A device for eliminating thermal stratification of fluid in microgravity environment

Abstract

The present application discloses a device for eliminating thermal stratification of fluid in a microgravity environment, which relates to the field of cryogenics and refrigeration engineering, including a liquid storage tank, a fluid pump, an ejector, and a liquid supply subsystem, etc.; according to the liquid source of the fluid pump, the liquid supply subsystem can be divided into an external liquid supply storage tank, or a combination of a metal mesh curtain and an outlet. The specific process is that after the liquid supply system obtains the liquid, the liquid flows into the ejector through the pressurization of the pump, and is ejected into the liquid storage tank through the small holes on the ejector. The ejector can be divided into a rod-shaped ejector, a spherical ejector, and a point-shaped ejector. When the liquid flows out droplets through the above three ejectors, it will be ejected into the storage tank in the form of a parabola (rod-shaped injection), a spherical surface (spherical injection) or a cone surface (point-shaped injection) through the small holes on the rod and mixed with the gas-liquid interface. When the gas-liquid interface is thermally stratified due to external heat leakage, the mixing of the droplets and the fluid at the two-phase interface will play a role in eliminating thermal stratification.

Description

Technical Field

[0001] The invention relates to a device for eliminating thermal stratification of fluid in a microgravity environment, and belongs to the technical field of cryogenics and refrigeration engineering. Background Art

[0002] In the aerospace field, liquid hydrogen / liquid oxygen binary combination cryogenic propellants have excellent characteristics such as high performance, non-toxicity and pollution-free, and will play a huge application value in future large-scale manned lunar landings, Mars exploration and longer-distance deep space exploration missions. However, during the on-orbit application of cryogenic propellants, due to the heat leakage of the external environment, the internal fluid will establish thermal stratification with a temperature gradient along a certain dimension. The thermal stratification of cryogenic propellants along different dimensions under microgravity will affect the heat storage capacity of the fluid. Therefore, changes or interferences to the thermal stratification will reconstruct the heat distribution in the tank. Generally, thermal stratification will limit the heat storage capacity of the fluid. Destroying the thermal stratification and achieving temperature uniformity can induce gas phase cooling and condensation, which is beneficial to reducing the tank pressure.

[0003] However, unlike the normal gravity environment on the ground, the gas-liquid two-phase flow in the space environment has no clear boundary line. The two-phase flow in the microgravity environment has no clear position distribution in the tank and is in a two-phase mixed state most of the time. If thermal stratification is to be eliminated by spraying liquid, a stable source of liquid for spraying is required. Summary of the invention

[0004] The technical problem solved by the present invention is to overcome the shortcomings of the prior art and provide a device for eliminating thermal stratification of fluid in a microgravity environment, which can realize related research such as fluid pressurization and mixed injection to eliminate thermal stratification in a microgravity environment and observation of jet flow patterns in a microgravity environment.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A device for eliminating thermal stratification of fluid in a microgravity environment, comprising a liquid storage tank, a liquid supply subsystem, a fluid pump, and an ejector;

[0007] The liquid tank is used to store the test liquid. The injector is located inside the liquid tank. The injector is hollow inside and has a plurality of jet holes distributed on the surface. The injector is connected with a liquid supply pipe, which is connected with a fluid pump and a liquid supply subsystem. The fluid pump brings the fluid from the liquid supply subsystem into the injector and injects it into the liquid tank in the form of a jet through the jet holes on the injector.

[0008] The liquid supply subsystem includes a liquid supply tank, in which a test liquid with a certain pressure is pre-stored, and a liquid supply pipe is connected to the liquid supply tank;

[0009] Alternatively, the liquid supply subsystem includes a metal mesh curtain and an outlet, the metal mesh curtain is fixedly connected to the inner side of the liquid storage tank, the outlet is opened in the liquid storage tank and communicates between the metal mesh curtain and the liquid storage tank, and the end of the liquid supply pipe is connected to the outlet;

[0010] The liquid storage capacity of the liquid supply tank or metal screen satisfies the following relationship:

[0011] M≥ρ*q V

[0012] Where M is the liquid storage capacity of the liquid supply tank or metal screen, kg; ρ is the fluid density of the test liquid, kg / m 3 ;q V is the volume flow rate of the fluid pump, m 3 / h.

