Hot surface ignition test system for aviation

Abstract

The present application relates to the technical field of ignition test, and discloses a hot surface ignition test system for aviation, which comprises an inlet pipeline, a test pipeline and an air extraction pipeline connected in sequence, wherein the end of the inlet pipeline is provided with a valve, the valve is used for controlling the opening size of the inlet pipeline, the bottom of the test pipeline is provided with a heating mechanism, the top of the test pipeline is provided with a dripping mechanism, the air extraction pipeline is connected with an air extraction fan, the bottom of the test pipeline is provided with a mounting opening, the mounting opening is used for detachably mounting different plates, the plates are used for simulating hot surfaces, the heating mechanism is used for heating the plates, and the dripping mechanism is used for dripping oil products on the plates. The present application can provide a simple and easy-to-operate test device for the aviation hot surface ignition test, can assist in constructing a high-fidelity ignition test environment conforming to different aviation working conditions, and can provide reliable data reference for the airworthiness evaluation of oil products.

Description

Technical Field

[0001] This invention relates to the field of ignition testing technology, and more specifically to an aviation hot surface ignition testing system. Background Technology

[0002] Hot surfaces are a typical type of ignition source. Common hot surface types include the surface of automobile engines, exhaust pipes, and hot fluid pipelines in chemical plants. When flammable liquids come into contact with these hot surfaces, if the temperature of the hot surface is higher than the auto-ignition temperature of the flammable liquid, a fire may occur.

[0003] In aircraft, taking the engine compartment as an example, there are numerous hot surfaces, including the surfaces of the engine, fuel lines, and exhaust pipes. Because the engine compartment often contains many fuel lines, during long-term operation, factors such as aircraft vibration, high temperatures, and structural aging can easily cause these fuel lines or containers to deform or rupture, leading to leaks of flammable liquids (i.e., oil). These leaks pose a risk of fire if they come into contact with hot surfaces. Furthermore, leaked oil evaporates rapidly on hot surfaces and, even after spontaneous combustion, does not leave significant combustion characteristics. Combined with the overall combustion within the aircraft after a fire, it is difficult to accurately identify hot surfaces as ignition sources. The ignition status of the hot surfaces and the actual spontaneous combustion of the oil are both difficult to confirm, making it challenging to assess potential aircraft fire risks.

[0004] Currently, common testing platforms and systems are all based on sealed test containers, primarily measuring the autoignition temperature (ATI) of substances. In specific tests, measurements are mostly conducted according to relevant standards, and the experimental equipment used varies depending on the standard; for example, some use round-bottom flasks, while others use conical flasks. However, the basic principle remains the same: to create a relatively closed, stable, and uniform high-temperature environment to accurately test the autoignition temperature of a substance upon heating. However, the ATI results cannot be used to characterize the actual ignition process on hot surfaces in aviation. While the autoignition temperature is an intrinsic characteristic of a substance, for fuels used in practical applications, the same autoignition temperature characteristic can result in drastically different fuel performance under different operating conditions, and the effects on different hot surfaces also differ significantly from theoretical predictions based on the substance's properties. In particular, due to the special aviation application environment and aircraft operating environment, the test conditions required for ignition tests of aircraft oils and aircraft internal hot surfaces are more stringent. Existing test systems cannot meet these requirements, and existing test schemes based on auto-ignition points cannot effectively measure the actual interaction characteristics between oils and hot surfaces. Summary of the Invention

[0005] The present invention aims to provide an aviation hot surface ignition test system, which can provide a simple and easy-to-operate test device for aviation hot surface ignition tests, can help to construct a highly realistic ignition test environment that conforms to different aviation operating conditions, and can provide reliable data reference for fuel airworthiness evaluation.

