CN106969901B - Continuous high-speed wind tunnel liquid nitrogen cooling and transporting system - Google Patents
Continuous high-speed wind tunnel liquid nitrogen cooling and transporting system Download PDFInfo
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Abstract
The invention provides a continuous high-speed wind tunnel liquid nitrogen cooling and transporting system, which comprises a liquid nitrogen storage device, a gas supply and distribution system and a liquid nitrogen injection device, wherein the liquid nitrogen storage device is connected with the gas supply and distribution system; the liquid nitrogen storage device comprises a liquid nitrogen storage tank and a self-pressurization system; the gas supply and distribution system comprises a liquid nitrogen low-temperature pump, a vaporizer and a high-pressure gas cylinder group; the self-pressurization system enables the pressure in the liquid nitrogen storage tank to be formed; part of liquid nitrogen in the storage tank can enter the liquid nitrogen cryogenic pump under the action of the pressure in the storage tank; the liquid nitrogen low-temperature pump conveys the liquid nitrogen to the vaporizer, the liquid nitrogen is vaporized and pressurized in the vaporizer, and then enters the high-pressure gas cylinder group; the high-pressure gas cylinder group is a high-pressure gas source for gas control, pre-pressurization of a storage tank and extrusion pushing of liquid nitrogen; the high-pressure nitrogen in the high-pressure gas cylinder group can push liquid nitrogen in the storage tank, and the liquid nitrogen is sprayed into the wind tunnel through the liquid nitrogen spraying device. The invention provides technical support for building the first continuous high-speed wind tunnel cooling system in China.
Description
Technical Field
The invention relates to a continuous high-speed wind tunnel liquid nitrogen cooling and transporting system which is suitable for storage, transmission and injection of liquid nitrogen of the continuous high-speed wind tunnel liquid nitrogen cooling system.
Background
The Reynolds number is an important similar parameter for simulating the actual flight capability of the aircraft in a wind tunnel experiment, and the development of the wind tunnel with the high Reynolds number has important strategic significance and engineering application value for the development of the aviation industry and the national defense science and technology in China. The continuous high-speed wind tunnel is a backflow high-speed aerodynamic experiment platform driven by an axial flow compressor and capable of continuously operating for a long time, and the flow field quality and the experiment efficiency of the continuous high-speed wind tunnel are far higher than those of the conventional temporary-rush wind tunnel. However, the continuous high-speed wind tunnel is driven by a high-power motor and limited by an energy system, and the reynolds number of the experimental section and the actual flying reynolds number of the continuous high-speed wind tunnel have a certain difference, so that the requirements of model experiments of fighters and large high-speed civil aircrafts can not be well met. The Reynolds number is determined by the density, temperature, speed and model size of the fluid, and the temperature reduction can increase the density of the fluid and reduce the viscosity coefficient under the condition that the size of the experimental section and the fluid medium are not easy to change, so that the method is an effective way for improving the Reynolds number of the experiment. At present, china is still blank in the aspect of low-temperature continuous high-speed wind tunnels, so that the development of a liquid nitrogen cooling system suitable for the continuous high-speed wind tunnels and related low-temperature experimental techniques thereof have important significance for the technical innovation of wind tunnels and the development of weaponry in China.
Technically speaking, a special refrigerating system can be configured in the wind tunnel to reduce the temperature of the air flow in the wind tunnel, but the special refrigerating system is limited by the size of the wind tunnel and cannot be easily realized due to the interference of a refrigerating device on the flow field of the wind tunnel. The liquid nitrogen is an inert substance with low boiling point, has the characteristics of quick evaporation, stable chemical property and the like, so that the heat in the wind tunnel can be taken away by utilizing the gasification heat absorption effect of the liquid nitrogen in a mode of spraying the liquid nitrogen into the wind tunnel, thereby realizing the purposes of reducing the temperature of the air flow and increasing the Reynolds number of an experiment. Therefore, according to the structural characteristics and the operation mode of the continuous high-speed wind tunnel, aiming at the physical characteristics of nitrogen, a set of liquid nitrogen transportation system and method suitable for the continuous high-speed wind tunnel needs to be developed so as to efficiently and controllably send liquid nitrogen into the wind tunnel and realize the cooling operation of the wind tunnel.
Disclosure of Invention
According to the structural characteristics of the continuous high-speed wind tunnel and the physical characteristics of liquid nitrogen, the invention calculates the total demand of the liquid nitrogen, designs a liquid nitrogen filling and self-pressurizing method, determines the driving mode of liquid nitrogen transmission, designs a liquid nitrogen spraying method, provides a continuous high-speed wind tunnel liquid nitrogen cooling and conveying system, solves the technical problems of liquid nitrogen storage, squeezing, flow control, overpressure and frost cracking of a wind tunnel body and the like, and establishes a safe and reliable liquid nitrogen conveying technical means for the continuous high-speed wind tunnel cooling system.
The technical scheme of the invention is as follows:
the continuous high-speed wind tunnel liquid nitrogen cooling and transporting system is characterized in that: comprises a liquid nitrogen storage device, a gas supply and distribution system and a liquid nitrogen injection device;
the liquid nitrogen storage device comprises a liquid nitrogen storage tank and a self-pressurization system; the gas supply and distribution system comprises a liquid nitrogen low-temperature pump, a vaporizer and a high-pressure gas cylinder group;
the self-pressurization system enables the pressure in the liquid nitrogen storage tank to be formed; part of liquid nitrogen in the storage tank can enter the liquid nitrogen cryogenic pump under the action of the pressure in the storage tank; the liquid nitrogen low-temperature pump conveys the liquid nitrogen to the vaporizer, the liquid nitrogen is vaporized and pressurized in the vaporizer, and then enters the high-pressure gas cylinder group; the high-pressure gas cylinder group is a high-pressure gas source for gas control, storage tank pre-pressurization and liquid nitrogen extrusion; the high-pressure nitrogen in the high-pressure gas cylinder group can push liquid nitrogen in the storage tank, and the liquid nitrogen is sprayed into the wind tunnel through the liquid nitrogen spraying device.
Further preferred scheme, the continuous high-speed wind tunnel liquid nitrogen cooling transportation system is characterized in that: a liquid nitrogen storage tank in the liquid nitrogen storage device adopts a vertical vacuum powder heat insulation low-temperature liquid storage tank; the storage tank is composed of a heat insulation material, an inner container, a shell and a vacuum filter; the total volume of the liquid nitrogen storage tank meets the liquid nitrogen flow demand under the stable operation working condition of the continuous high-speed wind tunnel, and simultaneously meets the liquid nitrogen quantity demand consumed in the preparation process and the transition process of the continuous high-speed wind tunnel.
Further preferred scheme, the continuous high-speed wind tunnel liquid nitrogen cooling transportation system is characterized in that: the self-pressurization system comprises a pressurization input valve, a pressure regulating valve, a self-pressurization carburetor and a pressurization output valve; the pressurization input valve, the pressure regulating valve, the self-pressurization vaporizer and the pressurization output valve are connected into a loop, and the pressurization input valve and the pressurization output valve are connected with the liquid nitrogen storage tank; after the low-temperature liquid nitrogen output from the pressurization output valve is subjected to heat absorption vaporization by the self-pressurization vaporizer, the generated nitrogen returns to the storage tank to increase the pressure.
