Hot surface oil leakage experimental device and experimental method for aircraft airworthiness certification

Abstract

The invention provides a hot surface oil leakage experimental device and experimental method for aircraft airworthiness certification, and relates to the technical field of aircraft fireproof airworthiness certification experiments, and the experimental device comprises a heat conduction panel, a heating assembly, an oil spraying assembly, a monitoring assembly, a ventilation assembly, a fire extinguishing assembly and an experiment table. The heat conduction panel is arranged on the experiment table. The heating assembly is adapted to heat the thermally conductive panel to a target temperature to simulate an aircraft hot surface. The fuel spraying assembly is used for simulating aircraft fuel leakage. The monitoring assembly is used for measuring and recording a fluid velocity field, a flame propagation process, a temperature field and flame radiation intensity. The ventilation assembly outputs air flow to simulate ventilation of the fire area, and experimental data obtained after ventilation measures are applied are obtained; the fire extinguishing assembly applies a fire extinguishing agent in the leaked oil combustion process to simulate the fire extinguishing process so as to evaluate the effectiveness of ventilation measures and fire extinguishing measures.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft fireworthiness certification experiments, and more specifically, to a hot surface fuel leakage experimental device and an experimental method for aircraft airworthiness certification. Background Art

[0002] The safety issue of civil aviation aircraft has always been one of the core topics in the global aviation field. With the rapid development of the air transportation industry, the safety of aircraft has become the basis for ensuring the safety of passengers' lives and reducing accidents. Global airlines and regulatory agencies have invested a large amount of resources in safety management and accident prevention. However, despite the continuous development of aviation technology and management means, aviation accidents still occur from time to time, especially some serious accidents have had a profound impact on people's lives and society.

[0003] Among various aircraft safety accidents, fire accidents account for a relatively large proportion, and fuel leakage contacting a high-temperature hot surface and causing ignition is one of the main reasons. For example, engine component breakage leads to fuel tank rupture, contacting a high-temperature hot surface and causing a fire; hydraulic pipeline melting, hydraulic oil leakage onto a high-temperature brake disc, etc., are extremely likely to cause serious fire accidents. Therefore, in view of the requirements for fuel leakage fire prevention in airworthiness regulations, clarifying the occurrence and development process of such fire accidents is the key to preventing fires. Systematically proposing experimental methods for the evaporation and ignition of aviation fuel leakage onto the hot surface of an aircraft and airworthiness certification has important value for ensuring aviation safety.

[0004] However, there is currently no systematic research on the experimental method for the evaporation and ignition of fuel leakage onto the hot surface of an aircraft and airworthiness certification. Existing aviation fuel leakage evaporation and ignition simulation test benches usually have difficulty simulating various fuel leakage forms, and the coordination between measures such as ventilation and fire extinguishing agents and the fuel leakage ignition experiment is insufficient. Therefore, in view of the deficiencies in the above-mentioned civil aviation aircraft airworthiness certification verification methods, it is very necessary to invent an experimental device and method for aircraft hot surface leakage fuel fireworthiness certification to achieve a complete, scientific and reasonable verification experiment. Summary of the Invention

[0005] In view of this, the present invention provides a hot surface fuel leakage experimental device for aircraft airworthiness certification, which can simulate the fuel leakage and combustion process, flexibly adjust simulation parameters, provide more comprehensive reference data, and is conducive to improving the fire prevention experiment of airworthiness certification.

