A drag-reducing and heat-reducing device combining a large base partition with a liftable central structure.

Abstract

This invention relates to a drag-reducing and heat-cooling device combining a partitioned base with a liftable central structure. The device includes a central base structure, a peripheral base structure, a drive mechanism, and a cold air flow control system. The central base structure comprises an arc-shaped surface and a lifting rod. The arc-shaped surface is located at the center of the peripheral base structure surface. When the lifting rod is compressed, the arc-shaped surface remains flush with the peripheral base structure, forming an integrated heat shield. The cold air flow control system includes a gas pipeline, a cold air storage cylinder, and an ejector device. Cold air is uniformly injected from the ejector device through the gas pipeline and the lifting rod onto the surface of the central base structure, forming a gas film. The drive mechanism is located inside the reentry capsule and drives the lifting rod to extend or retract into the reentry capsule, thereby raising or lowering the arc-shaped surface of the central base structure. This invention effectively reduces the impact of heat flow while reducing aerodynamic load, improving the safety and reliability of reentry.

Description

Technical Field

[0001] This invention belongs to the field of reentry vehicle design technology and relates to a drag reduction and heat reduction device that combines a large bottom partition with a liftable central structure. Background Technology

[0002] During their return to Earth, manned spacecraft reentry capsules and other reentry vehicles must traverse the atmosphere and experience extreme aerodynamic and thermal environments. To reduce the heat flux density upon atmospheric reentry, reentry capsules typically employ a blunt-nosed design, meaning a larger radius of curvature at the nose of the capsule to create a strong bow shock wave, thereby reducing the heat flux density directly acting on the spacecraft surface. However, while the blunt-nosed design offers advantages in heat protection, it also presents a series of aerodynamic and thermal challenges.

[0003] First, during reentry, the blunt-nosed shape of the reentry capsule is subjected to tremendous aerodynamic forces, leading to increased G-forces. Because the reentry capsule's frontal surface is relatively blunt, its entry into the atmosphere at hypersonic speeds generates a strong shock wave and produces intense aerodynamic effects. Especially for manned space missions, excessive G-forces not only affect the structural safety of the spacecraft but can also place extreme stress on the astronauts' bodies, impacting their physiological comfort and operational capabilities. During reentry, astronauts may experience accelerations exceeding 4-5 times gravity, or even higher levels of G-force, which can significantly impact their cardiovascular, nervous, and musculoskeletal systems, reducing their ability to perform missions.

[0004] Secondly, to address the potential for aerodynamic heating caused by high-speed airflow, which could lead to ablation of spacecraft surface materials, structural damage, and even compromise the reentry capsule's airtightness and astronaut safety, the reentry capsule typically requires highly efficient heat protection measures. Traditionally, the bottom of the reentry capsule is covered entirely with high-strength heat-resistant materials to withstand the intense heat. For example, the Apollo spacecraft reentry capsule used ablation-resistant thermal insulation materials, which sublimate or peel off under high temperatures, carrying away a significant amount of heat. However, such comprehensive, high-intensity thermal protection measures significantly increase the spacecraft's mass, impacting fuel consumption, mission economy, and payload capacity.

[0005] To address these challenges, an optimized design approach is needed that can reduce aerodynamic load (drag reduction) and effectively minimize the effects of aerodynamic heating (heat reduction). This aims to ensure astronaut safety and comfort while reducing the overall mass of the spacecraft and improving reentry efficiency and reliability. Currently, scientists and engineers have proposed various improvement schemes for drag reduction and heat reduction design of high-speed spacecraft, such as reverse jet (Huang & Liu, 2015), drag-reducing rods (Gerdroodbary, Imani & Ganji, 2014), and cold gas mass ejection (Sun, Guo & Huang, 2016). The core idea of ​​these methods is to reduce nose pressure and optimize flow field distribution by disrupting the bow shock wave structure. While each of these methods has its advantages, a single method often cannot simultaneously meet multiple key requirements, such as drag reduction, heat reduction, stability, and structural feasibility. For example, reverse jets require additional propellant or high-pressure gas sources, increasing the spacecraft's energy consumption and deteriorating under high Mach number conditions; drag-reducing rods are susceptible to thermal stress and aerodynamic vibrations, which may lead to damage or deformation; mass ejections may cause boundary layer separation, increasing the difficulty of control.

