A slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse

Abstract

The present application relates to an aerodynamic drag reduction structure for a slender satellite based on the reuse of the wake of an electric thruster, which is applied to a slender satellite body, and includes a fluid that fully or partially wraps the outer surface of the side wall of the slender satellite body, the fluid is in a flow state extending along the length direction of the slender satellite body, and the fluid flows from the upstream end of the slender satellite body to the downstream end of the slender satellite body, and the fluid is used to collide with the incoming flow molecules in the atmosphere and return the incoming flow molecules after the collision to the atmosphere. The present application covers the side wall of the slender satellite body with a layer of fluid, so that the incoming flow molecules that would originally collide with the side wall of the satellite body collide with the fluid in advance, and the incoming flow molecules after the collision are reflected back to the atmosphere, thereby reducing the number of molecules that hit the side wall surface per unit time, and has the effect of reducing the aerodynamic drag of the side wall surface.

Description

Technical Field

[0001] The present application relates to the field of drag reduction technology for slender satellites, and in particular to an aerodynamic drag reduction structure for slender satellites based on the reuse of electric thruster wake. Background Art

[0002] Ultra-low orbit space refers to the space with an altitude between 100km and 300km. Since the beginning of the 21st century, humans have begun to gradually explore and utilize ultra-low orbit space in depth. However, as the flight altitude decreases, the atmospheric density increases at an exponential rate, and the aerodynamic drag of the satellite increases significantly. Below 200km, due to the orbit reduction caused by aerodynamic drag, a satellite flying without power will fall into the atmosphere in just a few days to a few weeks. In order to achieve the long-term residence of satellites in ultra-low orbit airspace, in addition to the need to use high specific impulse thrust systems (such as Hall thrusters, ion thrusters, etc.), it is also necessary to find ways to reduce the aerodynamic drag of satellites.

[0003] Research shows that for the free molecular flow field where the satellite orbit is located, under the premise of ensuring that the satellite volume remains unchanged, the slender body shape usually has lower aerodynamic drag than the flat body shape. However, as the aspect ratio increases, the windward surface area of ​​the satellite decreases and the side wall area increases, resulting in an increase in the proportion of the side wall aerodynamic drag in the total aerodynamic drag, which reduces the drag reduction effect of the satellite. Summary of the invention

[0004] In order to reduce the aerodynamic drag of the satellite side wall, the present application provides a slender satellite aerodynamic drag reduction structure based on the reuse of electric thruster wake.

[0005] The present application provides a slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse, which adopts the following technical solutions:

[0006] A slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse is applied to a slender satellite body, including a fluid that fully or partially wraps around the outer surface of the side wall of the slender satellite body, the fluid is in a flow state extending along the length direction of the slender satellite body, and the fluid flows from the upstream end of the slender satellite body to the downstream end of the slender satellite body, and the fluid is used to collide with incoming flow molecules in the atmosphere and return the incoming flow molecules after the collision to the atmosphere.

[0007] By adopting the above technical solution, a layer of fluid is covered on the side wall of the slender satellite body, so that the incoming flow molecules that would originally collide with the side wall of the satellite body collide with the fluid in advance, and the incoming flow molecules after the collision are reflected back to the atmosphere, thereby reducing the number of molecules hitting the side wall per unit time, thereby reducing the aerodynamic resistance of the side wall. The fluid is coated on the side wall of the slender satellite body in a flowing state, and the flow direction of the fluid is consistent with the moving direction of the slender satellite body. Therefore, adding the fluid will not have a significant impact on the aerodynamic resistance of the end face of the slender satellite body.

[0008] Preferably, it further comprises a jet component, which is used to spray out the fluid, and the jet component is arranged at one end close to the flow-facing end of the slender satellite body.

[0009] By adopting the above technical solution, the jet component is used to generate a sprayed fluid to achieve the wrapping and covering of the side wall of the slender satellite body by the fluid in a flowing state. The jet component is arranged at one end close to the flow-facing end of the slender satellite body. The sprayed fluid flows toward the departing end of the slender satellite body during flight so as to fully wrap the slender satellite body.

