A space orbit attitude control water thruster

Abstract

The present invention discloses a space orbit attitude control water thruster, comprising a water injector, a pressurizing assembly, a water thrust chamber, a heating assembly, a sensor monitoring assembly, and a Laval nozzle. The water injector stores liquid water. The water thrust chamber is a rectangular parallelepiped with a square cross-section, and its height is less than the side length of the square cross-section. A cylindrical heating chamber is coaxially provided at the center of the water thrust chamber, and the height of the heating chamber is less than the diameter of its own circular cross-section. The pressurizing assembly can inject liquid water from the water injector into the heating chamber through a capillary tube, and maintain the pressure of the water in the heating chamber at P0. The heating assembly is used to heat the heating chamber and maintain the temperature of the heating chamber at T0. The pressure P0 and temperature T0 are the supercritical water state points. The present invention has an upper limit of a specific impulse range of the order of 300 seconds, and in terms of propellant demand, it can better adapt to attitude control tasks such as microsatellite precise attitude adjustment and orbit maintenance.

Description

Technical Field

[0001] The present invention relates to a spacecraft, in particular to a space orbit attitude control water thruster. Background Art

[0002] The ability and level of a spacecraft's attitude and orbit control determine its overall performance and have significant military and economic benefits. While there are many different types of attitude and orbit control propulsion systems, no single thruster can be considered universal. The exploration of new technologies for space attitude and orbit control propulsion continues unabated.

[0003] The current space environment is becoming increasingly complex. With the development and implementation of concepts such as distributed space architectures and low-orbit mega-constellations, the number of spacecraft in orbit is growing exponentially. Maintaining the operation of large-capacity spacecraft in orbit requires low-cost, stable, and long-life propulsion systems. On Earth, water can be used as a working fluid in steam engines to power various devices. We envision transporting this to space and harnessing the energy stored in water's phase change for space propulsion.

[0004] Compared with traditional chemical propulsion, water vapor propulsion is inexpensive and has a higher density-specific impulse; water is stable and environmentally friendly, and can be stored for a long time, effectively increasing the on-orbit life of the spacecraft, and is particularly suitable for long-term deployment of spacecraft in space for attitude and orbit control purposes; based on the technical principles of the present invention combined with MEMS technology to realize the design of a micro water thruster, it will have the advantages of small pulse impulse and high adjustment accuracy, and is suitable for fine attitude adjustment of on-orbit spacecraft; compared with electric propulsion, the voltage required for water propulsion is low, and the plume does not produce ionized particles, which will not affect or interfere with the communication, optical and other payloads of the spacecraft, and is also beneficial to protecting the spacecraft.

[0005] Up to now, my country has achieved research results in the field of space orbit attitude control water thrusters. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a space orbit attitude control water thruster solution based on the potential advantages of space water propulsion. The space orbit attitude control water thruster increases the pressure of water in the water injector under the squeezing of gas pressure through a pressurizing component, and enters the heating chamber through a micro-pipeline; the temperature of the ceramic heating plate rises rapidly to several hundred degrees Celsius, and the water is rapidly heated in the heating chamber, quickly reaches a critical state and begins to vaporize, the pressure in the heating chamber increases, and the high-pressure water vapor is pushed to the nozzle, and the gas flow rate is accelerated through the Laval nozzle structure, and the high-speed ejection generates a certain thrust, while providing a driving force in the opposite direction for the thruster.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A space orbit attitude control water thruster comprises a water injector, a pressurizing component, a water thrust chamber, a heating component, a sensor monitoring component and a Laval nozzle.

[0009] Liquid water is stored in the water injector.

[0010] The water thrust chamber is a rectangular parallelepiped with a square cross section; the height of the water thrust chamber is smaller than the side length of the square cross section; a cylindrical heating chamber is coaxially arranged at the center of the water thrust chamber, and the height of the heating chamber is smaller than the diameter of its own circular cross section.

