Active cooling type thermal shield system and vehicle including the same

Abstract

The actively cooled heat shield system includes a heat shield, a tank, a pump, a heat exchanger, and a turbine. The heat shield defines the windward side of the vehicle. The tank stores a coolant. The pump receives the coolant from the tank and outputs the pressurized coolant. The heat exchanger is integrally connected to the heat shield. The heat exchanger receives the pressurized coolant from the pump, transfers heat from the heat shield to the pressurized coolant to generate a heated fluid, and outputs the heated fluid. The turbine includes an inlet, a shaft, and an outlet. The inlet receives the heated fluid output from the heat exchanger. The shaft is coupled to the pump and includes turbine blades. The shaft rotates when the heated fluid received from the heat exchanger acts on the turbine blades, providing power to the pump. The outlet outputs the heated fluid.

Description

Cross - Reference to Related Applications

[0001] This application claims priority based on U.S. Provisional Patent Application No. 62 / 942,886, filed on December 3, 2019, the content of which is hereby incorporated by reference in its entirety.

Technical Field

[0002] The present disclosure generally relates to cooling systems for vehicles that are subjected to high - level heating. More specifically, the present disclosure relates to an actively - cooled thermal shield system for use in rockets and other vehicles that move at hypersonic speeds or above, such as re - entry vehicles, aircraft, and missiles.

Background Art

[0003] The reusability of aircraft, etc. for rockets has long been the "holy grail" of rocket research due to the potential for huge cost - benefits. The ability to recover and reuse the upper - stage rocket of a multi - stage rocket system (e.g., the second - stage rocket of a two - stage rocket system) remains a significant technological gap that has not yet been solved by the industry. Reusing the upper stage of a multi - stage rocket is difficult due to the harsh re - entry environment and the performance penalty associated with the increased structural mass required for robust reuse. Upper - stage rockets are typically constructed with minimal structure and complexity because adding mass to the second stage results in a 1:1 decrease in payload capacity. Therefore, reusing the upper - stage rocket requires not only significant additional functionality but also minimal mass loading.

[0004] Rockets and other vehicles that move at hypersonic speeds or above (e.g., space reentry vehicles, aircraft, missiles, etc.) require means to protect themselves from the heating that occurs at such high speeds. Conventional solutions for reducing such heating include one or more of the following uses. (i) Ablative materials, which undergo pyrolysis and produce gases that move downstream to form a protective film layer in the boundary layer. (ii) High-temperature materials (e.g., ceramics, carbon-carbon, etc.). (iii) Composite materials, which insulate the base material and radiate heat away from it. (iv) Transpiration cooling, which involves the use of a thin protective film provided by a gas passing through a semi-porous wall. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] Existing thermal management solutions have cost, operational, and / or mass impacts that may not be conveniently compatible in certain applications such as reusable vehicles. For example, ablative materials and brittle ceramics are not compatible with highly reusable systems. Transpiration cooling of thermal shields is costly and difficult to control. What is needed is a cooling system that is very robust, highly controllable, and well-suited for long-term reusability.

[0006] Aspects of the present invention are directed to these and other problems. MEANS FOR SOLVING THE PROBLEM

[0007] According to one aspect of the present invention, an active cooling type thermal shield system includes a thermal shield, a tank, a pump, a heat exchanger, and a turbine. The thermal shield defines the upwind side of the vehicle. The tank is mounted on the vehicle and configured to store a coolant. The pump is mounted on the vehicle and configured to receive the coolant from the tank and output a pressurized coolant. The heat exchanger is mounted on the vehicle and integrally connected to the thermal shield. The heat exchanger is configured to receive the pressurized coolant from the pump, transfer heat from the thermal shield to the pressurized coolant to generate a heated fluid, and output the heated fluid. The turbine is mounted on the vehicle and includes an inlet, a shaft, and an outlet. The inlet is configured to receive the output of the heated fluid from the heat exchanger. The shaft is coupled to the pump and includes turbine blades mounted thereon. The shaft is configured to rotate when the heated fluid received from the heat exchanger acts on the turbine blades, thereby supplying power to the pump. The outlet is configured to output the heated fluid.

