Ammonia fuel supply system and method for ramjet of test platform

Abstract

The invention belongs to the technical field of ramjet engines, and provides a ramjet engine ammonia fuel gas supply system and method of a test platform, and the system is composed of two subsystems of an ammonia fuel filling system and an ammonia fuel constant pressure supply system. When the ramjet is subjected to the bench test, the nitrogen is introduced into the ammonia fuel tank, so that the pressure in the ammonia fuel tank is kept stable, and the liquid ammonia fuel in the ammonia fuel tank is supplied to the ramjet at the constant pressure. Meanwhile, the characteristic of good expansibility of gas is ingeniously utilized, the large-volume constant-pressure nitrogen tank is adopted, when slight pressure fluctuation exists in the ammonia fuel tank, nitrogen can be rapidly filled, the pressure in the ammonia fuel tank is kept stable, and then it is guaranteed that the pressure of liquid ammonia fuel supplied to the ramjet engine is stable.

Description

Technical Field

[0001] The present invention belongs to the technical field of ramjet engines, and in particular relates to an ammonia fuel supply system and method for a ramjet engine of a test platform. Background Art

[0002] The ramjet engine consists of three parts: the air intake, the combustion chamber, and the propulsion nozzle. Its working principle is that when the ramjet engine is working, the relative airflow enters the engine air intake to decelerate and increase pressure, converting kinetic energy into pressure energy. When the air pressure and temperature of the airflow increase, it enters the fuel chamber and mixes with the fuel to burn. The high-temperature combustion gas then expands and accelerates through the propulsion nozzle, and finally ejects from the nozzle at high speed to generate thrust.

[0003] Ramjet engines are mainly used in aircraft, so a large number of bench tests need to be carried out on land before they are actually used. Bench tests refer to certain simulated test runs before the equipment is officially put into operation, in order to obtain various relevant performance parameters. When a ramjet engine is bench tested, it is necessary to continuously supply fuel to the combustion chamber, and the fuel in the combustion chamber is usually kerosene. With the continuous improvement and optimization of aircraft, aircraft are also trying various new clean energy sources for the fuel in the combustion chamber of ramjet engines. Among them, ammonia fuel, as a hydrogen-rich fuel, does not produce CO2 after complete combustion. Therefore, ammonia fuel is a more ideal fuel for ramjet engines.

[0004] When ammonia fuel is used as the supply fuel for bench testing of ramjet engines, a pump is usually used to deliver fuel to the ramjet engine to maintain the stable fuel supply pressure, so as to obtain various data required for the operation of the ramjet engine. However, when a pump is used to supply fuel to the ramjet engine, on the one hand, due to the small molecular distance between liquids and poor compressibility, when the liquid volume changes slightly, the pressure will change greatly, resulting in certain fluctuations in the pressure when the pump supplies liquid ammonia to the ramjet engine; on the other hand, the liquid ammonia supply pump usually adopts a volumetric pump. The structure and principle of the volumetric pump itself can achieve basic stability of flow and pressure, but cannot achieve high-precision stability of flow and pressure. When the pump is used to supply fuel to the ramjet engine, the pressure fluctuates to a certain extent, which makes the measured test data less accurate. Therefore, when the ramjet engine is subjected to bench testing, it is necessary to control the pressure fluctuation of liquid ammonia supply as small as possible and the pressure is stable.

[0005] Based on the above reasons, if a ramjet ammonia fuel supply system and method for a test platform can be proposed, ammonia fuel can be supplied to the ramjet engine in the bench test at a constant pressure, reducing the pressure fluctuation during the supply of liquid ammonia and ensuring that the measured test data is more accurate. Summary of the invention

[0006] The present invention substantially solves the above problems and proposes an ammonia fuel supply system and method for a ramjet engine of a test platform. The first purpose of the present invention is to propose an ammonia fuel supply system for a ramjet engine of a test platform, which consists of two subsystems: an ammonia fuel constant pressure supply system and an ammonia fuel filling system.

