Method for testing fuel potential during shaking of fuel tank

Abstract

The invention belongs to the field of aircraft fuel tank structure electrostatic protection design, and particularly relates to a fuel tank shaking fuel potential testing method. Comprising the following steps: S1, under-rack preparation work: cleaning an oil tank product and a potential test system component; confirming a test environment; carrying out insulation confirmation on a product installation fixture of the potential test device; testing the resistivity of an oil product; s2, the test product is put on a shelf; s3, performing preparation work before testing, wherein the preparation work comprises oil tank product insulation confirmation; oil tank product nitrogen replacement; filling an oil product; installing a potential testing system; carrying out secondary nitrogen replacement on the oil tank product; and S4, testing the potential. According to the invention, by collecting and cutting a plurality of test standards and through test traction, a set of complete test method is provided for fuel potential test when a metal or composite externally-hung fuel tank or an integral fuel tank shakes, and the problem of fuel potential test measurement when the fuel tank shakes is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of static protection design of aircraft fuel tank structure, and particularly relates to a fuel tank sloshing fuel potential test method. BACKGROUND

[0002] With the use of composite materials in the main load-bearing structure of an aircraft, i.e., a wing component, the composite material structure constituting the overall fuel tank of the wing is usually not a good electrical conductor, which is not conducive to the conduction of fuel static electricity generated by the sloshing of the overall fuel tank of the wing. The accumulation of static electricity may generate a high potential that affects the fuel tank system and further endangers flight safety. The high and low of the static potential generated by the sloshing of the fuel tank is related to the size of the fuel tank, the detail design of the fuel tank system and the selection of the oil product. At present, it is difficult to calculate and simulate the fuel potential of the sloshing of the fuel tank, and only test measurement can be used. The existing standards or documents rarely involve the measurement test of the fuel potential of the sloshing of the fuel tank, and there is no complete test process and method that can be referred to.

[0003] Therefore, there is an urgent need for a technical solution to overcome or alleviate at least one of the above-mentioned defects of the prior art. SUMMARY

[0004] The purpose of the present application is to provide a fuel tank sloshing fuel potential test method to solve at least one problem existing in the prior art.

[0005] The technical solution of the present application is:

[0006] A fuel tank sloshing fuel potential test method, comprising:

[0007] Step S1, preparation work under the rack includes:

[0008] cleaning the fuel tank product and the potential test system components;

[0009] confirming the test environment;

[0010] confirming the product installation type rack insulation of the potential test device;

[0011] testing the resistivity of the oil product;

[0012] Step S2, test the product on the rack;

[0013] Step S3, test preparation work includes:

[0014] confirming the insulation of the fuel tank product;

[0015] nitrogen replacement of the fuel tank product;

[0016] oil filling;

[0017] installation of the potential test system;

[0018] secondary nitrogen replacement of the fuel tank product;

[0019] Step S4, test potential.

[0020] In at least one embodiment of the present application, in step S1, the oil tank product, the potential test system components are cleaned, including:

[0021] The insulating copper ball components of the oil tank product, the potential test system are cleaned multiple times by anhydrous ethanol.

[0022] In at least one embodiment of the present application, in step S1, the test environment is confirmed, including:

[0023] Check whether the ground wire lap joint of the potential test device is intact;

[0024] Record the temperature and humidity of the test room environment.

[0025] In at least one embodiment of the present application, in step S1, the product installation rack insulation of the potential test device is confirmed, including:

[0026] Test the ground insulation resistance of the product installation rack by a static high resistance meter, and the ground insulation resistance is required to be greater than 10 14 Ω;

[0027] Measure the ground capacitance of the product installation rack by a static capacitance meter, and the ground capacitance is required to be less than 100 pF.

[0028] In at least one embodiment of the present application, in step S1, the oil product resistivity test, including:

[0029] Add the oil product to the resistivity test fixture, connect the resistivity tester and the test fixture by a wire, read the measured resistance value, and calculate the oil product resistivity according to the structure size of the resistivity test fixture.

