Method and system for determining fuel oil level angle of aircraft oil tank

Abstract

The invention belongs to the technical field of aviation power control, and particularly relates to an aircraft fuel tank fuel oil level angle determination method and system.The aircraft fuel oil level angle theta is defined according to the flight attitude of an aircraft, and when the aircraft flies linearly at a constant speed or is in a static state, the fuel oil level angle theta can be indirectly obtained by reading the attitude angle of the aircraft; when an aircraft accelerates or decelerates, the fuel is acted by the supporting force of the fuel tank structure, the magnitude and direction of the supporting force directly influence the change of the fuel level angle theta, and the relationship between the acceleration, the attitude angle and the fuel level angle theta can be obtained by carrying out stress analysis and calculation on the fuel of a certain mass point in the fuel tank. Related formulas can be compiled and calculated through simple computer languages, the calculation precision of the fuel oil measurement system can be improved, and the problem that the calculation precision of the fuel oil measurement system is low when the attitude of an airplane is changed is solved.

Description

Technical Field

[0001] This invention belongs to the field of aviation power control technology, specifically relating to a method and system for determining the fuel level angle of an aircraft fuel tank. Background Technology

[0002] Aircraft fuel measurement systems typically use a fixed fuel level angle as input parameter to calculate the fuel level in the tank. However, this method suffers from low accuracy when the aircraft's attitude changes. During flight, the fuel level in the tank is affected by flight attitude and acceleration, causing the fuel level angle to constantly change. This changing angle directly impacts the accuracy of the fuel measurement system. If the accuracy of the fuel measurement system falls below the set value, flight safety is compromised. Summary of the Invention

[0003] Purpose of the invention: In view of the above-mentioned prior art, the purpose of this invention is to overcome the shortcomings of the prior art, adapt to the needs of reality, and provide a method for determining the fuel surface angle of an aircraft fuel tank. Using this method, the calculation accuracy of the fuel measurement system can be improved, and the problem of low calculation accuracy of the fuel measurement system when the flight attitude or acceleration changes can be solved.

[0004] Technical Solution: To achieve the above objectives, this invention provides a method for determining the fuel surface angle of an aircraft fuel tank, the method comprising the following steps: Step S1: Define the fuel level angle θ of the aircraft fuel tank according to the aircraft's flight attitude; Step S2: Obtain the aircraft's flight attitude angles. Under the aircraft's accelerated flight state, perform a force analysis on the fuel in the fuel tank and construct a mapping relationship between the aircraft's flight parameters and the fuel level angle in the fuel tank. Step S3: Obtain the aircraft's tilt angle φ and axial acceleration a. x and normal acceleration a z The relationship between the fuel level angle θ in the fuel tank and the fuel level angle in the fuel tank.

[0005] Furthermore, the fuel level angle θ of an aircraft fuel tank is the angle formed between the aircraft fuel tank and the inclined plane at the tilt angle φ relative to the free liquid surface.

[0006] Furthermore, the free surface refers to the fuel level in the fuel tank being parallel to the horizontal plane when the aircraft is in uniform linear motion or at rest; this fuel level is called the free surface.

[0007] Furthermore, when the aircraft accelerates horizontally, the acceleration direction is forward, and the fuel level in the fuel tank is tilted downward relative to the free surface. The fuel level angle θ is defined as a positive value, with the unit being degrees. When the aircraft decelerates horizontally, the acceleration direction is backward, and the fuel level in the fuel tank is tilted upward relative to the free surface. The fuel level angle θ is defined as a negative value, with the unit being degrees.

[0008] Furthermore, in step S2, the force analysis process is as follows: assuming the aircraft fuel tank accelerates upwards at an angle φ, the accelerations in the body coordinate system are respectively axial a... x and normal direction a z acceleration a x and a z It can be decomposed into horizontal acceleration a h Vertical acceleration a v ; The external forces acting on particle A on the surface of the oil include: the downward vertical gravity W=mg; and the resultant force P of the fuel tank wall supporting the fuel, which is perpendicular to the inclined liquid surface.