[0007] The ammonia fuel supply system comprises: a low-pressure nitrogen tank, a compressor, a constant-pressure nitrogen tank, a pressure regulating valve, a stop valve, an ammonia fuel tank, a supply valve, and a ramjet engine.

[0008] The ammonia fuel filling system includes: an ammonia fuel tank, a gas phase supply interface, a gas phase receiving interface, a liquid ammonia storage tank, a liquid phase filling interface, a liquid phase receiving interface, a liquid level sensor, a relief valve, a safety valve, and a test filling platform.

[0009] In the ammonia fuel supply system, the low-pressure nitrogen tank is connected to the compressor; the compressor is connected to the constant-pressure nitrogen tank; the pressure regulating valve is respectively connected to the low-pressure nitrogen tank and the constant-pressure nitrogen tank to maintain the pressure in the constant-pressure nitrogen tank stable; the constant-pressure nitrogen tank is connected to the stop valve; the stop valve is connected to the ammonia fuel tank; the ammonia fuel tank is connected to the supply valve; and the supply valve is connected to the ramjet engine.

[0010] In the ammonia fuel filling system, the ammonia fuel tank is connected to the gas supply interface; the gas supply interface is connected to the gas receiving interface through a pipeline; the gas receiving interface is connected to the liquid ammonia storage tank; the liquid ammonia storage tank is connected to the liquid phase filling interface; the liquid phase filling interface is connected to the liquid phase receiving interface through a pipeline; the liquid phase receiving interface is connected to the ammonia fuel tank; the liquid level sensor is placed in the ammonia fuel tank; a safety valve and a release valve are provided on the top of the ammonia fuel tank, wherein the safety valve automatically opens when the pressure in the ammonia fuel tank is too high to prevent danger caused by excessive pressure in the ammonia fuel tank.

[0011] Furthermore, in order to ensure that the deviation between the pressure of the constant pressure nitrogen tank and the nitrogen pressure of the ammonia fuel tank is as small as possible, the diameter of the pipe connecting the constant pressure nitrogen tank and the ammonia fuel tank should satisfy formula (I):

[0012]

[0013] Where, D-pipe diameter, m;

[0014] Q-nitrogen supply flow rate, m 3 / s;

[0015] v-nitrogen supply speed, m / s.

[0016] According to the actual requirements of the project, the nitrogen supply speed v cannot exceed 20m / s. Therefore, the above formula can be written as:

[0017]

[0018] Furthermore, the test filling platform is located at a height higher than the top of the ammonia fuel tank, so that liquid ammonia can be injected into the ammonia fuel tank from the liquid ammonia storage tank under the action of its own gravity; the liquid ammonia storage tanks are placed on the test filling platform, and their number is determined according to the amount of liquid ammonia fuel required for the ramjet engine bench test.

[0019] Furthermore, the volume of the constant pressure nitrogen tank is more than 3 times the volume of the ammonia fuel tank. The reason is that when the ammonia fuel tank supplies fuel to the ramjet, the pressure in the pipeline supplying liquid ammonia fuel will fluctuate slightly due to the working conditions of the ramjet itself, which will lead to unstable pressure in the ammonia fuel tank. There are liquid ammonia and nitrogen in the whole composed of the ammonia fuel tank and the constant pressure nitrogen tank, and the space occupied by liquid ammonia is very small. When the pressure in the ammonia fuel tank fluctuates slightly, the nitrogen can be quickly replenished to maintain the pressure in the ammonia fuel tank stable because the constant pressure nitrogen tank is large enough and the gas has good expansion properties, thereby ensuring the stable pressure of the liquid ammonia fuel when it is supplied to the ramjet.

