Active cooling heat shield system and vehicle including same

Abstract

An active cooling heat shield system includes a heat shield, a tank, a pump, a heat exchanger, and a turbine. The heat shield defines a windward side of the vehicle. The tank stores a coolant. The pump receives coolant from the tank and outputs pressurized coolant. The heat exchanger is integrally connected with 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 heating fluid output from the heat exchanger. A shaft is coupled to the pump and includes turbine blades. The shaft rotates and powers the pump when the heating fluid received from the heat exchanger acts on the turbine blades. The outlet outputs the heating fluid.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 942,886, filed on December 3, 2019, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] The present disclosure generally relates to cooling systems for vehicles that are subject to high levels of heating. The present disclosure more particularly relates to actively cooled heat shield systems for use in rockets and other vehicles that travel at or above hypersonic speeds, such as space reentry vehicles, aircraft, and missiles. Background Art

[0003] Aircraft-like reusability for rockets has long been the "holy grail" of rocket technology due to the potential for tremendous cost benefits. The ability to recover and reuse the upper stages of a multi-stage rocket system (e.g., the second stage of a two-stage rocket system) remains a significant technology gap that the industry has yet to address. Reusing the upper stages of a multi-stage rocket is challenging due to the harsh reentry environment and the performance penalties associated with the increased structural mass required for robust reuse. Upper stages are typically built with minimal structure and complexity because any mass increase in the second stage is a 1:1 reduction in payload capacity. Therefore, reusing an upper stage requires a significant amount of additional functionality with minimal added mass.

[0004] Rockets and other vehicles traveling at or above hypersonic speeds (e.g., space reentry vehicles, aircraft, missiles, etc.) require a device to protect themselves from the heating that occurs at such high speeds. Conventional solutions for mitigating such heating include the use of one or more of the following: (i) ablative materials that undergo pyrolysis and generate gases that move downstream in the boundary layer to form a protective film layer; (ii) high temperature materials (e.g., ceramics, carbon-carbon, etc.); (iii) composite materials that insulate and radiate heat away from a base material; and (iv) evaporative cooling, which involves the use of a thin protective film provided by a gas passing through a semi-porous wall.

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

[0006] Aspects of the present invention address these and other issues. Summary of the invention

[0007] According to aspects of the present invention, an active cooling 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 is mounted on the vehicle and is configured to store coolant. The pump is mounted on the vehicle and is configured to receive coolant from the tank and output pressurized coolant. The heat exchanger is mounted on the vehicle and is integrally connected to the heat shield. The heat exchanger is configured to receive pressurized coolant from the pump, transfer heat from the heat shield to the pressurized coolant to generate a heating fluid and output the heating fluid. The turbine is mounted on the vehicle and includes an inlet, a shaft, and an outlet. The inlet is configured to receive the heating fluid output from the heat exchanger. The shaft is coupled to the pump and includes turbine blades mounted on the shaft. The shaft is configured to rotate when the heating fluid received from the heat exchanger acts on the turbine blades and thereby energizes the pump. The outlet is configured to output the heating fluid.

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

[0009] According to another aspect of the invention, a reusable upper stage of a multi-stage rocket system includes an actively cooled heat 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 windward side of an upper stage rocket of a multi-stage rocket system during atmospheric re-entry includes the following steps: starting a drive of a pump carried on the upper stage rocket to start the output of pressurized coolant from the pump; causing the pressurized coolant output by the pump to flow through a heat exchanger, which is integrally connected to a heat shield that defines at least a portion 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 to a turbine carried on the upper stage rocket, the turbine including a shaft connected to the pump and turbine blades mounted to the shaft; and exposing the turbine blades to the heating fluid to drive the shaft and thereby continue to drive the pump.