[0006] In summary, any single method for reducing drag and heat in high-speed aircraft has insurmountable drawbacks and is difficult to fully meet the drag reduction and heat reduction requirements of large reentry spacecraft. Summary of the Invention

[0007] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a drag-reducing and heat-reducing device that combines a large bottom partition with a liftable central structure, which can effectively reduce the impact of heat flow while reducing aerodynamic load, thereby improving the safety and reliability of reentry and return.

[0008] The solution to the technical problem of this invention is: a drag-reducing and heat-reducing device that combines a large bottom partition with a liftable central structure, including a large bottom central structure, a large bottom peripheral structure, a drive mechanism and a cold air flow control system;

[0009] The outer bottom center structure includes an arc-shaped surface and a lifting rod perpendicularly connected to the center of the arc-shaped surface. The arc-shaped surface is located at the center of the outer bottom peripheral structure. When the lifting rod is in a compressed state and extends into the return capsule, the arc-shaped surface of the outer bottom center structure remains flush with the outer bottom peripheral structure, forming an integral heat shield.

[0010] The cold air flow control system includes a gas pipeline, a cold air storage cylinder, and an ejector device. The cold air storage cylinder is located inside the return capsule and is connected to the lifting rod through the gas pipeline. The ejector device is set on the arc-shaped surface of the bottom center structure. The cold air in the cold air storage cylinder is evenly sprayed from the ejector device to the surface of the bottom center structure through the gas pipeline and the lifting rod to form a gas film.

[0011] The drive mechanism is located inside the return capsule and is connected to the lifting rod. It drives the lifting rod to extend or retract the return capsule, thereby raising or lowering the arc-shaped surface of the bottom center structure.

[0012] Furthermore, the material of the arc-shaped surface is a carbon / carbon composite material, a nickel-based superalloy, or a graphene / ceramic composite material.

[0013] Furthermore, the arc-shaped surface forms a microporous structure inside the material through chemical vapor deposition to ensure that the cold gas is drawn out from the inside of the material.

[0014] Furthermore, the lifting rod has a hollow structure with an outer heat-insulating shell and an inner cold air transmission pipeline. The lifting rod is made of titanium alloy, nickel-based high-temperature alloy, or carbon / carbon composite material.

[0015] Furthermore, the surface of the lifting rod is coated with a nanoporous aerogel.

[0016] Furthermore, the material of the outer perimeter structure is a ceramic matrix composite, a carbon / phenolic composite, or a carbon fiber reinforced polymer.

[0017] Furthermore, the cold gas stored in the cold gas storage cylinder is supercritical carbon dioxide.

[0018] Furthermore, the ejector device employs an adjustable injection valve with an annular gap designed on its surface.

[0019] Furthermore, the drive mechanism includes a motor, a gear transmission mechanism, a lead screw / linkage mechanism, and a locking device. The output shaft of the motor is connected to the gear transmission mechanism, the gear transmission mechanism is connected to the lead screw / linkage mechanism, the lead screw / linkage mechanism drives the lifting rod, and a locking device is provided.

[0020] The gear transmission mechanism is used to transmit the rotational motion of the motor to the lead screw / linkage mechanism. The lead screw / linkage mechanism is used to convert the rotational motion of the gear transmission mechanism into linear motion, so that the lifting rod pushes up or retracts the center structure of the outsole. The locking device is used to prevent the center structure of the outsole from shifting when it is not in operation.