[0006] The basic solution provided by this invention is: an aviation hot surface ignition test system, including a connected inlet pipe, a test pipe, and an exhaust pipe; a valve is provided at the end of the inlet pipe; the valve is used to control the opening size of the inlet pipe; a heating mechanism is provided at the bottom of the test pipe; a dripping mechanism is provided at the top of the test pipe; the exhaust pipe is connected to an exhaust fan; an installation port is provided at the bottom of the test pipe for detachably installing different plates; the plates are used to simulate hot surfaces; the heating mechanism is used to heat the plates; and the dripping mechanism is used to drip oil onto the plates.

[0007] Furthermore, during the experiment, the valves and the exhaust fan worked together to create a dynamic negative pressure test environment.

[0008] Furthermore, the plate material includes flat plate material and curved plate material; the material of the plate material includes titanium alloy, high-strength steel and high-temperature alloy; the oil in the dripping mechanism is aviation hydraulic oil, aviation fuel or aviation lubricating oil.

[0009] Furthermore, a cooling pipe is connected between the test pipe and the exhaust pipe; the cooling pipe is used to cool the airflow passing through the test pipe.

[0010] Furthermore, a rectifier pipe is connected between the inlet pipe and the test pipe; the rectifier pipe is used to stabilize the airflow entering the test pipe; and multiple rectifier plates are installed in the rectifier pipe.

[0011] Furthermore, an airflow heating pipe is provided between the rectifier pipe and the test pipe; the airflow heating pipe is used to heat the air introduced from the inlet pipe; and the air temperature heating threshold of the airflow heating pipe is 400°C.

[0012] Furthermore, it also includes a monitoring device; the monitoring device includes a camera and a high-speed schlieren for observing the contact surface between the plate and the oil droplets; the side of the test pipe is provided with an observation window; the camera and the high-speed schlieren are located around the test pipe and aligned with the observation window.

[0013] Furthermore, the dripping mechanism includes a rotating device and several needle-type injection pumps circumferentially fixed on the rotating device; and the several needle-type injection pumps store different types of oils respectively; when the needle-type injection pumps drip oil, they include single-drop dripping mode, continuous dripping mode and fine-line dripping mode.

[0014] Furthermore, the heating mechanism includes multiple sets of heating wires and a heating controller for controlling each set of heating wires; when controlling the heating wires, the heating controller automatically selects the heating wires to be heated and the corresponding heating temperature according to the heat surface simulation requirements; the bottom of the plate is provided with a heating wire mounting position.

[0015] Furthermore, the main control device includes a main control module; the main control module is used to collect the thermal surface simulation requirements, and control the operation of the heating mechanism, dripping mechanism, cooling pipe, airflow heating pipe, exhaust fan and electric valve respectively according to the thermal surface simulation requirements.

[0016] Furthermore, in the dynamic negative pressure test environment, the airflow velocity is 0 to 3.5 m / s and the pressure is 20 kPa to 101.3 kPa.

[0017] The working principle and advantages of this invention are as follows: In practical applications, the plate to be simulated is installed in the test pipe, and a heating mechanism and a dripping mechanism are configured. By adjusting the electric valve at the end of the inlet pipe and the wind speed of the exhaust fan, the test system can be made to be in a negative pressure environment. Under this negative pressure environment, the dripping mechanism is controlled to drip liquid droplets onto the plate. At the same time, a camera and a high-speed schlieren are used to observe the contact surface between the plate and the liquid droplets to obtain hot surface ignition test data.

[0018] First, this solution provides a simple and easy-to-operate testing device for aviation hot surface ignition tests. The overall structure of this testing system is simple, the plates are easy to replace, and the dripping mechanism can flexibly switch the types of oil added, facilitating different types of hot surface ignition tests. Second, this solution can help construct a highly realistic ignition test environment that conforms to different aviation operating conditions by adding and controlling negative pressure and airflow conditions. This allows for accurate testing of the actual ignition of the oil, providing more reliable and multi-dimensional data references for oil airworthiness evaluation.