[0008] According to another aspect of the present invention, a vehicle includes an active cooling type thermal shield system. The thermal shield system includes a thermal shield, a tank, a pump, a heat exchanger, and a turbine. The thermal shield defines the upwind side of the vehicle. The tank is mounted on the vehicle and configured to store a coolant. The pump is mounted on the vehicle and configured to receive the coolant from the tank and output a pressurized coolant. The heat exchanger is mounted on the vehicle and integrally connected to the thermal shield. The heat exchanger is configured to receive the pressurized coolant from the pump, transfer heat from the thermal shield to the pressurized coolant to generate a heated fluid, and output the heated fluid. The turbine is mounted on the vehicle and includes an inlet, a shaft, and an outlet. The inlet is configured to receive the output of the heated fluid from the heat exchanger. The shaft is coupled to the pump and includes turbine blades mounted thereon. The shaft is configured to rotate when the heated fluid received from the heat exchanger acts on the turbine blades, thereby supplying power to the pump. The outlet is configured to output the heated fluid.

[0009] According to another aspect of the present invention, a reusable upper stage rocket of a multistage rocket system includes an active cooling type thermal shield system that converts heat from a high Mach number flow environment into energy for driving a liquid coolant pump.

[0010] According to another aspect of the present invention, a method for actively cooling the upwind side of an upper stage rocket of a multistage rocket system during atmospheric reentry includes starting the drive of a pump mounted on the upper stage rocket to start the output of pressurized coolant from the pump, flowing the pressurized coolant output by the pump through a heat exchanger integrally connected to a thermal shield that defines at least a part of the upwind side of the upper stage rocket, transferring heat from the thermal shield to the pressurized coolant to generate a heated fluid, inputting the heated fluid into a turbine mounted on the upper stage rocket, the turbine including a shaft coupled to the pump and turbine blades attached to the shaft, and exposing the turbine blades to the heated fluid to drive the shaft, thereby continuing the drive of the pump.

[0011] In addition to one or more of the above features, or as an alternative thereto, further aspects of the present invention can include one or more of the following features, individually or in combination. · At least the heat exchanger, turbine, and pump are configured such that when the operation of the pump is started, the amount of energy supplied from the heat exchanger to the turbine is sufficient to continue the operation of the pump alone. · The thermal shield system is configured such that when the operation is started, the amount of energy transferred to the coolant by the heat exchanger is at least sufficient to sustain the operation. · The thermal shield, tank, pump, heat exchanger, and turbine are configured such that the amount of energy transferred to the coolant by the heat exchanger is at least sufficient to sustain the operation of the thermal shield system. · The heat shield, tank, pump, heat exchanger, and turbine are configured such that the amount of energy transferred to the coolant by the heat exchanger is at least sufficient to supply the power required to drive the pump to the turbine. · The coolant is at least one of an active coolant, a liquid coolant, and a cryogenic coolant. · The heating fluid is at least one of a gas and a supercritical fluid. · The heat shield system further includes a primary heating fluid conduit configured to transfer the heating fluid from the heat exchanger to the inlet of the turbine, and a bypass conduit configured to bypass excess energy in the heating fluid for power use by an auxiliary system from at least a portion of the primary heating fluid conduit. · The pressure of the coolant in the tank provides sufficient energy to start the rotation of the turbine and the pump alone, resulting in an increase in the pressure and power available to the turbine. · The heat exchanger and the heat shield are configured such that the flow of the coolant through the heat exchanger maintains an acceptable temperature on the heat shield while the vehicle re-enters the planetary atmosphere. · The heat shield is configured to be exposed to a high Mach number flow environment during normal operation. · The vehicle is the upper stage rocket of a multistage rocket system. · The upper stage rocket includes a propulsion engine disposed at its rear end, and the rear end defines the upwind side of the upper stage rocket during operation of the heat shield system. · The heat shield system and the propulsion engine share a multipurpose component, and the multipurpose component is at least one of the heat shield, the tank, the pump, the heat exchanger, and the turbine. · The pump of the heat shield system is the fuel pump of the propulsion engine. · The vehicle further includes an exhaust duct, and at least a portion of the heating fluid output from the turbine exits the upper stage rocket through the exhaust duct. The steps of transferring and inputting of the method supply the turbine with an amount of energy sufficient to continue driving the pump alone.

[0012] These and other aspects of the invention should become apparent in light of the drawings and detailed description provided below.

Brief Description of the Drawings

[0013]

Figure 1

[0014]

Figure 2

Best Mode for Carrying Out the Invention

[0015] Referring to FIGS. 1 and 2, the present disclosure describes an actively cooled thermal shield system 10 and a vehicle 12 including the same. The thermal shield system 10 converts heat from a high Mach number flow environment 14 into energy to drive a liquid coolant pump 16 (see FIG. 2).

[0016] Referring to FIG. 1, the vehicle 12 is a rocket (e.g., a multi-stage rocket, a single-stage-to-orbit (SSTO) rocket, an upper stage rocket, a booster rocket, etc.), a missile, a spacecraft, an aircraft, or other vehicle designed for movement (e.g., flight) at least supersonic (e.g., supersonic, hypersonic, reentry speed, etc.) in an atmospheric, suborbital, orbital, extraterrestrial, and / or interplanetary space environment.