[0011] The pressurizing component can spray the liquid water in the water injector into the heating chamber through the capillary tube and keep the pressure of the water in the heating chamber at P0.

[0012] The heating component is used to heat the heating chamber and maintain the temperature of the heating chamber at T0.

[0013] Pressure P0 and temperature T0 are the supercritical water state points.

[0014] The sensor monitoring component includes a pressure sensor and a temperature sensor; wherein the pressure sensor is used to monitor the pressure of the heating chamber; the temperature sensor is used to monitor the temperature of the heating chamber.

[0015] The Laval nozzle is arranged at the tail of the water thrust chamber and is connected to the heating chamber.

[0016] The water vapor velocity at the critical section of the throat of the Laval nozzle is υ t The calculation formula is:

[0017]

[0018] Where Rg is the gas constant, which is a constant value; γ is the specific heat ratio of supercritical water in the heating chamber, which is a known value.

[0019] Assume that the critical cross-section area of the Laval nozzle throat is A t The area of the Laval nozzle outlet is A, the Mach number of the Laval nozzle outlet is Ma, the gas density of the Laval nozzle outlet is ρ, the water vapor pressure of the Laval nozzle outlet is P, and the gas temperature of the Laval nozzle outlet is T. When the nozzle area ratio A and A is given, t Under the premise of the ratio, p, Ma, ρ and T are calculated using the following formulas:

[0020]

[0021]

[0022]

[0023]

[0024]

[0025] Where ρ0 is the density of water vapor in the heating chamber under stagnant state.

[0026] The calculation formula of the thrust F generated by the water thruster is:

[0027]

[0028] in,

[0029]

[0030] Where, is the mass flow rate at the Laval nozzle outlet; p a is the atmospheric pressure; v is the flow velocity at the Laval nozzle outlet, and the specific calculation formula is:

[0031]

[0032] in:

[0033]

[0034] Where C p is the specific heat capacity at constant pressure, which is a constant; v c is the flow rate inside the heating chamber, T in It is room temperature.

[0035] The calculation formula of the specific impulse I generated by the water thruster is:

[0036]

[0037] By increasing the pressure P0 and temperature T0 and raising the supercritical water state point, the specific impulse I can be increased, theoretically reaching a maximum of 300s, allowing precise attitude adjustment of micro-nano satellites, and the attitude control accuracy is expected to reach 4.4 arc seconds.

[0038] By reducing the volume of the heating chamber, the thrust F will be reduced in the same proportion.

[0039] The Laval nozzle is a Laval micro-nozzle arranged in an N*N array; where N≥1; the setting of the N*N Laval micro-nozzle can equivalently reduce the throat area and length of a single Laval nozzle, which is beneficial to the flat design of the thruster to improve its heating efficiency and structural compactness.

[0040] The volume of the heating chamber is one ten-thousandth of the water injector volume and is proportional to the thrust.

[0041] The calculation formula of the heating power W of the heating component to the heating chamber is:

[0042]

[0043] Where, T in is the room temperature, t is the residence time of water vapor in the heating chamber; ε is the heating efficiency, which is determined by the heat transfer loss of the system and ranges from 0.3 to 1.0.

[0044] The present invention has the following beneficial effects:

[0045] 1. The present invention has a simple and regular structure, low manufacturing difficulty, is easy to process and manufacture, and has the advantages of small size, light weight, low cost and easy integration.

[0046] 2. The heating chamber is designed as a nearly two-dimensional structure, and the ceramic heating plate is closely attached to the outer wall of the heating chamber, effectively achieving instant heating of the liquid in the chamber; compared with the traditional cylindrical thrust chamber, the heating area and heating capacity are improved.

[0047] 3. The high-pressure gas cylinder in the present invention is a sealed gas cylinder and can be stored for a long time like water, so the thruster system has high reliability in long-term standby.

