Wall surface temperature driven rarefied gas suction regulation and control device and implementation method

Abstract

The invention relates to the technical field of air suction type propulsion aircrafts, in particular to a wall surface temperature driven rarefied gas suction regulation and control device and an implementation method, the wall surface temperature driven rarefied gas suction regulation and control device comprises an air suction assembly and a heat management system, and an outlet of the air suction assembly is connected with a conveying pipeline; the heat management system is used for forming a temperature difference on the pipe wall of the conveying pipeline, and the temperature of the pipe wall of the conveying pipeline close to the air suction assembly is smaller than that of the pipe wall of the conveying pipeline away from the air suction assembly. According to the invention, the free molecular flow is effectively conveyed without moving parts, so that the gas capture rate and the compression ratio of the gas inlet device of the air-breathing electric propulsion system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air-breathing propulsion aircraft, in particular to a wall temperature driven rarefied gas air-breathing regulation device and implementation method. BACKGROUND

[0002] The ultra-low orbit aircraft operating below 400km has many advantages, such as facilitating high-resolution ground reconnaissance observation, being conducive to reducing communication delay and improving bandwidth, and low launch cost. However, due to the large atmospheric resistance, the ultra-low orbit aircraft needs to consume a large amount of fuel to maintain the orbital height, therefore, the service time of the current ultra-low orbit aircraft is generally short. The air-breathing electric propulsion system can capture the gas molecules at the top of the atmosphere, and after enrichment and pressurization, it can provide propellant for the electric thruster. This "collecting on the spot and using on the spot" mode can greatly reduce the propellant that needs to be carried by the aircraft during launch, thereby prolonging the on-orbit service life of the ultra-low orbit aircraft.

[0003] Collecting sufficient gas working medium from the outer rarefied atmosphere is the premise of ensuring the normal operation of the air-breathing electric propulsion system, which requires the design of a special air-breathing device to maximize the two core indicators of the air-breathing device: gas collection rate and compression ratio. At present, the academic and engineering circles mainly rely on the design of air inlet collimating grid, the design of contraction section geometric profile, the change of gas-solid surface scattering characteristics, and the uniform temperature of the overall wall to improve the gas collection rate and compression ratio of the air-breathing device. Although these measures have good effect on improving the compression ratio, they have little effect on the gas collection rate.

[0004] In addition, there is also an active regulation technology of using a rotating molecular pump in the contraction channel of the air inlet device, which can improve the gas compression ratio and collection rate to a certain extent. However, this additional moving mechanism also has many drawbacks, such as increasing the mechanical disturbance and mass burden of the ultra-low orbit aircraft, and reducing the reliability of the aircraft.

[0005] Therefore, it is necessary to provide a wall temperature driven rarefied gas air-breathing regulation device and implementation method to solve the above problems. SUMMARY

[0006] In order to solve the problem that the additional moving mechanism increases the mechanical disturbance and mass burden of the ultra-low orbit aircraft, and reduces the reliability of the aircraft, the present application provides a wall temperature driven rarefied gas air-breathing regulation device and implementation method to solve the existing problems.

[0007] The first aspect of the present application provides a wall temperature driven rarefied gas air-breathing regulation device, which adopts the following technical scheme, comprising: An air-breathing contraction section, the outlet of which is connected with a conveying pipeline; And a heat management system for forming a temperature difference on the pipe wall of the conveying pipe, wherein the pipe wall temperature of the conveying pipe close to the suction contraction section is lower than the pipe wall temperature of the conveying pipe away from the suction contraction section.

[0008] According to a further technical solution of the present invention, the thermal management system adopts an electric refrigeration structure, which includes: A thermocouple arm, one end of which is a cold end and the other end of which is a hot end, and both the cold end and the hot end face the wall of the conveying pipeline; and a power supply for powering the thermocouple arms; The cold end is connected to the pipe wall of the conveying pipeline close to the suction contraction section; the hot end is connected to the pipe wall of the conveying pipeline away from the suction contraction section.

[0009] According to a further technical solution of the present invention, the thermocouple arm adopts an N-type semiconductor and a P-type semiconductor connected together.

[0010] A further technical solution of the present invention is that the thermal management system includes: two heat pipes, one end of which is connected to the pipe wall of the conveying pipe near the air intake contraction section, and the other end of the heat pipe extends to the satellite's non-sunny side; one end of the other heat pipe is connected to the pipe wall of the conveying pipe away from the air intake contraction section, and the other end of the heat pipe extends to the satellite's sun-facing side.

[0011] According to a further technical solution of the present invention, the air intake contraction section comprises an air intake duct, wherein the geometrical surface of the air intake duct is a cone, a rotational parabola or a composite of a cylinder and a cone.

