Civil aircraft fuel oil measuring device based on optical fiber sensing

Abstract

The invention relates to a civil aircraft fuel oil measuring device based on optical fiber sensing, which comprises oil tank measurement integration, the oil tank measurement integration comprises an optical fiber grating sensor network consisting of optical fiber grating sensors, and the optical fiber grating sensors are arranged on the side wall of an oil tank; the fiber bragg grating demodulation system is connected with the fiber bragg grating sensor in the oil tank measurement integration; and the data processing system is connected with the fiber bragg grating demodulation system and is configured to obtain the liquid level distribution condition in the fuel tank according to the data from the fiber bragg grating demodulation system, so that the fuel volume in the fuel tank is calculated, and the accurate measurement of the fuel quantity of the airplane is realized.

Description

Technical Field

[0001] The present invention relates to the fields of aircraft health monitoring and route repair and maintenance, and more particularly to a civil aircraft fuel measurement system based on optical fiber sensing. Background Art

[0002] For civil aircraft, the fuel tank is a critical component of the aircraft's structure, a dangerous area that is difficult for maintenance personnel to access. Measuring the fuel (usually fuel oil) status within the tank is crucial for safe flight and improved flight quality. During route operations, maintaining stable fuel tank status is a crucial requirement for aircraft safety and reliability. Unstable fuel levels in the tanks can lead to fuel leaks and even catastrophic accidents.

[0003] Fuel measurement, a core function of aircraft fuel systems, accurately measures the aircraft's fuel load and its distribution within the tanks in real time. To accurately measure the remaining fuel in the tanks, rationally adjust the fuel distribution within each tank, and thereby optimize fuel usage sequencing, calculate aircraft endurance, and improve aircraft maneuverability and stability, real-time monitoring of the aircraft's fuel tank health is necessary.

[0004] At present, domestic aircraft fuel measurement still uses capacitive fuel measurement systems. Due to the limitations of its own principles and characteristics, many problems and defects have gradually been exposed during application, such as susceptibility to electromagnetic interference and complex installation and maintenance. There is a certain gap compared with similar foreign aircraft in terms of measurement accuracy, reliability and maintainability.

[0005] Therefore, in view of the defects of civil aircraft fuel tanks being difficult to access and having a high risk factor, a new type of fuel monitoring method is currently desired, which can solve or minimize the above problems. Summary of the Invention

[0006] To address the issues of current aircraft fuel measurement methods being susceptible to interference and having low security, the present invention proposes a civil aircraft fuel measurement device based on fiber optic sensing. This device uses fiber grating sensors to monitor the fuel tank level and temperature in real time, thereby measuring the fuel distribution in the aircraft tank at different times. This device offers the advantages of high precision and remote monitoring.

[0007] Specifically, this fiber-optic sensing-based fuel measurement device for civil aircraft includes a fuel tank measurement system, which includes a fiber grating sensor network composed of fiber grating sensors arranged in an array on the side walls of the fuel tank; a fiber grating demodulation system, to which the fiber grating sensors in the fuel tank measurement system are connected; and a data processing system, which uses data from the fiber grating demodulation system to determine the liquid level distribution in the fuel tank and thus calculate the fuel volume in the tank. Compared with traditional fuel measurement systems, this system not only achieves high-precision fuel measurement and identifies potential risks such as fuel leaks, but also reduces the installation and maintenance costs of the fuel tank measurement system, which is of great significance for improving the reliability and economic efficiency of aircraft operations.

[0008] In various embodiments, the fuel tank measurement integration includes a left wing fuel tank measurement integration, a right wing fuel tank measurement integration, and a center tank measurement integration.

[0009] In an embodiment of the present invention, fiber grating sensors are arranged in an array on each side wall of the oil tank.

[0010] Advantageously, the fiber grating sensors are arranged such that at least three fiber grating sensors are immersed in the fuel in the fuel tank at any attitude angle of the aircraft.

[0011] Advantageously, the device further comprises an optical fiber sealing joint configured to connect the optical fiber Bragg grating sensor network together through the optical fiber in the oil tank.

[0012] In an embodiment of the present invention, a fiber Bragg grating demodulation system includes a power supply module, a demodulation module, a data processing module, and a data transmission module.

