High-pressure liquid oxygen flow rapid adjusting system controlled by cavitation pipe matrix

Abstract

The invention relates to a high-pressure liquid oxygen flow rapid adjusting system controlled by a cavitation pipe matrix. The high-pressure liquid oxygen flow rapid adjusting system is used for a large air suction type scramjet engine test. Aiming at the characteristics of low temperature, high pressure, multiple working conditions and high flow control precision of a heater oxygenating system, the invention provides a high-pressure liquid oxygen flow rapid adjusting system controlled by adopting a cavitation pipe matrix, and various flow changes and high precision requirements are realized by the cavitation pipe matrix. The system is composed of a liquid oxygen container, a pressure reducer, a valve, a flow meter, a cavitation pipe, a temperature sensor, a pressure sensor, a pipeline and the like, and the functions of filling, pressurizing, flow adjusting, oxygen supplementing and the like can be independently achieved. According to the oxygenating working condition, the system is flexibly combined, and the flow is flexibly distributed. The container is directly pressurized through the pressure reducer, the pressure of the container is accurately controlled and stabilized, the pressurization flow range is covered, and the pressurization reliability is considered. The liquid oxygen flow is controlled through the cavitation pipes, liquid oxygen flow adjustment under different working conditions is met through combination and parallel connection, the flow is not interfered by downstream pressure fluctuation, and high-precision flow control is achieved. Experiments prove that the working pressure of liquid oxygen of the high-pressure liquid oxygen supply system controlled by the cavitation pipe matrix reaches 30 MPa, large-range flow adjustment can be achieved, the flow control precision is higher than 1%, oxygen supplementation of dozens of test working conditions within the flow envelope range can be achieved, the system works stably, the performance is reliable, and the good using effect is achieved.

Description

1. Technical Field

[0001] The invention relates to a cavitation tube matrix rapid flow control cryogenic liquid flow regulating system, which is used for air-breathing ramjet engine or liquid rocket engine test system, and various wind tunnels. 2. Background Technology

[0002] At present, hypersonic vehicles powered by scramjet engines and combined cycle power, such as hypersonic missiles and space planes, have become a hot topic of research in military powers such as the United States, Russia, Britain, and Japan. They rely on air-breathing scramjet engines to provide power or one of the power sources to achieve horizontal take-off and landing and hypersonic flight in the atmosphere. As we all know, flight Mach number and thrust are two important indicators of air-breathing engines. The development of high-speed and high-thrust engines requires the construction of large-scale test facilities with commensurate capabilities, such as free jet test benches or wind tunnels. Test facilities are generally composed of working fluid supply systems such as oxidizers and fuels, and the supply media include air, fuel, liquid oxygen (considering safety, liquid oxygen is safer than oxygen), etc.

[0003] The ground test of the scramjet engine relies on the heater to organize the combustion of the fuel and oxidant (oxygen-rich air) to produce a gas mixture, simulating the engine's incoming air intake parameters, including relative speed, total temperature, total pressure and other parameters. During the scramjet engine test, liquid oxygen needs to be mixed with the incoming air of the mixer to form oxygen-rich air, so that the oxygen component of the working fluid entering the engine after the heater burns is consistent with that of the air. The working characteristic of the scramjet engine is that the working conditions change with the flight Mach number and altitude, and it has the characteristics of many test conditions and a wide range of parameter spans. The heater operation usually proposes multiple oxygen supply conditions and gives multiple sets of oxygen supply back pressures and oxygen supply flow rates, namely {(P1,q1), (P2,q2),..., (P n ,q n )}. As a liquid oxygen supply system, it has high working pressure (30MPa), low temperature (-183℃), large flow, multiple working conditions (up to dozens of working conditions), high flow control accuracy, high comprehensive technical indicators, and high difficulty in transportation and regulation technology. It is necessary to solve engineering problems such as large flow boosting, high-pressure and low-temperature large flow liquid oxygen transportation, and high-precision flow regulation and control.