[0013] The liquid supply pipe is connected to a dye box, which is located between the fluid pump and the liquid supply subsystem. The interior of the dye box is filled with a dyeing substance that is soluble in the incoming liquid.

[0014] The liquid storage tank is provided with sensors, including temperature sensors and pressure sensors. The temperature sensor is used to measure the temperature parameters of the fluid at different positions in the storage tank, and the pressure sensor is used to monitor the pressure parameters of the gas phase space in the storage tank.

[0015] The temperature sensor is in array form, and the array can be arranged in a longitudinal one-dimensional linear manner, or in a planar two-dimensional arrangement in a horizontal and vertical cross-type; the temperature sensor array covers the liquid phase region and the gas phase region in the microgravity environment;

[0016] The pressure sensor is placed in the liquid storage tank, or a pressure sensor is arranged outside the tank body in the form of a pressure-guiding pipe arranged on the wall of the liquid storage tank to measure the tank pressure.

[0017] The material of the metal mesh curtain is an ablative porous medium structure or metal foam.

[0018] The injector meets the following requirements:

[0019]

[0020]

[0021] Where P is the fluid pressure at the i-th jet hole, pa; A i is the hole area at the i-th jet hole, m 2 ;m i is the mass flow rate of the jet from the i-th jet hole, kg / s; t is the jet time, s; θ is the angle between the jet direction and the radial direction of the liquid tank, rad; H is the distance from the jet hole to the top of the liquid tank, m; R is the radius of the liquid tank, m.

[0022] The injector is a rod-shaped injector, comprising an injection rod with a hollow interior, and the jet holes are evenly arranged along the axial direction and circumferential direction of the injection rod.

[0023] The injector is a spherical injector, comprising a lower flow channel and a spherical shell, one end of the lower flow channel is fixedly connected to the inner wall of the liquid storage tank, and the other end is fixedly connected to the spherical shell, the spherical shell is located in the gas phase region of the liquid storage tank, and the jet holes are evenly distributed on the spherical shell;

[0024] The spherical ejector satisfies: Q = (N-1) * q m

[0025] Q is the total flow rate through the lower flow channel, kg / s; N is the number of jet holes on the spherical shell; q m is the fluid flow rate passing through each jet orifice, kg / s.

[0026] The injector is a point-shaped injector, comprising a frustum fixed to the inner wall of the liquid storage tank, the frustum is located in the liquid phase region of the liquid storage tank, and the injection holes are distributed on the top surface and the circumferential surface of the frustum.

[0027] The point-shaped injector satisfies: Q = ρμ m A m N a +ρμ n A n N b

[0028] Q is the total flow rate through the flow channel, kg / s; μ m is the top jet fluid velocity, m / s; μ n is the velocity of the conical jet fluid, m / s, uniformly distributed circumferentially on the top surface N a There are several injection holes, and the area of ​​a single injection hole is A. m ; The cone surface has N openings along the circumference b Small holes, the area of ​​a single injection hole is A n .

[0029] In summary, this application at least includes the following beneficial technical effects:

[0030] The present invention realizes the spray mixing of droplets by the form of stable liquid supply outside the tank or internal absorption of liquid. The former requires a small liquid tank with a certain pressure to be carried outside the tank to squeeze out the liquid therein, and the liquid in the small tank should be the same as the liquid in the mainstream area; the latter absorbs liquid from the mainstream area. Since the position of the liquid is uncertain under microgravity, the present invention is configured with a metal mesh curtain and an integrated structure of the outlet to obtain stable liquid. In order to observe the jet flow pattern in the tank under microgravity environment, a dye is configured in the fluid pipeline so that the jet fluid and the liquid in the mainstream area are distinguished by color, and a transparent tank is used to load the liquid in the mainstream area, which is convenient for observation and recording through external video recording equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A device for eliminating thermal stratification of fluid in a microgravity environment according to the present invention;