[0020] The principle of constant pressure when liquid ammonia fuel is supplied to the ramjet is as follows: the nitrogen in the low-pressure nitrogen tank enters the constant-pressure nitrogen tank through the compressor, and the pressure regulating valve is used to maintain the constant pressure in the constant-pressure nitrogen tank. Then the nitrogen in the constant-pressure nitrogen tank enters the ammonia fuel tank through the stop valve, so that there is a constant back pressure in the ammonia fuel tank. Finally, the liquid ammonia fuel is supplied to the ramjet through the supply valve at a constant pressure. On the one hand, due to the continuous supply of nitrogen, the pressure of liquid ammonia supplied from the ammonia fuel tank to the ramjet is stable. On the other hand, due to the good expansion of the gas and the volume of the constant-pressure nitrogen tank is more than 3 times the volume of the ammonia fuel tank, even if the pressure in the ammonia fuel tank fluctuates slightly, the nitrogen in the constant-pressure nitrogen tank can be quickly filled into the ammonia fuel tank to maintain the pressure of the liquid ammonia fuel stable, thereby ensuring the stability of the pressure of the liquid ammonia fuel supplied to the ramjet.

[0021] The second object of the present invention is to provide a method for supplying ammonia fuel to a ramjet engine of a test platform.

[0022] Before the ramjet engine is tested on a bench, liquid ammonia fuel needs to be added from the liquid ammonia storage tank to the ammonia fuel tank. After the gas phase receiving interface and liquid phase filling interface of the liquid ammonia storage tank are connected to the gas phase supply interface and liquid phase receiving interface of the ammonia fuel tank through pipelines, the liquid ammonia fuel in the liquid ammonia storage tank is injected into the ammonia fuel tank under the action of its own gravity. When the liquid ammonia fuel reaches 80% of the volume of the ammonia fuel tank, the liquid level sensor sends a signal, and the filling is stopped at this time, and the gas phase receiving interface, liquid phase filling interface, gas phase supply interface, and liquid phase receiving interface are disconnected.

[0023] When the ramjet engine is bench tested, first, the pressure of the pressure regulating valve is set according to the pressure required by the ramjet engine, and the set pressure must be much higher than the saturation pressure of liquid ammonia at the test environment temperature to avoid the liquid ammonia fuel in the ammonia fuel tank from gasifying due to the high test environment temperature in extreme cases, and to ensure that the fuel supplied to the ramjet engine by the ammonia fuel tank is liquid. Then the nitrogen in the low-pressure nitrogen tank enters the constant-pressure nitrogen tank through the compressor, and at the same time, the nitrogen is discharged back to the low-pressure nitrogen tank through the pressure regulating valve to ensure that the pressure in the constant-pressure nitrogen tank is always the set pressure. Then the nitrogen in the constant-pressure nitrogen tank enters the ammonia fuel tank through the stop valve to ensure that the pressure in the ammonia fuel tank is also the set pressure. Finally, the liquid ammonia fuel is supplied to the ramjet engine through the supply valve at a constant pressure.

[0024] After a bench test of the ramjet engine is completed, before the next bench test, the amount of liquid ammonia fuel in the ammonia fuel tank cannot meet the consumption of one test, so it is necessary to add liquid ammonia to the ammonia fuel tank through the liquid ammonia storage tank. However, the pressure in the ammonia fuel tank is higher than the saturation pressure of liquid ammonia at the test environment temperature, which will cause the liquid ammonia fuel in the liquid ammonia storage tank to be unable to be injected into the ammonia fuel tank under the action of its own gravity. Therefore, first open the discharge valve, release the pressure in the ammonia fuel tank to the saturation pressure of ammonia at the bench test environment temperature, close the discharge valve, and then add liquid ammonia fuel.

[0025] Beneficial effects of the present invention:

[0026] 1. The present invention ensures that the ammonia fuel tank has a constant back pressure by introducing nitrogen at a constant pressure into the ammonia fuel tank, so that the liquid ammonia fuel in the ammonia fuel tank is supplied to the ramjet engine at a constant pressure to meet the high-precision test conditions of the ramjet engine.