[0030] In at least one embodiment of the present application, step S2, test the product on the rack, including:

[0031] Install the oil tank product on the product installation rack of the potential test device.

[0032] In at least one embodiment of the present application, in step S3, the oil tank product nitrogen replacement, including:

[0033] Fill nitrogen into the oil tank product to replace the air in the oil tank product, and the nitrogen injection amount is converted to three times the volume of the oil tank body at one atmosphere pressure.

[0034] In at least one embodiment of the present application, in step S3, the oil product filling, including:

[0035] Fill 80% of the oil tank volume of fuel into the oil tank product.

[0036] In at least one embodiment of the present application, in step S3, the potential test system is installed, including:

[0037] The insulating copper ball component of the potential test system is installed and fixed in the oil tank product through a flange, ensuring that at least one half of the insulating copper ball component invades the oil liquid, and the flange is insulatively connected with the oil tank product;

[0038] The potential test system is insulated and confirmed.

[0039] In at least one embodiment of the present application, in step S4, the potential is tested, including:

[0040] The initial potential measurement is 0 after being left for a predetermined time;

[0041] The shaking platform of the potential test device is started, and the shaking platform is shaken at a pitch ± 15° amplitude and a frequency of 16 times per minute, while being vibrated at an amplitude of 0.8 mm and a frequency of 33.3 Hz, for 25 hours of continuous shaking; every 0.5 seconds, the time taken from the fuel input into the oil tank product and the corresponding potential value are recorded.

[0042] The present application has at least the following beneficial technical effects:

[0043] The oil tank shaking fuel potential test method of the present application provides a complete test method for the fuel potential test of the metal or composite external oil tank or the whole oil tank when shaking, by collecting and cutting multiple test standards and through test test traction, solves the oil tank shaking fuel potential test measurement problem, and provides a reliable oil tank test system insulation design. BRIEF DESCRIPTION OF DRAWINGS

[0044] Fig. 1 is the oil tank shaking fuel potential test method flowchart of one embodiment of the present application;

[0045] Fig. 2 is a schematic diagram of the oil tank shaking fuel potential test device of one embodiment of the present application;

[0046] Fig. 3 is a schematic diagram of the oil tank shaking fuel potential test system of one embodiment of the present application. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0048] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0049] The following is in conjunction with the appendix Figs. 1 to 3 This application will be described in further detail.

[0050] This application provides a method for testing the fuel potential during fuel tank sloshing, such as... Fig. 1 As shown, it includes the following steps:

[0051] Step S1, preparation work under the rack includes:

[0052] Clean the fuel tank products and components of the potential testing system;

[0053] Test environment verification;

[0054] Insulation verification of the product mounting frame for the potential testing device;

[0055] Oil resistivity testing;

[0056] Step S2: Test product placement;

[0057] Step S3, Pre-test preparations include:

[0058] Insulation verification of fuel tank products;

[0059] Nitrogen purging of fuel tank products;

[0060] Oil filling;

[0061] Installation of the potential testing system;

[0062] Fuel tank products undergo secondary nitrogen purging;

[0063] Step S4: Test potential.

[0064] The fuel tank sloshing fuel potential test method of this application uses a potential testing device such as... Fig. 2 As shown, the potential testing device includes a product mounting frame, a vibration platform, and a vibration testing machine. The boxed product is fixed to the vibration platform of the vibration testing machine using the product mounting frame. Insulation between the product mounting frame and the vibration platform is achieved through the design of bakelite or rubber pads. The fixing fasteners can be insulated from the vibration platform using PTFE sleeves. The potential testing system used is as follows: Fig. 3 As shown, an insulating copper ball component is designed as a current collector electrode. The insulating copper ball component is arranged at the center of the oil level in the oil tank product, and the insulating copper ball component outputs a potential signal to the potential measuring instrument through a wire.