Further preferred scheme, the continuous high-speed wind tunnel liquid nitrogen cooling transportation system is characterized in that: the gas supply and distribution system also comprises a gas distribution system, a connecting pipeline and a matched valve; the high-pressure gas cylinder component comprises a gas control gas cylinder group and a squeezing gas cylinder group; the total volume of the high-pressure gas cylinder group meets the requirements of gas control gas, pre-pressurization of the storage tank and gas displacement required by squeezing and pushing; the high-pressure gas cylinder group is connected with a gas distribution system, and the gas distribution system performs pressure setting on four paths of gas in total to form four paths of outlets; wherein the gas accuse gas cylinder group corresponds two way exports of gas distribution system: a low pressure control gas port and a high pressure control gas port; the extruding and pushing gas cylinder group corresponds to two outlets of a gas distribution system: a pre-pressurization gas port and a squeezing and pushing gas port.
Further preferred scheme, the continuous high-speed wind tunnel liquid nitrogen cooling transportation system is characterized in that: the discharge capacity of the liquid nitrogen cryogenic pump is 250L/h, and the outlet pressure is 15MPa; the evaporation capacity of the vaporizer is 200Nm 3 H, working pressure 15MPa, outlet temperature rating: not less than 5 ℃; the high-pressure gas cylinder group consists of 27 same high-pressure gas cylinders which are arranged in a layered and stacked manner, and the volume of each gas cylinder is 0.12m 3 Total volume of 3.24m 3 The working pressure is 15MPa; wherein the pneumatic control gas cylinder group consists of 2 gas cylinders with the volume of 0.24m 3 The pneumatic valve is used for supplying air to a plurality of pneumatic valve cylinders to realize the quick opening and closing of the pneumatic valve valves, and the drift diameter of the corresponding converged air outlet main pipe is 15mm; the squeezing gas cylinder group consists of 25 gas cylinders with the volume of 3m 3 The device is used for pre-pressurizing and squeezing liquid nitrogen to a liquid nitrogen storage tank, and the drift diameter of the corresponding gas outlet main pipe is 25mm.
Further preferred scheme, the continuous high-speed wind tunnel liquid nitrogen cooling transportation system is characterized in that: the pressure of a low-pressure control air port of the air distribution system is configured to be 1MPa, the pressure of a high-pressure control air port is configured to be 5MPa, the pressure of a pre-pressurization air port is configured to be 2MPa, and the pressure of a squeezing pushing air supply port is configured to be 2.7MPa.
Further preferred scheme, a continuous type high-speed wind tunnel liquid nitrogen cooling transport system, its characterized in that: the liquid nitrogen injection device comprises a liquid collecting ring, an upstream liquid nitrogen nozzle group and a downstream liquid nitrogen nozzle group; the liquid nitrogen injection device is arranged in the liquid nitrogen injection section of the wind tunnel; the liquid collecting ring is an annular stainless steel pipeline, the inner diameter of the liquid collecting ring is the same as the outer diameter of the wall of the wind tunnel at the installation position, and the liquid collecting ring is annularly installed on the wall of the wind tunnel and used for receiving low-temperature liquid nitrogen from the main pipeline and conveying the liquid nitrogen to the liquid nitrogen nozzle group;
the upstream liquid nitrogen nozzle group comprises a plurality of upstream ultralow-temperature high-pressure tail end electromagnetic valves, a plurality of upstream liquid nitrogen nozzles and a plurality of upstream support pipelines, and the number of the upstream ultralow-temperature high-pressure tail end electromagnetic valves, the number of the upstream liquid nitrogen nozzles and the number of the upstream support pipelines are the same; the upstream liquid nitrogen nozzles are uniformly distributed along the outer circumference of the wall of the wind tunnel, receive liquid nitrogen from the liquid collecting ring through an upstream support pipeline and spray the liquid nitrogen into the wind tunnel under the control of an upstream ultralow-temperature high-pressure tail end electromagnetic valve;
the downstream liquid nitrogen nozzle group comprises a plurality of downstream ultralow-temperature high-pressure tail end electromagnetic valves, a plurality of downstream liquid nitrogen nozzles and a plurality of downstream support pipelines, and the number of the downstream ultralow-temperature high-pressure tail end electromagnetic valves, the number of the downstream liquid nitrogen nozzles and the number of the downstream support pipelines are the same; the downstream liquid nitrogen nozzles are uniformly distributed along the outer circumference of the wall of the wind tunnel, receive liquid nitrogen from the liquid collecting ring through a downstream support pipeline and spray the liquid nitrogen into the wind tunnel under the control of a downstream ultralow-temperature high-pressure tail end electromagnetic valve;
the upstream liquid nitrogen nozzle group and the downstream liquid nitrogen nozzle group are distributed in parallel along the axis of the air flow of the wind tunnel, the distance between the upstream liquid nitrogen nozzle group and the upstream end face of the experimental section is 0.61d, the distance between the downstream liquid nitrogen nozzle group and the upstream end face of the experimental section is 1.72d, and d is the inner diameter of the upstream end face of the experimental section.
Further preferred scheme, the continuous high-speed wind tunnel liquid nitrogen cooling transportation system is characterized in that: the upstream liquid nitrogen nozzle group consists of 16 upstream ultralow-temperature high-pressure tail end electromagnetic valves, 16 upstream liquid nitrogen nozzles and 16 upstream support pipelines, and the 16 upstream liquid nitrogen nozzles are uniformly distributed along the outer circumference of the experimental section hole wall; the 16 upstream liquid nitrogen nozzles are controlled by 0.5Mpa differential pressure, wherein the flow rate of 3 upstream liquid nitrogen nozzles is 0.02kg/s, the flow rate of 3 upstream liquid nitrogen nozzles is 0.12kg/s, the flow rate of 6 upstream liquid nitrogen nozzles is 0.6kg/s, and the flow rate of 4 upstream liquid nitrogen nozzles is 0.73kg/s;3 upstream liquid nitrogen nozzles with flow rate of 0.02kg/s are respectively arranged at the positions of 0 degree, 135 degrees and 225 degrees of the upstream injection section observed along the reverse air flow direction, 3 upstream liquid nitrogen nozzles with flow rate of 0.12kg/s are respectively arranged at the positions of 45 degrees, 180 degrees and 315 degrees of the upstream injection section observed along the reverse air flow direction, 6 upstream liquid nitrogen nozzles with flow rate of 0.6kg/s are respectively arranged at the positions of 67.5 degrees, 112.5 degrees, 157.5 degrees, 247.5 degrees, 292.5 degrees and 337.5 degrees of the upstream injection section observed along the reverse air flow direction, and 4 upstream liquid nitrogen nozzles with flow rate of 0.73kg/s are respectively arranged at the positions of 22.5 degrees, 90 degrees, 202.5 degrees and 270 degrees of the upstream injection section observed along the reverse air flow direction;
the downstream liquid nitrogen nozzle group consists of 16 downstream ultralow-temperature high-pressure tail end electromagnetic valves, 16 downstream liquid nitrogen nozzles and 16 downstream support pipelines, and the 16 downstream liquid nitrogen nozzles are uniformly distributed along the outer circumference of the experimental section hole wall; the 16 downstream liquid nitrogen nozzles are controlled by 0.5Mpa differential pressure, wherein the flow rate of 3 downstream liquid nitrogen nozzles is 0.02kg/s, the flow rate of 2 downstream liquid nitrogen nozzles is 0.12kg/s, the flow rate of 8 downstream liquid nitrogen nozzles is 0.6kg/s, and the flow rate of 3 downstream liquid nitrogen nozzles is 0.73kg/s;3 downstream liquid nitrogen nozzles with the flow rate of 0.02kg/s are respectively arranged at the positions of 45 degrees, 180 degrees and 315 degrees of the downstream injection section observed along the reverse air flow direction, 2 downstream liquid nitrogen nozzles with the flow rate of 0.12kg/s are respectively arranged at the positions of 90 degrees and 270 degrees of the downstream injection section observed along the reverse air flow direction, 8 downstream liquid nitrogen nozzles with the flow rate of 0.6kg/s are respectively arranged at the positions of 22.5 degrees, 67.5 degrees, 112.5 degrees, 157.5 degrees, 202.5 degrees, 247.5 degrees, 292.5 degrees and 337.5 degrees of the downstream injection section observed along the reverse air flow direction, and 3 downstream liquid nitrogen nozzles with the flow rate of 0.73kg/s are respectively arranged at the positions of 0 degrees, 135 degrees and 225 degrees of the downstream injection section observed along the reverse air flow direction.