[0013] In an embodiment of the present invention, the data processing system includes a power supply module, a monitoring and display module, a data storage module, a data calculation module, and a data transmission module.

[0014] In an embodiment of the present invention, the fuel volume in the fuel tank is calculated using the following formula:

[0015] ΔV i =ΔhS'=Δz·cosαS=Δz·S xoy ,

[0016] Where, ΔV i is the volume of slice i, Δh is the vertical height of the slice, Δz is the thickness of the slice in the z-axis direction, α is the pitch angle of the fuel liquid surface, S' is the bottom area of the slice, S xoy It is the projection of the intersection of the slice and the tank body on the xoy plane.

[0017] The present invention also relates to an aircraft comprising the above aircraft fuel measuring system.

[0018] Additional features and advantages of the described aircraft fuel gauging system will be set forth in the following detailed description, which includes the following detailed description and the accompanying drawings, and will become apparent to those skilled in the art from the following description or from practicing the embodiments described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] With reference to the above objects, the technical features of the present invention are clearly described in the following claims, and its advantages are apparent from the following detailed description with reference to the accompanying drawings, which show preferred embodiments of the present invention by way of example without limiting the scope of the inventive concept.

[0020] Figure 1 A schematic diagram showing the temperature change after the same volume of liquid and gas absorbs the same amount of heat.

[0021] Figure 2 A schematic diagram of an aircraft fuel measurement system according to an embodiment of the present invention is shown.

[0022] Figure 3 A schematic diagram illustrating the arrangement of a fiber Bragg grating sensor network of an aircraft fuel measurement system according to an embodiment of the present invention is shown.

[0023] Figure 4 A schematic diagram illustrating a fuel level of an aircraft fuel measurement system according to an embodiment of the present invention is shown.

[0024] Figure 5 A conceptual diagram showing a fiber Bragg grating demodulation system of an aircraft fuel measurement system according to an embodiment of the present invention.

[0025] Figure 6 A conceptual diagram illustrating a data processing system for an aircraft fuel measurement system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention in any way.

[0027] The "x-axis" used in this article refers to the axis along the left-right direction in the horizontal attitude of the aircraft (the horizontal axis, Figure 2 The "y-axis" refers to the axis along the left and right direction in the horizontal attitude of the aircraft (the horizontal longitudinal axis, Figure 2 along the vertical direction); and the "z-axis" direction refers to the axis along the vertical direction in the horizontal attitude of the aircraft (vertically passing through Figure 2 ), which is perpendicular to the x-axis and y-axis. The x-axis, y-axis, and z-axis form the aircraft's reference coordinate system. The plane defined by the x-axis and y-axis is called the xoy plane.

[0028] As used herein, "attitude" is used to describe the attitude of an aircraft during flight, such as level, pitch, and yaw. Furthermore, "attitude angle" is used to describe the Euler angles of the aircraft's spatial attitude relative to the aircraft's reference coordinate system formed by the aforementioned x-axis, y-axis, and z-axis, such as the pitch angle, yaw angle, and roll angle.

[0029] To improve the accuracy of fuel monitoring during aircraft flight operations, provide comprehensive warnings, accurately measure the remaining fuel in tanks in real time, rationally adjust fuel distribution across tanks, optimize fuel usage sequencing, calculate aircraft endurance, and improve aircraft maneuverability and stability, this invention utilizes a fiber Bragg grating (FBG) sensor network deployed within the fuel tanks to monitor fuel levels and temperature distribution in real time. Compared to traditional fuel measurement systems, this system not only achieves high-precision fuel measurement and identifies potential risks such as fuel leaks, but also reduces installation and maintenance costs for fuel tank measurement systems, significantly contributing to improved aircraft operational reliability and economic efficiency.

[0030] Refer to the following Figure 1 To illustrate the principle of measuring liquid level using a fiber Bragg grating temperature sensor used in the present invention:

[0031] A fiber Bragg grating (FBG) (referred to herein as "FBG") is an optical device made by periodically changing the refractive index distribution of an optical fiber core. Its core function is to selectively reflect light of a specific wavelength (called the Bragg wavelength) that meets the Bragg condition. It consists of an optical fiber substrate and a grating region, which has a corrugated structure.