[0032] Figure 2 It is the form of the thermal stratification elimination ejector of the present invention;

[0033] Figure 3 It is an expanded form of the device for eliminating thermal stratification of fluid in a microgravity environment of the present invention;

[0034] Figure 4 A system for eliminating thermal stratification of fluid in a microgravity environment according to an embodiment of the present invention;

[0035] Figure 5 a, b, and c are schematic diagrams of the design schemes of rod-shaped, spherical, and point-shaped injectors for eliminating thermal stratification according to the embodiments of the present invention, respectively.

[0036] Description of reference numerals: 1. liquid storage tank; 2. liquid supply subsystem; 3. dye box; 4. fluid pump; 5. ejector; 6. temperature sensor array; 7. pressure sensor; 8. video camera; 9. measurement and control system;

[0037] 2-a, metal mesh curtain; 2-b, outlet. DETAILED DESCRIPTION

[0038] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0039] The present application embodiment discloses a device for eliminating thermal stratification of fluid in a microgravity environment, such as Figure 1 As shown, it includes a liquid storage tank 1, a liquid supply subsystem 2, a dye box 3, a fluid pump 4, an injector 5, a sensor, a camera 8 and a measurement and control system 9.

[0040] The liquid tank 1 is used to store the test liquid. The injector 5 is located inside the liquid tank 1. The injector 5 is hollow inside and has a plurality of jet holes distributed on the surface. The injector 5 is connected to a liquid supply pipe, which is connected to the liquid supply subsystem 2, the dye box 3, and the fluid pump 4 at one time. The fluid pump 4 brings the fluid from the liquid supply subsystem 2 into the injector 5, and injects it into the liquid tank 1 in the form of a jet through the jet holes on the injector 5.

[0041] The liquid storage tank 1 is generally made of transparent material, metal material or multifunctional composite material; according to the type of storage medium, a temperature sensor array, a pressure sensor 7, a heating plate (block) and other devices can be arranged inside the liquid storage tank 1. The liquid storage tank 1 is spherical, or the liquid storage tank 1 is in the shape of a cylindrical section in the middle and elliptical heads at both ends.

[0042] According to the incoming flow acquisition form, the liquid supply subsystem 2 can be a liquid supply tank, or the liquid supply subsystem 2 includes a metal mesh 2-a and an outlet 2-b. When the liquid supply subsystem 2 is a liquid supply tank, a test medium with a certain pressure is pre-stored in the liquid supply tank, and the liquid supply pipe is connected to the liquid supply tank. When working, the tank valve is opened, and the liquid in the tank flows out to the dye box 3 under pressure. When the liquid supply subsystem 2 adopts a combination of a metal mesh 2-a and an outlet 2-b, the metal mesh 2-a is fixedly connected to the inner side of the liquid tank 1 and forms a closed space with the inner wall of the liquid tank 1. The outlet 2-b is opened in the liquid tank 1 and connects the closed space between the metal mesh 2-a and the liquid tank 1. The end of the liquid supply pipe is connected to the outlet 2-b. The material of the metal mesh 2-a is generally an ablated porous medium structure or metal foam. The main function of the metal mesh curtain 2-a is to capture and retain liquid so that the pipe in front of the inlet of the fluid pump 4 can be filled with liquid, and to avoid gas-liquid two-phase flow in the pipe in front of the inlet of the fluid pump 4, otherwise it will cause cavitation of the pump. When the structure of the metal mesh curtain 2-a is manufactured and formed, it is manufactured according to the shape of the inner wall of the storage tank, and can be fixed in various forms, such as setting a hook on the inner wall, or fixing the side of the metal mesh curtain in contact with the fluid with a mesh structure with elastic effect. This structure relies on the capillary pump action between the liquid in the liquid storage tank 1 and the metal mesh curtain 2-a to capture the liquid into the metal mesh curtain 2-a, forming a liquid distribution pattern along the inner wall of the storage tank. In the microgravity environment, the gas and liquid in the liquid tank 1 are in a mixed state. Under the surface tension between the metal mesh 2-a and the liquid, the metal mesh 2-a can capture the liquid. Driven by the pressure difference between the tank pressure of the liquid tank 1 and the suction port of the fluid pump 4, the liquid captured by the metal mesh 2-a enters the dye box 3 through the outlet 2-b; the liquid flows into the ejector 5 through the small hole on the ejector 5 and is ejected into the tank. The liquid storage capacity of the liquid supply tank or the metal mesh 2-a is determined according to the working condition of the fluid pump 4, and the following relationship must be satisfied:

[0043] M≥ρ*qV

[0044] Where M is the liquid storage capacity of the liquid supply tank or metal screen, kg; ρ is the fluid density of the test liquid, kg / m 3 ;q V is the volume flow rate of the fluid pump, m 3 / h.

[0045] The liquid inlet end of the dye box 3 is connected to the liquid outlet end of the liquid supply subsystem 2, and the liquid outlet end of the dye box 3 is connected to the inlet end of the fluid pump 4; the dye box 3 has good sealing performance and can be used in 10 -6 There is no leakage under the high vacuum environment of Pa; the dye box 3 is filled with dyeing material that can be dissolved in the incoming liquid. When the incoming liquid enters the dye box 3, the dyeing material therein is mixed with the incoming liquid, and the mixed fluid enters the fluid pump 4 through the outlet of the dye box 3. The dye box 3 is used to dye the incoming liquid of the liquid supply subsystem 2, so as to distinguish the color of the incoming liquid from the mainstream liquid in the liquid storage tank 1, so as to make it easier to observe the changes in the flow pattern of the incoming liquid.

[0046] The fluid pump 4 is arranged outside the liquid tank 1, between the dye box 3 and the injector 5, and is used to pressurize the incoming liquid from the liquid supply subsystem 2 and deliver it to the injector 5. The fluid pump 4 is a power circulation device for the entire system. External power supply drives the internal mechanism of the fluid pump 4 to rotate, driving the incoming flow from the dye box 3 to be disturbed, so that the incoming flow has a higher flow speed and then enters the injector 5 from the fluid pump 4.

[0047] The ejector 5 is located inside the liquid tank 1, and has a plurality of jet holes distributed on the surface. The fluid output by the fluid pump 4 enters the ejector 5, and is ejected back into the liquid tank 1 in the form of a jet through the plurality of jet holes on the ejector 5. The ejector 5 should be designed to ensure that the ejection range of the ejected fluid is within the tank, that is:

[0048]

[0049]

[0050] Where P is the fluid pressure at the i-th hole, pa; A i is the hole area at the ith hole, m 2 ;m i is the mass flow rate of the jet from the ith small hole, kg / s; t is the jet time, s; θ is the angle between the jet direction and the radial direction of the tank, rad; H is the distance from the jet hole to the top of the tank ellipsoid, m; R is the radius of the tank, m.

[0051] like Figure 2 , Figure 3 and Figure 5As shown, according to the application scenario requirements, the injector 5 can be divided into three typical forms, namely, a rod-shaped injector 5, a spherical injector 5, and a point-shaped injector 5. Accordingly, when the liquid flows out droplets through the above three injectors 5, it will be ejected into the tank through the small holes on the rod in the form of a parabola (rod-shaped injection), a sphere (spherical injection), or a cone (point-shaped injection) and mixed with the gas-liquid interface. When the gas-liquid interface is thermally stratified due to external heat leakage, the mixing of the droplets and the fluid at the two-phase interface will play a role in eliminating the thermal stratification.

[0052] The rod-shaped injector 5 comprises an injection rod with a hollow interior, and injection holes thereof are evenly arranged along the axial direction and circumferential direction of the injection rod.

