Shutdown protection system and method for passive injection high-altitude simulation hot test run

Abstract

The invention relates to a shutdown protection system and method for passive injection high-altitude simulation hot test run. The shutdown protection system comprises a storage tank, an air inlet valve, a liquid outlet valve, high-pressure nitrogen, liquid carbon dioxide and a connecting pipeline. Liquid carbon dioxide is injected into the storage box, high-pressure nitrogen is filled into the storage box, the liquid carbon dioxide is prevented from being solidified in the storage box, and it is guaranteed that the liquid carbon dioxide in the storage box is in a supercritical state; the air inlet valve controls on-off of an air inlet of the storage tank; the connecting pipeline extends into the storage tank to communicate the storage tank with the vacuum cabin, and the liquid outlet valve is arranged on the connecting pipeline to control on-off of the liquid outlet valve; after the engine is shut down, the liquid outlet valve is opened, the supercritical carbon dioxide in the storage tank is discharged into the vacuum chamber through the connecting pipeline under the action of high-pressure nitrogen to absorb heat, cool and rapidly gasify, rapid pressure boosting of the vacuum chamber is achieved, and high-temperature fuel gas is prevented from returning to the chamber to burn the engine. While the test run requirement of the delivered engine is met, the adverse effect on the delivered engine caused by shutdown high-temperature fuel gas returning to the cabin is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of engine thermal protection, and relates to a shutdown protection system and method for passive induced high-altitude simulated thermal test. Background Art

[0002] High-altitude simulated hot test is an important method for ground simulation assessment of the flight working state of the upper stage engine. During the test, the engine is placed in a vacuum chamber. The main schemes for the vacuum chamber to achieve full-time high-altitude simulated pressure are active ejection scheme or passive ejection scheme. The passive ejection high-model system only relies on the engine's own gas to work. The ejection system is simple, the test cost is low, and the test preparation cycle is short, which can greatly improve the efficiency of engine delivery.

[0003] Although the high-altitude simulation system based on passive injection can meet the test requirements of the delivered engines, according to the test results of a certain model, there is a possibility that high-temperature gas will fill the cabin after shutdown, causing flammable materials in the cabin such as electrical tape, foam layer, cables, etc. to burn and be damaged, which will have an adverse effect on the delivered engines. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a shutdown protection system and method for passive induced high-altitude simulated thermal testing, which can meet the test requirements of the delivered engine while avoiding the adverse effects of shutdown high-temperature fuel gas returning to the cabin on the delivered engine.

[0005] The solution to the technical problem of the present invention is: a shutdown protection system for passive induced high-altitude simulated thermal test, comprising a tank, an air inlet valve, a liquid outlet valve, high-pressure nitrogen, liquid carbon dioxide and a connecting pipeline; liquid carbon dioxide is injected into the tank through a filling port of the tank, and high-pressure nitrogen is filled into the tank through an air inlet at the upper end of the tank to prevent the liquid carbon dioxide from solidifying in the tank and ensure that the liquid carbon dioxide in the tank is in a supercritical state; the air inlet valve is used to control the on-off of the tank air inlet; the connecting pipeline extends into the tank to connect the tank and the vacuum cabin, and the liquid outlet valve is arranged on the connecting pipeline to control the on-off of the liquid outlet valve;

[0006] After the engine is shut down, the liquid outlet valve is opened, and the supercritical carbon dioxide in the storage tank is discharged into the vacuum cabin through the connecting pipeline under the action of high-pressure nitrogen to absorb heat and cool down, quickly vaporize, and achieve rapid pressurization of the vacuum cabin to prevent high-temperature fuel gas from returning to the cabin and burning the engine.

[0007] Furthermore, the supercritical state of liquid carbon dioxide is specifically:

[0008] The intersection point of the gas and liquid phases is the critical point. The critical point temperature and critical point pressure of carbon dioxide are 31.1℃ and 7.39MPa respectively.

[0009] Furthermore, the method for determining the liquid carbon dioxide filling height H is:

[0010] The filling height is related to the demand for purge protection and the size of the tank. Assuming that the demand for purge protection is x kg of liquid carbon dioxide, the density ρ of the supercritical carbon dioxide in the tank is converted into volume V, and then the filling height H is calculated based on the bottom area of ​​the tank.

[0011] Furthermore, the pressure of the high-pressure nitrogen is not lower than the critical point pressure of carbon dioxide.

[0012] Furthermore, the minimum pressure resistance of the storage tank is the critical pressure of liquid carbon dioxide.