Further preferred scheme, the continuous high-speed wind tunnel liquid nitrogen cooling transportation system is characterized in that: the front end of the support pipeline is connected to the liquid collecting ring through an expansion joint, the front end of the liquid nitrogen nozzle is connected to the tail end of the support pipeline through an ultralow-temperature high-pressure tail end electromagnetic valve, and the tail end of the liquid nitrogen nozzle is arranged on the wall of the experimental section; the ultralow temperature high pressure tail end electromagnetic valve controls the opening and closing of the liquid nitrogen nozzle.
Advantageous effects
The self-pressurization method for the liquid nitrogen storage tank provided by the scheme meets the requirements of high-pressure nitrogen preparation and pipeline presetting, the designed pipeline presetting method solves the problems of cleaning, precooling and filling of a liquid nitrogen pipeline, and the safety of a liquid nitrogen conveying pipeline is ensured; the gas supply and distribution system works stably, and the pre-pressurization and extrusion transportation of liquid nitrogen are realized; the annular liquid nitrogen injection scheme has reasonable design, realizes the accurate control of the liquid nitrogen injection flow, effectively solves the ultralow temperature frost cracking problem of the tunnel wall of the wind tunnel, and ensures the safety of the tunnel structure. By adopting the technical scheme, a technical guarantee is provided for building the first set of continuous high-speed wind tunnel cooling system in China.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a working schematic diagram of a liquid nitrogen transportation system of a continuous high-speed wind tunnel cooling system;
the method comprises the following steps of 1-a liquid nitrogen storage tank, 2-a diffuser, 3-a first pressure gauge, 4-a pressure transmitter, 5-a second pressure gauge, 6-a high-pressure gas cylinder group, 7-a liquid level meter, 8-a vaporizer, 9-a liquid nitrogen cryogenic pump, 10-a downstream nozzle group, 11-an upstream nozzle group and 12-a wind tunnel body.
FIG. 2 is a liquid nitrogen storage tank and self-pressurization system;
FIG. 3 is a diagram of a liquid nitrogen cooling gas supply and distribution system;
9-liquid nitrogen low-temperature pump, 8-vaporizer, 6-high-pressure gas cylinder group, 13-gas distribution system and 14-connecting pipeline.
FIG. 4 is an assembled relationship of the liquid nitrogen injection device;
15-liquid collecting ring, 11-upstream nozzle group, 10-downstream nozzle group, 16-expansion joint, 17-support pipeline and 12-wind tunnel body.
FIG. 5 is a NF-6 continuous high-speed wind tunnel cooling system;
18-a wind tunnel body, 19-a liquid nitrogen storage device, 20-a gas supply and distribution system, 21-a control system and 22-a liquid nitrogen injection device.
FIG. 6 shows the results of the atmospheric cooling test;
FIG. 7 shows the total temperature change in the atmospheric cooling test;
FIG. 8 shows the results of the pressure and temperature increase test;
FIG. 9 shows the total temperature change in the pressure increasing and temperature decreasing test;
FIG. 10 is a graph of the total temperature change for the repeatability test;
FIG. 11 shows the change in the number of repetitive tests Ma;
FIG. 12 shows the total pressure change in the reproducibility test.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, merely for convenience of description and simplification of the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
The embodiment is a set of liquid nitrogen transportation system for a continuous high-speed wind tunnel cooling system, and is used for storing, transmitting and injecting liquid nitrogen of the continuous high-speed wind tunnel liquid nitrogen cooling system.
The NF-6 wind tunnel is the first continuous high-speed wind tunnel in China and is the only continuous high-speed wind tunnel which is put into operation at present in China. The overall performance of the wind tunnel reaches the advanced domestic and international levels. In order to verify the feasibility and the beneficial effects of the invention, the NF-6 continuous high-speed wind tunnel is taken as an implementation platform, and a liquid nitrogen transportation system of the NF-6 continuous high-speed wind tunnel cooling system is designed and operated and debugged according to the overall scheme and the main technical requirements of the wind tunnel cooling system.
The NF-6 continuous high-speed wind tunnel cooling system consists of a wind tunnel body 18, a liquid nitrogen storage device 19, a gas supply and distribution system 20, a control system 21 and a liquid nitrogen injection device 22, and is shown in figure 5. The liquid nitrogen storage device is used for filling low-temperature liquid nitrogen, self-pressurization, overpressure protection and residual liquid discharge. The gas supply and distribution system is used for solving the problems of high-pressure nitrogen preparation and storage, liquid nitrogen storage tank pre-pressurization, pneumatic control gas and extrusion gas pressure and pneumatic electromagnetic valve control, and the liquid nitrogen injection device is used for liquid nitrogen injection and accurate flow control. The control system is used for overall control of all parameters in wind tunnel operation.
In the embodiment, the transportation and injection of the liquid nitrogen are realized by adopting methods of self-pressurization of a liquid nitrogen storage tank, preparation of high-pressure nitrogen, pre-pressurization of the storage tank, squeezing and pushing of the liquid nitrogen, annular injection and accurate control of a pneumatic solenoid valve, and the working principle is shown in figure 1. Firstly, a certain pressure is formed in a storage tank through a self-pressurization system of a liquid nitrogen storage device; then, part of liquid nitrogen is drained from the liquid nitrogen storage tank and enters the cryogenic pump, the liquid nitrogen enters the high-pressure gas bottle group after being vaporized and pressurized by the vaporizer, a high-pressure gas source required by liquid nitrogen extrusion and pneumatic solenoid valves is established, and the high-pressure nitrogen of the gas bottle group is utilized to pre-pressurize the liquid nitrogen storage tank, so that the pressure in the storage tank is further improved to be close to the working pressure; after the preparation work is finished, the wind tunnel cooling system starts to operate, a squeezing pipeline valve is opened, and liquid nitrogen in the storage tank is squeezed and pushed by high-pressure nitrogen; and finally, spraying liquid nitrogen into the wind tunnel through an annular spraying device.
The liquid nitrogen storage device in this embodiment is composed of a liquid nitrogen storage tank and an external pipeline.
