid conduit that conveys a primary fluid, and a leak detection system disposed around at least a portion of the primary fluid conduit and forming one or more detection volumes. The leak detection system determines whether there is a primary fluid leak into the one or more detection volumes by sensing a pressure change in the one or more detection volumes.

FIELD

This disclosure relates to pressurized fluid systems. There is always a need in the art for improvements to pressurized fluid systems (e.g., fuel systems) in the aerospace industry.

SUMMARY

In accordance with at least one aspect of this disclosure, a fluid system of an aircraft includes a primary fluid conduit that conveys a primary fluid, and a leak detection system disposed around at least a portion of the primary fluid conduit and forming one or more detection volumes. The leak detection system determines whether there is a primary fluid leak into the one or more detection volumes by sensing a pressure change in the one or more detection volumes.

In certain embodiments, the leak detection system includes one or more housings defining the one or more detection volumes, and one or more pressure sensors operatively connected to the one or more of the one or more housings to sense a pressure within a respective detection volume, within a plurality of detection volumes, or within all of the one or more detection volumes. In certain embodiments, the one or more detection volumes includes a first detection volume, and the one or more housings include a first housing disposed around an interface of the fluid conduit. In certain embodiments, the first housing surrounds an entirety of a first primary fluid line of the primary fluid conduit between a first primary fluid system component and a second primary fluid system component to form a first detection volume.

In certain embodiments, the first housing is sealed to the first primary system component and to the second primary system component to encompass a first connection and second connection of the first primary fluid line within the one or more detection volumes. In certain embodiments, the one or more housings include a first housing disposed around a first primary fluid line of the primary fluid conduit between a first primary fluid system component and a second primary fluid system component to form a first detection volume. In certain embodiments, the one or more housings include a second housing disposed around a second primary fluid line of the primary fluid conduit between the second primary fluid system component and a third primary fluid system component to form a second detection volume. In certain embodiments, the second housing is sealed to the second primary system component and to the third primary system component to encompass a first connection and second connection of the second primary fluid line within the one or more detection volumes.

In certain embodiments, the first detection volume and the second detection volume are fluidly isolated from each other. In certain embodiments, the one or more pressure sensors includes at least one pressure sensor for each detection volume.

In certain embodiments, the system includes a bypass line fluidly connecting the first housing and the second housing such that first detection volume and the second detection volume are fluidly connected. In certain embodiments, the one or more pressure sensors is a single pressure sensor.

In certain embodiments, the one or more housings include a single housing that surrounds one or more primary fluid system components of the primary fluid conduit. In certain embodiments, the single housing surrounds all primary fluid system components and all primary fluid lines.

In certain embodiments, the system can include a control system operatively connected to the one or more pressure sensors to determine whether there is a primary fluid leak based on pressure signals from the one or more pressure sensors. The control system can include any suitable computer hardware and/or software module(s) as appreciated by those having ordinary skill in the art.

In certain embodiments, the fluid system is a fuel system and the primary fluid is a fuel. In certain embodiments, the primary fluid is hydrogen. In certain embodiments, the system includes a pressurized secondary fluid filling the one or more detection volume at a lower pressure than an operating pressure of the primary fluid in the primary line.

In accordance with at least one aspect of this disclosure, an aircraft can include a fuel system that is the same as or similar to any suitable embodiment of a fluid system disclosed herein (e.g., described above). In the fuel system, the primary fluid is fuel, for example.

In accordance with at least one aspect of this disclosure, an aircraft engine includes one or more fuel components having a primary fluid conduit that conveys a primary fluid. In certain embodiments, the primary fluid is fuel. The aircraft engine can include a leak detection system as disclosed herein (e.g., as described above). Any other suitable engine components are contemplated herein.

In accordance with at least one aspect of this disclosure, a fluid system of an aircraft comprises a fluid conduit that conveys a primary fluid, the primary fluid being fuel, a housing disposed around at least a portion of the primary fluid conduit and forming a detection volume, and a pressure sensor disposed in operative communication with the housing to sense a pressure within the detection volume. The fluid system also includes a control system operatively connected to the pressure sensor to determine whether there is a primary fluid leak between the fluid conduit and the detection volume based on pressure signals from the pressure sensor.

In accordance with at least one aspect of this disclosure, a leak detection system includes a leak detection module that operatively connects to one or more pressure sensors to receive signals from the one or more pressure sensors that sense pressure of a secondary fluid in a detection volume, the leak detection module operable to execute a method. In certain embodiments, the method includes determining or receiving a detection volume pressure based on the signals from the one or more pressure sensors, comparing the detection volume pressure to a primary leak threshold, and outputting a primary fluid leak signal to indicate a primary fluid leak of a primary fluid between a primary fluid path and the detection volume when the detection volume pressure exceeds the primary leak threshold.

In certain embodiments, the method further includes monitoring the detection volume pressure after crossing the primary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure stabilizes below a primary fluid pressure threshold. In certain embodiments, the method further includes, monitoring the detection volume pressure after crossing the primary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure decreases after crossing the primary fluid leak threshold. In certain embodiments, the method further includes, monitoring the detection volume pressure after crossing the primary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure stabilizes above a primary fluid pressure threshold, and subsequently decreases below the primary fluid pressure threshold.