[0021] Furthermore, the motor is selected as a servo motor or a stepper motor, and adopts a dual redundancy configuration; the gear transmission mechanism realizes the lifting and lowering of the large base center structure through a planetary gear set or a worm gear, and the material of the planetary gear set is a nickel-based alloy;

[0022] The lead screw of the lead screw / linkage mechanism is a ball screw, and the linkage mechanism is made of titanium alloy or ceramic matrix composite material; the locking device is a mechanical ratchet or electromagnetic locking mechanism.

[0023] The advantages of this invention compared to the prior art are:

[0024] (1) The heat-resistant base of the present invention adopts a liftable central structure. When the aircraft enters the atmosphere at an extremely high speed close to the first cosmic velocity, the central part of the heat-resistant base can be lifted by the driving device to destroy the bow shock wave structure, reduce the intensity of the bow shock wave, and greatly reduce aerodynamic drag. At the same time, the shock wave is pushed away from the base, reducing the thermal environment of the area around the base, and has obvious drag reduction and heat reduction effect.

[0025] (2) The present invention adopts a heat protection design with partitions. Compared with the conventional configuration, the heat load borne by the protruding central structure of the base remains almost unchanged during high-speed flight. The mass ejection system can assist the central structure in heat protection. The heat flow in the area around the base is significantly reduced, and a lighter heat protection structure can be selected to further reduce the weight of the aircraft.

[0026] (3) This invention effectively reduces the impact of heat flow while reducing aerodynamic load, improves the safety and reliability of reentry and return, and has outstanding advantages such as flexible control, light weight, and good drag reduction and heat reduction effect. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the shape of a traditional recoverable spacecraft. In the ballistic return mode, the spacecraft's heat shield is facing the high-speed incoming flow.

[0028] Figure 2 This is a schematic diagram of a drag-reducing and heat-reducing device that combines a large-area zoned heat protection system with a liftable central structure. At this time, the large-area central structure is in a lifted state controlled by the drive mechanism and connected to the cold air flow control system for auxiliary heat protection.

[0029] Figure 3 This is a simplified flowchart of the working process of the drag reduction and heat reduction device of the present invention;

[0030] Figure 4 A three-dimensional diagram showing the front and back of the center mechanism of the outsole being raised.

[0031] Figure 5 This is a typical flow diagram of a traditional spacecraft. The high-speed incoming flow is compressed in front of the heat shield, forming an arc-shaped shock wave that is close to the shield. The gas pressure and temperature rise rapidly after the shock wave.

[0032] Figure 6 This is a typical flow diagram when the central mechanism of the base is lifted and no cold gas mass is ejected. The bow-shaped shock wave is pushed away from the spacecraft by the central mechanism, and the aerodynamic and thermal forces on the surrounding structure of the base decrease significantly. Under particularly high flight speeds, a reattached shock wave may appear at the edge of the spacecraft's base, forming a local heat flow high point.

[0033] Figure 7This is a typical flow diagram when the base center structure is lifted and cold gas mass is ejected. At this time, the bow shock wave is further pushed away from the aircraft, the aerodynamic heating degree of the base center structure decreases, and the surrounding structure does not have local heat flow high points due to shock wave reattachment.

[0034] Figure 8 Comparison of simulation results of flow temperature field distribution before and after the lifting of the center structure of the large bottom;

[0035] Figure 9 A comparison of simulation results of heat flow distribution on the spacecraft body wall before and after the central structure of the base is lifted. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] Figure 1 This is a schematic diagram of a traditional recoverable spacecraft. In ballistic return mode, the spacecraft's heat shield base faces the high-speed incoming flow, making it impossible to simultaneously meet multiple critical requirements, such as drag reduction, heat dissipation, stability, and structural feasibility. Therefore, this invention proposes a drag reduction and heat dissipation device that combines a partitioned base with a liftable central structure, such as... Figure 2 As shown, it includes the center structure of the outsole, the peripheral structure of the outsole, the drive mechanism, and the cold air flow control system;

[0038] The outer bottom center structure includes an arc-shaped surface and a lifting rod that is perpendicularly connected to the center of the arc-shaped surface. The arc-shaped surface of the outer bottom center structure is located at the center of the surface of the outer bottom peripheral structure. When the lifting rod is in a compressed state and extends into the return capsule, the arc-shaped surface of the outer bottom center structure remains flush with the outer bottom peripheral structure, forming an integral heat shield.