The liquid nitrogen storage tank adopts a vertical vacuum powder heat insulation low-temperature liquid storage tank, and the storage tank consists of a heat insulation material, an inner container, an outer shell and a vacuum filter. The liquid nitrogen demand in the continuous high-speed wind tunnel cooling operation process comprises two aspects, namely the liquid nitrogen flow demand under the stable operation working condition on the one hand, and the liquid nitrogen amount required to be consumed in the preparation process and the transition process on the other hand. Therefore, the total volume of the liquid nitrogen storage tank meets the liquid nitrogen flow requirement under the stable operation working condition of the continuous high-speed wind tunnel, and simultaneously meets the liquid nitrogen consumption required by the preparation process and the transition process of the continuous high-speed wind tunnel.
The liquid nitrogen amount required to be consumed in the continuous high-speed wind tunnel preparation process and the transition process comprises the liquid nitrogen amount evaporated by a liquid nitrogen storage tank, the liquid nitrogen amount consumed by squeezing gas, the liquid nitrogen amount consumed by cleaning, precooling and filling a pipeline, the liquid nitrogen amount consumed under the transition working condition and other losses. The fixed evaporation index of the liquid nitrogen storage tank is 1%/day, and the designed storage time is 7 days; the volume of the squeezing gas cylinder is 3.0m 3 The actual filling pressure is calculated according to 12MPa (from 3MPa to 15 MPa), and the total amount of liquid nitrogen requirement is about 420kg; the total length of the main liquid nitrogen conveying pipeline is 60m, and the inner diameter of the main liquid nitrogen conveying pipeline is
The amount of liquid nitrogen required for filling is about 548kg, and the amount of liquid nitrogen required for cleaning and precooling the pipeline is the same as the filling amount of the pipeline, namely 548kg; the running time of the transition working condition can be determined to be 360s, the liquid nitrogen flow is 1/3 of the maximum flow, and the liquid nitrogen consumption is 1920kg; other losses are considered as 5% of the total.
The liquid nitrogen flow under the stable operation condition mainly depends on the liquid nitrogen flow needed for counteracting the working power of the compressor on the airflow. And the liquid nitrogen flow for counteracting the working power of the compressor to the airflow is obtained through calculation of wind tunnel flow field calibration experimental data. According to the temperature rising curve of the air flow passing through the compressor, the maximum liquid nitrogen flow requirement under the stable working condition is 16kg/s.
According to the calculation result, if the steady-state operation time is 90s, the maximum total liquid nitrogen requirement of one-time operation is 5641kg, and the corresponding liquid nitrogen volume is 6.76m 3 Considering the factors of diffuser installation in the liquid nitrogen tank, limitation of filling coefficient of the liquid nitrogen tank and the like, the actual corresponding storage tank volume should be 7.76m 3 The total volume of the liquid nitrogen tank after some surplus is reserved should be larger than 10m 3 Finally determining the liquid nitrogen storage tank according to the relevant specifications of the low-temperature pressure containerHas a total volume of 13m 3 。
Therefore, the main technical parameters of the liquid nitrogen storage tank in the embodiment are as follows: volume 13m 3 The highest working pressure is 2.0MPa, the working temperature is-196 ℃ to 50 ℃, and the daily evaporation rate of liquid nitrogen is less than or equal to 1.0 percent.
The external pipeline consists of a combined filling system, a self-pressurization system, a storage tank safety system, a storage tank gas supply system and an instrument monitoring system, and is shown in figure 2.
The combined filling system is positioned on the front surface of the storage tank and is used for supplementing liquid into the storage tank, and comprises a top liquid inlet valve A-2, a bottom liquid inlet valve A-1, a residual liquid discharge valve A-7, an emptying valve A-12 and an overflow valve A-4.
The residual liquid discharge valve is used for discharging sundries in an external filling hose; the top liquid inlet valve and the bottom liquid inlet valve are jointly filled with 75% of the total amount of liquid nitrogen, and the rest 25% of liquid nitrogen is separately filled by the bottom liquid inlet valve; the emptying valve is used for adjusting the air inlet pressure to keep the air inlet pressure at 0.2MPa.
The specific liquid nitrogen filling method comprises the following steps: before the storage tank is fed with liquid, purging and replacing are firstly carried out, namely air is fed under 0.2MPa, pressure is maintained for 3 minutes, then air is exhausted, and the steps are carried out until the emptying valve A-12 is frosted. And simultaneously, the liquid level meter and the instrument joint are opened for purging. Before formal liquid feeding, a residual liquid discharge valve is opened to remove impurities such as air, moisture and the like in the filling hose, and when the filling hose is frosted, a top liquid feeding valve A-2 is opened to feed liquid. In the liquid inlet process, if the pressure of the storage tank is too close to that of the liquid inlet tank truck (less than 0.2MPa of pressure difference), an emptying valve A-12 can be opened to exhaust and reduce the pressure. After the pressure of the storage tank is stable, the bottom liquid inlet valve A-1 is opened at the same time, when liquid enters the storage tank by 3/4, the top liquid inlet valve A-2 is closed, the overflow valve A-4 is opened at the same time, when the overflow valve discharges liquid, the bottom liquid inlet valve A-1 is closed, the residual liquid discharge valve A-7 is opened, and the filling hose is removed.
The liquid nitrogen transportation and spraying of the cooling system are realized in a high-pressure extruding and pushing mode, so that the pressure in the tank is increased to 0.7-0.8 Mpa through a self-pressurization system of the storage tank before formal operation in order to save the consumption of high-pressure nitrogen in an extruding and pushing gas cylinder group. Because the main liquid nitrogen conveying pipeline is long, in order to ensure stable and reliable liquid nitrogen conveying, a liquid nitrogen flow channel needs to be properly cleaned and precooled to a specified temperature before the pipeline is filled with liquid nitrogen, and then the liquid nitrogen is filled into the pipeline. Tank pressure is provided and maintained by a self-pressurization system to accomplish purging, pre-chilling and filling of the main line.
The self-pressurization system is positioned at the lower part of the storage tank and comprises a pressurization input valve A-3, a pressure regulating valve C-1, a vaporizer B-1 and a pressurization output valve A-11. The pressure regulating valve, the vaporizer and the pressure boost output valve are connected into a loop, and the pressure boost input valve and the pressure boost output valve are connected with a liquid nitrogen storage tank; after the low-temperature liquid nitrogen output from the pressurization output valve is subjected to heat absorption vaporization by the vaporizer, the generated nitrogen returns to the storage tank to increase the pressure.
The specific method of self-pressurization is as follows: opening the booster input valve A-3 and the booster output valve A-11, tightening the adjusting screw of the pressure adjusting valve C-1 (the valve C-1 is used for setting the pressure of the storage tank, and tightening the adjusting screw increases the set pressure, otherwise, the set pressure is reduced), the booster pipeline and the vaporizer begin to frost, which indicates that low-temperature liquid nitrogen passes through the pipeline. And returning the nitrogen after heat absorption and vaporization to the storage tank to increase the pressure, starting defrosting by the supercharger or the pipeline when the supercharging is finished, and displaying the pressure by the pressure gauge as the set pressure of the C-1 valve. If the pressure does not meet the usage requirements, the process continues until the pre-boost set point is reached.
The storage tank safety system is positioned at 90 degrees on the left side of the storage tank, and comprises two safety valves YA-1A/1B, two groups of rupture discs FB-1A/1B, an outer cylinder explosion-proof device FB-2 and a safety discharge selection valve A-15; wherein, the single safety valve is connected with one group of rupture discs in series and is connected with the other group of safety valves and rupture discs in series in parallel; one set of safety valve and rupture disk connected in series is selected to work through the safety discharge selection valve, and the other set of safety valve and rupture disk connected in series is reserved; when the pressure of the storage tank is higher than the take-off pressure of the safety valve, the safety valve takes off and exhausts air, so that the inner container is prevented from being damaged due to overpressure. In addition, when the pressure of the storage tank is too high, the pressure of the storage tank can be reduced by opening the A-12 valve.