[0027] 2. The present invention sets the volume of the constant pressure nitrogen tank to more than three times the volume of the ammonia fuel tank, and cleverly utilizes the good expansion property of the gas. Even if the pressure in the ammonia fuel tank fluctuates slightly, the nitrogen can be quickly replenished to maintain a constant back pressure in the ammonia fuel tank, thereby ensuring that the pressure of the liquid ammonia fuel supplied to the ramjet engine is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Attached Figure 1 This is the system invention diagram

[0029] In the attached figure: 1. Low-pressure nitrogen tank; 2. Compressor; 3. Constant-pressure nitrogen tank; 4. Pressure regulating valve; 5. Shut-off valve; 6. Ammonia fuel tank; 7. Supply valve; 8. Ramjet engine; 9. Gas phase filling interface; 10. Gas phase receiving interface; 11. Liquid ammonia storage tank; 12. Liquid phase filling interface; 13. Liquid phase receiving interface; 14. Liquid level sensor; 15. Safety valve; 16. Release valve; 17. Test filling platform. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] A ramjet ammonia fuel supply system and method for a test platform, such as Figure 1 As shown, the system consists of two subsystems: an ammonia fuel constant pressure supply system and an ammonia fuel filling system.

[0032] The ammonia fuel constant pressure supply system includes: a low-pressure nitrogen tank 1, a compressor 2, a constant-pressure nitrogen tank 3, a pressure regulating valve 4, a stop valve 5, an ammonia fuel tank 6, a supply valve 7, and a ramjet engine 8; the ammonia fuel filling system includes: an ammonia fuel tank 6, a gas phase supply interface 9, a gas phase receiving interface 10, a liquid ammonia storage tank 11, a liquid phase filling interface 12, a liquid phase receiving interface 13, a liquid level sensor 14, a safety valve 15, a release valve 16, and a test filling platform 17.

[0033] In the ammonia fuel constant pressure supply system, the low-pressure nitrogen tank 1 is connected to the compressor 2; the compressor 2 is connected to the constant-pressure nitrogen tank 3 to realize the pressurization of the nitrogen; the pressure regulating valve 4 is connected to the low-pressure nitrogen tank 1 and the constant-pressure nitrogen tank 3 through pipelines, respectively, for maintaining the pressure in the constant-pressure nitrogen tank 3 stable; the constant-pressure nitrogen tank 3 is connected to the stop valve 5; the stop valve 5 is connected to the ammonia fuel tank 6; the ammonia fuel tank 6 is connected to the supply valve 7; the supply valve 7 is connected to the ramjet engine 8.

[0034] In the ammonia fuel filling system, the ammonia fuel tank 6 is connected to the gas supply interface 9; the gas supply interface 9 is connected to the gas receiving interface 10 through a pipeline; the gas receiving interface 10 is connected to the liquid ammonia storage tank 11; the liquid ammonia storage tank 11 is connected to the liquid phase filling interface 12; the liquid phase filling interface 12 is connected to the liquid phase receiving interface 13 through a pipeline; the liquid phase receiving interface 13 is connected to the ammonia fuel tank 6; the liquid level sensor 14 is placed in the ammonia fuel tank 6, and when the liquid ammonia is filled to 80% of the volume of the ammonia fuel tank 6, the liquid level sensor 14 sends a warning signal; a safety valve 15 and a relief valve 16 are provided on the top of the constant pressure ammonia fuel tank 6, wherein the safety valve 15 automatically opens when the pressure in the ammonia fuel tank 6 is too high to prevent the pressure in the ammonia fuel tank 6 from being too high and causing danger.

[0035] Furthermore, the diameter of the pipe connecting the constant pressure nitrogen tank 3 and the ammonia fuel tank 6 should be as large as possible to reduce the pipe resistance. On the one hand, it is necessary to ensure that the pressure deviation between the ammonia fuel tank 6 and the constant pressure nitrogen tank 3 is as small as possible; on the other hand, it is necessary to ensure that when the pressure of the ammonia fuel tank 6 fluctuates, the nitrogen in the constant pressure nitrogen tank 3 can be quickly replenished to the ammonia fuel tank 6 to maintain the pressure in the ammonia fuel tank 6 stable. Therefore, the diameter of the pipe connecting the constant pressure nitrogen tank 3 and the ammonia fuel tank 6 satisfies formula (I):

[0036]

[0037] Where, D-pipe diameter, m;

[0038] Q-nitrogen supply flow rate, m 3 / s;

[0039] v-nitrogen supply speed, m / s.