[0019] In particular, this solution can create a dynamic negative pressure test environment during testing by using valves and exhaust fans in combination. Specifically, by adjusting different valve openings and exhaust fan speeds, the pressure in the test environment can be dynamically adjusted to create a low-pressure environment. This allows for the simulation of the pressure environment experienced by an aircraft under different operating conditions (such as the operating conditions corresponding to different phases of flight, such as takeoff, cruise, and descent), thus meeting the simulation needs of various flight conditions.

[0020] Furthermore, the dynamic negative pressure test environment constructed in this scheme is a wind tunnel test environment under negative pressure conditions. In this environment, the air inside the test system is kept in a flowing state and a certain flow velocity (wind speed) is set. Unlike the conventional pressure adjustment methods similar to vacuuming or volume expansion, this scheme sets a negative pressure form that maintains airflow. Under this negative pressure form, the actual environment inside an aircraft engine compartment is simulated. In this compartment environment, due to the influence of the mechanical structure layout and the aerodynamic and ventilation systems, there is often flowing air, and there is actually a certain wind speed around each high-temperature component. When hot surface ignition occurs, the presence of this flowing air will also cause the ignition situation to differ from the conventionally expected ignition situation. Under the dynamic negative pressure conditions constructed in this scheme, the plate material at the test pipe and the falling oil droplets can equivalently reproduce the actual ignition situation under different aircraft operating conditions under the influence of real flowing air.

[0021] Furthermore, compared to existing methods for testing fuel based on auto-ignition temperature (ATI), this approach overcomes the bias in existing aviation fuel testing and related international testing standards that only focus on the ignition point of the fuel itself. Instead, it selects to test the specific hot surface ignition performance of the fuel under different external conditions. By capturing the hot surface ignition under different experimental conditions, it can more effectively and realistically reflect the ignition situation of the research object under actual operating conditions.

[0022] Furthermore, this solution overcomes the difficulties in constructing and maintaining the stability of a dynamic negative pressure test environment. In existing tests, it's often not considered to simultaneously set negative pressure and airflow conditions. Besides the aforementioned testing biases, the presence of airflow inevitably makes air pressure unstable, leading to inconsistent test results and poor reliability. This solution, however, utilizes the coordination of the inlet section and the exhaust fan to maintain the opening and closing of the inlet pipe, ensuring that the pressure value meets the standard. Furthermore, the inclusion of a rectifier section significantly reduces airflow fluctuations, effectively guaranteeing airflow stability, temperature uniformity, and pressure stability at the test pipeline, resulting in reliable test results. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the system structure of Embodiment 1 of the aviation hot surface ignition test system of the present invention;

[0024] Figure 2 This is a front view of a partial system structure of the aviation hot surface ignition test system of the present invention, according to Embodiment 1.

[0025] Figure 3 This is a top view of a partial structure of the aviation hot surface ignition test system of the present invention, according to Embodiment 1.

[0026] Figure 4 This is a schematic diagram of the dripping mechanism in Embodiment 1 of the aviation hot surface ignition test system of the present invention;

[0027] Figure 5 This is a partial cross-sectional view of the dropping hole in Embodiment 2 of the aviation hot surface ignition test system of the present invention;

[0028] Figure 6 This is a partial structural schematic diagram of the test pipe in Embodiment 2 of the aviation hot surface ignition test system of the present invention;

[0029] Figure 7 This is a schematic diagram of the sliding opening and closing plate structure of Embodiment 2 of the aviation hot surface ignition test system of the present invention. Detailed Implementation

[0030] The following detailed explanation illustrates the specific implementation methods:

[0031] The markings in the accompanying drawings include: inlet pipe 1, rectifier pipe 2, rectifier grid 201, airflow heating pipe 3, test pipe 4, observation window 401, cooling pipe 5, exhaust pipe 6, dripping mechanism 7, rotating device 701, needle pump 702, vertical guide rail 703, dripping hole 8, sliding opening and closing plate 9, opening and closing handle 901, sealing baffle 902, interlayer 10, opening and closing channel 11.