[0006] To achieve the above object, the present invention provides a hot surface fuel leakage experimental device for aircraft airworthiness certification, including an experimental bench, and further including: a heat conduction panel arranged on the experimental bench, the heat conduction panel being made of a metal material; a heating component adapted to heat the heat conduction panel to a target temperature to simulate the hot surface of an aircraft, including: a heat conduction base arranged on the lower surface of the heat conduction panel; a plurality of heating rods installed in the heat conduction base and configured to heat the heat conduction panel through the heat conduction base in an energized state; a first controller adapted to adjust the heating power of the heating rods to simulate different aircraft hot surface temperatures; a fuel spraying component for simulating aircraft fuel leakage, including: an oil injection syringe mounted on the experimental bench, adapted to accommodate fuel and spray it onto the central area of the heat conduction panel at a preset rate; an electric push rod adapted to push the piston of the oil injection syringe to move in the axial direction; a second controller electrically connected to the electric push rod and adapted to adjust the propulsion speed and propulsion duration of the electric push rod; a monitoring component including: a pulsed laser sheet light source arranged on the first side of the heat conduction panel, adapted to irradiate smoke particles in the flow field area above the heat conduction panel; a particle image velocimetry camera arranged on the second side of the heat conduction panel opposite to the first side, configured to record smoke particle images through at least two consecutive exposures; a camera adapted to photograph and record the flame propagation process; a plurality of thermocouples arranged vertically, arranged at intervals of 2 cm at a height of 1-20 cm above the center of the heat conduction panel and at intervals of 10 cm at a height of 20-80 cm, adapted to measure the temperature at different height positions above the heat conduction panel to obtain a temperature field; a plurality of heat radiometers arranged vertically, located on the first side of the heat conduction panel and arranged at intervals of 20 cm at a height of 20-80 cm above the experimental bench to measure the flame radiation intensity of the burning leaked fuel; a ventilation component adapted to apply an air flow of 1-15 m / s in the horizontal direction to simulate the ventilation intervention measures in the hot surface fuel leakage experiment; a fire extinguishing component configured to spray a fire extinguishing agent onto the heat conduction panel in response to a fire extinguishing signal to simulate the fire extinguishing measures in the hot surface fuel leakage experiment.

[0007] According to an embodiment of the present invention, the fuel spraying component further includes a first bracket arranged on the experimental bench, and the oil injection syringe is detachably mounted on the first bracket.

[0008] According to an embodiment of the present invention, the capacity of the oil injection syringe is 10-200 ml, and the preset rate range is 0.01-99 ml / min.

[0009] According to an embodiment of the present invention, the monitoring component further includes a balance placed on the experimental bench, adapted to measure the mass change of the fuel, and the graduation value of the balance is less than or equal to 0.01 g.

[0010] According to an embodiment of the present invention, the operating current of the above-mentioned pulsed laser sheet light source is 0 - 2000 milliamperes, which is suitable for generating green surface laser with a wavelength of 532 nanometers, a thickness of 1.5 millimeters, and a core power of 500 milliwatts to irradiate smoke particles.

[0011] According to an embodiment of the present invention, it further includes a ventilation component. The above-mentioned fire extinguishing component includes: a storage cabinet; a fire extinguishing agent container placed in the above-mentioned storage cabinet and filled with a fire extinguishing agent inside; a first valve installed on the above-mentioned fire extinguishing agent container and configured to allow the fire extinguishing agent to spray out of the above-mentioned fire extinguishing agent container in response to a fire extinguishing signal.

[0012] According to an embodiment of the present invention, the above-mentioned fire extinguishing component further includes: a driving gas container placed in the above-mentioned storage cabinet and filled with driving gas inside; a second valve installed on the above-mentioned driving gas container and configured to allow the driving gas to spray out of the above-mentioned driving gas container after a preset delay in response to a fire extinguishing signal, so as to entrain the fire extinguishing agent to the above-mentioned heat conducting panel for fire extinguishing.

[0013] The present invention also provides an experimental method for airworthiness certification of preventing fuel leakage from hot surfaces of an aircraft. Using the experimental device in any of the above embodiments, it includes: setting the target temperature of the hot surface to be simulated and the target leakage amount of the fuel; turning on the heating component to heat the heat conducting panel to the target temperature; the fuel spraying component sprays fuel onto the above-mentioned heat conducting panel at a preset rate; recording the images and fluid velocity field during the evaporation and combustion of the fuel, and obtaining at least one of the temperature change, ignition probability, and flame radiation intensity data generated by the fuel combustion during the combustion process.

[0014] According to an embodiment of the present invention, it further includes: turning on the ventilation component to make air flow at a preset flow rate flow horizontally above the above-mentioned heat conducting panel.

[0015] According to an embodiment of the present invention, it further includes: controlling the above-mentioned fire extinguishing component to spray the fire extinguishing agent onto the above-mentioned heat conducting panel; recording the fluid velocity field and / or the temperature data above the above-mentioned heat conducting panel after applying the fire extinguishing agent.