[0004] The high-precision control method for flow is generally to control the flow with a cavitation tube. By controlling the inlet pressure of the cavitation tube, the cavitation tube can achieve high-precision flow control. When there are many types of flow required, it is theoretically feasible to set a cavitation tube to control the flow for each flow, but it will increase the floor space of the test system and greatly increase the test cost.

[0005] In summary, a solution to control the flow rate by cavitation tube matrix is ​​proposed. By switching the control valve at the front end of the cavitation tube, the combination of the cavitation tubes is controlled to quickly and accurately control the flow rate. For example, four cavitation tubes can be used to control four flow rates. After the cavitation tube matrix is ​​formed, Type of traffic. III. Summary of the invention

[0006] The purpose of the present invention is to provide a high-pressure, large-flow, low-temperature, multiple high-precision controlled flow rate liquid oxygen supply system for a large-scale scramjet engine test bench, so as to realize multi-condition, high-pressure, and high-precision flow rate control, and provide a new solution for the multi-condition, high-precision cryogenic liquid supply of the test bench.

[0007] The technical solution adopted by the high-pressure liquid oxygen flow rapid regulation system controlled by the cavitation tube matrix of the present invention is as follows: Figure 1 As shown, the system is composed of a nitrogen shut-off valve 1, a pressure reducer 2, an air supply valve 3, a pressurization isolation valve 4, a high-pressure air release valve 5, a low-pressure air release valve 6, a liquid oxygen container 7, a filling valve 8, a liquid supply valve 9, a pipeline purge valve 10, a flow meter 11, a pressure sensor 12, a pre-pipe shut-off valve 13, a cavitation tube 14, a temperature sensor 15, a drain valve 16, a pre-spray valve 17, a pre-spray purge valve 18, a metal hose 19 and connecting pipelines, so as to realize the functions of pressurization, pre-cooling and filling, purge, flow regulation and control, discharge and supply of the liquid oxygen system.

[0008] A booster air supply valve 3 is arranged behind the pressure reducer 2. The pressure reducer 2 is a pilot-operated diaphragm pressure reducer, which is remotely controlled by a pilot valve and an electronic pressure controller. The corresponding pressure reducer outlet pressure can be set according to the container pressure and pipeline resistance loss. The pressure reducer 2 can adjust the opening autonomously through the internal balance structure composed of springs and diaphragms, and automatically control and stabilize the container pressure.

[0009] The flow meter 11 uses a balanced flow meter to measure the liquid oxygen flow in real time. It consists of a body, a three-valve group, a multi-parameter transmitter, a temperature sensor, etc. By measuring the pressure difference generated by the liquid flowing through the balance hole, using the temperature and pressure compensation of the multi-parameter transmitter, and converting through the formula, the mass flow of the medium is measured and output in real time, with an accuracy better than 1%.

[0010] The cavitation tube 14 controls the flow rate. The inner surface of the cavitation tube is a geometric shape that shrinks in front and expands in the back. The liquid flows through the throat to reach the saturated vapor pressure and vaporizes, producing a throttling effect. Each liquid oxygen system is connected in parallel by the same number of cavitation tubes 14 with different throat diameters. A pipe cut-off valve 13 is installed in front of the cavitation tube to switch the use of the cavitation tube 14. The number of cavitation tubes in parallel is 3 to 4. The throat diameter of each cavitation tube is controlled according to the oxygen supplementation parameters (oxygen supplementation back pressure and oxygen supplementation flow rate), according to the cavitation tube flow calculation formula, matching design, with the least number of cavitation tubes combined to cover all oxygen supplementation conditions. A pressure sensor 11 is set before and after the cavitation tube group to monitor the pressure and determine whether the cavitation tube is in a cavitation working state.