[0032] Example 1

[0033] The basic implementation examples are as follows: Figure 1 , Figure 2 and Figure 3 As shown: The aviation hot surface ignition test system includes an inlet pipe 1, a rectifier pipe 2, an airflow heating pipe 3, a test pipe 4, a cooling pipe 5, and an exhaust pipe 6 that are connected to each other; it also includes a monitoring device.

[0034] The inlet pipe 1 is used to introduce air, and a valve is provided at the end of the inlet pipe 1; the valve is used to control the opening size of the inlet pipe 1; in this embodiment, the valve is an electric valve, and by controlling the opening and closing degree of the electric valve, the amount of gas entering the test system can be quickly controlled, which facilitates the control of the gas flow rate.

[0035] The rectifier duct 2 is used to stabilize the airflow entering the test duct 4; a rectifier grid 201 is provided in the rectifier duct 2. In this embodiment, the rectifier grid 201 is provided with multiple honeycomb units. The rectifier grid 201 can stabilize the airflow entering from the inlet section, avoid turbulence affecting the temperature field at the hot surface to be constructed later, and the stabilized airflow environment is more consistent with the actual airflow environment in the aircraft engine compartment, resulting in a higher degree of realism in the test environment.

[0036] The airflow heating pipe 3 is used to heat the air introduced from the inlet pipe 1; and the air temperature heating threshold of the airflow heating pipe 3 is 400℃. In this embodiment, gas heating wire assemblies are evenly arranged on the inner wall of the airflow heating pipe 3, which can uniformly and quickly complete the airflow heating, and can avoid the direct introduction of cold air, which would affect the temperature field in the test pipe 4 and thus affect the determination of ignition conditions.

[0037] A heating mechanism is provided at the bottom of the test pipe 4; a dripping mechanism 7 is provided at the top of the test pipe 4; the exhaust pipe 6 is connected to an exhaust fan; an installation port is provided at the bottom of the test pipe 4 for detachable installation of different plates. The plates are used to simulate hot surfaces; the heating mechanism is used to heat the plates, and the dripping mechanism 7 is used to drip oil onto the plates.

[0038] Specifically, in this embodiment, the mounting port is a rectangular opening located at the center of the bottom (i.e., the base plate) of the test pipe 4, with the edge of the rectangular opening spaced a certain distance from the edge of the test pipe 4. The plate material includes flat plates and curved plates; the material of the plate material includes titanium alloy, high-strength steel, and high-temperature alloy. When installing the plate material, auxiliary connectors such as screws and bolts can be directly used to detachably fix the plate material to the mounting port.

[0039] The heating mechanism includes multiple sets of heating wires and a heating controller for controlling each set of heating wires. When controlling the heating wires, the heating controller automatically selects the heating wires to be heated and the corresponding heating temperature according to the simulated hot surface requirements. In this embodiment, the heating temperature range is set to 300℃~800℃. The bottom of the plate has heating wire mounting positions. Specifically, taking a flat plate as an example, multiple heating wire mounting positions are evenly arranged on the bottom of the flat plate. In practical applications, the heating wires can be clipped into the heating wire mounting positions for easy installation and removal. Preferably, after installing the heating wires, an additional insulation layer can be added below the heating wires. The insulation layer can be made of conventional heat insulation materials (such as polystyrene foam), which can ensure the heating effect of the heating mechanism and make temperature control precise.

[0040] As attached Figure 4As shown, the dripping mechanism 7 includes a rotating device 701 and several needle-type injection pumps 702 circumferentially fixed on the rotating device 701; and the needle-type injection pumps 702 respectively store different types of oil. When dripping oil, the needle-type injection pumps 702 include single-drop dripping mode, continuous dripping mode, and fine-line dripping mode. In this embodiment, the rotating device 701 is also circumferentially provided with several vertical guide rails 703; the needle-type injection pumps 702 are slidably connected to the vertical guide rails 703 respectively. The oil in the dripping mechanism 7 is aviation hydraulic oil, aviation fuel, or aviation lubricating oil. A dripping hole 8 is provided at the top of the test pipe 4 for engaging with the needle of the needle-type injection pump 702; the needle-type injection pump drips oil onto the plate through the dripping hole 8. In a specific application, the dripping mechanism 7 is fixed above the test pipe 4; taking aviation hydraulic oil as an example, the needle injection pump 702 containing aviation hydraulic oil is rotated to align with the dripping hole 8, and then the injection pump is controlled to move down along the vertical guide rail 703 and insert into the dripping hole 8, and then the oil is dripped.