[0065] The fuel tank sloshing fuel potential test method of this application includes the following specific steps:

[0066] In step S1, preparations are made under the rack:

[0067] First, 1) clean the oil tank product and the components of the potential testing system:

[0068] Before testing, the oil tank product and the insulating copper ball components of the potential testing system were cleaned twice with anhydrous ethanol to ensure the insulation of the product being tested and the accuracy of the testing system.

[0069] 2) Test environment verification:

[0070] Check that the grounding wire connection of the potential testing device is intact; ensure that the grounding wire connection of the potential testing device is good.

[0071] Record the ambient temperature and humidity of the laboratory.

[0072] 3) Insulation confirmation of product mounting frame:

[0073] The insulation resistance to ground of the product mounting frame is tested using an electrostatic high-resistance meter, and the insulation resistance to ground is required to be greater than 10. 14 Ω; if it cannot be reached, but can reach 10¹²Ω, the interval between the two measurements should not exceed 1 second;

[0074] Measure the capacitance to ground of the product mounting frame using a capacitance meter. The capacitance to ground should be less than 100 pF.

[0075] 4) Oil resistivity test:

[0076] Add the oil to the resistivity test fixture, connect the resistivity tester to the fixture with two wires, read the measured resistance value, and calculate the oil resistivity based on the structural dimensions of the resistivity test fixture.

[0077] In step S2, the test product is put on the shelf:

[0078] Install the oil tank product onto the product mounting frame of the potential testing device.

[0079] In step S3, the pre-test preparation work includes:

[0080] 1) Insulation confirmation of oil tank products:

[0081] Measure the resistance and capacitance of the oil tank product to ground again according to the insulation confirmation method in step S1 to ensure that the oil tank product is insulated from ground.

[0082] 2) Nitrogen purging of fuel tank products:

[0083] Nitrogen gas is filled into the fuel tank to replace the air inside and prevent the risk of combustion and explosion due to static electricity accumulation during subsequent fuel filling. Nitrogen is injected through the upper air inlet, and the air inside the test chamber is naturally discharged through the lower air outlet. The amount of nitrogen injected is equivalent to three times the volume of the fuel tank at one atmosphere of pressure.

[0084] 3) Oil filling:

[0085] The fuel tank is slowly filled to 80% capacity using the fuel filler nozzle. During the filling process, the nozzle is properly grounded to release static electricity in a timely manner.

[0086] 4) Installation of the potential testing system:

[0087] The insulating copper ball component of the potential testing system is installed and fixed in the oil tank product via a flange. The flange is insulated from the oil tank product. After connecting the potential testing system, the resistance and capacitance to ground of the potential testing system are measured in the same manner as in step S1, ensuring that the potential testing system is insulated from ground. The position of the insulating copper ball component is adjusted to ensure that at least half of the copper ball is submerged in the oil.

[0088] 5) Nitrogen purging of fuel tank products:

[0089] Because some air was introduced during the installation of the potential testing system, nitrogen needs to be replaced again.

[0090] In step S4, the test potential is:

[0091] 1) Initial potential measurement:

[0092] Let it stand for at least 10 minutes to eliminate static electricity and make the initial potential measurement 0;

[0093] 2) Continuous measurement of potential after tank vibration:

[0094] The vibration platform of the potential testing device was started, and it was vibrated at a pitch of ±15° and a frequency of 16 times / minute, while simultaneously oscillating at an amplitude of 0.8 mm and a frequency of 33.3 Hz for 25 hours. Every 0.5 seconds, the time from when the product was put into the fuel tank and the corresponding potential value were recorded. The measured potential of the copper ball is the fuel surface potential at the location of the copper ball.

[0095] This application's fuel tank sloshing potential test method, through the collection and adaptation of multiple test standards and the application of test experiments, has established a complete test method for fuel tank sloshing potential, clarifying the key aspects of the test design. It details the specific operational methods and procedures for each stage of the test, including preparation under the test rack, mounting the test product, pre-test preparation, and the actual test potential testing. A complete fuel tank potential test procedure is provided, clarifying the judgment criteria during the test and offering a reliable fuel tank system insulation design.