[0017] In the illustrated embodiment, vehicle 12 is the second stage rocket of a two-stage rocket system (not shown). Vehicle 12 (hereinafter, "second stage rocket 12") extends along centerline 24 between a front end 26 and an opposite rear end 28. Second stage rocket 12 includes a payload 30 that faces front end 26 and an engine 32 that faces rear end 28. Rear end 28 defines the upwind side 22 of second stage rocket 12. In the illustrated embodiment, engine 32 is an enhanced aerospike nozzle engine as disclosed in U.S. Provisional Patent Application No. 62 / 941,383 by the same inventor filed on November 27, 2019, and in an international patent application claiming priority to U.S. Provisional Patent Application No. 62 / 941,383, the content of which is hereby incorporated by reference in its entirety. In other embodiments, engine 32 is a bell nozzle engine or another type of rocket engine, or the vehicle may not include an engine at all.

[0018] Referring to FIG. 2, in use, second stage rocket 12 moves through environment 14 (e.g., atmosphere, space) at a free stream Mach number 18 that can reach Mach 30 for a space reentry vehicle. A bow shock 20 is formed upstream of second stage rocket 12, and the temperature on the vehicle side of bow shock 20 can reach thousands of Kelvin. The upwind side 22 of second stage rocket 12 is exposed to such high temperatures and thus requires cooling and / or other thermal protection for reuse.

[0019] The active cooling type thermal shield system 10 includes a thermal shield 34, a tank 36, a pump 16, a heat exchanger 38, and a turbine 40.

[0020] Thermal shield 34 defines the outer surface of the upwind side 22 of second stage rocket 12.

[0021] Tank 36 is mounted on second stage rocket 12 and stores a coolant (e.g., active coolant, liquid coolant, cryogenic coolant, etc.).

[0022] The pump 16 is mounted on the second-stage rocket 12 and receives the coolant from the tank 36. The pump 16 outputs pressurized coolant (for example, coolant having a pressure of several hundred psi or more). That is, the pressure of the coolant after passing through the pump 16 is greater than when the coolant is stored in the tank 36. The coolant is transferred from the tank 36 to the pump 16 via a coolant conduit 42 (for example, a duct, a tube, etc.).

[0023] The heat exchanger 38 is mounted on the second-stage rocket 12 and is integrally connected to the heat shield 34. The heat exchanger 38 receives the pressurized coolant from the pump 16, transfers heat from the heat shield 34 to the pressurized coolant to generate a heated fluid (for example, a gas, a supercritical fluid, etc.), and outputs the heated fluid. The pressurized coolant is transferred from the pump 16 to the heat exchanger 38 via a pressurized coolant conduit 44 (for example, a duct, a tube, etc.).

[0024] The turbine 40 is mounted on the second-stage rocket 12 and includes an inlet 46, a shaft 48, and an outlet 50. The inlet 46 receives the heated fluid output from the heat exchanger 38 via a primary heated fluid conduit 52 (e.g., a duct, a tube, etc.). In some embodiments, the heated fluid has excess energy, and this energy is bypassed around the turbine 40 via a bypass conduit 54 (e.g., a duct, a tube, etc.) and used to pressurize or supply power to an auxiliary system 56 (e.g., a tank, a gas thruster, an ablation cooling system, an auxiliary power unit (APU), etc.). The shaft 48 of the turbine 40 is coupled to the pump 16 (e.g., directly coupled, indirectly coupled via a coupler, etc.) and includes turbine blades (not shown) mounted thereon. When the heated fluid received from the heat exchanger 38 acts on the turbine blades (not shown), the shaft 48 rotates, thereby supplying power to the pump 16. The outlet 50 of the turbine 40 outputs the heated fluid. In some embodiments, the second-stage rocket 12 includes a discharge conduit 58, and the heated fluid exits the second-stage rocket 12 through the discharge conduit 58 (e.g., to provide thrust). Additionally or alternatively, the heated fluid output from the outlet 50 of the turbine 40 can be used to pressurize or supply power to an auxiliary system (e.g., a tank, a gas thruster, an ablation cooling system, an APU, etc.). The heated fluid output from the outlet 50 of the turbine 40 will have a lower pressure and energy than the pressure and energy of the heated fluid bypassed through the bypass conduit 54 to the auxiliary system 56. In some embodiments, the thermal shield system 10 further includes bearings, gears, and / or seals (not shown) that facilitate the coupling of the turbine 40 and the pump 16 via the shaft 48.