[0011] The liquid oxygen system is provided with two nitrogen purges, pipeline purge and pre-spray purge, which are controlled by pipeline purge valve 10 and pre-spray purge valve 18 respectively. Pipeline nitrogen purge is turned on before system precooling and filling or after oxygen replenishment, and its purpose is to replace pipeline purge with nitrogen state; pre-spray purge is carried out after oxygen replenishment, and a large flow of nitrogen is used to quickly remove the residual liquid oxygen in the pipeline after the pre-spray valve.

[0012] On the venting pipeline at the top of the liquid oxygen container 7, a high-pressure venting valve 5 and a low-pressure venting valve 6 are provided for venting the container at different stages. The high-pressure venting valve 5 has a small diameter and is opened after the test to discharge the high-pressure nitrogen in the container. The valve opens under high pressure to limit the venting flow rate and prevent the liquid oxygen container 7 from losing pressure quickly. The low-pressure venting valve 6 has a large diameter and is opened during the pre-cooling and filling stage of the container 7 to quickly discharge the low-pressure oxygen generated by the vaporization of liquid oxygen to prevent the pressure in the container from affecting the filling of liquid oxygen.

[0013] Before the pre-spray valve 17, a pipeline drain valve 16 is installed next to the pre-spray valve. It is opened after the pipeline is pre-cooled or the test is completed to discharge the liquid oxygen (oxygen) in the pipeline. The pre-spray valve 17 is installed at the end of the liquid oxygen pipeline to control the liquid oxygen supply. The pre-spray valve 17 is connected to the air-oxygen mixer by a metal hose 19 to isolate vibration and compensate for cold shrinkage.

[0014] The outstanding advantages of the present invention are: (1) By connecting the cavitation tube matrix in parallel, high-pressure liquid oxygen transportation with multiple types of flow rates is realized, the equipment maturity is high, and the technical risk is low; the flow of each system can be evenly divided or different, and it is flexible to use. (2) The pressure reducer directly pressurizes the container, with fewer throttling links, small pipeline resistance loss, and high utilization rate of the pressurized gas source. (3) The cavitation tubes are throttled in parallel, with simple control, high precision, good consistency, and a wide flow adjustment range. (4) A balanced flowmeter is used to measure the high-pressure liquid oxygen flow, which has fast response, high precision, wide range ratio, low failure rate, and long service life.

[0015] The use effects of the present invention are as follows: (1) According to experimental tests, the oxygen replenishment capacity of the liquid oxygen system exceeds the working pressure by 30 MPa; (2) By changing the container pressure and matching the cavitation tube combination, a wide range of flow regulation can be achieved, and as many as dozens of regulating working conditions can be achieved; (3) The liquid oxygen flow control accuracy is as high as 1%; (4) Due to the use of the cavitation tube, the flow stabilization time is within 2 seconds. IV. Description of the drawings

[0017] Figure 1 Schematic diagram of parallel high pressure and large flow liquid oxygen regulation system

[0018] Figure 1 middle:

[0019] It consists of a nitrogen cut-off valve 1, a pressure reducer 2, an air supply valve 3, a pressurization isolation valve 4, a high-pressure air release valve 5, a low-pressure air release valve 6, a liquid oxygen container 7, a filling valve 8, a liquid supply valve 9, a pipeline purge valve 10, a flow meter 11, a pressure sensor 12, a pre-pipe cut-off valve 13, a cavitation tube 14, a temperature sensor 15, a drain valve 16, a pre-spray valve 17, a pre-spray purge valve 18, a metal hose 19 and connecting pipelines. V. Specific implementation methods

[0020] The following is combined with Figure 1 The specific implementation modes of the present invention are described in detail.