[0096] The fuel potential testing method for fuel tank sloshing described in this application can be used to guide the testing of sloshing fuel potential in external or integral fuel tanks made of metal or composite materials. This method significantly reduces trial-and-error costs and shortens the testing cycle. This application has been applied to the sloshing fuel potential testing of an integral fuel tank made of composite material for an aircraft wing. Test results show that the fuel potential testing method for fuel tank sloshing described in this application is scientifically sound and reasonable.

[0097] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for testing fuel potential during fuel tank sloshing, characterized in that, include: Step S1, preparation work under the rack includes: Clean the fuel tank products and components of the potential testing system; Test environment verification; Insulation verification of the product mounting frame for the potential testing device; Oil resistivity testing; Step S2: Test product placement; Step S3, Pre-test preparations include: Insulation verification of fuel tank products; Nitrogen purging of fuel tank products; Oil filling; Installation of the potential testing system; Fuel tank products undergo secondary nitrogen purging; Step S4: Test potential.

2. The fuel tank sloshing fuel potential test method according to claim 1, characterized in that, In step S1, the oil tank product and the components of the potential testing system are cleaned, including: The insulating copper ball components of the oil tank product and the potential testing system were cleaned multiple times with anhydrous ethanol.

3. The fuel tank sloshing fuel potential test method according to claim 2, characterized in that, In step S1, the test environment is confirmed, including: Check whether the grounding wire connection of the potential test device is intact; Record the ambient temperature and humidity of the laboratory.

4. The fuel tank sloshing fuel potential test method according to claim 3, characterized in that, In step S1, the insulation verification of the product mounting frame of the potential testing device includes: The insulation resistance to ground of the product mounting frame is tested using an electrostatic high-resistance meter, and the insulation resistance to ground is required to be greater than 10. 14 Ω; Measure the capacitance to ground of the product mounting frame using a capacitance meter. The capacitance to ground should be less than 100 pF.

5. The fuel tank sloshing fuel potential test method according to claim 4, characterized in that, In step S1, the oil resistivity test includes: Add the oil to the resistivity test fixture, connect the resistivity tester to the fixture via wires, read the measured resistance value, and calculate the oil resistivity based on the structural dimensions of the resistivity test fixture.

6. The fuel tank sloshing fuel potential test method according to claim 5, characterized in that, Step S2, Product testing and listing, including: Install the oil tank product onto the product mounting frame of the potential testing device.

7. The fuel tank sloshing fuel potential test method according to claim 6, characterized in that, In step S3, nitrogen purging of the fuel tank product includes: Nitrogen gas is filled into the fuel tank to replace the air inside. The amount of nitrogen injected is three times the volume of the fuel tank at one atmosphere.

8. The fuel tank sloshing fuel potential test method according to claim 7, characterized in that, In step S3, oil filling includes: Fill the fuel tank product with fuel to 80% of its capacity.

9. The fuel tank sloshing fuel potential test method according to claim 8, characterized in that, In step S3, the potential testing system is installed, including: The insulating copper ball component of the potential testing system is installed and fixed in the oil tank product through a flange, ensuring that at least half of the insulating copper ball component is immersed in the oil, and the flange is insulated from the oil tank product. Insulation verification of the potential testing system.

10. The fuel tank sloshing fuel potential test method according to claim 9, characterized in that, In step S4, the test potential includes: Allow the sample to stand for a predetermined time so that the initial potential measurement is 0. Start the shaking platform of the potential test device, and shake the platform with an amplitude of ±15° and a frequency of 16 times / minute, while vibrating with an amplitude of 0.8mm and a frequency of 33.3Hz for 25 hours. Record the time taken from the fuel input tank product and its corresponding potential value every 0.5 seconds.

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