[0016] The experimental device for hot surface fuel leakage of an aircraft provided by the present invention heats the heat conducting panel through a heating component to simulate the hot surface on an aircraft that may ignite combustible liquids or vapors. At the same time, it sprays fuel onto the heat conducting panel through a fuel spraying component to simulate the leakage of combustible liquids or vapors, realizing the simulation of the process of temperature rise until combustion after the leakage of combustible liquids or vapors on the aircraft. In addition, by adjusting the simulation parameters, using the monitoring component to record and collect data throughout the process, it provides a more complete and comprehensive reference basis for aircraft airworthiness certification. Description of the Drawings

[0017] Figure 1Schematic diagram of a hot surface fuel leakage experiment device for aircraft airworthiness certification provided by an exemplary embodiment of the present invention;

[0018] Figure 2 Stereoscopic schematic diagram of a heating component in a hot surface fuel leakage experiment device for aircraft airworthiness certification provided by an exemplary embodiment of the present invention;

[0019] Figure 3 Stereoscopic schematic diagram of an oil spraying component in a hot surface fuel leakage experiment device for aircraft airworthiness certification provided by an exemplary embodiment of the present invention;

[0020] Figure 4 Flowchart of an aircraft hot surface leakage fuel fire prevention airworthiness certification experiment method provided by the first exemplary embodiment of the present invention;

[0021] Figure 5 Flowchart of an aircraft hot surface leakage fuel fire prevention airworthiness certification experiment method provided by the second exemplary embodiment of the present invention;

[0022] Figure 6 Flowchart of an aircraft hot surface leakage fuel fire prevention airworthiness certification experiment method provided by the third exemplary embodiment of the present invention;

[0023] Figure 7 Image recorded by a camera in an exemplary embodiment of the present invention.

[0024] In the said drawings, the meanings of the reference numerals are specifically as follows:

[0025] 1, heat conduction panel;

[0026] 2, heating component;

[0027] 21, heat conduction base;

[0028] 22, heating rod;

[0029] 23, first controller;

[0030] 24, flame retardant block;

[0031] 3, oil spraying component;

[0032] 31, first bracket;

[0033] 32, oil injection syringe;

[0034] 33, electric push rod;

[0035] 34, second controller;

[0036] 4, monitoring component;

[0037] 41, pulsed laser sheet light source;

[0038] 42. Particle Image Velocimetry Camera;

[0039] 43. Camera;

[0040] 44. Thermocouple;

[0041] 45. Thermal Radiometer;

[0042] 46. Balance;

[0043] 5. Ventilation Assembly;

[0044] 6. Fire Extinguishing Assembly;

[0045] 61. Storage Cabinet;

[0046] 62. Fire Extinguishing Agent Container;

[0047] 63. First Valve;

[0048] 64. Driving Gas Container;

[0049] 65. Second Valve;

[0050] 7. Experimental Bench. Detailed Implementation Manner

[0051] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake of explanation, many specific details are set forth in order to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0052] The terms used herein are merely for the purpose of describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0053] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0054] In the case of using expressions such as "at least one of A, B, and C", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression (for example, "a system having at least one of A, B, and C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0055] Figure 1 is a schematic diagram of a hot surface fuel leakage experiment device for aircraft airworthiness certification provided by an exemplary embodiment of the present invention, Figure 2 is a three-dimensional schematic diagram of a heating component in a hot surface fuel leakage experiment device for aircraft airworthiness certification provided by an exemplary embodiment of the present invention, Figure 3 is a three-dimensional schematic diagram of an oil spraying component in a hot surface fuel leakage experiment device for aircraft airworthiness certification provided by an exemplary embodiment of the present invention.