The storage tank gas supply system comprises a gas inlet valve A-13, a pump liquid inlet valve A-18 and a pump gas return valve A-16; the air inlet valve is used for being connected with an external vaporizer, and the pump liquid inlet valve and the pump air return valve are respectively connected with the liquid inlet and the air return port of the cryogenic pump.
The instrument monitoring system is positioned on the front side and above the combined filling valve, consists of a liquid level meter L1-1, a pressure gauge P1-1, a gas phase valve A-8, a liquid phase valve A-10, a balance valve A-9 and a gas inspection valve A-19, and is matched with a liquid level comparison gauge on the storage tank to realize real-time monitoring of the liquid nitrogen level in the storage tank.
The liquid nitrogen conveying pipeline presetting method comprises the following steps: cleaning the pipeline, replacing the original wet air in the pipeline to prevent water vapor condensation, and directly discharging the residual air into the atmosphere through a special pipeline without entering the wind tunnel. In specific operation, the liquid nitrogen supply pneumatic valve is started, and the wet air in the pipeline is replaced by a small nitrogen flow rate under the condition of keeping the temperature of the air flow in the flow passage not too low. And (3) pre-cooling the liquid nitrogen conveying pipeline, wherein during specific operation, a liquid nitrogen supply pneumatic valve is started to continuously cool the pipeline at a low liquid nitrogen flow rate until the temperature of a monitoring point in the pipeline reaches a preset value, and then the pipeline is stopped. During pre-cooling, the pressure in the pipeline needs to be monitored and enters the safety interlock of the control system to ensure that no overpressure exists. And filling the liquid nitrogen conveying pipeline, wherein the pipeline filling process and the pipeline precooling process can be combined, and during specific operation, the liquid nitrogen supply pneumatic valve is started to fill the pipeline with smaller liquid nitrogen flow until the highest point in the pipeline discharges liquid.
The gas supply and distribution system in the embodiment is used for solving the problems of high-pressure nitrogen preparation and storage, liquid nitrogen storage tank pre-pressurization, pneumatic control gas and extrusion gas pressure and flow control, and forms a stable and reliable valve control gas source and a liquid nitrogen driving source for a cooling system.
Before the gas supply and distribution system is established, the nitrogen demand of the gas supply and distribution system needs to be calculated, so that the volume of the high-pressure gas cylinder group, the discharge capacity of the liquid nitrogen booster pump and the evaporation capacity of the vaporizer are determined. FIG. 1 shows the liquid nitrogen demand flow under different incoming flow conditions of a continuous high-speed wind tunnel. It can be seen that when the Mach number is less than 0.3, the flow of liquid nitrogen is not more than 2kg/s, and the maximum flow requirement of liquid nitrogen under the stable working condition is 16kg/s. The flow of the extruding gas is calculated and shown in Table 1, and the maximum mass flow of the extruding gas is 1kg/s under the maximum extruding pressure (3 MPa) and the maximum liquid nitrogen flow (16 kg/s). According to the designMeasuring squeezing pressure, operation time and pre-pressurizing air consumption, and determining the air consumption of the air control gas to be 0.24m 3 The gas quantity required by the pre-pressurization and the squeezing of the storage tank is 3.0m 3 The total demand of high-pressure nitrogen is 3.24m 3 The working pressure is 16.5MPa.
TABLE 1 crowd propulsion flow calculation results
| Flow of liquid nitrogen in kg/s | 0.50 | 1.00 | 2 | 3 | 5.00 | 10.00 | 15.00 | 20.00 |
| Pushing the gas temperature, K | 233.00 | 233.00 | 233.00 | 233.00 | 233.00 | 233.00 | 233.00 | 233.00 |
| Extrusion pressure of gas, MPa | 3.00 | 3.00 | 3.00 | 3.00 | 3.00 | 3.00 | 3.00 | 3.00 |
| Compaction air density, kg/m 3 | 43.35 | 43.35 | 43.35 | 43.35 | 43.35 | 43.35 | 43.35 | 43.35 |
| Volume flow rate, m 3 /s | 0.0006 | 0.0012 | 0.0025 | 0.0037 | 0.0062 | 0.0124 | 0.0186 | 0.0248 |
| Mass flow rate, kg/s | 0.03 | 0.05 | 0.11 | 0.16 | 0.27 | 0.54 | 0.80 | 1.07 |
As shown in fig. 3, the continuous high-speed wind tunnel liquid nitrogen cooling gas supply and distribution system is composed of a liquid nitrogen low-temperature pump 9, a vaporizer 8, a high-pressure gas cylinder group 6, a gas distribution system 18, a connecting pipeline 19 and a matched valve, and the system achieves the purposes of pre-pressurization of a storage tank, driving of a pneumatic solenoid valve and extrusion and transportation of liquid nitrogen through high-pressure nitrogen preparation, storage and pipeline pressure regulation.
The high-pressure nitrogen preparation is completed by matching a liquid nitrogen pump and a vaporizer. The method comprises the following steps of firstly conveying liquid nitrogen in a storage tank to a vaporizer by a liquid nitrogen pump, further evaporating and pressurizing the liquid nitrogen in the vaporizer, and finally entering a high-pressure nitrogen cylinder group. Wherein the discharge capacity of the high-pressure liquid nitrogen pump is 250L/h, and the outlet pressure is 15MPa; the evaporation capacity of the vaporizer is 200Nm 3 H (the high-pressure gas cylinder group can be filled within 2.5 hours), the working pressure is 15MPa, and the outlet temperature grade is as follows: more than or equal to 5 ℃. And after the pressure of the high-pressure gas cylinder set reaches a target pressure value (15 MPa), stopping the operation of the liquid nitrogen cryopump, and finishing the nitrogen preparation work.
The high-pressure gas cylinder group consists of 27 same high-pressure gas cylinders which are arranged in a layered and stacked manner, and the volume of each gas cylinder is 0.12m 3 Total volume of 3.24m 3 The working pressure is 15MPa. Wherein the pneumatic control gas cylinder group 1 consists of 2 gas cylinders with the volume of 0.24m 3 The gas supply device is used for supplying gas to a plurality of pneumatic valve cylinders so as to realize the quick opening and closing of the valves, and the drift diameter of the corresponding converged gas outlet main pipe is 15mm; the squeezing gas cylinder group consists of 25 gas cylinders with the volume of 3m 3 The device is used for pre-pressurizing and extruding liquid nitrogen to a liquid nitrogen storage tank, and the corresponding main gas outlet pipe has a drift diameter of 25mm.