[0040] According to the actual requirements of the project, the nitrogen supply speed v cannot exceed 20m / s. Therefore, the above formula can be written as:

[0041]

[0042] For example, assuming that the nitrogen supply flow rate Q is 0.05m 3 / s, according to formula (II), it is calculated that the diameter D of the pipeline connecting the constant pressure nitrogen tank 3 and the ammonia fuel tank 6 is not less than 0.06m.

[0043] Furthermore, the test filling platform 17 is located at a height higher than the top of the ammonia fuel tank 6, so that liquid ammonia can be injected into the ammonia fuel tank 6 from the liquid ammonia storage tank 11 under the action of its own gravity; the liquid ammonia storage tank 11 is placed on the test filling platform 17, and the number of the liquid ammonia storage tanks 11 is determined according to the amount of liquid ammonia fuel required for the ramjet engine 8 to perform bench testing.

[0044] The amount of liquid ammonia fuel required for a bench test of the ramjet engine 8 needs to be determined according to the test time and the fuel supply of the ammonia fuel tank 6. For example: assuming that it takes 10 minutes for the ramjet engine 8 to perform a bench test, and the fuel supply of the ammonia fuel tank 6 is 25L / min, the liquid ammonia fuel required for a bench test of the ramjet engine 8 is 250L, and the ammonia fuel tank 6 can accommodate a maximum of 80% of its volume of liquid ammonia fuel. Therefore, in order to ensure that the amount of liquid ammonia fuel in the ammonia fuel tank 6 can meet the amount of a bench test, the volume of the ammonia fuel tank 6 cannot be less than 320L.

[0045] Furthermore, the volume of the constant pressure nitrogen tank 3 is more than 3 times the volume of the ammonia fuel tank 6. For example, when the volume of the ammonia fuel tank 6 is 320L, the volume of the constant pressure nitrogen tank 3 is set to at least 960L. This is because: when the ammonia fuel tank 6 supplies fuel to the ramjet 8, the pressure in the pipeline supplying the liquid ammonia fuel will fluctuate slightly due to the working conditions of the ramjet 8 itself, which will lead to unstable pressure in the ammonia fuel tank 6. There are liquid ammonia and nitrogen in the whole composed of the ammonia fuel tank 6 and the constant pressure nitrogen tank 3, and the space occupied by the liquid ammonia is very small. When the pressure in the ammonia fuel tank 6 fluctuates slightly, since the constant pressure nitrogen tank 3 is large enough and the gas has good expansibility, the nitrogen can be quickly replenished to maintain the pressure in the ammonia fuel tank 6 stable, thereby ensuring the pressure stability of the liquid ammonia fuel when it is supplied to the ramjet 8.

[0046] Before the ramjet engine 8 is subjected to bench testing, liquid ammonia fuel needs to be added to the ammonia fuel tank 6 from the liquid ammonia storage tank 11. First, the gas phase receiving interface 10 and the liquid phase filling interface 12 on the liquid ammonia storage tank 11 are respectively connected to the gas phase supply interface 9 and the liquid phase receiving interface 13 of the ammonia fuel tank 6 through pipelines, and the liquid ammonia fuel is injected into the ammonia fuel tank 6 from the liquid ammonia storage tank 11 under the action of its own gravity. When the liquid ammonia fuel reaches 80% of the volume of the ammonia fuel tank 6, the liquid level sensor 14 sends a signal, and the filling is stopped at this time, and the gas phase supply interface 9, the gas phase receiving interface 10, the liquid phase filling interface 12, and the liquid phase receiving interface 13 are disconnected.