[0012] According to a further technical solution of the present invention, an air intake collimating grid is provided in the inlet end of the air intake duct.

[0013] According to a further technical solution of the present invention, the cross section along the air intake direction of the air intake duct is a hyperbolic parabolic cross section, and the concave surfaces of the two parabolas of the hyperbolic parabolic cross section are opposite to each other.

[0014] A second aspect of the present invention provides an embodiment of a method for designing a wall temperature-driven rarefied gas intake control device, comprising: Determine the design parameters to be optimized, which are: pipe diameter distribution, wall adaptability coefficient and wall temperature of the suction pipe; Construct multiple sets of design parameters and use rarefied gas dynamics simulation methods to simulate the temperature and flow field distribution in the intake duct under each set of design parameters. Calculate the gas collection rate and compression ratio of the intake control device under each set of design parameters. Taking maximizing the gas collection rate and compression ratio of the intake control device as the optimization goal, a multi-parameter optimization algorithm is adopted to iteratively update the optimization design parameters. The set of design parameters corresponding to the gas collection rate and compression ratio of the intake control device converge to the maximum value is taken as the optimal design parameters, and the intake control device is designed based on the optimal design parameters.

[0015] The third aspect of the present invention provides an embodiment of an electric propulsion system, which includes a wall temperature-driven rarefied gas intake control device provided by the first aspect of the present invention, and the outlet of the delivery pipeline of the intake control device is connected to the working fluid inlet of the Hall electric thruster.

[0016] A fourth aspect of the present invention provides a satellite comprising an electric propulsion system provided by the third aspect of the present invention.

[0017] The beneficial effects of the present invention are: (1) The rarefied gas intake control device driven by wall temperature proposed in the present invention does not require any moving parts, will not cause vibration interference to the aircraft, and has high reliability. That is, it can effectively transport the free molecular flow without the need for moving parts, thereby solving the technical problem that the air intake device of the air-breathing electric propulsion system is difficult to adjust the gas capture rate.

[0018] (2) The present invention only requires the generation of a non-uniform temperature field on the inlet wall, without changing the overall temperature of the aircraft wall. Compared with technologies that reduce the overall wall temperature, the present invention requires lower cooling and heat dissipation, places less burden on the thermal management system, and has less additional mass.

[0019] (3) The design method of the wall temperature-driven rarefied gas intake control device of the present invention has good flexibility. Based on the optimized design of the existing intake device, a new method of controlling the gas collection rate by changing the wall temperature distribution is proposed. It is convenient to realize the flexible control of the intake volume of the intake device through dynamic electrical control rather than static geometric structure design. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic structural diagram of a rarefied gas intake control device driven by wall temperature in a first embodiment of a thermal management system according to an embodiment of the present invention; Figure 2 This is a schematic structural diagram of a first embodiment of a thermal management system in an embodiment of the present invention; Figure 3 Schematic diagram of the structure of a wall temperature-driven rarefied gas intake control device according to a second embodiment of the thermal management system in an embodiment of the present invention; Figure 4 This is a schematic diagram of the principle of temperature-driven rarefied gas flow in an embodiment of the present invention; Figure 5 A flow chart of a design method for a wall temperature-driven rarefied gas intake control device provided in the second embodiment of the present invention; Figure 6 for Figure 5 Schematic diagram of the design parameters of the air intake control device in step 1; Figure 7 This is a pressure distribution cloud diagram of the air intake control device without heat drive in an embodiment of the present invention; Figure 8 This is a pressure distribution cloud diagram of a heat-driven air intake control device according to an embodiment of the present invention; Figure 9 This is a density distribution cloud diagram of the air intake control device without heat drive in an embodiment of the present invention; Figure 10 This is a density distribution cloud diagram of a heat-driven air intake control device according to an embodiment of the present invention; Figure 11 A comparison diagram of pressure and density on the central axis of the heat-free air intake control device in an embodiment of the present invention; Figure 12 1 is a comparison diagram of pressure and density on the central axis of the heat-driven air intake control device in an embodiment of the present invention.

[0022] In the figure: 1. Intake contraction section; 2. Delivery pipeline; 3. Thermal management system; 11. Cold end; 12. Hot end; 13. Thermocouple arm; 111. Cold end facing away from the sun; 112. Hot end facing the sun; 113. Heat pipe. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] The first part of the present invention provides an embodiment of a rarefied gas suction control device driven by wall temperature, such as Figure 4As shown, according to the unique thermal driving flow effect of rarefied gas, when the rarefied gas molecules collide with the solid wall with temperature gradient, the driving force is directed from the low temperature end to the high temperature end. Therefore, the non-uniform temperature field is generated on the wall of the pipeline, and the delivery of the rarefied gas can be regulated. The present embodiment is based on this principle, and the wall temperature of the gas suction section pipeline is changed by using the thermal management technology, so as to generate the non-uniform temperature field on the wall, and generate the thermal driving force on the gas molecules in the pipeline, so as to actively regulate the gas capture rate without moving parts.