[0032] Fiber Bragg grating (FBG) sensors are a type of fiber optic sensor that obtains sensing information by modulating the Bragg wavelength of the fiber optic cable with external physical parameters.

[0033] Unless otherwise specified, fiber Bragg grating (FBG) sensors in this document are generally referred to as FBG temperature sensors. When the temperature rises, the fiber material (usually quartz) expands, changing the grating period and thus shifting the Bragg wavelength. Temperature changes also alter the effective refractive index of the fiber core, further affecting the Bragg wavelength. For example, for every 1°C change in temperature, the wavelength shifts by approximately 10 pm (picometers).

[0034] Data such as the Bragg wavelength can be directly read through the fiber Bragg grating demodulation system, and the data in the fiber Bragg grating demodulation system can be transmitted to the data processing system through the data transmission system. In addition to obtaining the number of sensors and the change in the emission wavelength of the layout points, the temperature change at the sensor position can be determined (for example, 1500.00nm changes to 1500.01nm, indicating a temperature increase of 1°C).

[0035] In short, fiber Bragg grating temperature sensors can detect changes in temperature.

[0036] Secondly, in thermodynamics, the specific heat capacity c is defined as

[0037]

[0038] Where Q is the heat of the object, m is the mass of the object, and ΔT is the temperature difference.

[0039] Then in the aircraft fuel tank, the ratio of temperature change after the same volume of fuel and gas absorb the same amount of heat satisfies:

[0040] ΔT1 / ΔT2=(c2·ρ2) / (c1·ρ1)

[0041] Where ρ is the density of the object (fuel and gas).

[0042] Analysis shows that the same volume of gas and liquid will have different temperature changes after absorbing the same amount of heat, and the temperature change of the liquid is much smaller than that of the gas. Figure 1 As shown in the figure, at the interface between liquid and gas, the temperature will change suddenly. By measuring with fiber grating sensor, this temperature change can be detected, thereby determining the interface between liquid and gas and realizing liquid level monitoring.

[0043] It should be understood that although the embodiments of the present invention use fiber Bragg grating temperature sensors to monitor the liquid level by measuring temperature changes, other types of fiber Bragg grating sensors can also be used to determine the real-time tank liquid level, and these types of fiber Bragg grating sensors are all included in the scope of the present invention.

[0044] like Figure 2 As shown, the aircraft fuel measurement system according to the present invention includes fuel tank measurement assemblies. These assemblies include a left wing tank measurement assembly 1, a right wing tank measurement assembly 2, and a center tank measurement assembly 3. Of course, they may also include measurement assemblies for other tanks. Each tank measurement assembly includes a fiber Bragg grating (FBG) sensor network consisting of fiber Bragg grating (FBG) sensors 10, with each FBG sensor 10 serving as a measurement point. In this embodiment of the present invention, the FBG sensors 10 are arranged in an array on each sidewall of each fuel tank.

[0045] Reference Figure 3-4In the array of fiber grating sensors 10, the vertical and horizontal spacing of the fiber grating sensors 10 can be adjusted according to the height of the fuel tank and the accuracy requirements. The vertical spacing of the fiber grating sensors is typically about 0.2m, about 0.3m, about 0.4m, about 0.5m, or any value therebetween. Alternatively, when high-precision monitoring is required, the spacing of the fiber grating sensors 10 can be as small as about 10cm, as small as about 5cm, or even as small as about 1cm. The fiber grating sensors 10 are uniformly distributed circumferentially in the horizontal direction and typically have a horizontal spacing of about 10cm, about 20cm, about 30cm, about 40cm, about 50cm, or any value therebetween to ensure comprehensive perception of the temperature field and fuel level changes in the fuel tank.