[0021] The working principle of the system is as follows: According to the oxygen replenishment parameters of the test (including oxygen replenishment flow rate and oxygen replenishment back pressure), each liquid oxygen subsystem allocates liquid oxygen flow rate, determines the cavitation tube used, the pressure before the cavitation tube and the working pressure of the container according to the flow rate, and specifies the outlet pressure of the pressure reducer. During operation, the pipeline system is first purged and replaced with nitrogen, and then liquid oxygen is added to the container and the filling pipeline is precooled. During the precooling and filling period, all the cut-off valves before the cavitation tube are opened, and all cavitation tubes are vented to cool all pipe sections. The oxygen generated by the liquid oxygen cooling pipeline and equipment is vented from the top of the container and discharged from the end of the pipeline to a safe place outdoors. When the pipeline temperature drops to 90K, the precooling and filling are in place, the cut-off valve before the unused cavitation tube is closed, and the vent valve and the drain valve are closed. After the high-pressure nitrogen is reduced by the pressure reducer, the container is pressurized in a step-by-step manner, with an increase of about 2MPa each time until the rated working pressure. When the test bench issues an instruction to replenish oxygen, the pre-spray valve is opened, and the liquid oxygen system supplies liquid oxygen to the air-oxygen blender, which is mixed with air to provide oxidant for the downstream heater. During the oxygen replenishment process, the pressure reducer automatically controls the container pressure, stabilizes the inlet pressure of the cavitation tube, and then accurately controls the flow of the liquid oxygen subsystem through the cavitation tube, ultimately ensuring the accuracy of the total flow of oxygen replenishment.

[0022] The system consists of a nitrogen shut-off valve 1, a pressure reducer 2, an air supply valve 3, a pressurization isolation valve 4, a high-pressure air release valve 5, a low-pressure air release valve 6, a liquid oxygen container 7, a filling valve 8, a liquid supply valve 9, a pipeline purge valve 10, a flow meter 11, a pressure sensor 12, a pre-pipe shut-off valve 13, a cavitation tube 14, a temperature sensor 15, a drain valve 16, a pre-spray valve 17, a pre-spray purge valve 18, a metal hose 19 and connecting pipelines to realize the functions of pressurization, pre-cooling and filling, purge, flow regulation and control, discharge and supply of the liquid oxygen system.

[0023] Open the nitrogen shut-off valve 1, the pressure reducer 2, the air supply valve 3, the boost isolation valve 4, the pipeline purge valve 10 and the pre-spray purge valve 18, pressurize the system with nitrogen to a fixed value and then stop pressurizing; close the boost isolation valve 4, open the high-pressure bleed valve 5, the low-pressure bleed valve 6, the pre-pipe shut-off valve 13, the drain valve 16, the pre-spray valve 17 and the pre-spray purge valve 18 to discharge the pressurized nitrogen until the system displays a gauge pressure of 0; close the high-pressure bleed valve 5, the low-pressure bleed valve 6, the pre-pipe shut-off valve 13, the drain valve 16 and the pre-spray valve 17; repeat the above process until the gas composition in the system meets the specification requirements.

[0024] Fill liquid oxygen into the liquid oxygen container 7 through the filling valve 8, open the high-pressure air release valve 5 and the low-pressure air release valve 6 to discharge the low-temperature oxygen in the liquid oxygen container 7; open the liquid supply valve 9, the front-pipe shut-off valve 13, and the drain valve 16 to pre-cool the pipeline. After the temperature sensor 15 shows that the liquid oxygen temperature has been reached and the specified amount of liquid oxygen has been reached in the liquid oxygen container 7, close the filling valve 8, the high-pressure air release valve 5, and the low-pressure air release valve 6.

[0025] The flow is controlled by a cavitation tube 14, and the inner profile of the cavitation tube is a geometric shape that shrinks in front and expands in the back. The throttling effect is produced by utilizing the saturated vapor pressure of the liquid at the throat to vaporize. Each liquid oxygen system is connected in parallel by a plurality of cavitation tubes 14 with different throat diameters, and a pipe shut-off valve 13 is installed in front of the cavitation tube to switch the use of the cavitation tube 14. Usually, the number of cavitation tubes in parallel is 3 to 4, and the throat diameter of each cavitation tube is controlled according to the oxygen supplementation parameters (oxygen supplementation back pressure and oxygen supplementation flow rate), and is obtained by matching design according to the cavitation tube flow calculation formula. The design goal is to cover all oxygen supplementation conditions with the least number of cavitation tube combinations. A pressure sensor 11 is set before and after the cavitation tube group to monitor the pressure and determine whether the cavitation tube is in a cavitation working state. Pre-select the cavitation tube 14 or a combination, open the boost isolation valve 4 to add high-pressure nitrogen into the liquid oxygen container 7, and when the pressure of P31 reaches the specified pressure value, open the pre-spray valve 17 to provide liquid hydrogen with a certain pressure and a certain high-precision flow rate. The pre-spray valve 17 is connected to the metal hose 19, which isolates the vibration from being transmitted to the system and performs low-temperature compensation on the system.