The pre-pressurization, extrusion pushing and flow control of the liquid nitrogen are completed through a gas distribution system. The outlet of the gas distribution system is divided into four paths, the pressure of a low-pressure control gas port is configured to be 1MPa, the pressure of a high-pressure control gas port is configured to be 5MPa, the pressure of a pre-pressurization gas port is configured to be 2MPa, and the pressure of a squeezing and pushing gas supply port is configured to be 2.7MPa. Before the wind tunnel runs, the pressurizing bypass is firstly opened to pre-pressurize the liquid nitrogen storage tank until the pressure of the storage tank reaches 1.3-1.4 MPa. After the pre-pressurization of the storage tank is finished, the wind tunnel is cleaned, the axial flow compressor is started to operate under a lower working condition (a smaller static blade angle and a lower rotating speed), liquid nitrogen is sprayed in through the atomizing nozzle at a smaller flow rate, the original air in the wind tunnel is replaced by the gaseous nitrogen evaporated from the sprayed liquid nitrogen, and the cleaning is stopped when the dew point temperature of the gas in the wind tunnel reaches-39 ℃. After the cleaning of the wind tunnel is finished, the cooling system starts to operate formally, the rotating speed of the wind tunnel axial flow compressor is adjusted to the experimental working condition, the high-pressure control air passage, the low-pressure control air passage and the liquid nitrogen squeezing air passage are opened, liquid nitrogen is sent into the wind tunnel by utilizing the pressure difference between the liquid nitrogen storage tank and the wind tunnel, the liquid nitrogen is controlled to be sprayed into the flow through the pneumatic solenoid valve, and the accurate control of the temperature and the pressure of the air flow in the wind tunnel is realized.
The liquid nitrogen has the characteristics of ultralow temperature, fast evaporation and large expansion coefficient, and the continuous high-speed wind tunnel is a steel closed container, so that the problems of frost cracking, overpressure and the like of metal materials are easily caused in the liquid nitrogen spraying process. Therefore, liquid nitrogen injection is a key technology of the integral cooling system and is used for uniformly and controllably injecting liquid nitrogen from the main pipeline into the wind tunnel.
The liquid nitrogen injection device of the continuous high-speed wind tunnel cooling system in the embodiment comprises a liquid collecting ring, an upstream liquid nitrogen nozzle group and a downstream liquid nitrogen nozzle group. The liquid nitrogen injection device is arranged in the liquid nitrogen injection experimental section; the liquid collecting ring is an annular low-temperature-resistant stainless steel pipeline, the inner diameter of the liquid collecting ring is the same as the outer diameter of the experimental section hole wall at the installation position, the liquid collecting ring is annularly arranged on the experimental section hole wall and used for receiving low-temperature liquid nitrogen from the main pipeline and conveying the liquid nitrogen to the liquid nitrogen nozzle group, and the liquid collecting ring is shown in fig. 4.
The upstream liquid nitrogen nozzle group consists of 16 upstream ultralow-temperature high-pressure tail end electromagnetic valves, 16 upstream liquid nitrogen nozzles and 16 upstream support pipelines, wherein the 16 upstream liquid nitrogen nozzles are uniformly distributed along the circumferential direction of the outer side of the experimental section hole wall, receive liquid nitrogen from the liquid collecting ring through the upstream support pipelines, and spray the liquid nitrogen into the wind tunnel under the control of the upstream ultralow-temperature high-pressure tail end electromagnetic valves. The 16 upstream liquid nitrogen nozzles are controlled by 0.5Mpa differential pressure, wherein the flow rate of 3 upstream liquid nitrogen nozzles is 0.02kg/s, the flow rate of 3 upstream liquid nitrogen nozzles is 0.12kg/s, the flow rate of 6 upstream liquid nitrogen nozzles is 0.6kg/s, and the flow rate of 4 upstream liquid nitrogen nozzles is 0.73kg/s;3 upstream liquid nitrogen nozzles with a flow rate of 0.02kg/s are respectively arranged at the positions of 0 degree, 135 degree and 225 degree of the upstream injection section observed along the reverse air flow direction, 3 upstream liquid nitrogen nozzles with a flow rate of 0.12kg/s are respectively arranged at the positions of 45 degrees, 180 degrees and 315 degrees of the upstream injection section observed along the reverse air flow direction, 6 upstream liquid nitrogen nozzles with a flow rate of 0.6kg/s are respectively arranged at the positions of 67.5 degrees, 112.5 degrees, 157.5 degrees, 247.5 degrees, 292.5 degrees and 337.5 degrees of the upstream injection section observed along the reverse air flow direction, and 4 upstream liquid nitrogen nozzles with a flow rate of 0.73kg/s are respectively arranged at the positions of 22.5 degrees, 90 degrees, 202.5 degrees and 270 degrees of the upstream injection section observed along the reverse air flow direction.
The downstream liquid nitrogen nozzle group consists of 16 downstream ultralow-temperature high-pressure tail end electromagnetic valves, 16 downstream liquid nitrogen nozzles and 16 downstream support pipelines, wherein the 16 downstream liquid nitrogen nozzles are uniformly distributed along the circumferential direction of the outer side of the experimental section hole wall, receive liquid nitrogen from the liquid collecting ring through the downstream support pipelines, and spray the liquid nitrogen into the wind tunnel under the control of the downstream ultralow-temperature high-pressure tail end electromagnetic valves. The 16 downstream liquid nitrogen nozzles are controlled by 0.5Mpa differential pressure, wherein the flow rate of 3 downstream liquid nitrogen nozzles is 0.02kg/s, the flow rate of 2 downstream liquid nitrogen nozzles is 0.12kg/s, the flow rate of 8 downstream liquid nitrogen nozzles is 0.6kg/s, and the flow rate of 3 downstream liquid nitrogen nozzles is 0.73kg/s;3 downstream liquid nitrogen nozzles with the flow rate of 0.02kg/s are respectively arranged at the positions of 45 degrees, 180 degrees and 315 degrees of the downstream injection section observed along the reverse air flow direction, 2 downstream liquid nitrogen nozzles with the flow rate of 0.12kg/s are respectively arranged at the positions of 90 degrees and 270 degrees of the downstream injection section observed along the reverse air flow direction, 8 downstream liquid nitrogen nozzles with the flow rate of 0.6kg/s are respectively arranged at the positions of 22.5 degrees, 67.5 degrees, 112.5 degrees, 157.5 degrees, 202.5 degrees, 247.5 degrees, 292.5 degrees and 337.5 degrees of the downstream injection section observed along the reverse air flow direction, and 3 downstream liquid nitrogen nozzles with the flow rate of 0.73kg/s are respectively arranged at the positions of 0 degrees, 135 degrees and 225 degrees of the downstream injection section observed along the reverse air flow direction.
The upstream liquid nitrogen nozzle group and the downstream liquid nitrogen nozzle group are distributed in parallel along the axis of the wind tunnel airflow, the distance between the upstream liquid nitrogen nozzle group and the upstream end face of the experimental section is 0.61d, the distance between the downstream liquid nitrogen nozzle group and the upstream end face of the experimental section is 1.72d, and d is the inner diameter of the upstream end face of the experimental section. In the embodiment, d =1800mm, the upstream liquid nitrogen nozzle group is 1100mm away from the upstream end face of the wind tunnel wall, and the downstream liquid nitrogen nozzle group is 3100mm away from the upstream end face of the wind tunnel wall.
The front end of the support pipeline is connected to the liquid collecting ring through an expansion joint, and the expansion joint is used for adjusting the positions of the nozzle device and the experimental section hole wall mounting hole; the front end of the liquid nitrogen nozzle is connected to the tail end of the support pipeline through an ultralow-temperature high-pressure tail end electromagnetic valve, and the tail end of the liquid nitrogen nozzle is arranged on the wall of the experimental section; the ultralow temperature high pressure tail end electromagnetic valve is used for controlling the opening and closing of the liquid nitrogen nozzle, the highest working pressure is 3MPa, and single action or combined action at will can be completed, so that the liquid nitrogen injection flow can be adjusted.