[0013] A shutdown protection method for passive induced high-altitude simulated thermal test, characterized in that it includes the following steps:

[0014] Before the engine is operated, the filling of liquid carbon dioxide is completed, and the filling height meets the preset requirement H. At the same time, the intake valve is kept open to ensure that the carbon dioxide in the tank is in a supercritical state;

[0015] After the carbon dioxide maintains a supercritical state, close the air inlet valve;

[0016] At time t, the engine completes the hot test and shuts down. The engine stops working, opens the air inlet valve and the liquid outlet valve to enter the post-shutdown purge phase. Under the action of high-pressure nitrogen, the liquid carbon dioxide in the tank enters the vacuum chamber through the liquid outlet valve and the connecting pipeline, achieving rapid recovery to normal pressure, high-temperature gas cooling and flame retardant functions to protect the engine product.

[0017] Furthermore, the preset requirement H for the filling height is related to the demand for purge protection and the size of the tank. Assuming that the demand for purge protection is x kg of liquid carbon dioxide, the density ρ of the supercritical carbon dioxide in the tank is converted into the volume V, and then the preset requirement H for the filling height is calculated based on the bottom area of ​​the tank.

[0018] Furthermore, the minimum pressure resistance of the storage tank is the critical pressure of liquid carbon dioxide.

[0019] The beneficial effects of the present invention compared with the prior art are:

[0020] (1) The present invention greatly improves the reliability of the engine's passive ejection high-altitude simulated thermal test. Compared with other purge solutions, liquid carbon dioxide has better room-temperature storage properties than other cryogenic media and is relatively cheap. Compared with the high-pressure nitrogen purge solution, the system pressure is lower and the system is simpler when the purge effect is the same.

[0021] (2) After the engine is shut down, the present invention can effectively prevent the combustion gas in the cabin from burning the engine and the flammable parts of the test bench, thereby achieving reliable engine delivery and ensuring test safety.

[0022] (3) Based on the existing normal temperature high pressure nitrogen shutdown purge solution, the present invention adds a liquid carbon dioxide shutdown purge solution. This greatly reduces the cost and cycle of test bench modification, and is expected to save 1 million yuan in costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a shutdown protection system for passive induced high-altitude simulated thermal test according to an embodiment of the present invention;

[0024] Figure 2 This is a shutdown and purge operation timing diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the embodiments.

[0026] Example 1

[0027] like Figure 1 As shown, the shutdown protection system of this embodiment includes a tank 1, an air inlet valve 2, a liquid outlet valve 3, high-pressure nitrogen 4, liquid carbon dioxide 5 and a connecting pipeline. The liquid carbon dioxide 5 is injected into the tank 1 through the filling port of the tank 1, and the high-pressure nitrogen 4 is filled into the tank 1 through the air inlet at the upper end of the tank 1 to prevent the liquid carbon dioxide 5 from solidifying in the tank 1 and ensure that the liquid carbon dioxide 5 in the tank 1 is in a supercritical state; the air inlet valve 2 is used to control the on-off of the air inlet of the tank 1; the connecting pipeline extends into the tank 1 to connect the tank 1 with the vacuum chamber, and the liquid outlet valve 3 is arranged on the connecting pipeline to control the on-off of the liquid outlet valve 3;

[0028] After the engine is shut down, the liquid outlet valve 3 is opened, and the supercritical carbon dioxide in the storage tank 1 is discharged into the vacuum cabin through the connecting pipeline under the action of the high-pressure nitrogen 4 to absorb heat and cool down, and quickly gasify, thereby achieving rapid pressurization of the vacuum cabin and preventing high-temperature fuel gas from returning to the cabin and burning the engine.

[0029] The supercritical state of liquid carbon dioxide 5 is specifically:

[0030] The intersection of the gas and liquid phases is the critical point, which corresponds to the critical temperature and critical pressure. When the temperature and pressure exceed the critical point, it enters the supercritical state. Supercritical fluids have similar diffusivity to gases, density and solubility to liquids, etc. The critical point temperature and pressure of carbon dioxide are 31.1°C and 7.39MPa respectively. Since the supercritical state of carbon dioxide has low requirements, it is easy to maintain.

[0031] Among them, the method for determining the filling height H of liquid carbon dioxide 5 is:

[0032] The filling height is related to the demand for purge protection and the size of the tank. Assuming that the demand for purge protection is xkg of liquid carbon dioxide, the density of supercritical carbon dioxide in the tank is converted into volume, and then the filling height H can be calculated based on the bottom area of ​​the tank. The demand for purge protection is related to the actual back pressure after the engine is shut down, the back pressure speed and the vacuum chamber volume: demand = carbon dioxide density (determined by the back pressure) * vacuum chamber volume.

[0033] The pressure of the high-pressure nitrogen 4 is not less than the critical pressure of carbon dioxide 7.39 MPa;

[0034] The storage tank 1 is a high-pressure storage tank, and the lowest pressure resistance is the critical pressure of the liquid carbon dioxide 5.