[0056] An exemplary embodiment of the present invention provides a hot surface fuel leakage experiment device for aircraft airworthiness certification, as Figures 1 to 3As shown in the figure, it includes a heat-conducting panel 1, a heating component 2, an oil spraying component 3, a monitoring component 4, a ventilation component 5, a fire extinguishing component 6 and a test bench 7. The heat-conducting panel 1 is arranged on the test bench 7. The heating component 2 is suitable for heating the heat-conducting panel 1 to a target temperature to simulate the hot surface of an aircraft. The heating component 2 includes a heat-conducting base 21, a plurality of heating rods 22 and a first controller 23. The heat-conducting base 21 is arranged on the lower surface of the heat-conducting panel 1, and the plurality of heating rods 22 are installed in the heat-conducting base 21 and are configured to heat the heat-conducting panel 1 through the heat-conducting base 21 in the energized state. The first controller 23 is suitable for adjusting the heating power of the heating rods 22 to simulate different aircraft hot surface temperatures. The oil spraying component 3 is used to simulate the oil leakage of an aircraft. It includes an oil injection syringe 32, an electric push rod 33 and a second controller 34. The oil injection syringe 32 is clamped on the test bench 7 and is suitable for containing oil and spraying it onto the central area of the heat-conducting panel 1 at a preset rate. The electric push rod 33 is suitable for pushing the piston of the oil injection syringe 32 to move in the axial direction. The second controller 34 is electrically connected to the electric push rod 33 and is suitable for adjusting the pushing speed and pushing duration of the electric push rod 33. The monitoring component 4 includes a pulsed laser sheet light source 41, a particle image velocimetry camera 42, a camera 43, a plurality of thermocouples 44 and a plurality of thermal radiometers 45. The pulsed laser sheet light source 41 is arranged on the first side of the heat-conducting panel 1 and is suitable for irradiating the smoke particles in the flow field area above the heat-conducting panel 1. The particle image velocimetry camera is arranged on the second side of the heat-conducting panel 1 opposite to the first side and is configured to record the smoke particle images through at least two consecutive exposures. The camera 43 is suitable for photographing and recording the flame propagation process. The plurality of thermocouples 44 are arranged in the vertical direction and are arranged at intervals of 2 cm at a height of 1-20 cm above the center of the heat-conducting panel 1 and at intervals of 10 cm at a height of 20-80 cm, and are suitable for measuring the temperatures at different height positions above the heat-conducting panel 1 to obtain the temperature field. The plurality of thermal radiometers 45 are arranged in the vertical direction, located on the first side of the heat-conducting panel 1, and are arranged at intervals of 2 cm at a height of 20-80 cm above the test bench to measure the flame radiation intensity of the burning leaked oil. The ventilation component 5 is suitable for applying an air flow of 1-15 m / s in the horizontal direction to simulate the ventilation intervention measures in the hot surface oil leakage experiment. The fire extinguishing component 6 is configured to spray a fire extinguishing agent onto the heat-conducting panel 1 in response to a fire extinguishing signal to simulate the fire extinguishing measures in the hot surface oil leakage experiment.

[0057] Section 25.863 Fire protection of flammable liquids in the Airworthiness Standards for Transport Category Airplanes stipulates that: (a) In areas where flammable liquids or vapors may escape due to leakage of liquid systems, measures must be taken to minimize the probability of ignition of the liquid and vapor and the dangerous consequences in case of ignition; (b) It must be shown by analysis or testing that the requirements of paragraph (a) of this section are met. For this purpose, in this embodiment, a hot surface fuel leakage experimental device for aircraft airworthiness certification is provided. The heat conducting panel 1 is heated by the heating component 2 to simulate the hot surface on the aircraft that may ignite flammable liquids or vapors. At the same time, fuel is sprayed onto the heat conducting panel 1 by the fuel spraying component 3 to simulate the leakage of flammable liquids or vapors, realizing the simulation of the temperature rise and even the combustion process after the leakage of flammable liquids or vapors on the aircraft. The monitoring component 4 is used to measure and record the fluid velocity field, the flame propagation process, the temperature field, and the flame radiation intensity, providing a reference basis for aircraft airworthiness certification.

[0058] Furthermore, Section 25.1187 Drainage and ventilation of fire zones in the Airworthiness Standards for Transport Category Airplanes stipulates that: (b) Each designated fire zone must be ventilated to prevent the accumulation of flammable vapors; (c) The ventilation openings shall not be located in positions where the flammable liquids, vapors, or flames of other fire zones can enter; (d) Each ventilation measure must be arranged so that the discharged vapors do not increase the fire hazard. For this purpose, in this embodiment, the ventilation component 5 is set to output airflows to simulate the ventilation of the fire zone, and the experimental data (such as the fluid velocity field, temperature field, flame radiation intensity, etc.) after applying the ventilation measures are used to judge whether the ventilation measures meet the airworthiness certification requirements. And Section 25.863 Fire protection of flammable liquids in the Airworthiness Standards for Transport Category Airplanes further stipulates that: (b) It must be shown by analysis or testing that the requirements of paragraph (a) of this section are met, and the following factors must be considered: ④ Means available for suppressing combustion or extinguishing fire, such as shutting off the liquid flow, shutting down the equipment, fireproof enclosures, or using fire extinguishing agents. For this purpose, in this embodiment, the fire extinguishing component 6 is set to apply fire extinguishing agents during the combustion process of the leaked fuel to simulate the fire extinguishing process, and the effectiveness of the fire extinguishing measures is evaluated based on the fire extinguishing effect (such as whether the open fire is extinguished) and the experimental data (such as the fluid velocity field, temperature field) after applying the fire extinguishing measures.