[0053] The spherical injector 5 is composed of a lower flow channel and a top spherical shell, which are fixedly connected. The spherical shell is located in the gas phase region of the liquid storage tank 1. Several injection holes are evenly distributed on the surface of the spherical shell, and the flow channel outlet is connected to a small hole of the spherical shell. The central axis of the lower flow channel coincides with the central axis of the top spherical shell, and passes through the center of the first small hole at the connection with the rod. The flow through the lower flow channel is conserved with the flow through the spherical shell, that is:

[0054] Q=(N-1)*q m

[0055] Q is the total flow rate through the flow channel, kg / s; N is the number of small holes on the spherical shell; q m is the fluid flow rate through each orifice, kg / s.

[0056] For the point-shaped injector, including a cone fixed to the inner wall of the liquid tank, the incoming flow enters the cone. Except for the central opening, the top surface of the cone is evenly distributed along the circumference. a There are injection holes, and the area of ​​a single hole is A m ; The cone surface has N openings along the circumference b Small holes, single hole area A n , the fluid is ejected in different directions through the cone surface; the bottom surface is opened, and the center lines of the small holes at the top of the cone and the small holes at the bottom coincide with the axis of the lower flow channel. According to the law of conservation of fluid mass, there is the following relationship:

[0057] Q=ρμ m A m N a +ρμ n A n N b

[0058] Q is the total flow rate through the bottom hole flow channel, kg / s; μ m is the top jet fluid velocity, m / s; μ n is the conical jet fluid velocity, m / s.

[0059] like Figure 4 As shown, the sensor includes a temperature sensor and a pressure sensor 7. The temperature sensor is used to measure the temperature parameters of the fluid at different positions in the space of the tank, and the pressure sensor 7 is used to monitor the pressure parameters of the gas phase space in the tank. In order to measure the temperature of the two-phase flow in the tank, the temperature sensor is an array type. The temperature sensor covers the liquid phase and the gas phase area, and monitors the temperature of the fluid in real time. According to the requirements of the temperature field measurement range, the array can be a longitudinal one-dimensional linear arrangement, or a horizontal and vertical cross-planar two-dimensional arrangement; the temperature sensor array should be able to cover the liquid phase area and the gas phase area in a microgravity environment; the pressure sensor 7 in the tank can be placed inside the tank, or a pressure sensor 7 can be set outside the tank in the form of a pressure pipe on the tank wall to measure the tank pressure.

[0060] The video camera 8 is located outside the liquid storage tank 1, and can record and photograph the transparent liquid storage tank 1 in real time, and record the real-time changes of the flow field in the liquid storage tank 1;

[0061] The measurement and control system 9 is located outside the liquid storage tank 1 and is powered by an additional power source. It can collect and display the temperature, pressure and operating data of the circulating pump in the microgravity environment fluid thermal stratification elimination system in real time.

[0062] Although the present invention is disclosed as above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. A device for eliminating thermal stratification of fluid in a microgravity environment, characterized in that: It comprises a liquid storage tank (1), a liquid supply subsystem (2), a fluid pump (4) and an ejector (5); The liquid storage tank (1) is used to store the test liquid. The injector (5) is located inside the liquid storage tank (1). The injector (5) is hollow inside and has a plurality of jet holes distributed on the surface. The injector (5) is connected to a liquid supply pipe, which is connected to a fluid pump (4) and a liquid supply subsystem (2). The fluid pump (4) allows the fluid from the liquid supply subsystem (2) to enter the injector (5), and then injects the fluid into the liquid storage tank (1) in the form of a jet through the jet holes on the injector (5). The liquid supply subsystem (2) comprises a liquid supply tank, in which a test liquid of a certain pressure is pre-stored, and a liquid supply pipe is connected to the liquid supply tank; Alternatively, the liquid supply subsystem (2) comprises a metal mesh curtain (2-a) and an outlet (2-b), wherein the metal mesh curtain (2-a) is fixedly connected to the inner side of the liquid storage tank (1), the outlet (2-b) is opened in the liquid storage tank (1) and communicates between the metal mesh curtain (2-a) and the liquid storage tank (1), and the end of the liquid supply pipe is connected to the outlet (2-b); The liquid storage capacity of the liquid supply tank or the metal mesh curtain (2-a) satisfies the following relationship: Wherein, M is the liquid storage capacity of the liquid supply tank or the metal screen (2-a), kg; ρ is the fluid density of the test liquid, kg / m 3 ;q V is the volume flow rate of the fluid pump, m 3 / h; The injector (5) satisfies: Where P is the fluid pressure at the i-th jet hole, pa; A i is the hole area at the i-th jet hole, m 2 ;m i is the mass flow rate of the jet of the i-th jet hole, kg / s; t is the jet time, s; θ is the angle between the jet direction and the radial direction of the liquid tank (1), rad; H is the distance between the jet hole and the top of the liquid tank (1), m; R is the radius of the liquid tank (1), m.