[0026] The balance flowmeter 11 measures the liquid oxygen flow in real time and is composed of a body, a three-valve group, a multi-parameter transmitter, a temperature sensor, etc. By measuring the pressure difference generated by the liquid flowing through the balance hole, using temperature and pressure compensation, the multi-parameter transmitter has a huge database of medium physical parameters built in, and directly outputs the mass flow rate after formula conversion. According to the output mass flow data, the combination of the switch states of the four pre-pipe cut-off valves 13 is controlled to achieve rapid changes in the flow rate.

[0027] The pressure inside the liquid oxygen container 7 is controlled by the pressure reducer 2, which is a pilot-operated membrane pressure reducer, which is remotely controlled by a pilot valve and an electronic pressure controller. The corresponding pressure reducer outlet pressure can be set according to the container pressure and pipeline resistance loss. The pressure reducer 2 can adjust the opening autonomously to automatically control and stabilize the container pressure.

[0028] After the system stops working, close the boost isolation valve 4 and the pre-spray valve 17, open the drain valve 16, and discharge the liquid oxygen (oxygen) in the pipeline. Open the purge valve 10 and the pre-spray purge valve 18 to purge nitrogen into the pipeline. The purge valve 10 is performed before or after the system pre-cooling and filling, and its purpose is to purge the pipeline into a nitrogen state; the pre-spray purge valve 18 is performed after the oxygen supplement is completed, and a large flow of nitrogen is used to quickly remove the residual liquid oxygen in the pipeline after the pre-spray valve. Open the vent valve 5 to vent the container. The valve opens under high pressure to control the venting flow to avoid rapid depressurization of the liquid oxygen container 7. When the liquid oxygen container reaches 0.3MPa, open the vent valve 6 to quickly discharge the low-pressure oxygen and pressurized nitrogen generated by the vaporization of liquid oxygen to prevent the pressure from affecting the system operation.

Claims

1. The high-pressure liquid oxygen flow rapid regulation system controlled by a cavitation tube matrix according to the present invention is characterized by: It is composed of a flow regulation matrix composed of multiple cavitation tubes with different flow rates, a high-pressure liquid oxygen container and its control valve, which can transport high-pressure, large-flow, low-temperature liquid oxygen and realize rapid regulation and control of a variety of high-precision liquid flows.

2. A parallel type high pressure and large flow rate cryogenic liquid flow control system according to claim 1, characterized in that: The cavitation tube is used to control the medium flow. The ratio of the inlet pressure to the outlet pressure of the cavitation tube meets certain conditions, so that it works in a cavitation state, shielding the interference of the downstream pressure of the cavitation tube and accurately controlling the liquid flow through the cavitation tube.

3. According to the multiple flow regulation systems described in claim 1, a cut-off valve is set in front of each cavitation tube, and the required matching flow is provided by controlling the switch of the cut-off valve under the condition of stable cavitation tube inlet pressure.

4. The ability to provide high pressure liquid oxygen according to claim 1, characterized in that: Liquid oxygen is stored in a high-pressure container, and the container is pressurized by high-pressure nitrogen to achieve the ability to provide high-pressure liquid oxygen.

5. The method for realizing rapid flow conversion according to claim 1 is characterized in that: A pneumatic shut-off valve is installed in front of each cavitation tube, and the flow rate can be quickly switched by remotely controlling the shut-off valve.

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