[0059] In such an embodiment, as Figure 2As shown, the heating rod 22 is installed in the heat-conducting base 21 and placed on the experimental bench 7. The heat-conducting panel 1 is placed on the heat-conducting base 21 for heat transfer by contact. A temperature sensor device is provided on the surface of the heat-conducting panel 1. The first controller 23 adjusts the heating power of the heating rod 22 by collecting the temperature information of the temperature sensor device, so as to simulate different hot surface temperatures, that is, different target temperatures. The temperature sensor device is preferably a thermocouple 44. The fuel injection syringe 32 includes a cylinder body and a piston. An accommodating space defined between the cylinder body and the piston is filled with fuel, and the capacity is 10 - 200 mL. The fuel injection port of the fuel injection syringe 32 is equipped with an extension tube to make the fuel spray or drip as much as possible in the central area of the heat-conducting panel 1, and avoid falling into the peripheral edge area, causing potential safety hazards. The second controller 34 adjusts the propulsion speed and propulsion duration of the electric push rod 33 to adjust the spraying rate (i.e., the preset rate) and spraying amount of the fuel, so as to simulate different leakage scenarios. The pulsed laser sheet light source 41 generates a thin sheet of light (with a thickness of about 0.1 mm - 2 mm) to illuminate the smoke particles, and the particle image velocimetry camera 42 records the position images of the smoke particles through two consecutive (or multiple) exposures, and the exposure moments are synchronized with the pulses of the pulsed laser sheet light source 41. Then, the particle displacement field and velocity vector are calculated using image processing algorithms. The flame propagation process recorded by the camera 43 is used to analyze the flame propagation speed, combustion duration, and flame morphology evolution characteristics, etc.

[0060] According to an embodiment of the present disclosure, the material of the heat-conducting panel 1 can be selected according to the experimental or test objectives. Specifically, the hot surface generally refers to the surface where the temperature rises significantly due to mechanical friction, aerodynamic friction, combustion heat transfer, etc., such as the engine housing, tail nozzle, wing, brake disc, etc. Therefore, for the hot surfaces at different positions on the aircraft, heat-conducting panels 1 of different materials (such as stainless steel, cast iron, etc.) need to be selected for experiments.

[0061] Furthermore, the target temperature is also set according to the different positions of the hot surface or the different working conditions of the hot surface. For example, air friction can cause the leading edge of the wing, nose cone and other positions to reach 100°C - 150°C, while the brake disc can reach 500°C or even higher during landing braking; the core section of the turbine fan engine housing has a temperature of about 150°C - 250°C during ground idle, and about 200°C - 400°C during cruise. Correspondingly, the temperature measurement range of the thermocouple 44 can be selected as 0°C - 1350°C.

[0062] Exemplarily, the heating rod 22 can be composed of a metal resistance heating wire (such as iron-chromium-aluminum alloy or nickel-chromium alloy), or a silicon carbide rod or a silicon molybdenum rod can also be used. The heat-conducting base 21 can be made of stainless steel. The number of heating rods 22 is preferably 6.

[0063] Exemplarily, the electric push rod 33 can adopt a lead screw drive. The motor drives the internal lead screw to rotate, and then makes the nut cooperating with the lead screw move in the axial direction. The nut directly acts on the piston of the fuel injection syringe 32, or acts on the piston of the fuel injection syringe 32 through a connecting member.

[0064] Exemplarily, the frame rate of the camera 43 is greater than or equal to 240 frames per second, preferably 200000 frames per second.

[0065] In some other embodiments, the heating assembly 2 further includes a flame retardant stopper 24, which is arranged around the periphery of the heat conducting panel and is used to prevent the fuel from flowing to the area outside the heat conducting panel 1, thereby igniting other experimental equipment.

[0066] In an exemplary embodiment, as Figure 3 shown, the fuel spraying assembly 3 further includes a first bracket 31, which is arranged on the experimental table 7, and the fuel injection syringe 32 is detachably installed on the first bracket 31.

[0067] In such an implementation manner, both the connection between the first bracket 31 and the experimental table 7 and the connection between the fuel injection syringe 32 and the first bracket 31 are detachable connections to maintain the stability of the fuel injection syringe 32 when spraying fuel.

[0068] In some alternative embodiments, the sprayed fuel includes but is not limited to RP-3 aviation kerosene, sustainable aviation fuel, or hydraulic oil.

[0069] In an exemplary embodiment, the capacity of the fuel injection syringe 32 is 10 - 200 milliliters, and the preset rate range is 0.01 - 99 milliliters per minute.