[0010] Preferably, the jet component is an electric thruster, which is arranged at the flow-incoming end of the slender satellite body, and the end face shape of the electric thruster is consistent with the end face shape of the flow-incoming end of the slender satellite body.

[0011] By adopting the above technical solution, the electric thruster is moved from the away end to the oncoming end, and the wake ejected by the electric thruster is used as the fluid covering the side wall surface of the slender satellite body. There is no need to install other components on the slender satellite body, so no additional burden is generated on the flight of the slender satellite body, and the utilization rate of the electric thruster wake is improved, which saves more energy.

[0012] Preferably, the ratio of the thickness of the electric thruster to the diameter of the flow-facing end of the slender satellite body is 1 / 10 to 1 / 15.

[0013] By adopting the above technical solution, in order to minimize the influence of the electric thruster on the aerodynamic drag of the flow-facing end of the slender satellite body, the thickness of the electric thruster should be set as small as possible under allowable circumstances to reduce the aerodynamic drag of the entire slender satellite body.

[0014] Preferably, it also includes an interference member for interfering with the flow body, and the interference member is used to make the flow body gradually move away from the side wall of the slender satellite body as it flows from the upstream end to the downstream end.

[0015] By adopting the above technical solution, the interference element can effectively control and adjust the flow state of the fluid, so that the fluid forms a trumpet shape, ensuring that the fluid does not have additional collisions with the side wall surface of the slender satellite body.

[0016] Preferably, the interference member comprises an electromagnetic field generating coil for generating electromagnetic interference with the fluid, and the interference member is arranged inside the slender satellite body and along the length direction of the slender satellite body.

[0017] By adopting the above technical solution, the charged characteristics of the electric thruster wake are utilized, and an electromagnetic field generating coil is set inside the slender satellite body to generate electromagnetic interference with the fluid to control the flow state of the fluid.

[0018] Preferably, the electromagnetic field generating coil comprises an insulator and a wire wound along the insulator, and there is a distance between a starting point of the wire and an end face of the electric thruster.

[0019] By adopting the above technical solution, since there is a certain distance between the starting point of the wire and the electric thruster, the fluid can be free from electromagnetic interference within this distance and can be ejected parallel to the surface of the slender satellite body, avoiding the range of the fluid being too large, causing the density of the fluid to decrease, and resulting in a decrease in the interception rate of incoming molecules in space.

[0020] Preferably, the aspect ratio of the elongated satellite body is greater than 3.

[0021] By adopting the above technical solution, the aerodynamic resistance of the end surface of the main body of the slender satellite is reduced by increasing the aspect ratio of the slender satellite.

[0022] In summary, the present application includes at least one of the following beneficial technical effects:

[0023] 1. The present application wraps a layer of fluid on the outer wall of the slender satellite body, so that the incoming flow molecules that would have collided with the side wall of the satellite body collide with the fluid in advance, and the incoming flow molecules after the collision are reflected back to the atmosphere, thereby reducing the number of molecules that hit the side wall per unit time, thereby reducing the aerodynamic resistance of the side wall;

[0024] 2. The present application moves the electric thruster from the backstream end to the frontstream end and utilizes the wake of the electric thruster as the fluid covering the side wall of the slender satellite body. There is no need to install other components on the slender satellite body, so no additional burden is generated on the flight of the slender satellite body, and the utilization rate of the wake of the electric thruster is improved, which saves more energy. 3. By arranging an electromagnetic field generating coil inside the slender satellite body and utilizing the charged characteristics of the wake of the electric thruster, the flow state of the fluid is rectified, so that the fluid forms a trumpet shape, ensuring that the fluid does not have additional collisions with the side wall of the slender satellite body. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The invention relates to the external structure of the main body of a slender satellite to which the aerodynamic drag reduction structure of the slender satellite based on the electric thruster wake reuse of the present invention is applied.

[0026] Figure 2 It is a schematic diagram of the collision between the aerodynamic drag reduction structure of the slender satellite based on the electric thruster wake reuse and the incoming flow molecules in the present application.