[0048] 4. The needle valve between the gas cylinder, the water injector, and the water injection valve port of the present invention can achieve pressure stabilization and lock, control the increase of water pressure in the water injector, prevent the backflow of liquid in the micro-channel, and stabilize the system pressure.

[0049] 5. The present invention designs a set of four Laval nozzles, which effectively reduces the throat area and length of a single Laval nozzle, facilitating a flat thruster design and improving the thruster's heating efficiency and structural compactness.

[0050] 6. Compared to the specific impulse of hypergolic (hydrazine) thrusters, which is approximately 310 seconds, the theoretical specific impulse of the present invention is close. The propellant is inexpensive and has a higher density (water has a density of 1000 kg / m³, while the specific impulse of hypergolic (hydrazine) propellants is approximately 800 kg / m³). This allows the present invention to carry more propellant in the same volume, making it particularly suitable for attitude and orbit control of long-term spacecraft deployments.

[0051] 7. Compared with electric propulsion, water propulsion requires a low voltage, and the plume does not produce ionized particles, which will not affect or interfere with the spacecraft's communications, optics and other payloads, and is also beneficial to protecting the spacecraft.

[0052] 8. The elemental impulse of the miniaturized water propulsion of the present invention can reach 0.2×10 -6 N·s, with attitude control accuracy expected to reach 4.4 arc seconds, a very high precision capable of serving as a power source for spacecraft attitude control. Selecting a supercritical water state with higher temperatures and pressures can achieve a greater specific impulse (theoretical upper limit of specific impulse is on the order of 300s), enabling more precise attitude adjustment of micro- and nano-satellites.

[0053] 9. The production capacity of solar panels on spacecraft in space is limited (usually within 3000W, except for special spacecraft such as space stations). The amount of electricity generated by micro-nano satellites is usually less than 10W. The energy consumption of this prototype is only 4.453W, which is suitable for the electrical power of micro-nano satellites. According to calculations, the actual energy consumption ratio is even lower after the thrust miniaturization design, which is conducive to improving the power efficiency and overall life of the Venus satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 A schematic structural diagram of a space orbit attitude control water thruster according to the present invention is shown.

[0055] Figure 2 A schematic diagram of the structure of a space orbit attitude control water thruster of the present invention is shown after the thermal insulation shell is removed.

[0056] Figure 3 A schematic structural diagram of a water thrust chamber equipped with a heating assembly according to the present invention is shown.

[0057] Figure 4 Shown is a schematic structural diagram of the water thrust chamber of the present invention.

[0058] Among them are:

[0059] 10. Water injector; 11. Water injector cover; 12. Water injection valve; 13. Water injection valve port; 14. Needle valve; 15. Capillary tube; 151. Capillary tube interface;

[0060] 20. Pressurizing assembly; 21. High-pressure gas cylinder; 22. Gas cylinder mounting bracket; 23. Gas cylinder locking nut;

[0061] 30. Water thrust chamber; 31. Heating chamber;

[0062] 40. Ceramic heating plate; 41. Insulation shell;

[0063] 50. Sensor monitoring component; 51. Sensor interface;

[0064] 60. Laval nozzle. DETAILED DESCRIPTION

[0065] The present invention will be further described in detail below with reference to the accompanying drawings and specific preferred embodiments.

[0066] In the description of the present invention, it should be understood that the terms "left side," "right side," "upper," "lower," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Terms such as "first" and "second" do not indicate the importance of components and therefore should not be construed as limitations on the present invention. The specific dimensions used in this embodiment are intended only to illustrate the technical solution and do not limit the scope of protection of the present invention.

[0067] like Figure 1 and Figure 2 As shown, a space orbit attitude control water thruster includes a water injector 10, a pressurizing component 20, a water thrust chamber 30, a heating component, a sensor monitoring component 50 and a Laval nozzle 60.

[0068] Liquid water is stored in the water injector, which is preferably arranged horizontally. The water outlet of the water injector is preferably a three-way water injection valve 12, and one of the valve ports of the water injection valve is provided with a needle valve 14. The other end of the water injector is a pressurized end, which is provided with a water injector sealing cover 11.