[0070] In an exemplary embodiment, as Figures 1 - 3 shown, the monitoring assembly 4 further includes a balance 46, which is placed on the experimental table 7 and is suitable for measuring the mass change of the fuel. The graduation value of the balance 46 is less than or equal to 0.01 grams.

[0071] In such an implementation manner, the balance 46 is placed on the experimental table 7, with a measurement range of 0 - 14200.00 grams. The heating assembly 2 together with the heat conducting panel 1 is placed on the balance 51 and zeroed before the experiment to measure the mass change of the fuel during the experiment.

[0072] In an exemplary embodiment, the working current of the pulsed laser sheet light source 41 is 0 - 2000 milliamperes, and it is suitable for generating a green surface laser with a wavelength of 532 nanometers, a thickness of 1.5 millimeters, and a core power of 500 milliwatts to irradiate the smoke particles.

[0073] In an exemplary embodiment, as Figures 1 - 3As shown, the fire extinguishing assembly 6 includes a storage cabinet 61, a fire extinguishing agent container 62, and a first valve 63. The fire extinguishing agent container 62 is placed in the storage cabinet 61 and contains fire extinguishing agent inside. The first valve 63 is installed on the fire extinguishing agent container 62 and is configured to respond to a fire extinguishing signal and allow the fire extinguishing agent to spray out from the fire extinguishing agent container 62. The fire extinguishing agent is driven to spray onto the heat conducting panel 1 to obtain the fluid velocity field after applying fire extinguishing measures and / or the temperature data above the heat conducting panel 1.

[0074] In such an embodiment, fire extinguishing is carried out by applying the fire extinguishing agent, and the effectiveness of the fire extinguishing measures is evaluated based on the fire extinguishing effect (such as whether the open fire is extinguished) and the experimental data after applying the fire extinguishing measures (such as the fluid velocity field and the temperature field above the heat conducting panel 1).

[0075] Exemplarily, the types of fire extinguishing agents include but are not limited to halon or perfluoromethylhexanone. The concentration of the fire extinguishing agent can be adjusted according to experimental requirements.

[0076] According to an embodiment of the present disclosure, the fire extinguishing assembly 6 further includes a driving gas container 64 and a second valve 65. The driving gas container 64 is placed in the storage cabinet 61 and contains driving gas inside. The second valve 65 is installed on the driving gas container 64 and is configured to respond to a fire extinguishing signal and allow the driving gas to spray out from the driving gas container 64 after a preset time delay, so as to carry the fire extinguishing agent to the heat conducting panel 1 for fire extinguishing.

[0077] In such an embodiment, after the fire extinguishing signal is issued, the first valve 63 is opened first, and the second valve 65 is opened after a preset time. The preset time can be adjusted according to the type of fire extinguishing agent, and it is appropriate that the fire extinguishing agent is successfully released into the air, preferably 1 - 2 seconds, so that the driving gas can carry the fire extinguishing agent in the air to the heat conducting panel 1 for fire extinguishing.

[0078] Figure 4 is the flowchart of the aircraft hot surface leaking fuel fire prevention airworthiness certification experiment method provided by the first exemplary embodiment of the present invention, Figure 5 is the flowchart of the aircraft hot surface leaking fuel fire prevention airworthiness certification experiment method provided by the second exemplary embodiment of the present invention, Figure 6 is the flowchart of the aircraft hot surface leaking fuel fire prevention airworthiness certification experiment method provided by the third exemplary embodiment of the present invention, Figure 7 is the image recorded by the camera in the exemplary embodiment of the present invention.

[0079] The exemplary embodiment of the present disclosure further provides an aircraft hot surface leaking fuel fire prevention airworthiness certification experiment method, which applies the experimental device in any of the above embodiments, such as Figure 4 As shown, it includes the following steps S1 - S4.

[0080] Step S1: Set the target temperature of the hot surface to be simulated and the target leakage amount of the fuel.

[0081] Step S2: Turn on the heating component 2 and heat the heat conducting panel 1 to the target temperature.

[0082] Step S3: The fuel spraying component 3 sprays fuel onto the heat conducting panel 1 at a preset rate.

[0083] Step S4: Record the images and fluid velocity fields during the evaporation and combustion of the fuel, and obtain the temperature change, ignition probability, and flame radiation intensity generated by the fuel combustion during the combustion process.