[0039] The cold air flow control system includes a gas pipeline, a cold air storage cylinder, and an ejector device. The cold air storage cylinder is located inside the return capsule and is connected to the lifting rod through the gas pipeline. The ejector device is set on the arc-shaped surface of the bottom center structure. The cold air in the cold air storage cylinder is evenly sprayed from the ejector device to the surface of the bottom center structure through the gas pipeline and the lifting rod to form a gas film.

[0040] The drive mechanism is located inside the return capsule and is connected to the lifting rod. It drives the lifting rod to extend or retract the return capsule, thereby raising or lowering the arc-shaped surface of the bottom center structure.

[0041] The outer perimeter structure is made of lightweight, heat-resistant materials, preferably ceramic matrix composites (CMC), carbon / phenolic composites, or carbon fiber reinforced polymers, to reduce the total mass of the return capsule and is non-movable.

[0042] The curved surface of the outsole's central structure is made of a high-temperature resistant material, preferably a carbon / carbon composite material, a nickel-based high-temperature alloy, or a graphene / ceramic composite material, to accommodate higher heat flux densities. The curved surface of the outsole's central structure forms a microporous structure within the heat-resistant material through methods such as chemical vapor deposition, ensuring that cool air can be drawn outwards from within the heat-resistant material, reducing the temperature near the wall surface.

[0043] The lifting rod has a hollow structure with a heat-insulating outer shell and a cold gas transmission pipeline inside. During operation, gas from the cold gas storage cylinder is transported via the gas delivery pipeline and the cold gas transmission pipeline to the ejector device at the rear of the base's central structure. The lifting rod is made of titanium alloy, nickel-based high-temperature alloy, or carbon / carbon composite material to ensure sufficient rigidity and heat resistance under high-temperature aerodynamic environments. Furthermore, the surface of the lifting rod is treated with a high-temperature resistant nanoporous aerogel coating to reduce the impact of the external thermal environment on the internal cold gas flow.

[0044] The drive mechanism includes a motor, a gear transmission mechanism, a lead screw / linkage mechanism, and a locking device; the output shaft of the motor is connected to the gear transmission mechanism, the gear transmission mechanism is connected to the lead screw / linkage mechanism, the lead screw / linkage mechanism drives the lifting rod, and a locking device is provided.

[0045] The motor serves as the power source, employing either a high-torque servo motor or a stepper motor to ensure sufficient driving force and precise motion control under high-temperature and high-acceleration conditions. To enhance system reliability, the motors utilize a dual-redundancy configuration, meaning that in the event of a main motor failure, a backup motor can take over, ensuring the smooth extension or retraction of the central structure.

[0046] Gear transmission mechanisms are used to transmit the rotational motion of a motor to a lead screw / connecting rod mechanism, achieving the lifting and lowering of the large base center structure through planetary gear sets or worm gears. Planetary gear sets are characterized by their small size, large transmission ratio, and high efficiency, effectively improving the transmission stability of the drive mechanism. Simultaneously, to reduce frictional losses, the planetary gear sets are made of high-temperature resistant, high-strength alloys, preferably nickel-based alloys, and high-temperature resistant lubricants are added to the bearing parts to ensure long-term reliable operation of the system in high-temperature environments.

[0047] The lead screw / linkage mechanism converts the rotary motion of the gear transmission mechanism into linear motion, enabling the lifting rod to push up or retract the center structure of the base. The lead screw is a ball screw, which offers high transmission efficiency and low friction loss, maintaining good motion accuracy under high load conditions. The linkage mechanism uses high-strength titanium alloy or ceramic matrix composite materials, balancing lightweight design and heat resistance to ensure stable operation even in extreme environments.