[0047] When the ramjet engine 8 is subjected to bench test, the pressure of the pressure regulating valve 4 is first set according to the pressure required by the ramjet engine 8, and the set pressure needs to be much higher than the saturation pressure of liquid ammonia at the test environment temperature, so as to avoid the liquid ammonia fuel in the ammonia fuel tank 6 being gasified due to the excessively high test environment temperature in extreme cases, and to ensure that the fuel supplied to the ramjet engine 8 by the ammonia fuel tank 6 is liquid. In this embodiment, the setting pressure of the pressure regulating valve 4 is 5.5MPa as an example for explanation. First, the nitrogen in the low-pressure nitrogen tank 1 enters the constant-pressure nitrogen tank 3 through the compressor 2, and the nitrogen is discharged back to the low-pressure nitrogen tank 1 through the pressure regulating valve 4 to ensure that the pressure in the constant-pressure nitrogen tank 3 is always stable at 5.5MPa, and then the stop valve 5 is opened. At this time, the nitrogen in the constant-pressure nitrogen tank 3 enters the ammonia fuel tank 6 through the pipeline, so that the pressure in the ammonia fuel tank 6 is maintained at 5.5MPa, and then the supply valve 7 is opened, and the liquid ammonia fuel is supplied to the ramjet engine 8 through the pipeline at a constant pressure for bench test. After the test is completed, the pressure regulating valve 4, the stop valve 5, and the supply valve 7 are closed, and the compressor 2 stops running.

[0048] After a bench test of the ramjet engine 8 is completed, before the next bench test is carried out, the amount of liquid ammonia fuel in the ammonia fuel tank 6 cannot meet the consumption of one test, and liquid ammonia fuel needs to be added to the ammonia fuel tank 6 from the liquid ammonia storage tank 11. However, the pressure in the liquid ammonia storage tank 11 is the saturated pressure of liquid ammonia at the test environment temperature (for example, the saturated pressure of liquid ammonia at 25°C is about 1MPa), and after the last bench test, the pressure in the ammonia fuel tank 6 is maintained at 5.5MPa, which is much higher than the pressure in the liquid ammonia storage tank 11. If refilling is carried out at this time, the liquid ammonia in the liquid ammonia storage tank 11 will not be able to be added to the ammonia fuel tank 6 under the action of its own gravity. Therefore, before refilling the liquid ammonia fuel, first open the discharge valve 16, release the pressure in the ammonia fuel tank 6 to the saturated pressure of ammonia at the test environment temperature, close the discharge valve 16, and then refill the liquid ammonia.

[0049] The above embodiment is described by taking the pressure of the pressure regulating valve 4 set to 5.5 MPa as an example. In the specific implementation process, the set pressure of the pressure regulating valve 4 can be flexibly adjusted according to the fuel supply pressure required for the bench test of the ramjet engine 8.

[0050] When the ramjet engine 8 is bench tested, it is necessary to continuously supply liquid ammonia fuel to the combustion chamber, and using a pump to supply liquid ammonia fuel to the ramjet engine 8 will cause pressure fluctuations, which will lead to insufficient accuracy of the measured test data. Therefore, when the ramjet engine 8 is bench tested, the present invention introduces nitrogen into the ammonia fuel tank 6 from the constant pressure nitrogen tank 3 to maintain the pressure in the ammonia fuel tank 6 stable, thereby ensuring the stability of the pressure of the liquid ammonia fuel supplied to the ramjet engine 8; at the same time, the present invention sets the volume of the constant pressure nitrogen tank 3 to more than 3 times the volume of the ammonia fuel tank 6, and cleverly utilizes the good expansion property of the gas. Even if the pressure in the ammonia fuel tank 6 fluctuates slightly, the nitrogen can be quickly replenished to maintain a constant back pressure in the ammonia fuel tank 6, ensuring the stability of the pressure of the liquid ammonia fuel supplied to the ramjet engine 8.