[0027] Explanation of the reference numerals: 1. Slender satellite body; 2. Jet element; 3. Fluid body; 4. Electric thruster; 5. Interference element; 51. Electromagnetic field generating coil; 511. Insulator; 512. Wire. DETAILED DESCRIPTION

[0028] The following is combined with Figure 1-2 This application is described in further detail.

[0029] The embodiment of the present application discloses an aerodynamic drag reduction structure of a slender satellite based on the reuse of electric thruster wake, which is applied to a slender satellite body 1. Figure 1-Figure 2The aerodynamic drag reduction structure of a slender satellite based on the reuse of the wake of an electric thruster includes a fluid 3 that is fully or partially wrapped around the outer surface of the side wall of the slender satellite body 1. The fluid 3 causes the incoming flow molecules that would have collided with the side wall of the satellite body to collide with the fluid 3 in advance, and the incoming flow molecules after the collision are reflected back to the atmosphere, thereby reducing the number of molecules that hit the side wall per unit time, thereby reducing the aerodynamic drag of the side wall. The fluid 3 can be coated on the side wall of the slender satellite body 1 in advance by various means, or it can be generated during the flight of the slender satellite body 1 and coated on the side wall of the slender satellite body 1. In the present application, the aerodynamic drag reduction structure of the slender satellite based on the reuse of the electric thruster wake also includes a jet component 2 for ejecting a fluid 3, and the jet component 2 is arranged at one end close to the upstream end of the slender satellite body 1. As the slender satellite body 1 flies, the fluid 3 ejected by the jet component 2 is in a flow state extending along the length direction of the slender satellite body 1, and the fluid 3 flows from the upstream end of the slender satellite body 1 to the downstream end of the slender satellite body 1, thereby reducing the influence of the fluid 3 on the aerodynamic resistance of the end face of the slender satellite body 1.

[0030] Preferably, the jet element 2 of the present application is configured as an electric thruster 4. The electric thruster 4 is arranged at the flow-incoming end of the slender satellite body 1, so that the wake of the electric thruster 4 is used as a jet wrapped around the side wall of the slender satellite body 1. No additional components need to be installed on the slender satellite body 1, so that no additional burden is imposed on the flight of the slender satellite body 1, and the utilization rate of the wake of the electric thruster 4 is improved, which saves more energy. In order to ensure that the fluid 3 is fully covered on the side wall of the slender satellite body 1, the end face shape of the electric thruster 4 is consistent with the end face shape of the flow-incoming end of the slender satellite body 1.

[0031] In order to minimize the effect of the electric thruster 4 on the aerodynamic drag of the flow-facing end of the slender satellite body 1, the thickness of the electric thruster 4 should be set as small as possible under allowable conditions to reduce the aerodynamic drag of the entire slender satellite body 1. In the present application, the ratio of the thickness of the electric thruster 4 to the diameter of the flow-facing end of the slender satellite body 1 is 1 / 10 to 1 / 15.

[0032] In order to reduce the aerodynamic drag on the end surface of the slender satellite body 1 , the aspect ratio of the slender satellite body 1 of the present application is 5-6.

[0033] The aerodynamic drag reduction structure of the slender satellite based on the reuse of the wake of the electric thruster also includes an interference member 5 for interfering with the fluid 3. The interference member 5 is used to make the fluid 3 gradually move away from the side wall of the slender satellite body 1 as it flows from the upstream end to the downstream end, so that the flow state of the fluid 3 can be effectively controlled and adjusted, so that the fluid 3 forms a trumpet shape, ensuring that the fluid 3 does not collide with the side wall surface of the slender satellite body 1. In one embodiment, the interference member 5 includes an electromagnetic field generating coil 51 arranged inside the slender satellite body 1 for generating electromagnetic interference with the fluid 3. And the interference member 5 is arranged along the length direction of the slender satellite body 1. Utilizing the charged characteristics of the wake of the electric thruster 4, the electromagnetic field generating coil 51 inside the slender satellite body 1 generates electromagnetic interference with the fluid 3 to control the flow state of the fluid 3.