[0046] Since the aircraft's attitude changes during flight, the relationship between the fuel level and the fuel level changes, resulting in attitude errors. Sometimes it is impossible to directly know the fuel level in the fuel tank. Therefore, it is necessary to determine the number and layout of the fiber Bragg grating sensors 10 within the design requirements of the attitude angle range and fuel level range to ensure the continuity of fuel measurement. Figure 3 As shown, the fiber grating sensors 10 are arranged according to the aircraft's attitude changes during flight to form a fiber grating sensor network. Specifically, the unusable fuel level and the maximum usable fuel level in the aircraft's horizontal attitude serve as the sensor installation reference planes. The fiber grating sensors are arranged so that at any aircraft attitude angle, at least three fiber grating sensors 10 are immersed in the fuel in the fuel tank.

[0047] return Figure 2 The aircraft fuel measurement system further includes an optical fiber sealing joint 4, which is configured to connect the fiber Bragg grating sensor network together through the optical fiber in the fuel tank.

[0048] Furthermore, the aircraft fuel measurement system also includes a fiber Bragg grating demodulation system 5, and the fiber Bragg grating sensors in the fuel tank measurement integration are connected to the fiber Bragg grating demodulation system 5, so that data can be obtained from the signals transmitted by the fiber Bragg grating sensors, such as the temperature at the location of each sensor. Figure 5 As shown, the fiber Bragg grating demodulation system 5 includes a power module, a demodulation module, a data processing module, and a data transmission module. The demodulation module is used to calculate the changes in the measured parameters by measuring the wavelength offset and transmit these changes to the data processing module. The data processing module obtains relevant data such as the liquid level and oil level based on the changes in the measured parameters received. The data transmission module is used to transmit the obtained data to the data processing system 6 described below. The uses of these modules are well known to those skilled in the art and will not be detailed here.

[0049] In addition, the aircraft fuel measurement system also includes a data processing system 6, which is connected to the fiber Bragg grating demodulation system 5 and obtains the distribution of the liquid level in the fuel tank based on the data from the fiber Bragg grating demodulation system 5. For example, if there is a significant temperature difference at the positions of two sensors in the vertical direction, it can be known that a part of the liquid level is between the two sensors. The data processing system 6 can also calculate the volume of fuel in the fuel tank based on this. Figure 6 As shown, the data processing system 6 includes a power supply module, a monitoring and display module, a data storage module, a data calculation module, and a data transmission module. The uses of these modules are well known to those skilled in the art and will not be described in detail herein.

[0050] In an embodiment of the present invention, the fuel volume in the fuel tank is calculated using the following formula:

[0051] ΔV i =ΔhS'=Δz·cosαS=Δz·S xoy ,

[0052] Where, ΔV i is the volume of slice i, S' is the bottom area of the slice, Δh is the vertical height perpendicular to the bottom of the slice, Δz is the thickness of the slice in the z-axis direction, α is the pitch angle of the fuel level, S xoy is the projection of the intersection of the slice and the tank body on the xoy plane. The height of slice i can be small enough to be approximated as a cuboid.

[0053] The fuel volume is divided into multiple (i) slices, and the fuel volume in the tank can be obtained by accumulating the slice volumes: V = ∑ΔV i .

[0054] The present invention also provides an aircraft fuel measurement method, which mainly includes the following steps: arranging fiber grating sensors in the fuel tank according to the changes in the aircraft's attitude during flight to form a fiber grating sensor network, and the fiber grating sensors are arranged in an array on the side wall of the fuel tank; using a fiber grating demodulation system to determine data including the liquid level oil surface height and oil surface angle based on the position information and reflection wavelength of the fiber grating sensor network, and the fiber grating sensors are connected to the fiber grating demodulation system; and using a data processing system to calculate the fuel volume in the fuel tank.

[0055] Here are the practical steps for fuel tank monitoring:

[0056] 1) Calibrate the sensitivity coefficient and reflection wavelength of the fiber Bragg grating sensor in different media and temperatures;

[0057] 2) Arrange and fix fiber Bragg grating temperature sensors on the inner wall of the fuel tank according to the sensor layout optimization calculation results, number the fiber Bragg grating sensors with layout numbers, and select sealant for sealing protection;

[0058] 3) Connecting the completed fiber optic Bragg grating sensor network to the fiber optic sealing connector through the optical fiber in the fuel tank, thereby fixing and oil-proofing the optical fiber in the fuel tank;

[0059] 4) Connect the optical fiber sealed connector to the fiber optic Bragg grating demodulation system through the optical fiber in the fuel tank, and the fiber optic Bragg grating demodulation system is provided with direct current through the onboard power supply;