2. The device for eliminating thermal stratification of fluid in a microgravity environment according to claim 1, characterized in that: The liquid supply pipe is connected to a dye box (3), the dye box (3) is located between the fluid pump (4) and the liquid supply subsystem (2), and the interior of the dye box (3) is filled with a dyeing substance that is soluble in the incoming liquid.

3. The device for eliminating thermal stratification of fluid in a microgravity environment according to claim 1, characterized in that: The liquid storage tank (1) is provided with sensors, including a temperature sensor and a pressure sensor (7). The temperature sensor is used to measure the temperature parameters of the fluid at different positions in the space of the storage tank, and the pressure sensor (7) is used to monitor the pressure parameters of the gas phase space in the storage tank.

4. The device for eliminating thermal stratification of fluid in a microgravity environment according to claim 3, characterized in that: The temperature sensor is in array form, and the array can be arranged in a longitudinal one-dimensional linear manner, or in a planar two-dimensional arrangement in a horizontal and vertical cross-type; the temperature sensor array covers the liquid phase region and the gas phase region in the microgravity environment; The pressure sensor (7) is placed inside the liquid storage tank (1), or the pressure sensor (7) is arranged outside the tank body by arranging a pressure-guiding pipe on the wall surface of the liquid storage tank (1) to measure the tank pressure.

5. The device for eliminating thermal stratification of fluid in a microgravity environment according to claim 1, characterized in that: The material of the metal mesh curtain (2-a) is an ablated porous medium structure or metal foam.

6. The device for eliminating thermal stratification of fluid in a microgravity environment according to claim 1, characterized in that: The injector (5) is a rod-shaped injector (5), comprising an injection rod with a hollow interior, and the jet holes are evenly arranged along the axial direction and circumferential direction of the injection rod.

7. The device for eliminating thermal stratification of fluid in a microgravity environment according to claim 1, characterized in that: The injector (5) is a spherical injector, comprising a lower flow channel and a spherical shell, one end of the lower flow channel is fixedly connected to the inner wall of the liquid storage tank (1), and the other end is fixedly connected to the spherical shell, the spherical shell is located in the gas phase region of the liquid storage tank (1), and the jet holes are evenly distributed on the spherical shell; The spherical ejector (5) satisfies: Q is the total flow rate through the lower flow channel, kg / s; N is the number of jet holes on the spherical shell; q m is the fluid flow rate passing through each jet orifice, kg / s.

8. The device for eliminating thermal stratification of fluid in a microgravity environment according to claim 1, characterized in that: The injector (5) is a point-shaped injector, comprising a frustum fixed to the inner wall of the liquid storage tank, the frustum being located in the liquid phase region of the liquid storage tank, and the injection holes being distributed on the top surface and the circumferential surface of the frustum.

9. The device for eliminating thermal stratification of fluid in a microgravity environment according to claim 8, characterized in that: The point injector satisfies: Q is the total flow rate through the flow channel at the bottom of the cone, kg / s; μ m is the top jet fluid velocity, m / s; μ n is the velocity of the conical jet fluid, m / s, uniformly distributed circumferentially on the top surface of the frustum N a There are several injection holes, and the area of ​​a single injection hole is A. m ; The cone surface has N openings along the circumference b Small holes, the area of ​​a single injection hole is A n .

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