Aircraft fuel system capable of preventing water hammer effect

Abstract

The invention discloses an aircraft fuel oil system capable of preventing water hammer effect, which comprises a fuel oil supply pipeline and an oil return pipeline, the fuel oil supply pipeline comprises an oil tank, a generator and a fuel oil supply pipeline connecting the oil tank and the generator; an electric centrifugal pump, a first one-way valve, a first pressure sensor and an electric gear pump are sequentially mounted on the fuel supply pipeline in the direction from the fuel tank to the generator; the oil return pipeline comprises an oil return pipeline, one end of the oil return pipeline is connected to the fuel oil supply pipeline between the first one-way valve and the first pressure sensor, the other end of the oil return pipeline is connected with the oil tank, a second one-way valve is arranged on the oil return pipeline, and the opening pressure of the second one-way valve is larger than that of the first one-way valve.

Description

Technical Field

[0001] The invention relates to aircraft fuel system technology, and in particular to an aircraft fuel system that is free from water hammer effect. Background Art

[0002] The aircraft fuel system is a comprehensive system that integrates many functional subsystems. Figure 1 As shown, it includes a fuel tank 11 and a generator 12 and a fuel supply pipeline 13 connecting the fuel tank 11 and the generator 12. The fuel supply pipeline 13 is sequentially installed with an electric centrifugal pump 14, a first non-return valve 15, a first pressure sensor 16 and an electric gear pump 17 from the fuel tank 11 to the generator 12. The aircraft fuel system mainly provides fuel with a certain pressure and flow rate for the aircraft power unit. At present, there are few studies on the pressure pulsation of aircraft fuel systems at home and abroad. When the refueling shut-off valve is closed or when the engine, electric gear pump, etc. are suddenly closed, the pressure in the upstream pipeline will increase. For the single-point refueling system, there is an obvious "water hammer" phenomenon, which causes a strong impact on the first pressure sensor, making its diaphragm prone to pits, which affects its acquisition accuracy and even causes damage. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the aircraft fuel system with water hammer resistance provided by the present invention solves the problem that the diaphragm of the pressure sensor of the prior aircraft fuel system is prone to pitting under the water hammer phenomenon.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] Provided is an aircraft fuel system that resists water hammer effect, comprising a fuel supply pipeline and an oil return pipeline, wherein the fuel supply pipeline comprises a fuel tank and a generator and a fuel supply pipeline connecting the fuel tank and the generator, wherein the fuel supply pipeline is sequentially installed with an electric centrifugal pump, a first one-way valve, a first pressure sensor and an electric gear pump in a direction from the fuel tank to the generator;

[0006] The oil return pipeline includes an oil return pipeline, one end of which is connected to the fuel supply pipeline between the first one-way valve and the first pressure sensor, and the other end is connected to the fuel tank. A second one-way valve is arranged on the oil return pipeline, and the opening pressure of the second one-way valve is greater than the opening pressure of the first one-way valve.

[0007] Furthermore, when the aircraft fuel system is not provided with an oil return pipeline, if the energy generated by the water hammer effect meets the energy recovery requirements, an axial flow generator set is provided between the fuel tank and the second one-way valve, and the axial flow generator set is connected to the battery.

[0008] Furthermore, the method for determining whether the energy generated by the water hammer effect meets the energy recovery requirement includes:

[0009] S1. Calculate the pressure wave velocity Vw based on the inner diameter, wall thickness and elastic modulus of the fuel supply pipeline:

[0010]

[0011] Where K is the bulk elastic modulus of the medium in the fuel supply pipeline, Pa; ρ is the density of the fuel medium, kg / m 3 ;d i is the inner diameter of the fuel supply pipeline, mm; t is the wall thickness of the fuel supply pipeline, mm; E is the elastic modulus of the pipeline, Pa;

[0012] S2. Calculate the pressure change ΔP caused by water hammer based on the pressure wave velocity:

[0013] ΔP=Vw·ΔV·ρ·10 -5

[0014] Among them, V W is the pressure wave velocity, m / s; △V is the fuel medium flow velocity, m / s;

[0015] S3. Calculate the energy recovery efficiency based on the pressure change and the speed and torque of the axial flow generator set:

[0016] η=ΔP·Q / (n·T)

[0017] Where η is the energy recovery efficiency, kW; Q is the fuel medium flow, m 3 / kg; n is the speed of the axial flow generator set, r / min; T is the torque of the axial flow generator set, N·m;

[0018] S4. Determine whether the energy recovery efficiency is greater than or equal to the preset recovery rate. If so, it is considered that the energy generated by the water hammer effect meets the energy recovery requirements. Otherwise, it is considered that the energy generated by the water hammer effect does not meet the energy recovery requirements.