[0060] 5) After the system is connected, carry out on-board joint debugging test, sealing inspection and electromagnetic compatibility test to verify the normal operation of the test and the good sealing of the fuel tank;

[0061] 6) Record the number of fiber Bragg grating sensors detected, record the wavelength obtained in the fiber Bragg grating demodulation system, monitor the measured liquid level height h and liquid surface angle α, and calculate the fuel volume;

[0062] 7) During flight, the data in the fiber Bragg grating demodulation system is transmitted to the data processing system through the data transmission system to obtain the number of fiber Bragg grating sensors and the emission wavelength change of the fiber Bragg grating sensors at the measurement point;

[0063] 8) Combined with the wavelength variation of the fiber grating sensor, the data processing system analyzes and obtains the fuel distribution in the aircraft tank at different times.

[0064] This invention implements fuel monitoring by deploying a fiber Bragg grating sensor network inside the fuel tank, providing real-time measurements of aircraft fuel levels, temperature distribution, and other conditions. Compared to traditional fuel measurement systems, this not only enables high-precision fuel measurement and identifies potential risks such as fuel leaks, but also reduces installation and maintenance costs, significantly improving aircraft operational reliability and economic efficiency.

[0065] Although the structure of the present invention has been described above in conjunction with preferred embodiments, those skilled in the art will recognize that the above examples are for illustration only and are not intended to limit the present invention. Therefore, modifications and variations may be made to the present invention, and such modifications and variations will fall within the scope of the claims appended hereto.

Claims

1. A civil aircraft fuel measurement device based on optical fiber sensing, comprising: A fuel tank measurement integration, comprising a fiber grating sensor network composed of fiber grating sensors, wherein the fiber grating sensors are arranged on the side wall of the fuel tank; A fiber Bragg grating demodulation system, the fiber Bragg grating demodulation system is connected to the fiber Bragg grating sensor in the fuel tank measurement integration; as well as A data processing system is connected to the fiber Bragg grating demodulation system and is configured to obtain the liquid level distribution in the fuel tank based on the data from the fiber Bragg grating demodulation system, thereby calculating the fuel volume in the fuel tank.

2. The civil aircraft fuel measurement device based on optical fiber sensing according to claim 1, characterized in that: The fuel tank measurement integration includes left wing fuel tank measurement integration, right wing fuel tank measurement integration and central fuel tank measurement integration.

3. The civil aircraft fuel measurement device based on optical fiber sensing according to claim 1, characterized in that: The fiber grating sensors are arranged in an array on each side wall of the oil tank.

4. The civil aircraft fuel measurement device based on optical fiber sensing according to claim 3, characterized in that: The fiber grating sensors are arranged so that at least three fiber grating sensors are immersed in the fuel in the fuel tank at any attitude angle of the aircraft.

5. The civil aircraft fuel measurement device based on optical fiber sensing according to claim 1, characterized in that: The invention also includes an optical fiber sealing joint, which is configured to connect the optical fiber Bragg grating sensor network together through the optical fiber in the oil tank.

6. The civil aircraft fuel measurement device based on optical fiber sensing according to claim 1, characterized in that: The fiber Bragg grating demodulation system includes a power supply module, a demodulation module, a data processing module and a data transmission module.

7. The civil aircraft fuel measurement device based on optical fiber sensing according to claim 1, characterized in that: The data processing system includes a power supply module, a monitoring and display module, a data storage module, a data calculation module and a data transmission module.

8. The civil aircraft fuel measurement device based on optical fiber sensing according to claim 1, characterized in that: The fuel volume in the tank is calculated using the following formula: ΔV i =ΔhS'=Δz·cosαS=Δz·S xoy , Where, ΔV i is the volume of slice i, Δh is the vertical height of the slice, Δz is the thickness of the slice in the z-axis direction, α is the oil surface pitch angle, S' is the bottom area of the slice, S xoy It is the projection of the intersection of the slice and the tank body on the xoy plane.

9. A civil aircraft, comprising the civil aircraft fuel measuring device based on optical fiber sensing according to any one of claims 1 to 8.

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