[0009] Furthermore, by decomposing the gravity W and the supporting force P, the net external force on particle A in the horizontal direction is F. H The net external force acting on particle A in the perpendicular direction is F. V The formula is as follows: F H = ma h =P*sinθ(1) F V = ma V =P*cosθ-mg(2) Furthermore, taking the acceleration of fuel in the fuel tank up a slope as a typical example for force analysis, the net external force on particle A in the horizontal direction is found to be F. H The net external force acting on particle A in the perpendicular direction is F. V The formula is as follows: F H =maxcosφ-mazsinφ(3) F V = maxsinφ+mazcosφ(4) An airplane accelerates up an inclined plane, and the net external force on particle A in the horizontal direction is F. H Therefore, we can substitute formula (1) into formula (3) to obtain formula (5). P*sinθ= maxcosφ-mazsinφ(5) An airplane accelerates up an inclined plane, and the net external force acting on particle A in the vertical direction is F. v Therefore, we can substitute formula (2) into formula (4) and simplify it to obtain formula (6). P*cosθ= maxsinφ+mazcosφ+mg(6).

[0010] Furthermore, dividing formulas (5) and (6) yields the tangent formula (7) for the oil surface angle of particle A. tanθ= (7).

[0011] Furthermore, the relationship between the aircraft's tilt angle φ, axial acceleration ax, and normal acceleration az and the fuel level angle θ in the fuel tank during flight is derived as follows: θ=arctan( (8).

[0012] In another aspect, the present invention also proposes a system for determining the fuel level angle of an aircraft fuel tank, the system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the determination method described above.

[0013] Technical effects: The method of this invention is simple, and the relevant formulas can be compiled and calculated using a simple computer language, which can improve the calculation accuracy of the fuel measurement system and solve the problem of low calculation accuracy of the fuel measurement system when the aircraft attitude changes. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the change in fuel level in the fuel tank according to the present invention; Figure 2 This is a schematic diagram of the forces acting on the fuel level in the fuel tank according to the present invention; Figure 3 This is a schematic diagram comparing the liquid level positions according to the present invention. Detailed Implementation

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings or specific implementation examples. It should be noted that some (but not all) of the disclosed examples are shown in the drawings. In fact, many different examples can be described, and these examples should not be construed as limited to the examples set forth herein. Rather, these examples are described to better demonstrate the positive effects of the present invention, and all aspects not detailed herein are considered to be well-known or conventional techniques in the art.

[0016] See appendix Figures 1-3 The method for determining the fuel level angle of an aircraft fuel tank proposed in the specific implementation of this invention defines the fuel level angle θ according to the aircraft's flight attitude. When the aircraft is flying at a constant speed in a straight line or is stationary, the fuel level angle θ can be indirectly obtained by reading the aircraft's attitude angle. When the aircraft accelerates or decelerates, the fuel is subjected to the support force of the fuel tank structure. The magnitude and direction of the support force directly affect the change of the fuel level angle θ. By performing force analysis and calculation on the fuel at a certain mass point in the fuel tank, the relationship between acceleration, attitude angle and fuel level angle θ can be obtained.

[0017] In this implementation, the force analysis process is as follows: taking the acceleration motion of a typical fuel tank on an inclined plane with an angle of inclination φ as an example, the change of the fuel surface angle in the fuel tank when the aircraft accelerates at an angle of pitch φ can be simulated. First, the fuel surface angle θ of the fuel tank needs to be defined. Then, based on the attitude and acceleration of the aircraft at that moment, the force analysis of the fuel in the fuel tank is carried out. Finally, the fuel surface angle θ is obtained through relevant calculation formulas. When the aircraft fuel tank accelerates upward at an angle φ, the accelerations in the body coordinate system are axial ax and normal az, respectively; the accelerations ax and az can be decomposed into horizontal acceleration ah and vertical acceleration av. The external forces acting on particle A on the surface of the oil include: the downward vertical gravity W=mg; and the resultant force P of the fuel tank wall supporting the fuel, which is perpendicular to the inclined liquid surface.