[0069] The water thrust chamber is a rectangular parallelepiped with a square cross-section. Its height is less than the side length of the square cross-section. A cylindrical heating chamber 31 (also called an evaporation chamber) is coaxially located in the center of the water thrust chamber. The height of the heating chamber is less than the diameter of its circular cross-section. The volume of the heating chamber is preferably one ten-thousandth of the volume of the water injector and is proportional to the thrust.

[0070] The pressurizing component can spray the liquid water in the water injector into the heating chamber through the capillary tube and keep the pressure of the water in the heating chamber at P0.

[0071] The pressurizing assembly preferably includes a high-pressure gas cylinder 21, which is placed in a gas cylinder fixing seat 22 and is locked and fixed by a gas cylinder locking nut 23. The top of the high-pressure gas cylinder 21 is preferably connected to the water injector sealing cap 11 through a needle valve 14.

[0072] like Figure 3 and Figure 4 As shown, one of the side surfaces A of the water thrust chamber is preferably provided with a capillary interface 151 and a sensor interface 51 .

[0073] The heating component is used to heat the heating chamber and maintain the temperature of the heating chamber at T0.

[0074] The above pressure P0 and temperature T0 are the supercritical water state points. For this prototype, the preferred temperature T0 is 240°C and the pressure P0 is 3.347 MPa.

[0075] In this embodiment, the heating assembly preferably includes a ceramic heating plate 40 and a heat-insulating shell 41 .

[0076] The ceramic heating plates are preferably arranged on the other three sides of the water thrust chamber except the side A, and the heat-insulating shell is used for heat-insulating the water thrust chamber.

[0077] The sensor monitoring component includes a pressure sensor and a temperature sensor; wherein the pressure sensor is used to monitor the pressure of the heating chamber; the temperature sensor is used to monitor the temperature of the heating chamber.

[0078] The Laval nozzle is arranged at the tail of the water thrust chamber and is connected to the heating chamber.

[0079] The Laval nozzles are arranged in an NxN array of Laval micro-nozzles, where N ≥ 1. In this prototype, N = 2 is preferred. This NxN arrangement effectively reduces the throat area and length of a single Laval nozzle, facilitating a flat thruster design that improves heating efficiency and structural compactness.

[0080] The water vapor velocity at the critical section of the throat of the Laval nozzle is υ t The calculation formula is:

[0081]

[0082] Wherein, Rg is the gas constant, which is a constant value; γ is the specific heat ratio of supercritical water in the heating chamber, which is a known value, preferably γ = 1.2.

[0083] Assume that the critical cross-section area of the Laval nozzle throat is A t (The diameter is preferably 4 mm in this prototype), the area of the Laval nozzle outlet end is A, the Mach number of the Laval nozzle outlet end is Ma, the gas density of the Laval nozzle outlet end is ρ, the water vapor pressure of the Laval nozzle outlet end is P, and the gas temperature of the Laval nozzle outlet end is T. When the nozzle area ratio A and A is given, t Under the premise of the ratio (also called expansion ratio, 5.198 is preferred in this prototype), for the complete gas, when the air flow velocity of the fluid in the cross section is small, that is, the water flow velocity in the evaporation chamber υ0→0, it is considered that the actual parameters in the chamber are stagnation parameters (total parameters), that is, the total specific enthalpy h0, total pressure p0 (3.347MPa) and total temperature T0 (240℃), ρ0 is the density of water vapor in the stagnant state in the chamber, and the water vapor in the heating chamber is adiabatic isentropic flow, then p, Ma, ρ and T are calculated using the following formulas:

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] Where ρ0 is the density of water vapor in the heating chamber under stagnant state. In this prototype, the equivalent nozzle outlet cross-sectional area A=65.270mm 3 , the equivalent nozzle outlet diameter is 9.12 mm, and the ratio of p0 to the outlet pressure P Ma=2.813、Gas density at outlet ρ=0.9082kg / m 3 .