[0025] During operation of the thermal shield system 10, the pressurized coolant enters the heat exchanger 38 (e.g., channels or other conduits formed within the thermal shield 34) at a rate (i.e., heat flux) characteristic of a hypersonic reentry vehicle, e.g., 0.01 - 10 BTU / in 2Capture heat 60 at a rate that may be within the range of ·s. The heat exchanger 38 serves a dual purpose of cooling the upwind side 22 of the second stage rocket 12 and adding energy to the coolant used to drive the turbine 40 and then supply power to the pump 16. Until the coolant exits the heat exchanger 38 as the heated fluid, the pressure of the coolant decreases while the total enthalpy increases along the heat exchanger 38. The primary flow of the heated fluid enters the turbine 40 where energy is extracted. The heated fluid exiting the turbine 40 is discharged from the second stage rocket 12 to the external environment 14 or used for another purpose (e.g., re-cooled by an onboard system and returned through the heat exchanger 38 in a closed loop cycle).

[0026] In some embodiments, the pressure of the coolant in the tank 36 provides sufficient energy to independently initiate the rotation of the turbine 40 and the pump 16, resulting in an increase in the pressure and power available to the turbine 40. In other embodiments, the pressure of the coolant in the tank 36 does not provide sufficient energy to initiate the rotation of the turbine 40 and the pump 16. In some such embodiments, the thermal shield system 10 further includes an external starter source such as a motor connected to the turbine shaft 48 or a high-pressure gas directed at the turbine 40.

[0027] In some embodiments, at least one component (e.g., the tank 36, the pump 16, the turbine 40, etc.) is an existing component of the engine 32. For example, in some embodiments, the engine 32 includes at least a pump and a turbine that push the coolant through the engine's heat exchanger. In such embodiments, the fuel pump and turbine of the engine 32 serve a dual purpose by functioning as the pump 16 and turbine 40 of the thermal shield system 10, respectively, and the heat exchanger of the engine 32 forms at least a part of the heat exchanger 38 of the thermal shield system 10.

[0028] In some embodiments, the thermal shield system 10 further includes at least one component that is passively cooled (e.g., using high temperature materials, etc.) additionally or alternatively.

[0029] When the operation of the thermal shield system 10 is initiated, the thermal energy added to the coolant is sufficient to sustain the operation. Specifically, the energy added to the coolant is sufficient to supply the power required to drive the pump 16 to the turbine 40, taking into account all losses of the system 10, including the inefficiencies of the pump 16 and the turbine 40, the pressure losses in the heat exchanger 38, and other losses from friction and other mechanisms.

[0030] The coolant flowing through the heat exchanger 38 incorporated in the upwind side 22 of the second stage rocket 12 is sufficient to maintain acceptable temperatures on the thermal shield 34 and other walls of the second stage rocket 12 while the second stage rocket 12 passes through a severe thermal environment (e.g., while the second stage rocket 12 re-enters the atmosphere). Thus, the thermal shield system 10 enables the second stage rocket 12 to execute a base-first re-entry trajectory. This provides several important advantages over other proposed nose-first or body-first (also known as belly flop) strategies. (i) It eliminates the need to challenge the in-atmosphere reorientation maneuvers required for nose-first re-entry vehicles or body-first (also known as belly flop) re-entry vehicles with a vertical landing profile. (ii) It maintains the primary load path axially throughout all stages of flight, enabling more efficient structural solutions. (iii) The general vertical orientation during ascent and re-entry simplifies the cryogenic fluid management challenges by minimizing slosh and related boil-off. (iv) It minimizes the overall heat load managed by the vehicle during re-entry by minimizing the thermal shield surface area while maintaining a low ballistic coefficient.

[0031] Although several embodiments have been disclosed, it should be apparent to those skilled in the art that aspects of the invention include many more embodiments. Accordingly, aspects of the invention should not be limited, except when considering the appended claims and their equivalents. It should also be apparent to those skilled in the art that changes and modifications can be made without departing from the true scope of the disclosure. For example, in some cases, one or more features disclosed in connection with one embodiment can be used alone or in combination with one or more features of one or more other embodiments.