The liquid nitrogen injection method comprises the following steps: the gas supply and distribution control system is ready, after the experimental working condition is modulated by the wind tunnel, the liquid nitrogen injection device starts to work, and the system automatically adjusts the opening and closing quantity of the nozzles and the front and back pressure difference of the nozzles according to the temperature and pressure feedback of airflow in the wind tunnel, so that the accurate control of the liquid nitrogen injection quantity is realized. Table 2 gives the liquid nitrogen injection quantities at different pressure differences. It can be seen that when the pressure difference between the front and the rear of the nozzle is greater than 8bar, the liquid nitrogen injection amount injected into the wind tunnel by the injection device is greater than 18.0kg/s, and the liquid nitrogen injection amount requirement of the continuous high-speed wind tunnel cooling system is met.
TABLE 2 amount of injected liquid nitrogen at different differential pressures
Normal pressure cooling operation test:
during the normal pressure test of spraying liquid nitrogen, the exhaust valve of the wind tunnel is opened and then the liquid nitrogen is sprayed into the wind tunnel, so that the total pressure of the wind tunnel is ensured to be at the normal pressure level.
Taking an atmospheric cooling test with M =0.5 as an example, fig. 6 shows the physical parameter change in the whole cooling test process, and fig. 7 shows the change of the total temperature of the stable section. As can be seen from the figure, in this test:
1) The average value of 9 total temperature measuring points in the stable section reaches-20 ℃, and the requirement is met
2) The average value of the Ma number of the test section reaches 0.5, and the Mach number deviation is | delta Ma | < 0.003, namely, the sigma is satisfied Ma ≤0.003；
3) The average value of the total pressure of the stable section is 1.022bar, and the variation amplitude of the total pressure of the stable section meets the requirement
4) The effective time of the wind tunnel cooling operation exceeds 90s.
And (3) supercharging and cooling operation test:
taking a supercharging and cooling test with M =0.8 as an example, fig. 8 shows the change of physical parameters in the whole cooling test process, and fig. 9 shows the change of the total temperature of the stable section, and it can be seen from the graph that in this test:
1) The average value of 9 total temperature measuring points in the stable section reaches-20 ℃, and the requirement is met
2) The average value of the Ma number of the test section reaches 0.8, and the Mach number deviation is | delta Ma | < 0.003, namely, the sigma is satisfied Ma ≤0.003；
3) The average value of the total pressure of the stable section reaches 1.7bar, and the variation range of the total pressure of the stable section meets the requirement
4) The effective time of the wind tunnel cooling operation exceeds 90s.
The result of the repeatability test is as follows:
taking a repeatability test of M =0.5 normal pressure as an example, the reliability of the cooling system is tested. Fig. 10 shows the change of the total temperature of the steady state section, fig. 11 shows the change of the number of the test sections Ma, and fig. 12 shows the change of the total pressure of the steady state section, and it can be seen from the graph that in this test:
1) The average value of 9 total temperature measuring points in the stable section reaches-20 ℃, and the requirement is met
2) The average value of the number of the test section Ma reaches 0.5, and the Mach number deviation is | Delta Ma | < 0.003, namely, the sigma is satisfied Ma ≤0.003；
3) The average value of the total pressure of the stable section is 1.018 bars, and the variation range of the total pressure satisfies
4) The effective time of the wind tunnel cooling operation exceeds 90s.
According to the operation test and the repeatability experiment results, the liquid nitrogen transportation system designed by the invention is proper, the liquid nitrogen injection is accurate and controllable, and the phenomenon that liquid nitrogen drips on the tunnel wall of the wind tunnel does not occur; the flow field of the wind tunnel is not interfered, the wind tunnel cooling system works stably, and the temperature index and the effective operation time meet the design requirements.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that those skilled in the art may make variations, modifications, substitutions and alterations within the scope of the present invention without departing from the spirit and scope of the present invention.
Claims (6)
1. The utility model provides a high-speed wind-tunnel liquid nitrogen cooling transport system of continuous type which characterized in that: comprises a liquid nitrogen storage device, a gas supply and distribution system and a liquid nitrogen injection device;
the liquid nitrogen storage device comprises a liquid nitrogen storage tank and a self-pressurization system; the gas supply and distribution system comprises a liquid nitrogen low-temperature pump, a vaporizer and a high-pressure gas cylinder group;
the self-pressurization system enables the pressure in the liquid nitrogen storage tank to be formed; part of liquid nitrogen in the storage tank can enter the liquid nitrogen cryogenic pump under the action of the pressure in the storage tank; the liquid nitrogen low-temperature pump conveys the liquid nitrogen to the vaporizer, the liquid nitrogen is vaporized and pressurized in the vaporizer, and then enters the high-pressure gas cylinder group; the high-pressure gas cylinder group is a high-pressure gas source for gas control, storage tank pre-pressurization and liquid nitrogen extrusion; the high-pressure nitrogen in the high-pressure gas cylinder group can push liquid nitrogen in the storage tank, and the liquid nitrogen is sprayed into the wind tunnel through the liquid nitrogen spraying device;
a liquid nitrogen storage tank in the liquid nitrogen storage device adopts a vertical vacuum powder heat insulation low-temperature liquid storage tank; the storage tank is composed of a heat insulation material, an inner container, a shell and a vacuum filter; the total volume of the liquid nitrogen storage tank meets the liquid nitrogen flow demand under the stable operation working condition of the continuous high-speed wind tunnel, and simultaneously meets the liquid nitrogen quantity demand consumed in the preparation process and the transition process of the continuous high-speed wind tunnel;
the self-pressurization system comprises a pressurization input valve, a pressure regulating valve, a self-pressurization carburetor and a pressurization output valve; the pressurization input valve, the pressure regulating valve, the self-pressurization vaporizer and the pressurization output valve are connected into a loop, and the pressurization input valve and the pressurization output valve are connected with the liquid nitrogen storage tank; after low-temperature liquid nitrogen output from the pressurization output valve is subjected to heat absorption vaporization by the self-pressurization vaporizer, generated nitrogen returns to the storage tank to increase the pressure;
the gas supply and distribution system also comprises a gas distribution system, a connecting pipeline and a matched valve; the high-pressure gas cylinder component comprises a gas control gas cylinder group and a squeezing gas cylinder group; the total volume of the high-pressure gas cylinder group meets the gas quantity requirements of gas control, storage tank pre-pressurization and squeezing gas; the high-pressure gas cylinder group is connected with a gas distribution system, and the gas distribution system performs pressure setting on four paths of gas in total to form four paths of outlets; wherein the gas accuse gas cylinder group corresponds two way exports of gas distribution system: a low pressure control gas port and a high pressure control gas port; the extruding and pushing gas cylinder group corresponds to two outlets of a gas distribution system: a pre-pressurization gas port and a push-push gas supply port.
2. The continuous high-speed wind tunnel liquid nitrogen cooling and transportation system according to claim 1, characterized in that: the discharge capacity of the liquid nitrogen cryogenic pump is 250L/h, and the outlet pressure is 15MPa; the evaporation capacity of the vaporizer is 200Nm 3 H, working pressure 15MPa, outlet temperature grade: not less than 5 ℃; the high-pressure gas cylinder group consists of 27 same high-pressure gas cylinders which are arranged in a layered and stacked manner, and the volume of each gas cylinder is 0.12m 3 Total volume of 3.24m 3 The working pressure is 15MPa; wherein the pneumatic control gas cylinder group consists of 2 gas cylinders with the volume of 0.24m 3 The pneumatic valve is used for supplying air to a plurality of pneumatic valve cylinders to realize the quick opening and closing of pneumatic valve valves, and the drift diameter of the corresponding converged air outlet main pipe is 15mm; the squeezing gas cylinder group consists of 25 gas cylinders with the volume of 3m 3 The device is used for pre-pressurizing and extruding liquid nitrogen to a liquid nitrogen storage tank, and the corresponding main gas outlet pipe has a drift diameter of 25mm.