In certain embodiments, the method further includes comparing the detection volume pressure to a secondary leak threshold, and outputting a secondary fluid leak signal to indicate a secondary fluid leak between the detection volume and an atmosphere if the detection volume pressure declines below the secondary leak threshold. In certain embodiments, the method further includes monitoring the detection volume pressure after crossing the secondary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure stabilizes above an atmosphere pressure threshold. In certain embodiments, the method further includes monitoring the detection volume pressure after crossing the secondary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure increases after crossing the secondary fluid leak threshold.

In certain embodiments, the method further includes monitoring the detection volume pressure after crossing the secondary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure stabilizes below an atmosphere pressure threshold, and subsequently increases above the atmosphere pressure threshold.

In certain embodiments, the system can include an engine control module that controls an engine based on signals received from the leak detection module. In certain embodiments, the engine control module shutdowns the engine and/or a fuel system thereof if a dual primary-secondary fluid leak is detected.

In accordance with at least one aspect of this disclosure, a method for detecting a leak in a fuel system can include determining or receiving a detection volume pressure based on signals from one or more pressure sensors, comparing the detection volume pressure to a primary fluid leak threshold, and outputting a primary fluid leak signal to indicate a primary fluid leak of a primary fluid between a primary fluid path and the detection volume if the detection volume pressure exceeds the primary leak threshold. In certain embodiments, the method further includes monitoring the detection volume pressure after crossing the primary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure stabilizes below a primary fluid pressure threshold.

In accordance with at least one aspect of this disclosure, a method for leak detection of a fluid system includes pressurizing a primary fluid system to a primary fluid pressure, monitoring a detection volume pressure different from the primary fluid pressure, and if the detection volume pressure increases above a primary fluid leak threshold, outputting a primary fluid leak signal, and if the detection volume pressure decreases below a secondary fluid leak threshold, outputting a secondary fluid leak signal. In certain embodiments, the method further includes activating a maintenance indicator in response to the primary fluid leak signal alone or the secondary fluid leak signal alone.

In certain embodiments, the method further includes monitoring the detection volume pressure after outputting the primary fluid leak signal, and if the detection volume pressure decreases from a highest point, determining a dual secondary fluid leak also exists and shutting down the primary fluid system. In certain embodiments, the method further includes monitoring the detection volume pressure after outputting the primary fluid leak signal, and if the detection volume pressure stabilized below a primary fluid pressure threshold, determining a secondary fluid leak also exists and shutting down the primary fluid system.

In certain embodiments, the method further includes monitoring the detection volume pressure after outputting the secondary fluid leak signal, and if the detection volume pressure increases from a lowest point, determining a primary fluid leak also exists and shutting down the primary fluid system. In certain embodiments, the method further includes monitoring the detection volume pressure after outputting the secondary fluid leak signal, and if the detection volume pressure stabilizes above an atmosphere pressure threshold, determining a dual primary-secondary fluid leak exists and shutting down the primary fluid system.

In certain embodiments, the fluid system is a fuel system. In certain embodiments, the fuel system is a hydrogen fuel system for an aircraft. Any other suitable fluid system or fuel type system is contemplated herein.

DETAILED DESCRIPTION

In certain embodiments, referring toFIG.1, an aircraft1can include an engine10, where the engine can be a propulsive energy engine (e.g. creating thrust for the aircraft1), or a non-propulsive energy engine. The engine can include a fluid system100, configured to convey a primary fluid therethrough. In certain embodiments, the primary fluid is fuel. In certain embodiments, the primary fluid is hydrogen (e.g., liquid or gas). For example, the embodiment of a fluid system100shown inFIG.1is a high pressure hydrogen fuel system with plurality of fuel system components (e.g., a tank, a shut off valve, a pump, an accumulator, a pressure regulating valve (PRV), a metering unit, and a manifold shutoff valve, or any other suitable components or combination thereof).

In the present embodiment, the engine10is a turbofan engine, although the present technology may likewise be used with other engine types. The engine10includes a compressor14in a primary gas path12to supply compressed air to a combustor of the aircraft engine10. The fluid system100can be or include any suitable embodiment of a fluid system disclosed herein below, e.g., fluid system200,300,400, or500as described below. As shown in the embodiment ofFIG.1, the fluid system100is a fuel system that supplies fuel to the combustor through a nozzle manifold for mixture with the pressurized air and combustion within the combustor.

In accordance with at least one aspect of this disclosure, referring toFIG.2, the fluid system200can include a primary fluid conduit201that conveys a primary fluid (e.g., a fuel or any other suitable pressurized fluid). The fluid system200can include a first primary fluid line203a. A leak detection system250can be disposed around at least a portion of the primary fluid conduit201and forms one or more detection volumes (e.g., detection volume251a). The leak detection system250can determine whether there is a primary fluid leak into the one or more detection volumes251aby sensing a pressure change in the one or more detection volumes251a. For example, the leak detection system250can include a housing253athat defines a detection volume251a, surrounding the first primary fluid line203a. The one or more detection volumes251acan be a sealed volume in certain embodiments, e.g., as shown, with no flow intended therein such that the one or more detection volumes251ahold a static pressure.