[0025] As shown in the drawings, Figure 1 A wall temperature driven rarefied gas suction regulation device embodiment includes a gas suction assembly and a thermal management system 3, and the outlet of the gas suction assembly is connected with a delivery pipeline 2, and the outlet of the delivery pipeline 2 is connected with the working fluid inlet of the electric propulsion system, wherein the thermal management system 3 is used to form a temperature difference on the wall of the delivery pipeline 2, and the wall temperature of the delivery pipeline 2 close to the gas suction assembly is less than the wall temperature of the delivery pipeline 2 away from the gas suction assembly, that is, the temperature difference can generate the thermal driving force on the wall of the delivery pipeline 2 to the gas molecules, so as to accelerate the movement of the gas molecules, and further improve the gas collection rate of the gas suction assembly. It should be noted that the gas suction assembly and the delivery pipeline 2 together constitute the gas channel for collecting the gas molecules for the air-breathing electric propulsion system of the aircraft.

[0026] As shown in the drawings, Figure 1 In a specific embodiment, the first embodiment of the thermal management system 3 adopts an electric refrigeration structure, as shown in the drawings, Figure 2 The electric refrigeration structure includes a thermocouple arm 13 and a power supply for supplying power to the thermocouple arm 13, one end of the thermocouple arm 13 is a cold end 11, the other end of the thermocouple arm 13 is a hot end 12, and the cold end 11 and the hot end 12 are both towards the wall of the delivery pipeline 2; wherein the cold end 11 is connected to the wall of the delivery pipeline 2 close to the gas suction assembly; and the hot end 12 is connected to the wall of the delivery pipeline 2 away from the gas suction assembly. Specifically, in the present embodiment, the thermocouple arm 13 adopts N-type semiconductor and P-type semiconductor connected together, that is, the P-N junction formed by the special semiconductor material forms a thermocouple pair, generates Peltier effect, and realizes refrigeration by direct current; it should be noted that when the current passes through the thermocouple arm 13, the Peltier effect will be generated, and the heat transfer will be generated between the two ends of the thermocouple arm 13, so as to generate the temperature difference to form the cold and hot ends. By connecting the cold end of the thermal management system 3 with the wall of the inlet end of the target area, and connecting the hot end with the wall of the outlet end of the target area, the temperature regulation of the wall can be realized, and the rarefied gas delivery pipeline with temperature driving effect can be obtained.

[0027] As shown in the drawings, Figure 3As shown, in one specific embodiment, the second embodiment of the thermal management system 3, the thermal management system 3 comprises: two heat pipes 113, one end of one of the heat pipes 113 is connected to the pipe wall near the inlet of the delivery pipe 2 of the air intake assembly, the other end of the heat pipe 113 extends to the sun-avoiding surface of the satellite (the end is the sun-avoiding cold end 111), one end of the other heat pipe 113 is connected to the pipe wall away from the outlet of the delivery pipe 2 of the air intake assembly, the other end of the heat pipe 113 extends to the sun-facing surface of the satellite (i.e. the end is the sun-facing hot end 112); the sun-avoiding cold end provided by the embodiment continuously dissipates heat to the space through radiation, and maintains a low temperature. The sun-facing hot end 112 is continuously heated by absorbing solar radiation, and maintains a high temperature; the two groups of heat pipes 113 respectively connect the sun-avoiding cold end 111 and the inlet end wall surface of the delivery pipe 2, and connect the sun-facing hot end 112 and the outlet end wall surface of the delivery pipe 2, so that the temperature of the wall surface can be regulated, and the thin gas delivery pipe with temperature driving effect can be obtained; it should be noted that the heat pipe 113 uses the phase change process of the working medium to realize rapid heat transfer, and when working, the working medium absorbs heat and evaporates in the evaporation section, the steam is transported to the condensation section through the capillary structure, releases heat in the condensation section and returns to the liquid phase, so as to complete the cycle.