[0048] The locking device uses a mechanical ratchet or electromagnetic locking mechanism to prevent displacement of the outsole center structure when it is not in operation.

[0049] The cold gas storage cylinder is located inside the reentry capsule and is connected to the gas supply pipeline to provide the gas required for cold gas ejection. The cold gas storage cylinder adopts a high-pressure storage system, storing supercritical carbon dioxide, which has a strong heat absorption capacity and can be uniformly injected in the supercritical state to form a stable cooling gas film, thereby improving cooling efficiency.

[0050] The ejector device is used to uniformly spray cold air onto the surface of the outsole's central structure. Its design incorporates an adjustable injection valve and annular gaps on the surface, allowing cold air to escape and form an air film, thus aiding in cooling. The ejector device can adjust the flow rate and direction of the cold air injection in real time according to different heat flux conditions during reentry, optimizing the cooling effect. The ejected cold air not only lowers the surface temperature of the central portion but also forms an air film insulation layer, reducing direct erosion from high-temperature gases and improving overall heat insulation performance.

[0051] Figure 3 The working process of a drag-reducing and heat-reducing device that combines a large-area zoned heat protection system with a liftable central structure.

[0052] Before re-entering the atmosphere, the return capsule maintains a conventional configuration, meaning the central structure of the bottom is flush with the surrounding structures, forming a unified heat shield to improve flight stability; the lift rod is in a compressed state, and the drive mechanism is in a ready state, such as... Figure 4 As shown in the left figure.

[0053] When the aircraft re-enters the atmosphere and generates a strong bow-shaped shock wave in front of its underbody, the motor-driven gear transmission mechanism rotates, which in turn drives the lead screw / linkage mechanism to extend the lifting rod outward, lifting the central structure of the underbody. Figure 4 As shown in the figure on the right.

[0054] After the center structure of the outsole is raised, the high-temperature and high-pressure zone of the bow-shaped shock wave is moved away from the outsole surface, reducing the direct heat flow and improving thermal protection. Compared with before the center structure of the outsole was raised, the pressure and heat flow on the surface of the center structure of the outsole did not change much, but the pressure and heat flow on the surface of the surrounding structure of the outsole were significantly reduced, thereby achieving the purpose of reducing overload and optimizing thermal protection. Figure 5 , 6 As shown.

[0055] At extremely high flight speeds, the dynamic pressure is significant, and the bow-shaped shock wave may rapidly interact with the boundary layer near the perimeter structure of the base structure behind the central structure, thus forming a reattached shock wave. The pressure and heat flux in the shock wave reattachment zone are significantly enhanced, which is detrimental to the aircraft's overload reduction and thermal protection. To further optimize the thermal drag reduction structure, a cold air flow control system is activated. Cold air is delivered to the surface of the central structure through air pipes within the hollow lifting rod and uniformly ejected from surface micropores or annular nozzles, forming a cold air film to assist in cooling. This cold air film reduces the surface temperature of the central part and further pushes the bow-shaped shock wave away, preventing shock wave reattachment and improving thermal protection efficiency. Figure 7 As shown.

[0056] After the high-speed reentry process is completed, the spacecraft jettisons its bottom plate. All mechanisms included in this invention detach from the spacecraft, and the aerodynamic performance and structural stability of the spacecraft are not affected during the low-altitude descent and landing phase.

[0057] Example 1

[0058] This embodiment simulates the aerodynamic performance optimization of the liftable base center structure. To illustrate a more general application scenario, a two-dimensional simulation is used. The spacecraft shape is simplified to a circle with a diameter of 0.6m, the diameter of the base center structure is 0.2m, the lifting height during operation is 0.1m, the spacecraft's flight Mach number Ma = 5, corresponding to a flight altitude of approximately 88km. Figure 8 The diagrams show streamlines and temperature distribution contours, with the upper part corresponding to the basic configuration (circle) and the lower part corresponding to the raised center structure configuration of the large base in this invention. The results show that, compared to the basic configuration, the raised center structure pushes the high-temperature region in the flow field away from the spacecraft, reducing the heat protection burden on the spacecraft body. Figure 9 The heat flux distribution on the spacecraft's main body wall is further presented, where the abscissa θ is the angle between the line connecting a point on the wall and the center of the circle and the negative x-axis. The results show that after the central structure is raised, the heat flux on the spacecraft's main body wall is significantly reduced, with the peak heat flux decreasing by 47.9% compared to the basic configuration.