[0019] Furthermore, the preset recovery rate is 90%.

[0020] Furthermore, a second pressure sensor is provided between the electric centrifugal pump and the first one-way valve.

[0021] Furthermore, when the electric centrifugal pump and the electric gear pump are working, the electric centrifugal pump is started before the electric gear pump.

[0022] Furthermore, a vent valve is provided on the oil tank.

[0023] The beneficial effects of the present invention are as follows: after the return oil pipeline is set in this scheme, when the generator and the electric gear pump are closed, the pressure between the first one-way valve and the electric gear pump will increase in a short time. When the pressure increases to the opening pressure of the second one-way valve, the second one-way valve will be opened. At this time, the fuel between the first one-way valve and the electric gear pump will return to the fuel tank through the return oil pipeline, and the pressure between the first one-way valve and the electric gear pump will be released to avoid the impact of a large pressure on the first pressure sensor, thereby avoiding the appearance of pits in the diaphragm of the first pressure sensor, which will cause poor pressure measurement accuracy or sensor damage.

[0024] The premise of setting up an axial flow generator set in this scheme is that the energy generated by the water hammer effect meets the energy recovery requirements. This is because the water hammer effect lasts for a relatively short time. Only when the energy recovery rate is relatively high can the axial flow generator set recover a certain amount of energy for power generation. Early judgment can avoid the situation where the axial flow generator set cannot recover energy, thereby improving the utilization rate of the axial flow generator set. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a functional block diagram of an aircraft fuel system in the prior art.

[0026] Figure 2 The schematic diagram of an aircraft fuel system that is resistant to water hammer effect is shown in FIG.

[0027] Among them, 1. fuel supply pipeline; 11. fuel tank; 12. generator; 13. fuel supply pipeline; 14. electric centrifugal pump; 15. first one-way valve; 16. first pressure sensor; 17. electric gear pump; 18. second pressure sensor; 19. vent valve; 2. oil return pipeline; 21. second one-way valve; 22. axial flow generator set; 23. battery; 24. oil return pipeline. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0029] like Figure 2As shown, the present solution provides an aircraft fuel system that is resistant to water hammer effect, which includes a fuel supply pipeline 1 and an oil return pipeline 2. The fuel supply pipeline 1 includes a fuel tank 11 and a generator 12 and a fuel supply pipeline 13 connecting the fuel tank 11 and the generator 12. The fuel supply pipeline 13 is sequentially installed with an electric centrifugal pump 14, a first one-way valve 15, a first pressure sensor 16 and an electric gear pump 17 from the fuel tank 11 to the generator 12; and a vent valve 19 is arranged on the fuel tank 11.

[0030] The oil return pipeline 2 includes an oil return pipeline 24, one end of which is connected to the fuel supply pipeline 13 between the first one-way valve 15 and the first pressure sensor 16, and the other end is connected to the fuel tank 11. A second one-way valve 21 is arranged on the oil return pipeline 24, and the opening pressure of the second one-way valve 21 is greater than the opening pressure of the first one-way valve 15.

[0031] The purpose of setting the first pressure sensor 16 is to detect whether the flow rate in the fuel supply pipeline 1 changes abnormally, so as to determine the amount of oil in the fuel tank 11, or whether the aircraft fuel system is in normal working condition, so as to make corresponding response strategies in time.

[0032] During implementation, this solution preferably provides an axial flow generator set 22 between the fuel tank 11 and the second one-way valve 21 when the aircraft fuel system is not provided with an oil return line 2. If the energy generated by the water hammer effect meets the energy recovery requirements, the axial flow generator set 22 is connected to the battery 23.

[0033] In one embodiment of the present invention, a method for determining whether the energy generated by the water hammer effect meets the energy recovery requirement includes:

[0034] S1. Calculate the pressure wave velocity Vw based on the inner diameter, wall thickness and elastic modulus of the fuel supply pipe 13:

[0035]

[0036] Where K is the bulk elastic modulus of the medium in the fuel supply pipeline 13, Pa; ρ is the density of the fuel medium, kg / m 3 ;d i is the inner diameter of the fuel supply pipeline 13, mm; t is the wall thickness of the fuel supply pipeline 13, mm; E is the elastic modulus of the pipeline, Pa;

[0037] S2. Calculate the pressure change ΔP caused by water hammer based on the pressure wave velocity:

[0038] ΔP=Vw·ΔV·ρ·10 -5

[0039] Among them, V Wis the pressure wave velocity, m / s; △V is the fuel medium flow velocity, m / s;

[0040] S3. Calculate the energy recovery efficiency according to the pressure change and the speed and torque of the axial flow generator set 22:

[0041] η=ΔP·Q / (n·T)

[0042] Where η is the energy recovery efficiency, kW; Q is the fuel medium flow, m 3 / kg; n is the rotation speed of the axial flow generator set 22, r / min; T is the torque of the axial flow generator set 22, N·m;

[0043] S4. Determine whether the energy recovery efficiency is greater than or equal to the preset recovery rate. If so, it is considered that the energy generated by the water hammer effect meets the energy recovery requirements. Otherwise, it is considered that the energy generated by the water hammer effect does not meet the energy recovery requirements. The preset recovery rate is preferably 90%.