Each sealed detection volume251acan be pressurized with any suitable static pressurized fluid. For example, the static pressurized fluid can include air, inert gas, or any other suitable fluid and can fill the one or more detection volumes251aat a lower pressure than an operating pressure of the primary fluid (e.g., hydrogen) in the primary fluid conduit201(to allow the primary fluid to leak into the one or more detection volumes and raise a pressure thereof to detect the leak). However, it is contemplated a higher pressure can be had in the detection volume251asuch that the static pressurized fluid is allowed to leak into the primary fluid conduit201to cause a drop in pressure, where a drop in pressure can be indicative of a leak between the primary fluid conduit201and the respective detection volume251a(e.g., assuming no leak to the atmosphere).

While certain embodiments can have one or more detection volumes251athat are sealed (e.g. holding a static fluid), certain embodiments can may be an unsealed volume (e.g., sweep structure where static pressure increase can be detected in flow). In certain embodiments, it is contemplated that the one or more detection volumes251amay form a portion of any suitable secondary flow channel.

In certain embodiments, the one or more housings can be or include a first housing253adisposed around a first primary fluid line203aof the primary fluid conduit201between a first primary fluid system component205aand a second primary fluid system component205bto form a first detection volume251a. In certain embodiments, the first housing253asurrounds and entirety of a first primary fluid line203aof the primary fluid conduit201between a first primary fluid system component205aand a second primary fluid system component205bto form a first detection volume251a.

The housing253acan be disposed between any suitable system components (e.g., system components205aand205b) in the first primary fluid line203a. For example, the system components205a,205bcan include a valve, a pump, a metering device, or any other suitable component (e.g., in a fuel system for example). In certain embodiments, the housing253ais sealed to the first primary system component205a(e.g., at a first end of the housing253a) and to the second primary system component205b(e.g., at a second end of the housing253a) to encompass a first connection207aand second connection207bof the first portion of the first primary fluid line203awithin the interior detection volumes251a.

The leak detection system250can include a pressure sensor255adisposed in operative communication with the housing253ato sense a pressure within the detection volume251a, e.g., to sense changes in pressure within the detection volume251a. The pressure sensor255acan be used to determine whether there is a fluid leak between the primary fluid conduit201and the detection volume251aby sensing a pressure change in the detection volume251a. While a single housing253a, detection volume251a, and sensor255ais shown in the embodiment ofFIG.2, it is contemplated herein that any suitable number of housings, detection volumes, and sensors is contemplated herein, for example as described further herein below with respect to systems300,400, and500. Similarly, any suitable portion(s) of the fluid conduit (e.g., lines and or components) can be covered by any suitable number of housings and detection volumes.

In certain embodiments, a control system259is operatively connected to the pressure sensor255aand includes a leak detection module259a, to determine whether there is a fluid leak from (or into) the primary fluid conduit201based on pressure signals from pressure sensors255a. For example, in certain embodiments, if the static pressure of the detection volume251aincreases above a predetermined threshold, the control system259will indicate there is a leak from at least the primary fluid conduit into the detection volume251a. Also, in certain embodiments, if the static pressure of the detection volume251adecreases below a predetermined threshold, the control system259will indicate there is at least a leak in the housing253asuch that fluid is escaping from the detection volume251ato the atmosphere. Embodiments of control logic of the control system259are described further herein below (e.g., with respect toFIGS.6-10).

In certain embodiments, the leak detection system can include an engine control module259boperatively connected to the leak detection module259a. The engine control module259bcan be part of or otherwise separate from the control system259, similar to the leak detection module259a. The engine control module259bcan control an engine (e.g., aircraft engine10) based on signals received from the leak detection module259a. In certain embodiments, the engine control module259bshutdowns the engine and/or a fuel system thereof if a dual primary-secondary fluid leak is detected, for example. In certain embodiments, the engine control module259bcan continue to operate if only one leak type is detected, while sending a maintenance and/or warning signal (e.g., to a cockpit device).

The control system259, the leak detection module259a, the engine control module259b, and any other module(s) disclosed herein can include any suitable computer hardware and/or software module(s) configured to execute a method (e.g., computer executable instructions stored on a non-transitory computer readable medium of the control system259). Any suitable portion (e.g., all) of the leak detection module259aand engine control module259bcan be hosted on the control system259and/or in any other suitable location in any suitable delineation.

Referring to the system300ofFIG.3, in certain embodiments, a leak detection system350can be similar to that of leak detection system250. For brevity, the description of common elements that have been described above are not repeated. In leak detection system350, a second housing253bcan be disposed around a second primary fluid line203bof the fluid conduit301, forming a second detection volume251bfluidly isolated from the fluid conduit301. The second housing253bcan be sealed to the second primary system component205band to a third primary system component205cto encompass a first connection207cand second connection207dof the second primary fluid pipe203bwithin the detection volume251b.

In certain embodiments, the pressure sensor255acan include at least one pressure sensor255a,255bfor each detection volume251a,251b. In certain embodiments, the pressures within the different detection volumes251a,251bcan be different (e.g., due to different primary fluid pressure at different sections of the primary fluid conduit). However, in certain embodiments, pressure can be the same in different detection volumes.