[0034] The electromagnetic field generating coil 51 includes an insulator 511 and a wire 512 wound along the insulator 511. There is a distance between the starting point of the wire 512 and the electric thruster 4, so that the fluid 3 can be free from electromagnetic interference within this distance and can be ejected parallel to the surface of the slender satellite body 1, avoiding the range of the fluid 3 being too large, causing the density of the fluid 3 to decrease, resulting in a decrease in the interception rate of incoming flow molecules in space.

[0035] The following calculation is performed to verify the drag reduction effect of this scheme.

[0036] Assume that the probability of collision between incoming molecules when they pass through the jet is P collision According to the spatial symmetry, the probability of the incoming molecules continuing to move toward the wall and moving away from the wall after the collision is 1 / 2 respectively. Therefore, the side wall resistance can be reduced to the original 1-0.5P collision .P collision It can be obtained by the kinetic theory of gases. The average thermal motion speed of the incoming flow molecules is:

[0037] Where k is the Boltzmann constant, T is the incoming flow velocity, and m is the incoming flow molecular mass.

[0038] Therefore, the time required to traverse a jet of thickness d is: The collision rate of incoming molecules in the jet is (taking the hard sphere model as an example)

[0039] n is the jet density, σ T , T ref is the collision cross section between the incoming flow molecules and the jet flow molecules, m r is the collision-reduced mass of the incoming flow molecules and the jet molecules, T ref is the reference temperature.

[0040] Finally, P collision=vt

[0041] It can be seen that as the jet density increases, P collision The larger the value, the more obvious the drag reduction effect.

[0042] Finally, the calculation results of a specific working condition are given:

[0043] (1) The molar molecular mass of air is 28.8 g / mol, so the average molecular mass is 4.78e-26 kg. If the atmospheric temperature is 600 K, then v s =721m / s.

[0044] (2) Assuming the thickness of the annular jet is 1 cm, then t = 1.39e-5s.

[0045] (3) Assume the jet component is Ar and the jet density is 1e20m 3 Then the collision rate between air molecules and Ar molecules is 0.334e5s -1 .

[0046] (4) Finally, we can get P collision =0.464, that is, the resistance is reduced to 76.8% of the original.

[0047] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse, characterized in that: The invention is applied to a slender satellite body (1), comprising a fluid body (3) which is completely or partially wrapped around the outer surface of the side wall of the slender satellite body (1), wherein the fluid body (3) is in a flow state extending along the length direction of the slender satellite body (1), and the fluid body (3) flows from the upstream end of the slender satellite body (1) to the downstream end of the slender satellite body (1), and the fluid body (3) is used to collide with incoming flow molecules in the atmosphere and return the incoming flow molecules after the collision to the atmosphere; The slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse also includes an interference member (5) for interfering with the flow body (3), and the interference member (5) is used to make the flow body (3) gradually move away from the side wall of the slender satellite body (1) as it flows from the upstream end to the downstream end.

2. The slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse according to claim 1 is characterized in that: It also comprises a jet component (2), the jet component (2) being used to spray out the fluid (3), and the jet component (2) being arranged at one end close to the flow-facing end of the slender satellite body (1).

3. The slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse according to claim 2 is characterized in that: The jet component (2) is an electric thruster (4), which is arranged at the flow-incoming end of the slender satellite body (1), and the end face shape of the electric thruster (4) is consistent with the end face shape of the flow-incoming end of the slender satellite body (1).

4. The slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse according to claim 3 is characterized in that: The ratio of the thickness of the electric thruster (4) to the diameter of the flow-incoming end of the slender satellite body (1) is 1 / 10 to 1 / 15.

5. The slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse according to claim 1 is characterized in that: The interference member (5) comprises an electromagnetic field generating coil (51) for generating electromagnetic interference with the fluid (3); the interference member (5) is arranged inside the slender satellite body (1) and along the length direction of the slender satellite body (1).

6. The slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse according to claim 5 is characterized in that: The electromagnetic field generating coil (51) comprises an insulator (511) and a wire (512) wound along the insulator (511), and there is a distance between a starting point of the wire (512) and an end face of the electric thruster (4).

7. The slender satellite aerodynamic drag reduction structure based on electric thruster wake reuse according to any one of claims 1 to 6, characterized in that: The length-to-diameter ratio of the elongated satellite body (1) is greater than 3.

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