[0090] The calculation formula of the thrust F generated by the water thruster is:

[0091]

[0092] in,

[0093]

[0094] Where, is the mass flow rate at the Laval nozzle outlet; p a is the atmospheric pressure, v is the flow velocity at the Laval nozzle outlet, and the specific calculation formula is:

[0095]

[0096] in:

[0097]

[0098] Where C p is the specific heat capacity at constant pressure, which is a constant; v c is the flow rate inside the heating chamber, T in It is room temperature.

[0099] The calculation formula of the specific impulse I generated by the water thruster is:

[0100]

[0101] In this prototype, the mass flow rate of the gas at the nozzle outlet is calculated (approximately constant in the chamber), and the mass flow rate is calculated to be 5.4g / s, the pulse thrust is 0.453N, and the specific impulse is 133.75s.

[0102] By increasing the pressure P0 and temperature T0 and raising the supercritical water state point, the specific impulse I can be increased, theoretically reaching a maximum of 300s, allowing precise attitude adjustment of micro-nano satellites, and the attitude control accuracy is expected to reach 4.4 arc seconds.

[0103] By reducing the volume of the heating chamber, the thrust F will be reduced proportionally.

[0104] The calculation formula of the heating power W of the heating component to the heating chamber is:

[0105]

[0106] Where, T in is room temperature, t represents the residence time of water vapor in the heating chamber; ε is determined by the heat transfer loss of the system and is usually between 0.3 and 1.0. The required heating power of the present invention is calculated to be 4.453W by the classical combustion chamber geometric dimension design method: T in The temperature is room temperature 20°C, and t represents the water vapor residence time (0.2s).

[0107] The water propulsion in the present invention is cheaper and has a higher density-to-density impulse than traditional chemical propulsion; water has stable properties, is environmentally friendly, and can be stored for a long time, effectively increasing the on-orbit life of the spacecraft, and is particularly suitable for long-term deployment of spacecraft in space for attitude and orbit control purposes; based on the technical principles of the present invention combined with MEMS technology to realize the design of a micro water thruster, it will have the advantages of small pulse impulse and high adjustment accuracy, and is suitable for fine attitude adjustment of on-orbit spacecraft; compared with electric propulsion, the voltage required for water propulsion is low, and the plume does not generate ionized particles, which will not affect or interfere with the communication, optical and other payloads of the spacecraft, and is also beneficial to protecting the spacecraft.

[0108] Under the same structural design conditions, the specific impulse increases with the increase of the supercritical temperature of water (theoretically, the specific impulse can be as high as 300s); reducing the volume of the heating chamber will proportionally reduce the thrust F.

[0109] Based on practical experience and cost constraints, this prototype uses a supercritical water state point with a temperature T0 of 240°C and a pressure P0 of 3.347 MPa, with a specific heat ratio γ = 1.2. A 2×2 array of Laval micronozzles with a convergent-divergent section is used, with a throat diameter of 4 mm and an expansion ratio of 5.198. The heating chamber's inner wall is designed to be 26 mm in diameter, 6.78 mm in height, and 10 mm in thickness. The prototype's specific impulse is approximately 130 to 180 seconds, with a mass flow rate of 5.391 g / s. A power of 4.452 W can generate a thrust of 0.453 N. The prototype's heating chamber is designed as a nearly two-dimensional oblate cylindrical shape, with a small chamber volume and walls that ensure rapid heat conduction, ensuring instantaneous heating of the water vapor within the chamber. Furthermore, the array nozzles are used as equivalent to a single nozzle, reducing the nozzle throat flow rate and increasing the internal chamber pressure. This ensures that, even at low heating power, the water can reach a supercritical state instantaneously or for a short period of time, thereby generating significant kinetic energy. The mass flow rate of a single operation is small, and the prototype can occupy one ten-thousandth of the capacity of the carried water. The actual single consumption ratio can be even smaller, which greatly increases the on-orbit life of the spacecraft.