In certain embodiments, referring toFIG.4, the system400can be similar to that of leak detection systems200and300. For brevity, the description of common elements that have been described above are not repeated. Leak detection system450can additionally include a bypass line257fluidly connecting the first housing253aand the second housing253bsuch that first detection volume251aand the second detection volume251bare fluidly connected. In certain embodiments, pressure sensor255acan be a single pressure sensor255adetection volume251aand251b.

In certain embodiments, e.g., as shown in the system500ofFIG.5the system500can be similar to that of leak detection systems200,300, and400. For brevity, the description of common elements that have been described above are not repeated. Leak detection system550can include a single housing553that surrounds fluid system components205a,205b,205cof the fluid conduit301. In certain embodiments, e.g., as shown inFIG.5, the single housing553surrounds all primary fluid system components205a,205b,205cand all fluid lines203a,203b. In certain embodiments, the pressure sensor255acan be a single pressure sensor255afor the detection volume551.

Any suitable number of housings and detection volumes is contemplated herein. Any suitable portion(s) of the primary fluid line (e.g., pipes and or components) can be covered by any suitable number of housings and detection volumes.

In accordance with at least one aspect of this disclosure, an aircraft engine includes one or more fuel components having a primary fluid line that conveys a primary fluid. In certain embodiments, the primary fluid is fuel. The aircraft engine can include a fluid system as disclosed herein (e.g., as described above) and a leak detection system (e.g.,250,350,450,550) as disclosed herein (e.g., as described above). Any other suitable engine components are contemplated herein.

In accordance with at least one aspect of this disclosure, a fluid system (e.g.200,300,400,500) of an aircraft1includes a fluid conduit201that conveys a primary fluid (e.g. hydrogen fuel), a housing253adisposed around at least a portion of the primary fluid conduit201and forming a detection volume251a, a pressure sensor255adisposed in operative communication with the housing253ato sense a pressure within the detection volume251a, and a control system259operatively connected to the pressure sensor255ato determine whether there is a primary fluid leak between the fluid conduit201and the detection volume251abased on pressure signals from the pressure sensor255a. Any other suitable fluid system components are contemplated herein.

As shown inFIG.6, and with additional reference toFIGS.7-10, in certain embodiments, a method600can include determining or receiving (e.g., at block601) a detection volume pressure702based on the signals from the pressure sensors255a,255b. The method600can also include comparing (e.g., at block603) the detection volume pressure702to a primary leak threshold704(e.g., as shown inFIG.7). The method600can also include outputting (e.g., at block605) a primary fluid leak signal to indicate a primary fluid leak of a primary fluid between a primary fluid path and the detection volume251aif the detection volume pressure702exceeds the primary leak threshold704(e.g., as shown in the primary leak example ofFIG.8). Different detection volumes can include different pressure thresholds than that shown inFIG.8. Any suitable pressure thresholds, the same or different, among isolated detection volumes is contemplated herein.

In certain embodiments, the method can further include monitoring the detection volume pressure702after crossing the primary fluid leak threshold704, and outputting a dual primary-secondary fluid leak signal (e.g., individual signals indicating individual leaks, or a single signal indicating both types of leaks) indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure702stabilizes below a primary fluid pressure threshold704(e.g., as indicated inFIG.9where the secondary pressure702stabilizes below the primary pressure706). In certain embodiments, the method further includes monitoring the detection volume pressure702after crossing the primary fluid leak threshold704, and outputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure702decreases after crossing the primary fluid leak threshold704(e.g., as indicated inFIG.9where there the pressure drops after stabilizing). In certain embodiments, the method further includes monitoring the detection volume pressure702after crossing the primary fluid leak threshold704, and outputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume702pressure stabilizes above a primary fluid pressure threshold704, and subsequently decreases below the primary fluid pressure threshold704(e.g., as indicated inFIG.9where the secondary pressure702stabilizes in the primary fluid operating pressure range and then decreases more than the optional secondary pressure delta threshold708).

In certain embodiments, the method further includes comparing the detection volume pressure702to a secondary leak threshold710, and outputting a secondary fluid leak signal to indicate a secondary fluid leak between the detection volume251aand an atmosphere if the detection volume pressure702declines below the secondary leak threshold710(e.g., indicated inFIG.8). In certain embodiments, the method further includes monitoring the detection volume pressure702after crossing the secondary fluid leak threshold710, and outputting a dual primary-secondary fluid leak signal (e.g., as disclosed above) indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure stabilizes above an atmosphere pressure threshold712(e.g., as indicated inFIG.9).

In certain embodiments, the method further includes monitoring the detection volume pressure after crossing the secondary fluid leak threshold710, and outputting a dual primary-secondary fluid leak signal indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure702increases after crossing the secondary fluid leak threshold710(e.g., as shown inFIG.9where pressure increases after stabilizing in the ambient pressure range). In certain embodiments, the method further includes monitoring the detection volume pressure702after crossing the secondary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure702stabilizes below an atmosphere pressure threshold712, and subsequently increases above the atmosphere pressure threshold712(e.g., as shown inFIG.9where pressure increases above a secondary pressure delta714for the secondary leak, e.g., bottom right ofFIG.9).

Any suitable action can be taken in response to an output primary fluid leak signal, a secondary fluid leak signal, or a dual primary-secondary fluid leak signal. For example, in certain embodiments, the control system259can continue to flow primary fluid through the primary fluid conduit if only a single leak is detected, but to shut down the flow of primary fluid if both leaks are detected.