3. The continuous high-speed wind tunnel liquid nitrogen cooling and transportation system according to claim 2, characterized in that: the pressure of a low-pressure control air port of the air distribution system is configured to be 1MPa, the pressure of a high-pressure control air port is configured to be 5MPa, the pressure of a pre-pressurization air port is configured to be 2MPa, and the pressure of a squeezing and pushing air supply port is configured to be 2.7MPa.
4. The continuous high-speed wind tunnel liquid nitrogen cooling and transportation system according to claim 1, characterized in that: the liquid nitrogen injection device comprises a liquid collecting ring, an upstream liquid nitrogen nozzle group and a downstream liquid nitrogen nozzle group; the liquid nitrogen injection device is arranged in the liquid nitrogen injection section of the wind tunnel; the liquid collecting ring is an annular stainless steel pipeline, the inner diameter of the liquid collecting ring is the same as the outer diameter of the wall of the wind tunnel at the mounting position, and the liquid collecting ring is annularly mounted on the wall of the wind tunnel and used for receiving low-temperature liquid nitrogen from the main pipeline and conveying the liquid nitrogen to the liquid nitrogen nozzle group;
the upstream liquid nitrogen nozzle group comprises a plurality of upstream ultralow-temperature high-pressure tail end electromagnetic valves, a plurality of upstream liquid nitrogen nozzles and a plurality of upstream support pipelines, and the number of the upstream ultralow-temperature high-pressure tail end electromagnetic valves, the number of the upstream liquid nitrogen nozzles and the number of the upstream support pipelines are the same; the plurality of upstream liquid nitrogen nozzles are uniformly distributed along the outer circumference of the wall of the wind tunnel, receive liquid nitrogen from the liquid collecting ring through an upstream support pipeline and spray the liquid nitrogen into the wind tunnel under the control of an upstream ultralow-temperature high-pressure tail end electromagnetic valve;
the downstream liquid nitrogen nozzle group comprises a plurality of downstream ultralow-temperature high-pressure tail end electromagnetic valves, a plurality of downstream liquid nitrogen nozzles and a plurality of downstream support pipelines, and the number of the downstream ultralow-temperature high-pressure tail end electromagnetic valves, the number of the downstream liquid nitrogen nozzles and the number of the downstream support pipelines are the same; the downstream liquid nitrogen nozzles are uniformly distributed along the outer circumference of the tunnel wall of the wind tunnel, receive liquid nitrogen from the liquid collecting ring through a downstream support pipeline and spray the liquid nitrogen into the wind tunnel under the control of a downstream ultralow-temperature high-pressure tail end electromagnetic valve;
the upstream liquid nitrogen nozzle group and the downstream liquid nitrogen nozzle group are distributed in parallel along the air flow axis of the wind tunnel, and the distance between the upstream liquid nitrogen nozzle group and the upstream end surface of the experimental section is 0.61dAnd the upstream end face of the downstream liquid nitrogen nozzle group spacing experimental section is 1.72dWhereindThe inner diameter of the upstream end face of the experimental section.
5. The continuous high-speed wind tunnel liquid nitrogen cooling and transportation system according to claim 4, characterized in that: the upstream liquid nitrogen nozzle group consists of 16 upstream ultralow-temperature high-pressure tail end electromagnetic valves, 16 upstream liquid nitrogen nozzles and 16 upstream support pipelines, and the 16 upstream liquid nitrogen nozzles are uniformly distributed along the circumferential direction of the outer side of the experimental section hole wall; the 16 upstream liquid nitrogen nozzles are controlled by 0.5Mpa differential pressure, wherein the flow rate of 3 upstream liquid nitrogen nozzles is 0.02kg/s, the flow rate of 3 upstream liquid nitrogen nozzles is 0.12kg/s, the flow rate of 6 upstream liquid nitrogen nozzles is 0.6kg/s, and the flow rate of 4 upstream liquid nitrogen nozzles is 0.73kg/s;3 upstream liquid nitrogen nozzles with flow rate of 0.02kg/s are respectively arranged at 0 of upstream jet section observed along the direction opposite to the airflow direction o 、135 o 、225 o At the position, 3 upstream liquid nitrogen nozzles with a flow rate of 0.12kg/s were respectively installed at 45 upstream nozzle cross-sections viewed in the counter-gas flow direction o 、180 o 、315 o At the position, 6 upstream liquid nitrogen nozzles with a flow rate of 0.6kg/s were respectively installed at 67.5 of the upstream jet section viewed in the counter-airflow direction o 、112.5 o 、157.5 o 、247.5 o 、292.5 o 、337.5 o At the position, 4 upstream liquid nitrogen nozzles with the flow rate of 0.73kg/s are respectively arranged at 22.5 of the upstream jet section observed along the reverse airflow direction o 、90 o 、202.5 o 、270 o A location;
the downstream liquid nitrogen nozzle group consists of 16 downstream ultralow-temperature high-pressure tail end electromagnetic valves, 16 downstream liquid nitrogen nozzles and 16 downstream support pipelines, and the 16 downstream liquid nitrogen nozzles are uniformly distributed along the outer circumference of the experimental section hole wall; 16 downstream liquid nitrogen nozzlesUnder the pressure difference of 0.5Mpa, the flow of 3 downstream liquid nitrogen nozzles is 0.02kg/s, the flow of 2 downstream liquid nitrogen nozzles is 0.12kg/s, the flow of 8 downstream liquid nitrogen nozzles is 0.6kg/s, and the flow of 3 downstream liquid nitrogen nozzles is 0.73kg/s;3 downstream liquid nitrogen nozzles with flow rate of 0.02kg/s are respectively arranged on 45 downstream injection cross sections observed along the direction opposite to the airflow direction o 、180 o 、315 o At the position, 2 downstream liquid nitrogen nozzles with a flow rate of 0.12kg/s were respectively installed at 90 downstream injection cross-sections viewed in the counter-gas flow direction o 、270 o At the position, 8 downstream liquid nitrogen nozzles with the flow rate of 0.6kg/s are respectively arranged at 22.5 downstream spray cross sections observed along the reverse airflow direction o 、67.5 o 、112.5 o 、157.5 o 、202.5 o 、247.5 o 、292.5 o 、337.5 o At the position, 3 downstream liquid nitrogen nozzles with the flow rate of 0.73kg/s are respectively arranged at 0 of the downstream spray section observed along the reverse airflow direction o 、135 o 、225 o Location.
6. The continuous high-speed wind tunnel liquid nitrogen cooling and transporting system according to claim 4, characterized in that: the front end of the support pipeline is connected to the liquid collecting ring through an expansion joint, the front end of the liquid nitrogen nozzle is connected to the tail end of the support pipeline through an ultralow-temperature high-pressure tail end electromagnetic valve, and the tail end of the liquid nitrogen nozzle is arranged on the wall of the experimental section; the ultralow temperature high pressure tail end electromagnetic valve controls the opening and closing of the liquid nitrogen nozzle.
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