Claims

**Claim 1**: A vehicle comprising a front end, a rear end opposite the front end, a propulsion engine disposed at the rear end, and an active cooling type heat shield system configured to operate while moving in an atmospheric reentry trajectory, wherein the active cooling type heat shield system includes a heat shield at the rear end that defines the upwind side of the vehicle during movement of the vehicle in an atmospheric reentry trajectory, a tank mounted on the vehicle and configured to store a coolant, a pump mounted on the vehicle and configured to receive the coolant from the tank and output a pressurized coolant, a heat exchanger mounted on the vehicle and integrally connected to the heat shield, the heat exchanger receiving the pressurized coolant from the pump, transferring heat from the heat shield to the pressurized coolant to generate a heated fluid, and outputting the heated fluid, and a turbine mounted on the vehicle, wherein the turbine includes an inlet configured to receive the output of the heated fluid from the heat exchanger, a shaft coupled to and having turbine blades mounted thereon to the pump, the shaft configured to rotate when the heated fluid received from the heat exchanger acts on the turbine blades, thereby supplying power to the pump, and an outlet configured to output the heated fluid. **Claim 2**: The vehicle according to claim 1, wherein the heat shield system is configured such that, when operation is started, the amount of energy transferred to the coolant by the heat exchanger is at least sufficient to sustain the operation. **Claim 3**: The vehicle according to claim 1, wherein the heat shield, the tank, the pump, the heat exchanger, and the turbine are configured such that the amount of energy transferred to the coolant by the heat exchanger is at least sufficient to sustain the operation of the heat shield system. **Claim 4**: The vehicle according to claim 1, wherein the heat shield, the tank, the pump, the heat exchanger, and the turbine are configured such that the amount of energy transferred to the coolant by the heat exchanger is at least sufficient to supply the amount of power required to drive the pump to the turbine. **Claim 5**: The vehicle according to claim 1, wherein the coolant is at least one of an active coolant, a liquid coolant, and an ultra-low temperature coolant. **Claim 6**: The vehicle according to claim 1, wherein the heating fluid is at least one of a gas and a supercritical fluid. **Claim 7**: The active cooling type thermal shield system A primary heating fluid conduit configured to transfer the heating fluid from the heat exchanger to the inlet of the turbine; The vehicle according to claim 1, further comprising a bypass conduit configured to bypass excess energy in the heating fluid for power use by an auxiliary system from at least a portion of the primary heating fluid conduit. **Claim 8**: The vehicle according to claim 1, wherein the pressure of the coolant in the tank provides sufficient energy to independently start the rotation of the turbine and the pump, resulting in an increase in the pressure and power available to the turbine. **Claim 9**: The vehicle according to claim 1, wherein the heat exchanger and the thermal shield are configured such that the flow of the coolant through the heat exchanger maintains an acceptable temperature on the thermal shield while the vehicle is moving in an atmospheric reentry orbit. **Claim 10** At least the heat exchanger, the turbine, and the pump are configured such that when the operation of the pump is started, the amount of energy supplied from the heat exchanger to the turbine is sufficient to independently continue the operation of the pump. **Claim 11** **Claim 10**: The vehicle according to claim 1, wherein the thermal shield is configured to be exposed to a high Mach number flow environment during normal operation. **Claim 12** **Claim 12**: The vehicle according to claim 1, wherein the vehicle is the upper stage rocket of a multi-stage rocket system. **Claim 13** The thermal shield system and the propulsion engine share multi-purpose components, **Claim 15**: The vehicle according to claim 1, wherein the multi-purpose component is at least one of the thermal shield, the tank, the pump, the heat exchanger, and the turbine. **Claim 14** **Claim 17**: The vehicle according to claim 13, wherein the pump of the thermal shield system is the fuel pump of the propulsion engine. **Claim 15** **Claim 19**: The vehicle according to claim 12, further comprising an exhaust conduit, and at least a portion of the heating fluid output from the turbine exits the upper stage rocket through the exhaust conduit. **Claim 16** A method for actively cooling the windward side of the upper stage rocket of a multistage rocket system during atmospheric reentry, starting the drive of a pump mounted on the upper stage rocket and starting the output of pressurized coolant from the pump; flowing the pressurized coolant output by the pump through a heat exchanger integrally connected to a heat shield that defines at least a part of the windward side of the upper stage rocket; transferring heat from the heat shield to the pressurized coolant to generate a heating fluid; inputting the heating fluid into a turbine mounted on the upper stage rocket, the turbine including a shaft coupled to the pump and turbine blades attached to the shaft; exposing the turbine blades to the heating fluid to drive the shaft, thereby continuing the drive of the pump.

17. The method according to claim 19, wherein the steps of transferring and inputting supply the turbine with an amount of energy sufficient alone to continue driving the pump.

18. The vehicle according to claim 7, wherein the auxiliary system is a tank.

19. The vehicle according to claim 7, wherein the auxiliary system is a gas thruster.

20. The vehicle according to claim 7, wherein the auxiliary system is an evaporative cooling system.

21. The vehicle according to claim 7, wherein the auxiliary system is an auxiliary power unit (APU).

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