[0051] The above is only a preferred embodiment of the present invention. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A ramjet ammonia fuel supply system for a test platform, characterized in that: The system comprises a low-pressure nitrogen tank (1), a compressor (2), a constant-pressure nitrogen tank (3), a pressure regulating valve (4), a stop valve (5), an ammonia fuel tank (6), a supply valve (7), a ramjet engine (8), a gas supply interface (9), a gas receiving interface (10), a liquid ammonia storage tank (11), a liquid filling interface (12), a liquid receiving interface (13), a liquid level sensor (14), a safety valve (15), a discharge valve (16), and a test filling platform (17); The low-pressure nitrogen tank (1) is connected to a compressor (2), the compressor (2) is connected to a constant-pressure nitrogen tank (3), the pressure regulating valve (4) is connected to the low-pressure nitrogen tank (1) and the constant-pressure nitrogen tank (3) respectively through pipelines, the constant-pressure nitrogen tank (3), the stop valve (5), the ammonia fuel tank (6), the supply valve (7), and the ramjet engine (8) are connected in sequence through pipelines, the ammonia fuel tank (6), the gas phase supply interface (9), the gas phase receiving interface (10), and the liquid ammonia storage tank (11) are connected in sequence through pipelines, and the liquid ammonia storage tank (11), the liquid phase filling interface (12), the liquid phase receiving interface (13), and the ammonia fuel tank (6) are connected in sequence through pipelines; the liquid level sensor (14) is placed in the ammonia fuel tank (6), and a safety valve (15) and a discharge valve (16) are provided on the top of the ammonia fuel tank (6).

2. According to the test platform ramjet engine ammonia fuel supply system of claim 1, it is characterized by: The test filling platform (17) is located at a height higher than the top of the ammonia fuel tank (6); and the liquid ammonia storage tank (11) is placed on the test filling platform (17).

3. The ammonia fuel supply system for a ramjet engine of a test platform according to claim 1, characterized in that: The volume of the constant pressure nitrogen tank (3) is more than three times the volume of the ammonia fuel tank (6).

4. The ammonia fuel supply system for a ramjet engine of a test platform according to claim 1, characterized in that: The diameter of the pipe connecting the constant pressure nitrogen tank (3) and the ammonia fuel tank (6) satisfies the formula: Where, D-pipe diameter, m; Q-nitrogen supply flow rate, m 3 / s.

5. A method for supplying ammonia fuel to a ramjet engine on a test platform based on the system of claim 1, characterized in that: Before the ramjet engine (8) is subjected to bench testing, the ammonia fuel tank (6) needs to be filled with fuel through the liquid ammonia storage tank (11). First, the gas phase receiving interface (10) and the liquid phase filling interface (12) on the liquid ammonia storage tank (11) are respectively connected to the gas phase supply interface (9) and the liquid phase receiving interface (13) of the ammonia fuel tank (6). Then, the liquid ammonia fuel is injected into the ammonia fuel tank (6) from the liquid ammonia storage tank (11) under the action of its own gravity. When the liquid ammonia reaches 80% of the volume of the ammonia fuel tank (6), the filling is stopped, and the gas phase receiving interface (10), the liquid phase filling interface (12), the gas phase supply interface (9), and the liquid phase receiving interface (13) are disconnected. When the ramjet engine (8) is subjected to a bench test, the pressure of the regulating valve (4) is set according to the fuel supply pressure required by the ramjet engine (8), and the set pressure is much higher than the saturation pressure of liquid ammonia at the test environment temperature. First, the nitrogen in the low-pressure nitrogen tank (1) enters the constant-pressure nitrogen tank (3) through the compressor (2), and the pressure regulating valve (4) maintains the constant-pressure nitrogen tank (3) at the set pressure all the time. Then, the nitrogen enters the ammonia fuel tank (6) through the stop valve (5), so that there is a constant back pressure in the ammonia fuel tank (6). Finally, the liquid ammonia fuel is supplied to the ramjet engine (8) through the supply valve (7) at a constant pressure. When the bench test is completed, the pressure regulating valve (4), the stop valve (5), and the supply valve (7) are closed, and the compressor (2) stops running. When the current test of the ramjet engine (8) is completed and before the next bench test is carried out, the relief valve (16) is first opened to release the pressure in the ammonia fuel tank (6) to the saturation pressure of liquid ammonia at the test environment temperature, and then the relief valve (16) is closed and liquid ammonia fuel is added.

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