[0028] As an example, in one specific embodiment, by designing the air intake assembly, more gas can be captured by the air-breathing electric propulsion system, so the air intake assembly in the embodiment comprises: an air intake contraction section 1, the geometric profile of the air intake contraction section 1 is a conical profile, a rotating parabolic profile or a cylindrical-conical composite profile; specifically, in the embodiment, as shown in the figure, Figure 1 As shown, in one specific embodiment, the air intake contraction section 1 adopts a rotating parabolic profile, the cross section along the air intake direction of the air intake contraction section 1 is a hyperbolic parabolic cross section, and the concave surfaces of the two parabolas of the hyperbolic parabolic cross section are opposite.

[0029] In one specific embodiment, a gas inlet collimating grid is arranged in the inlet end of the air intake contraction section 1.

[0030] The second part of the application provides an embodiment of a design method of a wall surface temperature driven thin gas air intake regulation device, specifically, as shown in the figure, Figure 5 The design method comprises: Step 1, determining the design parameters to be optimized; Specifically, the design parameters to be optimized are determined, and the design parameters to be optimized are: the tube diameter of the intake contraction section, the wall adaptation coefficient and the wall temperature. It should be noted that the tube diameter of the intake contraction section affects the ballistic flight trajectory of the gas molecules, and directly determines the convergence and diffusion flow of the rarefied gas. The wall adaptation coefficient is determined by the wall conditions, and is mainly affected by the wall material and roughness. The wall adaptation coefficient tends to 0, which represents mirror reflection with no energy exchange, and the wall adaptation coefficient tends to 1, which represents diffuse reflection with sufficient energy exchange. The wall adaptation coefficient and the wall temperature jointly affect the scattering behavior of gas molecules after colliding with the tube wall, and directly determine the thermal driving effect of the wall. Therefore, the gas collection effect of the intake device is mainly affected by the above three design parameters. For example, Figure 6 As shown, in a specific embodiment, the pipe diameter, wall adaptation coefficient, and wall temperature at each position on the suction contraction section are obtained to obtain the pipe diameter distribution of the entire suction contraction section. , wall adaptation coefficient distribution and wall temperature distribution ,in, It is the position coordinate of the suction contraction section along the axial direction.

[0031] Step 2: Construct multiple sets of design parameters and calculate the gas collection rate and compression ratio under each set of design parameters; Specifically, in the parameter design space, a parameter sampling method (such as Latin hypercube sampling, orthogonal design sampling, and uniform design sampling) is adopted. In this embodiment, Latin hypercube sampling is adopted to construct multiple sets of design parameters. A rarefied gas dynamics simulation method (such as DSMC) is used to simulate the temperature field and flow field distribution in the intake contraction section under each set of design parameters, and the gas collection rate and compression ratio of the intake control device under each set of design parameters are calculated.

[0032] Step 3: Optimize parameters and obtain the optimal design result of the suction control device With maximizing the gas collection rate and compression ratio of the air intake control device as the optimization goal, a multi-parameter optimization algorithm is used to iteratively update the optimized design parameters. The set of design parameters corresponding to the maximum convergence of the gas collection rate and compression ratio of the air intake control device is determined as the optimal design parameters. The air intake control device is designed based on the optimal design parameters. It should be noted that the multi-parameter optimization algorithm includes a genetic algorithm, a linear programming algorithm, and a multivariate quadratic programming algorithm. In this embodiment, the genetic algorithm is used for parameter optimization.

[0033] The third part of the present invention provides an embodiment of an electric propulsion system, which includes a wall temperature-driven rarefied gas intake control device provided in the first part of the present invention, and the outlet of the delivery pipe 2 of the intake control device is connected to the working fluid inlet of the Hall electric thruster.

[0034] The fourth part of the present application provides a satellite comprising the third part of the present application.

[0035] The present application is further described below in combination with Figures 7 to 12 and specific simulation data: This embodiment takes a total length of 1m of the air intake device as the object, wherein the air intake contraction section has an inlet radius of 250mm, a throat radius of 50mm, and a generatrix of a circular arc with a radius of 810mm. The air intake device is connected with a horizontal straight section conveying pipeline. Two devices are compared: (1) a conventional non-thermal driven air intake regulation device with a wall temperature of 350K; and (2) a thermal driven air intake regulation device with the wall surface of the straight section conveying pipeline 2 linearly heated from 100K to 600K.

[0036] In order to verify the effect of the thin gas air intake regulation device driven by the wall surface temperature proposed in this paper, an axisymmetric two-dimensional simulation is carried out in the direct Monte Carlo simulation (DSMC) to simulate the flow field of the air intake at an orbital height of 180km. The incident gas components in the simulation include nitrogen atoms, oxygen atoms, nitrogen molecules and oxygen molecules, the incident velocity is 7796m / s, and the incident temperature is 618K. The variable soft sphere collision model is used between the particles, the CLL collision model is used between the particles and the solid wall, and the tangential and normal energy accommodation coefficients are both set to 0.8.