[0041] The cooling pipe 5 is used to cool the airflow passing through the test pipe 4. Specifically, in this embodiment, a connection port is opened on the side of the cooling pipe 5, and a compressor cooler is arranged around the cooling pipe 5. The compressor cooler is connected to the cooling pipe 5 through the connection port to cool the airflow.

[0042] The monitoring device includes a camera and a high-speed schlieren spectrometer for observing the contact surface between the plate and oil droplets; an observation window 401 is provided on the side of the test pipe 4; the camera and high-speed schlieren spectrometer are located around the test pipe 4 and aligned with the observation window 401. In this embodiment, the observation window 401 is provided with high-transparency glass, which can effectively ensure the sealing of the pipe while facilitating the monitoring device to observe the internal conditions of the test pipe 4. In particular, by setting up a high-speed schlieren spectrometer, it is possible to assist in observing experimental process details that are difficult to observe with the naked eye, such as oil evaporation and gas flow, and to accurately observe and record the development and changes of the flow field, providing multi-dimensional experimental information.

[0043] In the actual test, the simulated plate is installed in the test pipe 4, and a heating mechanism and a dripping mechanism 7 are configured. A dynamic negative pressure test environment is created by adjusting the electric valve at the end of the inlet pipe 1 and the airflow speed of the exhaust fan. Under this dynamic negative pressure test environment, the dripping mechanism 7 is controlled to drip droplets onto the plate. Simultaneously, a camera and a high-speed schlieren imager are used to observe the contact surface between the plate and the droplets to obtain hot surface ignition test data. Furthermore, in the dynamic negative pressure test environment, the airflow velocity is 0–3.5 m / s, and the pressure is 20 kPa–101.3 kPa. Under these conditions, the hot surface in the test is equivalent to being in an actual aircraft environment, making the test environment more realistic and the test results more authentic. It can also cover different aircraft operating conditions and meet different test simulation needs.

[0044] This embodiment provides an aviation hot surface ignition test system that offers a simple and easy-to-operate test device for aviation hot surface ignition tests. It can help construct a highly realistic ignition test environment that conforms to different aviation operating conditions and provide reliable data references for fuel airworthiness evaluation.

[0045] Example 2

[0046] The aviation hot surface ignition test system, based on Example 1, also includes an oil drain port in the cooling pipe 5.

[0047] Specifically, the oil drain port is used to drain excess oil generated at the test section to prevent oil accumulation in the pipeline and potential risks. Furthermore, the oil drain port is located at the cooling pipe 5, which effectively avoids the opening affecting the pressure environment at the test pipe 4, resulting in a more stable test environment.

[0048] In this embodiment, the dripping mechanism 7 is provided in two sets, and multiple dripping holes 8 are provided on the upper surface of the test pipe 4, with a sliding opening and closing piece 9 at each dripping hole 8, as shown in the attached figure. Figure 7 As shown, the sliding opening and closing piece 9 includes an opening and closing handle 901 and a sealing baffle 902 connected thereto and disposed in the interlayer 10 on the upper surface of the test pipe 4; as shown in the attached figure. Figure 5 As shown in the attached diagram. The surface of the test pipe 4 is also provided with an opening / closing channel 11, which is offset from the position of the dripping hole 8. Figure 6 As shown. The opening and closing handle 901 is located at the opening and closing channel 11 and is slidably connected to it. In specific applications, the sliding opening and closing piece 9 can be moved to open or close different dripping holes 8 according to the dripping needs. This setting can provide more convenient dripping position selection while ensuring the sealing of the test system to the greatest extent, which helps to ensure the stability of the dynamic negative pressure environment.