[0018] Decomposing the gravity W and the supporting force P, the net external force on particle A in the horizontal direction is F. H The net external force acting on particle A in the perpendicular direction is F. V The formula is as follows: F H = ma h =P*sinθ(1) F V = ma V =P*cosθ-mg(2) Taking the acceleration of fuel in a fuel tank up an inclined plane as a typical example, force analysis is performed, and the net external force on particle A in the horizontal direction is found to be F. H The net external force acting on particle A in the perpendicular direction is F. V The formula is as follows: F H =maxcosφ-mazsinφ(3) F V = maxsinφ+mazcosφ(4) An airplane accelerates up an inclined plane, and the net external force on particle A in the horizontal direction is F. H Therefore, we can substitute formula (1) into formula (3) to obtain formula (5). P*sinθ= maxcosφ-mazsinφ(5) An airplane accelerates up an inclined plane, and the net external force acting on particle A in the vertical direction is F. v Therefore, we can substitute formula (2) into formula (4) and simplify it to obtain formula (6). P*cosθ= maxsinφ+mazcosφ+mg(6).

[0019] Furthermore, by dividing formula (5) by (6), we obtain the tangent formula (7) for the oil surface angle of particle A. tanθ= (7) The relationships between the aircraft's bank angle φ, axial acceleration ax, and normal acceleration az and the fuel level angle θ in the fuel tank during flight are as follows: θ=arctan( (8).

[0020] Example 2, as follows Figures 1 to 2 As shown, this invention provides a method for determining the fuel level angle of an aircraft fuel tank. It requires defining the acceleration direction and unit for each axis of the aircraft, the angular direction of the aircraft, and the direction and unit of the free fuel level angle based on the aircraft coordinate system, thereby calculating the free fuel level angle of the fuel tank. The axial acceleration ax is defined as positive forward, and the normal acceleration az is defined as positive upward. Assuming the aircraft accelerates at a pitch angle of 2°, the acceleration ax at that moment is 1.5 m / s². 2 az = 0.8 m / s 2 The tilt angle φ = 2°. Based on formula (8), the fuel level angle θ in the fuel tank is 7.85°, and the liquid level shape is as follows: Figure 1 .

[0021] like Figure 3 As shown, taking a cube with dimensions of 1000mm (length, width, and height) as an example, a single sensor measures the highest liquid level, and the corresponding volume is output based on the liquid level height-volume relationship. If sensor 8 outputs a height of 1000mm, and using a fixed fuel level angle θ=0°, the volume corresponding to the liquid level position 6 in the fuel tank is calculated to be 1000L. The actual fuel level angle in the fuel tank is θ=7.85°, and the liquid level position is 7, corresponding to a volume of 931L. The difference between the two is 69L, and the ratio of this difference to the actual volume is approximately 7.4%. Therefore, using the fuel level angle determined by this patented method, the liquid volume calculation is more accurate.

[0022] In the specific implementation process, the fuel tank fuel level angle is provided to the aircraft fuel measurement system based on the defined free fuel level angle direction and the calculated value. The fuel measurement system then analyzes the corresponding fuel tank quantity.

[0023] The above specific embodiments or examples are only used to explain the technical solutions of the present invention and are not intended to limit the present application. Parts not described in detail are considered to be conventional technical means or common knowledge in the field. It can be understood by those skilled in the art that, based on the design concept of the present application, the technical solutions described in the foregoing embodiments can be adapted or some or all of the technical features can be equivalently replaced. These modifications, equivalent replacements, and adaptive improvements do not depart from the technical essence of the present invention and should all be covered within the protection scope of the present application.