[0084] In such an implementation manner, the experimental method for airworthiness certification of fuel leakage prevention on the hot surface of an aircraft is designed according to the requirements for preventing combustion of combustible liquids in the "Airworthiness Standards for Transport Category Aircraft". First, set the target temperature of the hot surface and the target leakage amount of the fuel, and accordingly adjust the heating power of the heating component 2 and the fuel injection rate of the fuel spraying component 3. Turn on the heating component 2 to heat the heat conducting panel 1 to the target temperature, and minimize the temperature fluctuation range as much as possible. After the fuel spraying component 3 sprays the fuel onto the heat conducting panel 1, start recording the changes in the fuel and collect the experimental data during the fuel combustion process.

[0085] Specifically, the first controller 23 controls the heating rod 22 to heat at a calculated heating power. After the heat conducting panel 1 reaches the target temperature, the heating power of the heating rod 22 is reduced to keep the heat conducting panel 1 warm. The second controller 34 controls the electric push rod 33 to drive the fuel injection syringe 32 to spray fuel at a calculated propulsion speed and propulsion duration. At the same time, the particle image velocimetry camera 42 takes images of the positions of smoke particles (the starting time of shooting can be set according to the actual situation), and the camera 43 records the video throughout the process to obtain the reference experimental results for aircraft airworthiness certification.

[0086] It should be noted that the thermocouple 44, the thermal radiometer 45, and the balance 46 all need to be calibrated. The target temperature and the target leakage amount can be adjusted according to the experimental object. The fuel ignition probability is obtained by counting the number of ignition times / the total number of experiments under the same experimental conditions through the video images recorded by the camera 43. Another example is Figure 7 As shown, the ignition delay time is obtained by calculating the difference between the time when the ignition core appears and the time when the fuel leaks to the hot surface.

[0087] According to an embodiment of the present disclosure, as Figure 5 shown, the above experimental method further includes step S3a: Turn on the ventilation component 5 to make an air flow with a preset flow rate flow horizontally above the heat conducting panel 1.

[0088] In such an embodiment, after step S3, the ventilation component 5 is immediately turned on to simulate the evaporation and combustion process of the leaked oil under ventilation measures, and the air flow velocity can be adjusted according to the experimental object. In this embodiment, the experimental results obtained through step S4 are used to compare with the reference experimental results in the previous embodiment to evaluate the design effectiveness of the ventilation measures.

[0089] In some other embodiments, the ventilation component 5 can also be used to simulate the external air flow environment. For example, if the simulated object of the hot surface is the part of the aircraft body exposed to the atmospheric environment, the preset flow velocity of the ventilation component 5 changes according to the altitude.

[0090] In another exemplary embodiment, as Figure 6 shown, the above experimental method further includes step S3b: controlling the fire extinguishing component 6 to spray the fire extinguishing agent onto the heat conducting panel 1. Record the fluid velocity field and / or the temperature data above the heat conducting panel 1 after the fire extinguishing agent is applied.

[0091] In such an embodiment, after step S3, the leaked oil burns stably. When abnormal temperature, smoke concentration, and flame signals are detected, a fire extinguishing signal is sent, and after being confirmed by the operator, the fire extinguishing component 6 is immediately turned on to simulate the fire extinguishing action when the leaked oil is burning. In this embodiment, if the open fire is not extinguished, the experimental results are still obtained with reference to step S4; if the open fire has been extinguished, record the fluid velocity field and / or the temperature field above the heat conducting panel 1 after the fire extinguishing, and compare with the reference experimental results in the above embodiment to evaluate the design effectiveness of the fire extinguishing measures.

[0092] Those skilled in the art can understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0093] The embodiments of the present invention have been described above. However, these embodiments are only for illustrative purposes and not for limiting the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present invention.