[0037] The pressure distribution cloud chart of the non-thermal driven air intake regulation device obtained by simulation is shown in Figure 7 , the density distribution cloud chart of the non-thermal driven air intake regulation device is shown in Figure 9 , the comparison chart of the pressure and the density on the central axis of the non-thermal driven air intake regulation device is shown in Figure 11 , the pressure distribution cloud chart of the thermal driven air intake regulation device is shown in Figure 8 , the density distribution cloud chart of the thermal driven air intake regulation device is shown in Figure 10 , and the comparison chart of the pressure and the density on the central axis of the thermal driven air intake regulation device is shown in Figure 12 From the above charts, it can be seen that after the straight section conveying pipeline 2 is provided with the wall surface temperature driving effect, the peak values of the pressure and the density in the air intake regulation device are both obviously improved, and the increase is about 50%. In addition, the key index parameters of the non-thermal driven air intake regulation device and the thermal driven air intake regulation device, i.e. the gas collection rate and the compression ratio, are calculated and compared as shown in Table 1. From Table 1, it can be seen that after the straight section conveying pipeline 2 is provided with the wall surface temperature driving effect, the gas collection rate of the air intake device is increased from 26.6% to 30.0%, and the compression ratio is increased from 372 to 552.

[0038] Table 1

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rarefied gas intake control device driven by wall temperature, characterized in that: include: an air suction component, the outlet of which is connected to a delivery pipeline; A heat management system is provided for forming a temperature difference on the wall of the delivery pipe, wherein the wall temperature of the delivery pipe close to the air induction assembly is lower than the wall temperature of the delivery pipe away from the air induction assembly.

2. A wall temperature driven rarefied gas intake control device according to claim 1, characterized in that: The thermal management system adopts an electric cooling structure, which includes: A thermocouple arm, one end of which is a cold end and the other end of which is a hot end, and both the cold end and the hot end face the wall of the conveying pipeline; and a power supply for powering the thermocouple arms; The cold end is connected to the pipe wall of the delivery pipe close to the air inhalation component; the hot end is connected to the pipe wall of the delivery pipe away from the air inhalation component.

3. The wall temperature driven rarefied gas intake control device according to claim 2, characterized in that: The thermocouple arms use an N-type semiconductor and a P-type semiconductor connected together.

4. The wall temperature driven rarefied gas intake control device according to claim 1, characterized in that: The thermal management system includes: two heat pipes, one end of which is connected to the pipe wall of the delivery pipe close to the air intake component, and the other end of the heat pipe extends to the satellite's non-sunny side; one end of the other heat pipe is connected to the pipe wall of the delivery pipe away from the air intake component, and the other end of the heat pipe extends to the satellite's sun-facing side.

5. The wall temperature driven rarefied gas intake control device according to claim 1, characterized in that: The air intake component comprises an air intake contraction section, wherein the geometrical surface of the air intake contraction section is a cone, a rotational parabola or a composite of a cylinder and a cone.

6. The wall temperature driven rarefied gas intake control device according to claim 5, characterized in that: An air intake collimating grid is provided in the inlet end of the air intake contraction section.

7. The wall temperature driven rarefied gas intake control device according to claim 5, characterized in that: The cross section along the air inlet direction of the suction contraction section is a hyperbolic parabolic cross section, and the concave surfaces of the two parabolas of the hyperbolic parabolic cross section are opposite to each other.

8. A design method for a rarefied gas intake control device driven by wall temperature, characterized in that: include: Determine the design parameters to be optimized, which are: pipe diameter distribution, wall adaptation coefficient and wall temperature of the suction contraction section; Constructing multiple sets of design parameters, using a rarefied gas dynamics simulation method, simulating the temperature field and flow field distribution in the intake contraction section under each set of design parameters, and calculating the gas collection rate and compression ratio of the intake control device according to any one of claims 1 to 7 under each set of design parameters; Taking maximizing the gas collection rate and compression ratio of the intake control device as the optimization goal, a multi-parameter optimization algorithm is adopted to iteratively update the optimization design parameters. The set of design parameters corresponding to the gas collection rate and compression ratio of the intake control device converge to the maximum value is taken as the optimal design parameters, and the intake control device is designed based on the optimal design parameters.

9. An electric propulsion system, characterized in that: It comprises a Hall electric thruster and a wall temperature-driven rarefied gas intake control device as described in any one of claims 1 to 7, and the outlet of the delivery pipeline of the intake control device is connected to the working medium inlet of the Hall electric thruster.

10. A satellite, characterized in that: Including the electric propulsion system as claimed in claim 9.

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