In accordance with at least one aspect of this disclosure, a method for detecting a leak in a fuel system can include determining or receiving a detection volume pressure based on signals from one or more pressure sensors, comparing the detection volume pressure to a primary fluid leak threshold, and outputting a primary fluid leak signal to indicate a primary fluid leak of a primary fluid between a primary fluid path and the detection volume if the detection volume pressure exceeds the primary leak threshold. In certain embodiments, the method further includes monitoring the detection volume pressure after crossing the primary fluid leak threshold, and outputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure stabilizes below a primary fluid pressure threshold.

In accordance with at least one aspect of this disclosure, referring toFIG.10, a method1000for leak detection of a fluid system includes pressurizing (e.g., at block1001) a primary fluid system to a primary fluid pressure, monitoring a detection volume pressure different from the primary fluid pressure (e.g., at block1003), and if the detection volume pressure increases above a primary fluid leak threshold (e.g., as determined at decision block1007), outputting (e.g., at block1009) a primary fluid leak signal. In certain embodiments, if the detection volume pressure decreases below a secondary fluid leak threshold (e.g., as determined at decision block1005), the method1000can include outputting (e.g., at block1011) a secondary fluid leak signal. In certain embodiments, the method1000further includes activating a maintenance indicator (e.g., generating a maintenance action) in response to the primary fluid leak signal alone or the secondary fluid leak signal alone. In certain embodiments, the primary fluid system may continue to function (e.g., if a fuel system, allowing the engine to continue to operate) while notifying a user (e.g., a pilot) that there is a primary or secondary leak and maintenance action is needed.

In certain embodiments, the method1000further includes monitoring (e.g., within block1013) the detection volume pressure after outputting the primary fluid leak signal (e.g., at block1009), and if the detection volume pressure decreases from a highest point (e.g., as determined at decision block1013a), determining a dual secondary fluid leak also exists and shutting down the primary fluid system (e.g., at block1013c). In certain embodiments, the method1000further includes monitoring (e.g., within block1013) the detection volume pressure after outputting the primary fluid leak signal, and if the detection volume pressure stabilizes below a primary fluid pressure threshold (e.g., as determined at block1013b), determining a secondary fluid leak also exists and shutting down the primary fluid system (e.g., at block1013c). As shown, if either condition is true within block1013(which lead to the determination that both leak types are present), the primary flow can be shut down (e.g., shutting down an engine as a result). As shown, there can be a delta to provide hysteresis to prevent false determinations due to error, for example.

In certain embodiments, the method1000further includes monitoring (e.g., within block1015the detection volume pressure after outputting the secondary fluid leak signal, and if the detection volume pressure increases from a lowest point (e.g., as determined at block1015a), determining a primary fluid leak also exists and shutting down the primary fluid system (e.g., at block1015c). In certain embodiments, the method1000further includes monitoring (e.g., within block1015) the detection volume pressure after outputting the secondary fluid leak signal (e.g., at block1011), and if the detection volume pressure stabilizes above an atmosphere pressure threshold (e.g., as determined at block1015b), determining a dual primary-secondary fluid leak exists and shutting down the primary fluid system (e.g., at block1015c). As shown, if either condition is true within1013b(which lead to the determination that both leak types are present), the primary flow can be shut down (e.g., shutting down an engine as a result). As shown, there can be a delta to provide hysteresis to prevent false determinations due to error, for example.

In certain embodiments, the fluid system is a fuel system. In certain embodiments, the fuel system is a hydrogen fuel system for an aircraft. Any other suitable fluid system or fuel type system is contemplated herein.

Embodiments include a secondary system with a pressurized gas or other fluid. With a sealed secondary system, the detection volume can be statically pressurized and the pressure can be monitored for changes to indicate a leak in the primary or secondary system. Any suitable structure is suitable for sealing (e.g., having one or more face seals or other sealing interfaces). Embodiments can have a check valve where one can inject pressurized air or inert gas (e.g., N2), which can allow repressurizing after losing pressure (e.g., if you need to access to primary fluid line).

In certain embodiments, secondary pressure will be less than primary fluid pressure (e.g., which can be at about 650 psi to about 950 psi for hydrogen systems), and higher than the ambient pressure to detect a leak from the secondary fluid into the ambient atmosphere. In certain embodiments, the secondary pressure can be about 25 psi to about 500 psi. Any suitable pressure for the secondary fluid is contemplated herein (e.g., 50 psi, 300 psi, etc.). In certain embodiments, the housing of the leak detection system can be designed to withstand the pressure of the primary fluid, for example to contain a hydrogen leak, e.g., for at least an emergency period of time.

Embodiments can include a pressure sensor that can be in fluid communication with the detection volume. Embodiments can have a pressure sensor for each zone, and can allow accurate determination of where the leak is. In certain embodiments static pressure is shared by two or more detection volumes via a bypass around component in certain embodiments allowing use of a single pressure sensor if desired. In certain embodiments, everything (lines, components) is enclosed within a detection volume.

Embodiments can include a control system having one or more modules. The control system can be part of an engine controller (EEC) or any other suitable aircraft controller, for example. Any other suitable delineation or location is contemplated herein.