Claims

1. A hot surface fuel leakage experimental device for aircraft airworthiness certification, including an experimental bench, characterized in that, Further included are: A heat-conducting panel, arranged on the experimental table, and made of a metallic material; A heating assembly, adapted to heat the heat-conducting panel to a target temperature to simulate a hot surface of an aircraft, including: A heat-conducting base, arranged on the lower surface of the heat-conducting panel; A plurality of heating rods, installed in the heat-conducting base, and configured to heat the heat-conducting panel through the heat-conducting base in an energized state; A first controller, adapted to adjust the heating power of the heating rods to simulate different hot surface temperatures of the aircraft; An oil spraying assembly, for simulating an oil leak of an aircraft, including: An injection syringe, mounted on the experimental table, adapted to hold oil and spray it onto the central area of the heat-conducting panel at a preset rate; An electric push rod, adapted to push the piston of the injection syringe to move axially; A second controller, electrically connected to the electric push rod, adapted to adjust the pushing speed and pushing duration of the electric push rod; A monitoring assembly, including: A pulsed laser sheet light source, arranged on a first side of the heat-conducting panel, adapted to irradiate smoke particles in the flow field area above the heat-conducting panel; A particle image velocimetry camera, arranged on a second side of the heat-conducting panel opposite to the first side, configured to record smoke particle images through at least two consecutive exposures; A camera, adapted to photograph and record the flame propagation process; A plurality of thermocouples arranged vertically, arranged at intervals of 2 cm at a height of 1 - 20 cm above the center of the heat-conducting panel and at intervals of 10 cm at a height of 20 - 80 cm, adapted to measure the temperatures at different height positions above the heat-conducting panel to obtain a temperature field; A plurality of heat radiometers arranged vertically, located on the first side of the heat-conducting panel, and arranged at intervals above the experimental table to measure the flame radiation intensity of the burning of the leaked oil; A ventilation assembly, adapted to apply an air flow of 1 - 15 m / s horizontally to simulate ventilation intervention measures in a hot surface oil leak experiment; A fire extinguishing assembly, configured to spray a fire extinguishing agent onto the heat-conducting panel in response to a fire extinguishing signal to simulate fire extinguishing measures in a hot surface oil leak experiment.

2. The hot surface fuel leakage experimental device for aircraft airworthiness certification according to claim 1, characterized in that, The oil spraying assembly further includes a first bracket, arranged on the experimental table, and the injection syringe is detachably mounted on the first bracket.

3. The hot surface fuel leakage experimental device for aircraft airworthiness certification according to claim 1, wherein, The capacity of the injection syringe is 10 - 200 ml, and the preset rate range is 0.01 - 99 ml / min.

4. The hot surface fuel leakage test device for aircraft airworthiness certification according to claim 1, characterized in that The monitoring assembly further includes a balance, placed on the experimental table, adapted to measure the mass change of the oil, and the graduation value of the balance is less than or equal to 0.01 g.

5. The hot surface fuel leakage test device for aircraft airworthiness certification according to claim 1, characterized in that, The working current of the pulsed laser sheet light source is 0 - 2000 mA, adapted to generate a green surface laser with a wavelength of 532 nm, a thickness of 1.5 mm, and a core power of 500 mW to irradiate smoke particles.

6. The hot surface fuel leakage experimental device for aircraft airworthiness certification according to any one of claims 1-5, characterized in that The fire extinguishing assembly includes: A storage cabinet; A fire extinguishing agent container, placed in the storage cabinet, and filled with a fire extinguishing agent inside; A first valve, installed on the fire extinguishing agent container, and configured to allow the fire extinguishing agent to be ejected from the fire extinguishing agent container in response to a fire extinguishing signal.

7. The experimental device for hot surface fuel leakage for aircraft airworthiness certification according to claim 6, characterized in that, The fire extinguishing assembly further includes: A driving gas container, placed in the storage cabinet, and filled with a driving gas inside; A second valve, installed in the driving gas container and configured to respond to a fire extinguishing signal, allows the driving gas to be ejected from the driving gas container after a preset time delay to entrain the fire extinguishing agent to the heat conducting panel for fire extinguishing.

8. An experimental method for airworthiness certification of preventing fire caused by fuel leakage from hot surfaces of an aircraft, characterized in that, Applying the experimental device according to any one of claims 1-7, comprising: Setting the target temperature of the hot surface to be simulated and the target leakage amount of the oil; Turning on the heating component to heat the heat conducting panel to the target temperature; The oil spraying component sprays oil on the heat conducting panel at a preset rate; Recording images and fluid velocity fields during the evaporation and combustion of the oil, and obtaining at least one of the temperature change, ignition probability, and flame radiation intensity data generated by the combustion of the oil during the combustion process.

9. The experimental method according to claim 8, wherein Further comprising: Turning on the ventilation component to allow an air flow at a preset flow rate to flow horizontally above the heat conducting panel.

10. The experimental method according to claim 8, characterized in that Further comprising: Controlling the fire extinguishing component to spray the fire extinguishing agent onto the heat conducting panel; Recording the fluid velocity field and / or the temperature data above the heat conducting panel after the fire extinguishing agent is applied.

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