Claims

1. A method for determining the fuel level angle in an aircraft fuel tank, characterized in that, The method includes the following steps: Step S1: Define the fuel level angle θ of the aircraft fuel tank according to the aircraft's flight attitude; Step S2: Obtain the aircraft's flight attitude angles. Under the aircraft's accelerated flight state, perform a force analysis on the fuel in the fuel tank and construct a mapping relationship between the aircraft's flight parameters and the fuel level angle in the fuel tank. Step S3: Obtain the aircraft's tilt angle φ and axial acceleration a. x and normal acceleration a z The relationship between the fuel level angle θ in the fuel tank and the fuel level angle in the fuel tank.

2. The method for determining the fuel level angle in an aircraft fuel tank as described in claim 1, characterized in that, The fuel level angle θ of an aircraft fuel tank is the angle formed between the aircraft fuel tank and the free surface at an inclination angle φ.

3. The method for determining the fuel level angle in an aircraft fuel tank as described in claim 1, characterized in that, The free surface is the fuel level in the fuel tank that is parallel to the horizontal plane when the aircraft is in uniform linear motion or at rest.

4. The method for determining the fuel level angle in an aircraft fuel tank as described in claim 1, characterized in that, When the aircraft accelerates horizontally, the acceleration direction is forward, and the fuel level in the fuel tank is tilted downward relative to the free surface. The fuel level angle θ is defined as a positive value, with the unit being degrees. When the aircraft decelerates horizontally, the acceleration direction is backward, and the fuel level in the fuel tank is tilted upward relative to the free surface. The fuel level angle θ is defined as a negative value, with the unit being degrees.

5. The method for determining the fuel level angle in an aircraft fuel tank as described in claim 4, characterized in that, In step S2, the force analysis process is as follows: assuming the aircraft fuel tank accelerates upwards at an angle φ, the accelerations in the body coordinate system are axial a and axial a. x and normal direction a z acceleration a x and a z It can be decomposed into horizontal acceleration a h Vertical acceleration a v ; The external forces acting on particle A on the surface of the oil include: the downward vertical gravity W=mg; and the resultant force P of the fuel tank wall supporting the fuel, which is perpendicular to the inclined liquid surface.

6. The method for determining the fuel level angle in an aircraft fuel tank as described in claim 5, characterized in that, Decomposing the gravity W and the supporting force P, the net external force on particle A in the horizontal direction is F. H The net external force acting on particle A in the perpendicular direction is F. V The formula is as follows: F H = but h =P*sinθ(1) F V = ma V =P*cosθ-mg(2) 。 7. The method for determining the fuel level angle in an aircraft fuel tank as described in claim 6, characterized in that, Force analysis was performed on the fuel in the tank accelerating up an inclined plane, and the net external force on particle A in the horizontal direction was found to be F. H The net external force acting on particle A in the perpendicular direction is F. V The formula is as follows: F H =maxcosφ-mazsinφ(3) F V = maxsinφ+mazcosφ(4) An airplane accelerates up an inclined plane, and the net external force on particle A in the horizontal direction is F. H Therefore, we can substitute formula (1) into formula (3) to obtain formula (5). P*sinθ= maxcosφ-mazsinφ(5) An airplane accelerates up an inclined plane, and the net external force acting on particle A in the vertical direction is F. v Therefore, we can substitute formula (2) into formula (4) and simplify it to obtain formula (6). P*cosθ= maxsinφ+mazcosφ+mg(6).

8. The method for determining the fuel level angle in an aircraft fuel tank as described in claim 7, characterized in that, Dividing formulas (5) and (6) yields the tangent formula (7) for the oil surface angle of particle A. tanθ= (7)。 9. The method for determining the fuel level angle in an aircraft fuel tank as described in claim 8, characterized in that, The relationships between the aircraft's bank angle φ, axial acceleration ax, and normal acceleration az and the fuel level angle θ in the fuel tank during flight are as follows: θ=arctan( )(8)。 10. A system for determining the fuel level angle of an aircraft fuel tank, the system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the determination method as described in any one of claims 1 to 9.

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