Embodiments can include a secondary jacket or line surrounding a primary fluid/fuel (H2 in this case) carrying line that is intended to contain leakage from the primary line or system. The primary lines can be connected between components carrying or using the primary fluid such as fuel tank, regulator, accessories, pumps, metering valves, sensors etc. In certain embodiments, the secondary fluid system can be sealed at all interfaces and is not vented. In certain embodiments, the secondary fluid system can be pressurized to a pressure higher than ambient but lower than the primary fuel pressure. As a non-limiting example, if the primary fluid pressure is between 100 psig and 200 psig, the secondary system can be pressurized to 30 psig. A pressure detector can be installed on the secondary system to detect pressure change. Changes in pressure can indicate leakage.

In certain embodiments, the one or more housings can include a tube fitting for fitting the secondary system to the primary components can be similar to the one described in U.S. patent application Ser. No. 17/246,382, filed Apr. 30, 2021, incorporated by reference herein, except that the connector does not need to contain a “T” for the air vent bridge tube, since no venting is necessary. In certain embodiments, the sealing faces to the secondary line and to the component can be a threaded interface.

Embodiments can include multiple secondary housings and multiple pressure sensors. The secondary system may be arranged such that each primary line has an independent secondary housing such that the secondary housings are not connected. Embodiments can include a multiple pressure sensor arrangement where each secondary system may have different pressure thresholds since the primary pressures may be different from one line to another. In such a system, each secondary line may have a separate pressure sensor. Different thresholds may translate into better detection accuracy. In the case of a leak, this arrangement makes it easy to identify which line is leaking since all the secondary lines are independent.

Certain embodiments can have a single pressure sensor and a bypass connecting a plurality of detection volumes. In such arrangements, multiple or all secondary housings can be connected together through bypass connections that connect adjacent secondary housings around the primary fluid components allowing for a single pressure transducer to detect leakage, which is cost effective.

Certain embodiments can include a single pressure sensor and container. The secondary system can be arranged to completely enclose the primary lines and components. Such arrangements may be most practical if the primary components are small and don't have other interfaces such as electrical connectors. However, any suitable application is contemplated herein.

Embodiments can include a secondary line surrounding a primary line that is sealing the primary line and all the primary line interfaces with adjacent components. In certain embodiments, the primary line carries fluid between two or more components. In certain embodiments, the area between the primary and secondary line is sealed and pressurized with a secondary fluid (may be air) to a pressure higher than ambient air (at all operating altitudes) and lower than the operating pressure range of the primary fluid. In certain embodiments, a pressure sensor is connected to the secondary system to measure the secondary pressure and determine if there is a leak on the primary, secondary or on both systems. In certain embodiments, a single pressure sensor and multiple secondary systems can all be connected via secondary bypass lines. In certain embodiments, multiple secondary systems can be connected to multiple pressure sensors, each system under different secondary pressure. In certain embodiments, a secondary system completely encloses all primary lines and components with a single pressure sensor on the entire secondary system.

Embodiments of this disclosure can address the potential of hydrogen leakage from multiple locations (fittings and connections between hydrogen lines and hydrogen accessories) on a Hydrogen engine, for example. Any other suitable use is contemplated herein. Embodiments can utilize a double jacketed lines with provision for leak protection at the interfaces, in addition to pressurizing the secondary system and having a pressure detection incorporated for leak detection.

During operation (i.e., primary system is pressurized), if the pressure of the secondary system drops below the secondary leak threshold (e.g., 30 psig and some negative margin e.g., about 25 psig), it can indicate that the secondary system has a leak to the outside. At this point, the control system may flag a maintenance action that should be taken to replace the leaking secondary system since it acts as a leak protection of the primary system. If, following the secondary system pressure drop below the secondary leak threshold, the pressure either increases by a value (Secondary Pressure Delta Increase) or stabilizes above ambient pressure, then this indicates that the primary system is also leaking. At this point, the control system may elect to shut down the fuel flow.

For detecting a primary leak, if the pressure of the secondary system increases above the primary leak threshold (e.g., 30 psig and some margin, e.g., about 35 psig), it indicates that there is a leak of the primary fuel into the secondary system. If the secondary system was leak free prior to the primary leak detection, then the control system may allow the pilot to continue flight and flag a maintenance action. If, following the secondary system pressure rise above the primary leak threshold, the pressure either decreases by a value (Secondary Pressure Delta Decrease) or stabilizes below the primary fluid pressure, then this indicates that the secondary system is also leaking. At this point, the control system may elect to shut down the fuel flow.

If, following the secondary system pressure drop below the secondary leak threshold, the pressure stabilizes above ambient pressure, then this indicates that the primary system is also leaking or that the secondary leak has stopped. At this point, the control system may elect to continue pressurizing the primary system (i.e. keep running the engine) and continue monitoring the secondary pressure.

If, following the secondary system pressure increase above the primary leak threshold, the pressure stabilizes below the primary fluid pressure, then this indicates that the secondary system is also leaking or that the primary leak has stopped. At this point, the control system may elect to continue pressurizing the primary system (i.e. keep running the engine) and continue monitoring the secondary pressure.