[0059] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0060] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A drag-reducing and heat-reducing device combining a large base partition with a liftable central structure, characterized in that, This includes the outsole center structure, outsole perimeter structure, drive mechanism, and cold air flow control system; The outer bottom center structure includes an arc-shaped surface and a lifting rod perpendicularly connected to the center of the arc-shaped surface. The arc-shaped surface is located at the center of the outer bottom peripheral structure. When the lifting rod is in a compressed state and extends into the return capsule, the arc-shaped surface of the outer bottom center structure remains flush with the outer bottom peripheral structure, forming an integral heat shield. The cold air flow control system includes a gas pipeline, a cold air storage cylinder, and an ejector device. The cold air storage cylinder is located inside the return capsule and is connected to the lifting rod through the gas pipeline. The ejector device is set on the surface of the arc-shaped center structure of the bottom, away from the lifting rod. The cold air in the cold air storage cylinder is evenly sprayed from the ejector device to the surface of the center structure of the bottom through the gas pipeline and the lifting rod to form a gas film. The drive mechanism is located inside the return capsule and is connected to the lifting rod. It drives the lifting rod to extend or retract the return capsule, thereby raising or lowering the arc-shaped surface of the bottom center structure.

2. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 1, characterized in that, The material of the arc-shaped surface is a carbon / carbon composite material, a nickel-based superalloy, or a graphene / ceramic composite material.

3. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 1, characterized in that, The arc-shaped surface forms a microporous structure inside the material through chemical vapor deposition to ensure that cold gas is drawn out from the inside of the material.

4. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 1, characterized in that, The lifting rod has a hollow structure with a heat-insulating outer shell and a cold air transmission pipeline inside. The lifting rod is made of titanium alloy, nickel-based high-temperature alloy or carbon / carbon composite material.

5. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 1, characterized in that, The surface of the lifting rod is coated with a nanoporous aerogel.

6. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 1, characterized in that, The material of the outer outsole perimeter structure is a ceramic matrix composite, a carbon / phenolic composite, or a carbon fiber reinforced polymer.

7. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 1, characterized in that, The cold gas stored in the cold gas storage cylinder is supercritical carbon dioxide.

8. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 1, characterized in that, The ejector device uses an adjustable injection valve with an annular gap designed on its surface.

9. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 1, characterized in that, The drive mechanism includes a motor, a gear transmission mechanism, a lead screw linkage mechanism, and a locking device. The output shaft of the motor is connected to the gear transmission mechanism, the gear transmission mechanism is connected to the lead screw linkage mechanism, the lead screw linkage mechanism drives the lifting rod, and a locking device is provided. The gear transmission mechanism is used to transmit the rotational motion of the motor to the lead screw linkage mechanism. The lead screw linkage mechanism is used to convert the rotational motion of the gear transmission mechanism into linear motion, so that the lifting rod pushes up or retracts the center structure of the outsole. The locking device is used to prevent the center structure of the outsole from shifting when it is not in operation.

10. The drag-reducing and heat-reducing device combining a large base partition and a liftable central structure according to claim 9, characterized in that, The motor is either a servo motor or a stepper motor, and adopts a dual-redundant configuration; the gear transmission mechanism realizes the lifting and lowering of the large base center structure through a planetary gear set or a worm gear, and the planetary gear set is made of a nickel-based alloy. The lead screw of the lead screw linkage mechanism is a ball screw, and the linkage mechanism is made of titanium alloy or ceramic matrix composite material; the locking device is a mechanical ratchet or electromagnetic locking mechanism.

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