[0044] This solution adopts the above method to determine whether to set up the axial flow generator set 22, which can avoid introducing the axial flow generator set 22 when the recovery rate is relatively low, which will waste equipment resources and increase equipment investment costs.

[0045] Reference again Figure 1 A second pressure sensor 18 is provided between the electric centrifugal pump 14 and the first one-way valve 15. When the electric centrifugal pump 14 and the electric gear pump 17 are working, the electric centrifugal pump 14 is started before the electric gear pump 17, in order to prevent the electric gear pump 17 from cutting off the flow of fuel between the second pressure sensor 18 and the electric gear pump 17, causing a short-term oil cut-off at the rear end of the electric centrifugal pump 14.

[0046] In summary, after the oil return line 2 is provided in this solution, the impact of a large pressure on the first pressure sensor 16 can be avoided, thereby avoiding pits on the diaphragm of the first pressure sensor 16, resulting in poor accuracy or damage.

Claims

1. An aircraft fuel system that is resistant to water hammer effect, characterized in that: It includes a fuel supply pipeline and an oil return pipeline, wherein the fuel supply pipeline includes a fuel tank and a generator and a fuel supply pipeline connecting the fuel tank and the generator, and the fuel supply pipeline is sequentially installed with an electric centrifugal pump, a first one-way valve, a first pressure sensor and an electric gear pump in the direction from the fuel tank to the generator; The oil return pipeline includes an oil return pipeline, one end of which is connected to the fuel supply pipeline between the first one-way valve and the first pressure sensor, and the other end is connected to the fuel tank. A second one-way valve is arranged on the oil return pipeline, and the opening pressure of the second one-way valve is greater than the opening pressure of the first one-way valve.

2. The aircraft fuel system against water hammer effect according to claim 1, characterized in that: When the aircraft fuel system is not provided with an oil return pipeline, if the energy generated by the water hammer effect meets the energy recovery requirements, an axial flow generator set is provided between the fuel tank and the second one-way valve, and the axial flow generator set is connected to the battery.

3. The aircraft fuel system against water hammer effect according to claim 2, characterized in that: Methods for determining whether the energy generated by the water hammer effect meets the energy recovery requirements include: S1. Calculate the pressure wave velocity Vw based on the inner diameter, wall thickness and elastic modulus of the fuel supply pipeline: Where K is the bulk elastic modulus of the medium in the fuel supply pipeline, Pa; ρ is the density of the fuel medium, kg / m 3 ;d i is the inner diameter of the fuel supply pipeline, mm; t is the wall thickness of the fuel supply pipeline, mm; E is the elastic modulus of the pipeline, Pa; S2. Calculate the pressure change ΔP caused by water hammer based on the pressure wave velocity: ΔP=Vw·ΔV·ρ·10 -5 Among them, V W is the pressure wave velocity, m / s; △V is the fuel medium flow velocity, m / s; S3. Calculate the energy recovery efficiency based on the pressure change and the speed and torque of the axial flow generator set: η=ΔP·Q / (n·T) Where η is the energy recovery efficiency, kW; Q is the fuel medium flow, m 3 / kg; n is the speed of the axial flow generator set, r / min; T is the torque of the axial flow generator set, N·m; S4. Determine whether the energy recovery efficiency is greater than or equal to the preset recovery rate. If so, it is considered that the energy generated by the water hammer effect meets the energy recovery requirements. Otherwise, it is considered that the energy generated by the water hammer effect does not meet the energy recovery requirements.

4. The aircraft fuel system against water hammer effect according to claim 3, characterized in that: The preset recovery rate is 90%.

5. The aircraft fuel system against water hammer effect according to claim 1, characterized in that: A second pressure sensor is arranged between the electric centrifugal pump and the first one-way valve.

6. The aircraft fuel system against water hammer effect according to claim 1, characterized in that: When the electric centrifugal pump and the electric gear pump are working, the electric centrifugal pump starts before the electric gear pump.

7. The aircraft fuel system against water hammer effect according to any one of claims 1 to 6, characterized in that: A vent valve is arranged on the oil tank.

Images