[0049] In practical applications, the material to be simulated is installed in the test pipe 4, and the heating mechanism is configured. The desired drip hole 8 is selected, and its corresponding sliding opening / closing plate 9 is opened, while the sliding opening / closing plates 9 of the remaining drip holes 8 are closed. The position of the dripping mechanism 7 is adjusted so that the needle of the syringe pump 702 is inserted into the drip hole 8, and this drip hole 8 can be relatively sealed, which helps to ensure the pressure stability of the subsequently constructed negative pressure test environment. Then, by adjusting the electric valve at the end of the inlet pipe 1 and the airflow of the exhaust fan, a dynamic negative pressure test environment is formed through the cooperation of the valve and the exhaust fan.

[0050] This embodiment provides an aviation hot surface ignition test system that minimizes oil accumulation, making testing safer. Furthermore, compared to Embodiment 1, this solution enables multi-point drip-addition hot surface ignition tests, allowing for the creation of more diverse test scenarios and offering enhanced functionality.

[0051] Example 3

[0052] The aviation hot surface ignition test system, based on Example 1, also includes a main control device.

[0053] The main control device includes a main control module and an interaction module. The main control module is used to collect the thermal surface simulation requirements and, according to these requirements, control the operation of the heating mechanism, dripping mechanism 7, cooling pipe 5, airflow heating pipe 3, exhaust fan, and electric valves. The interaction module is used for the experimenters to input the thermal surface simulation requirements.

[0054] In this embodiment, the requirement options corresponding to the thermal surface simulation requirements include: the type of device to which the thermal surface belongs (e.g., a thermal surface belonging to the engine casing), the type of oil added, the aircraft operating conditions, airflow velocity, pressure value, airflow heating temperature, and plate heating temperature. Different aircraft operating conditions correspond to a default configuration of airflow velocity and pressure value. The aircraft operating conditions include takeoff, cruise, and descent. Taking the cruise condition of an aircraft at an altitude of 10,000 meters as an example, the default configuration corresponds to an airflow velocity of 2 m / s and a pressure value of 25.2 kPa.

[0055] Preferably, the hot surface simulation requirement also includes: the location of the component to which the hot surface belongs (e.g., the location of the engine casing within the engine compartment corresponding to a hot surface belonging to the engine casing). The main control module pre-stores pipe layout diagrams and component layout diagrams. When inputting the hot surface simulation requirement, the location of the component to which the hot surface belongs can be set based on the component layout diagram. Furthermore, based on the pipe layout diagram, the set location of the component to which the hot surface belongs, and the set aircraft operating conditions, the remaining requirement options generate modifiable recommended parameters for the test personnel to determine. In addition, the main control module also fine-tunes the heating temperature of the plate according to the location of the component to which the hot surface belongs, and different fine-tuning ratios are set for different component locations. With this setting, this solution can further and more accurately reproduce the real hot surface conditions at different locations in the aircraft engine compartment.

[0056] Optionally, in this embodiment, when setting the fine-tuning ratio, firstly, based on the device layout diagram, taking the aircraft engine nacelle as an example, a spatial distribution coordinate system is established with the aircraft engine as the origin. According to the spatial distance z between the device location and the origin, when the z value is greater than 2m, the fine-tuning ratio is -0.04*(z-2)+x℃; when the z value is less than 2m, the fine-tuning ratio is +0.02*(z-2)+x℃. The value of x is set according to the oil temperature inside the pipe corresponding to the device location in the pipe layout diagram. Let the oil temperature inside the pipe be A, then x = 1.3%*A. The above numerical parameters can be adjusted according to the actual conditions inside the aircraft cabin.