Embodiments can provide monitoring the pressurized volume of fluid between a primary fluid carrying line and a secondary line, which is sealing the primary line along its length and interfaces. At no leak conditions, the secondary fluid pressure is between ambient air and the operating pressure of the primary fluid. During normal operation, if the secondary pressure rises above a first threshold, it indicates that the primary fluid is leaking into the secondary line. During normal operation, if the secondary pressure drops below a second threshold, it indicates that the secondary system is leaking. If after rising above first threshold, the secondary pressure drops by a certain amount or stabilizes below the primary pressure, it may indicate that the primary system started leaking first followed by a leak on the secondary. Primary fluid shutoff may be required. If after dropping below the second threshold, the secondary pressure rises by a certain amount or stabilizes above ambient, it may indicate that the secondary system started leaking first followed by a leak on the secondary. Primary fluid shutoff may be required.

While the apparatus and methods of the subject disclosure have been shown and described, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.

For example, the following particular embodiments of the present technology are likewise contemplated, as described herein next by clauses.

Clause 1. A fluid system (100,200,300,400, or500) of an aircraft (1), comprising:a primary fluid conduit (201) that conveys a primary fluid; anda leak detection system (250,350,450,550) disposed around at least a portion of the primary fluid conduit and forming one or more detection volumes (251), wherein the leak detection system determines whether there is a primary fluid leak into the one or more detection volumes by sensing a pressure change in the one or more detection volumes.

Clause 2. The system of clause 1, wherein the leak detection system includes;one or more housings (253) defining the one or more detection volumes; andone or more pressure sensors (255) operatively connected to the one or more of the one or more housings to sense a pressure within a respective detection volume, within a plurality of detection volumes, or within all of the one or more detection volumes.

Clause 3. The system of clause 2, wherein the one or more detection volumes includes a first detection volume (251a), wherein the one or more housings include a first housing (253a) disposed around an interface of the fluid conduit.

Clause 4. The system of clause 3, wherein the first housing surrounds and entirety of a first primary fluid line (203a) of the primary fluid conduit between a first primary fluid system component (205a) and a second primary fluid system component (205b) to form a first detection volume (251a).

Clause 5. The system of clause 3, wherein the first housing is sealed to the first primary system component and to the second primary system component to encompass a first connection (207a) and second connection (207b) of the first primary fluid line within the one or more detection volumes.

Clause 6. The system of clause 3, wherein the one or more housings include a second housing (253b) disposed around a second primary fluid line (203b) of the primary fluid conduit between the second primary fluid system component and a third primary fluid system component (205c) to form a second detection volume (251b).

Clause 7. The system of clause 6, wherein the second housing is sealed to the second primary system component and to the third primary system component to encompass a first connection (207c) and second connection (207d) of the second primary fluid line (203b) within the one or more detection volumes.

Clause 8. The system of clause 6, wherein the first detection volume and the second detection volume are fluidly isolated from each other, wherein the one or more pressure sensors includes at least one pressure sensor for each detection volume.

Clause 9. The system of clause 6, further comprising a bypass line (257) fluidly connecting the first housing and the second housing such that first detection volume and the second detection volume are fluidly connected.

Clause 10. The system of clause 9, wherein the one or more pressure sensors is a single pressure sensor (255).

Clause 11. The system of clause 3, wherein the one or more housings include a single housing (253) that surrounds one or more primary fluid system components of the primary fluid conduit.

Clause 12. The system of clause 11, wherein the single housing surrounds all primary fluid system components and all primary fluid lines.

Clause 13. The system of clause 2, further comprising a control system (259) operatively connected to the one or more pressure sensors to determine whether there is a primary fluid leak based on pressure signals from the one or more pressure sensors.

Clause 14. The system of clause 1, wherein the fluid system is a fuel system (100) and the primary fluid is a fuel.

Clause 15. The system of clause 13, wherein the primary fluid is hydrogen.

Clause 16. The system of clause 1, further comprising a pressurized secondary fluid filling the one or more detection volume at a lower pressure than an operating pressure of the primary fluid in the primary line.

Clause 17. An aircraft (1), comprising:a fuel system (100,200,300,400,500), comprising:a primary fluid conduit (201) that conveys a primary fluid, wherein the primary fluid is fuel; anda leak detection system (250,350,450,550) disposed around at least a portion of the primary fluid conduit and forming one or more detection volumes (251), wherein the leak detection system determines whether there is a primary fluid leak into the one or more detection volumes by sensing a pressure change in the one or more detection volumes.

Clause 18. The aircraft of clause 17, wherein the leak detection system includes;one or more housings (253) defining the one or more detection volumes; andone or more pressure sensors (255) disposed on the housing that sense a pressure within the one or more detection volumes.

Clause 19. The aircraft of clause 18, wherein the one or more housings include a first housing (253a) disposed around a first primary fluid line (203a) of the primary fluid conduit between a first primary fluid system component (205a) and a second primary fluid system component (205b) to form a first detection volume (251a).

Clause 20. A fluid system (100,200,300,400,500) of an aircraft (1), comprising:a fluid conduit (201) that conveys a primary fluid, wherein the primary fluid is fuel;a housing (253) disposed around at least a portion of the primary fluid conduit and forming a detection volume (251);a pressure sensor (255) disposed in operative communication with the housing to sense a pressure within the detection volume; anda control system (259) operatively connected to the pressure sensor to determine whether there is a primary fluid leak between the fluid conduit and the detection volume based on pressure signals from the pressure sensor.