[0110] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. A space orbit attitude control water thruster, characterized by: Includes water injector, pressurization assembly, water thrust chamber, heating assembly, sensor monitoring assembly and Laval nozzle; Liquid water is stored in the water injector; The water thrust chamber is a rectangular parallelepiped with a square cross section; the height of the water thrust chamber is less than the side length of the square cross section; a cylindrical heating chamber is coaxially arranged at the center of the water thrust chamber, and the height of the heating chamber is less than the diameter of its own circular cross section; The pressurizing component can spray the liquid water in the water injector into the heating chamber through the capillary tube and keep the pressure of the water in the heating chamber at P0; The heating component is used to heat the heating chamber and keep the temperature of the heating chamber at T0; Pressure P0 and temperature T0 are the supercritical water state points; The sensor monitoring component includes a pressure sensor and a temperature sensor; wherein the pressure sensor is used to monitor the pressure of the heating chamber; the temperature sensor is used to monitor the temperature of the heating chamber; The Laval nozzle is arranged at the tail of the water thrust chamber and is connected to the heating chamber.

2. The space orbit attitude control water thruster according to claim 1, characterized in that: The water vapor velocity at the critical section of the throat of the Laval nozzle is υ t The calculation formula is: Where Rg is the gas constant, which is a constant value; γ is the specific heat ratio of supercritical water in the heating chamber, which is a known value.

3. The space orbit attitude control water thruster according to claim 2, characterized in that: Assume that the critical cross-section area of the Laval nozzle throat is A t The area of the Laval nozzle outlet is A, the Mach number of the Laval nozzle outlet is Ma, the gas density of the Laval nozzle outlet is ρ, the water vapor pressure of the Laval nozzle outlet is P, and the gas temperature of the Laval nozzle outlet is T. When the nozzle area ratio A and A is given, t Under the premise of the ratio, p, Ma, ρ and T are calculated using the following formulas: Where ρ0 is the density of water vapor in the heating chamber under stagnant state.

4. The space orbit attitude control water thruster according to claim 3, characterized in that: The calculation formula of the thrust F generated by the water thruster is: in, Where, is the mass flow rate at the Laval nozzle outlet; p a is the atmospheric pressure; v is the flow velocity at the Laval nozzle outlet, and the specific calculation formula is: in: Where C p is the specific heat capacity at constant pressure, which is a constant; v c is the flow rate inside the heating chamber, T in It is room temperature.

5. The space orbit attitude control water thruster according to claim 4, characterized in that: The calculation formula of the specific impulse I generated by the water thruster is:

6. The space orbit attitude control water thruster according to claim 1 or 5, characterized in that: By increasing the pressure P0 and temperature T0, the supercritical water state point can be raised and the specific impulse I can be increased.

7. The space orbit attitude control water thruster according to claim 1 or 5, characterized in that: By reducing the volume of the heating chamber, the thrust F will be reduced proportionally.

8. The space orbit attitude control water thruster according to claim 1, characterized in that: The Laval nozzle is a Laval micro-nozzle arranged in an N*N array; where N≥1; the setting of the N*N Laval micro-nozzle can equivalently reduce the throat area and length of a single Laval nozzle, which is beneficial to the flat design of the thruster to improve its heating efficiency and structural compactness.

9. The space orbit attitude control water thruster according to claim 1, characterized in that: The volume of the heating chamber is one ten-thousandth of the water injector volume and is proportional to the thrust.

10. The space orbit attitude control water thruster according to claim 4, characterized in that: The calculation formula of the heating power W of the heating component to the heating chamber is: Where, T in is the room temperature, and t is the residence time of water vapor in the heating chamber; ε is the heating efficiency, which is determined by the heat transfer loss of the system and ranges from 0.3 to 1.0.

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