[0035] This embodiment provides a shutdown protection method for passive induced high-altitude simulated thermal test, including the following steps:

[0036] Before the engine is operated, the liquid carbon dioxide 5 is filled to a height that meets the preset requirement H, and the intake valve 2 is kept open to ensure that the carbon dioxide in the tank 1 is in a supercritical state;

[0037] After the carbon dioxide maintains a supercritical state, the air inlet valve 2 is closed;

[0038] At time t, the engine is shut down after completing the hot test and the engine stops working. The air inlet valve 2 and the liquid outlet valve 3 are opened to enter the post-shutdown purge phase. Under the action of high-pressure nitrogen 4, the liquid carbon dioxide 5 in the tank 1 enters the vacuum chamber through the liquid outlet valve 3 and the connecting pipeline to quickly restore the normal pressure, cool the high-temperature gas and prevent flame retardancy, so as to better protect the engine product. Figure 2 shown.

[0039] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0040] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A shutdown protection system for passive induced high-altitude simulated thermal test, characterized in that: The invention comprises a storage tank (1), an air inlet valve (2), a liquid outlet valve (3), high-pressure nitrogen (4), liquid carbon dioxide (5) and a connecting pipeline; the liquid carbon dioxide (5) is injected into the storage tank (1) through a filling port of the storage tank (1), and the high-pressure nitrogen (4) is filled into the storage tank (1) through an air inlet at the upper end of the storage tank (1) to prevent the liquid carbon dioxide (5) from solidifying in the storage tank (1) and ensure that the liquid carbon dioxide (5) in the storage tank (1) is in a supercritical state; the air inlet valve (2) is used to control the on-off of the air inlet of the storage tank (1); the connecting pipeline extends into the storage tank (1) to connect the storage tank (1) with the vacuum chamber, and the liquid outlet valve (3) is arranged on the connecting pipeline to control the on-off of the liquid outlet valve (3); After the engine is shut down, the liquid outlet valve (3) is opened, and the supercritical carbon dioxide in the storage tank (1) is discharged into the vacuum cabin through the connecting pipeline under the action of the high-pressure nitrogen (4) to absorb heat and cool down, and quickly gasify, thereby achieving rapid pressure increase in the vacuum cabin and preventing high-temperature gas from returning to the cabin and burning the engine.

2. A shutdown protection system for passive induced high-altitude simulated thermal test according to claim 1, characterized in that: The supercritical state of liquid carbon dioxide (5) is: The intersection point of the gas and liquid phases is the critical point. The critical point temperature and critical point pressure of carbon dioxide are 31.1°C and 7.39MPa respectively.

3. A shutdown protection system for passive induced high-altitude simulated thermal test according to claim 1, characterized in that: The method for determining the filling height H of liquid carbon dioxide (5) is: The filling height is related to the demand for purge protection and the size of the tank. Assuming that the demand for purge protection is x kg of liquid carbon dioxide (5), the density ρ of the supercritical carbon dioxide in the tank (1) is converted into volume V, and then the filling height H is calculated based on the bottom area of ​​the tank (1).

4. A shutdown protection system for passive induced high-altitude simulated thermal test according to claim 2, characterized in that: The pressure of the high-pressure nitrogen (4) is not lower than the critical point pressure of carbon dioxide.

5. A shutdown protection system for passive induced high-altitude simulated thermal test according to claim 2, characterized in that: The lowest pressure resistance of the storage tank (1) is the critical pressure of the liquid carbon dioxide (5).

6. A shutdown protection method for passive induced high-altitude simulated thermal test based on the system according to any one of claims 1 to 5, characterized in that: The following steps are involved: Before the engine is operated, the liquid carbon dioxide (5) is filled, and the filling height meets the preset requirement H, while the intake valve (2) is kept open to ensure that the carbon dioxide in the tank (1) is in a supercritical state; After the carbon dioxide maintains a supercritical state, the air inlet valve (2) is closed; At time t, the engine is shut down after completing the hot test and assessment, and the engine stops working. The air inlet valve (2) and the liquid outlet valve (3) are opened to enter the post-shutdown purge phase. Under the action of the high-pressure nitrogen (4), the liquid carbon dioxide (5) in the storage tank (1) enters the vacuum chamber through the liquid outlet valve (3) and the connecting pipeline, thereby realizing the rapid recovery of normal pressure, high-temperature fuel gas cooling and flame retardant functions, and protecting the engine product.

7. A shutdown protection method for passive induced high-altitude simulated thermal test according to claim 6, characterized in that: The preset requirement H for the filling height is related to the demand for purge protection and the size of the tank. Assuming that the demand for purge protection is x kg of liquid carbon dioxide (5), the density ρ of the supercritical carbon dioxide in the tank (1) is converted into volume V, and then the preset requirement H for the filling height is calculated based on the bottom area of ​​the tank (1).

8. The shutdown protection method for passive induced high-altitude simulated thermal test according to claim 6 is characterized in that: The lowest pressure resistance of the storage tank (1) is the critical pressure of the liquid carbon dioxide (5).

Images