[0057] This embodiment provides an aviation hot surface ignition test system, which is more intelligent than Embodiment 1. Through the main control device, test parameters for each mechanism and pipeline can be automatically set according to test requirements, effectively reducing the workload of test control and making operation easier. In particular, this solution includes options for the type of device to which the hot surface belongs, aircraft operating conditions, and the location of the device to which the hot surface belongs. By taking into account the pipeline layout and flight conditions, this solution can specifically recreate the surrounding environment of the hot surface, further refining different realistic hot surface ignition scenarios. Furthermore, this solution can intelligently recommend other test parameters based on selected parameters, further simplifying the test control workload and making it suitable for operation and control by personnel with limited testing experience.

[0058] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics of the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. An aviation hot surface ignition test system, characterized in that, It includes an interconnected inlet pipe, a test pipe, and an exhaust pipe; the inlet pipe is equipped with a valve at its end; the valve is used to control the opening size of the inlet pipe; the bottom of the test pipe is equipped with a heating mechanism; the top of the test pipe is equipped with a dripping mechanism; the exhaust pipe is connected to an exhaust fan; the bottom of the test pipe has an installation port for detachably installing different plates; the plates are used to simulate hot surfaces; the heating mechanism is used to heat the plates; and the dripping mechanism is used to drip oil onto the plates. A rectifier pipe is also connected between the inlet pipe and the test pipe; the rectifier pipe is used to stabilize the airflow entering the test pipe; a rectifier grid is provided in the rectifier pipe; and multiple honeycomb units are provided on the rectifier grid. Furthermore, the system can create a dynamic negative pressure test environment by combining and adjusting different valve openings and exhaust fan speeds; in the dynamic negative pressure test environment, the airflow velocity is 0~3.5m / s and the pressure is 20kPa~101.3kPa.

2. The aviation hot surface ignition test system according to claim 1, characterized in that, The plate material includes flat plate material and curved plate material; the material of the plate material includes titanium alloy, high-strength steel and high-temperature alloy; the oil in the dripping mechanism is aviation hydraulic oil, aviation fuel or aviation lubricating oil.

3. The aviation hot surface ignition test system according to claim 1, characterized in that, A cooling pipe is also connected between the test pipe and the exhaust pipe; the cooling pipe is used to cool the airflow passing through the test pipe.

4. The aviation hot surface ignition test system according to claim 1, characterized in that, An airflow heating pipe is also provided between the rectifier pipe and the test pipe; the airflow heating pipe is used to heat the air introduced from the inlet pipe; and the air temperature heating threshold of the airflow heating pipe is 400℃.

5. The aviation hot surface ignition test system according to claim 1, characterized in that, It also includes a monitoring device; the monitoring device includes a camera and a high-speed schlieren for observing the contact surface between the plate and the oil droplets; the side of the test pipe is provided with an observation window; the camera and the high-speed schlieren are located around the test pipe and aligned with the observation window.

6. The aviation hot surface ignition test system according to claim 1, characterized in that, The dripping mechanism includes a rotating device and several needle-type injection pumps circumferentially fixed on the rotating device; and the several needle-type injection pumps store different types of oils respectively; when the needle-type injection pumps drip oil, they include single-drop dripping mode, continuous dripping mode and fine-line dripping mode.

7. The aviation hot surface ignition test system according to claim 1, characterized in that, The heating mechanism includes multiple sets of heating wires and a heating controller for controlling each set of heating wires; when controlling the heating wires, the heating controller automatically selects the heating wires to be heated and the corresponding heating temperature according to the heat surface simulation requirements; the bottom of the plate is provided with a heating wire mounting position.

8. The aviation hot surface ignition test system according to claim 4, characterized in that, It also includes a main control device; the main control device includes a main control module; the main control module is used to collect the thermal surface simulation requirements, and control the operation of the heating mechanism, dripping mechanism, cooling pipe, airflow heating pipe, exhaust fan and valve respectively according to the thermal surface simulation requirements.

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