Clause 21. A leak detection system (250,350,450,550), comprising:a leak detection module (259a) that operatively connects to one or more pressure sensors (255) to receive signals from the one or more pressure sensors that sense pressure in a detection volume (251), the leak detection module operable to execute a method, the method comprising:determining or receiving a detection volume pressure based on the signals from the one or more pressure sensors;comparing the detection volume pressure to a primary leak threshold (704); andoutputting a primary fluid leak signal to indicate a primary fluid leak of a primary fluid between a primary fluid path and the detection volume when the detection volume pressure exceeds the primary leak threshold.

Clause 22. The system of clause 21, wherein the method further includes:monitoring the detection volume pressure (702) after crossing the primary fluid leak threshold; andoutputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure stabilizes below a primary fluid pressure threshold (706).

Clause 23. The system of clause 21, wherein the method further includes:monitoring the detection volume pressure after crossing the primary fluid leak threshold; andoutputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure decreases after crossing the primary fluid leak threshold.

Clause 24. The system of clause 21, wherein the method further includes:monitoring the detection volume pressure after crossing the primary fluid leak threshold; andoutputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure stabilizes above a primary fluid pressure threshold (706), and subsequently decreases below the primary fluid pressure threshold.

Clause 25. The system of clause 21, wherein the method further includes:comparing the detection volume pressure to a secondary leak threshold (710); andoutputting a secondary fluid leak signal to indicate a secondary fluid leak between the detection volume and an atmosphere if the detection volume pressure declines below the secondary leak threshold.

Clause 26. The system of clause 25, wherein the method further includes:monitoring the detection volume pressure after crossing the secondary fluid leak threshold; andoutputting a dual primary-secondary fluid leak signal indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure stabilizes above an atmosphere pressure threshold (712).

Clause 27. The system of clause 25, wherein the method further includes:monitoring the detection volume pressure after crossing the secondary fluid leak threshold; andoutputting a dual primary-secondary fluid leak signal indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure increases after crossing the secondary fluid leak threshold.

Clause 28. The system of clause 25, wherein the method further includes:monitoring the detection volume pressure after crossing the secondary fluid leak threshold; andoutputting a dual primary-secondary fluid leak signal indicating a primary fluid leak in addition to the secondary fluid leak if the detection volume pressure stabilizes below an atmosphere pressure threshold (712), and subsequently increases above the atmosphere pressure threshold.

Clause 29. The system of clause 21, further comprising an engine control module (259b) that controls an engine (10) based on signals received from the leak detection module.

Clause 30. The system of clause 29, wherein the engine control module shutdowns the engine and/or a fuel system (100,200,300,400,500) thereof if a dual primary-secondary fluid leak is detected.

Clause 31. A method for detecting a leak in a fuel system (100,200,300,400,500), comprising:determining or receiving a detection volume pressure (702) based on signals from one or more pressure sensors (255);comparing the detection volume pressure to a primary fluid leak threshold (704);andoutputting a primary fluid leak signal to indicate a primary fluid leak of a primary fluid between a primary fluid path and the detection volume if the detection volume pressure exceeds the primary leak threshold.

Clause 32. The method of clause 31, further comprising:monitoring the detection volume pressure after crossing the primary fluid leak threshold; andoutputting a dual primary-secondary fluid leak signal indicating a secondary fluid leak in addition to the primary fluid leak if the detection volume pressure stabilizes below a primary fluid pressure threshold (706).

Clause 33. A method for leak detection of a fluid system (100,200,300,400,500), comprising:pressurizing a primary fluid system to a primary fluid pressure (706);monitoring a detection volume pressure (702) different from the primary fluid pressure; andwherein if the detection volume pressure increases above a primary fluid leak threshold (704), outputting a primary fluid leak signal, and wherein if the detection volume pressure decreases below a secondary fluid leak threshold (710), outputting a secondary fluid leak signal.

Clause 34. The method of clause 33, further comprising activating a maintenance indicator in response to the primary fluid leak signal alone or the secondary fluid leak signal alone.

Clause 35. The method of clause 34, further comprising:monitoring the detection volume pressure after outputting the primary fluid leak signal; andwherein if the detection volume pressure decreases from a highest point, determining a dual secondary fluid leak also exists and shutting down the primary fluid system.

Clause 36. The method of clause 34, further comprising:monitoring the detection volume pressure after outputting the primary fluid leak signal; andwherein if the detection volume pressure stabilized below a primary fluid pressure threshold (706), determining a secondary fluid leak also exists and shutting down the primary fluid system.

Clause 37. The method of clause 34, further comprising:monitoring the detection volume pressure after outputting the secondary fluid leak signal; andwherein if the detection volume pressure increases from a lowest point, determining a primary fluid leak also exists and shutting down the primary fluid system.

Clause 38. The method of clause 34, further comprising:monitoring the detection volume pressure after outputting the secondary fluid leak signal; andwherein if the detection volume pressure stabilizes above an atmosphere pressure threshold (712), determining a dual primary-secondary fluid leak exists and shutting down the primary fluid system.

Clause 39. The method of clause 33, wherein the fluid system is a fuel system.

Clause 40. The method of clause 33, wherein the fuel system is a hydrogen fuel system for an aircraft (1).