[0011] In addition to or as an alternative to one or more of the features described above, further aspects of the present invention may include one or more of the following features, alone or in combination: - at least the heat exchanger, the turbine and the pump are configured such that: once operation of the pump has begun, the amount of energy supplied to the turbine from the heat exchanger alone is sufficient to continue operation of the pump; - the heat shield system is configured so that: once operation begins, the amount of energy transferred by the heat exchanger to the coolant is at least sufficient to maintain operation; - the heat shield, tank, pump, heat exchanger, and turbine are configured so that the amount of energy transferred by the heat exchanger to the coolant is at least sufficient to maintain operation of the heat shield system; - the heat shield, the tank, the pump, the heat exchanger and the turbine are configured so that the amount of energy transferred by the heat exchanger to the coolant is at least sufficient to supply the turbine with an amount of power required to drive the pump; - the coolant is at least one of an active coolant, a liquid coolant and a low-temperature coolant; - the heating fluid is at least one of a gas and a supercritical fluid; - the heat shield system further comprises a main heating fluid conduit configured to transfer the heating fluid from the heat exchanger to an inlet of the turbine and a bypass conduit configured to bypass excess energy in the heating fluid from at least a portion of the main heating fluid conduit for power use by the auxiliary system; - The pressure of the coolant in the tank alone provides enough energy to start spinning the turbine and pump, thereby creating increased pressure and increased power available to the turbine; - The heat exchanger and heat shield are configured so that coolant flow through the heat exchanger maintains an acceptable temperature at the heat shield upon vehicle reentry into a planetary atmosphere; - The heat shield is constructed to be exposed to high Mach number flow environments during normal operations; - The carrier is the upper stage of a multi-stage rocket system; - the upper stage rocket comprises a propulsion engine arranged at its rear end portion and the rear end portion defines the windward side of the upper stage rocket during operation of the heat shield system; - the heat shield system and the propulsion engine share a multi-purpose component, and the multi-purpose 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 also comprises an exhaust duct through which at least part of the heating fluid output from the turbine leaves the upper stage rocket; and - The transferring and inputting steps 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 will become apparent from the drawings and detailed description provided below. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a perspective view of a vehicle including the present heat shield system.

[0014] Figure 2 for Figure 1 Schematic cross-sectional view of the rear end portion of a vehicle showing components of the heat shield system. DETAILED DESCRIPTION

[0015] Reference Figure 1 and Figure 2 , the present disclosure describes an actively cooled heat shield system 10 and a vehicle 12 including the actively cooled heat shield system 10. The heat shield system 10 converts heat from a high Mach number flow environment 14 into energy for driving a liquid coolant pump 16 (see Figure 2 ).

[0016] Reference Figure 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 another vehicle designed to travel (e.g., fly) at up to at least supersonic speeds (e.g., supersonic speeds, hypersonic speeds, reentry speeds, etc.) in an atmospheric, suborbital, orbital, extraterrestrial and / or outer space environment.

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

[0018] Reference Figure 2During use, the second stage 12 moves through the environment 14 (e.g., atmosphere, space) at a freestream Mach number 18, which for a space reentry vehicle may approach thirty (30) Mach. A bow shock 20 forms upstream of the second stage 12, and the temperature of the vehicle side of the bow shock 20 may reach thousands of degrees Kelvin. The windward side 22 of the second stage 12 is exposed to these high temperatures, and therefore, cooling and / or other thermal protection is necessary for reusability.

[0019] The actively cooled heat shield system 10 includes a heat shield 34 , a tank 36 , a pump 16 , a heat exchanger 38 , and a turbine 40 .

[0020] The heat shield 34 defines the exterior surface of the windward side 22 of the second stage rocket 12 .

[0021] The tank 36 is carried on the second stage rocket 12 and stores coolant (eg, active coolant, liquid coolant, cryogenic coolant, etc.).

[0022] The pump 16 is carried on the second stage rocket 12 and receives coolant from the tank 36. The pump 16 outputs pressurized coolant (e.g., coolant having a pressure of hundreds of psi or more). That is, the pressure of the coolant is greater after the coolant passes through the pump 16 than when stored in the tank 36. The coolant is transferred from the tank 36 to the pump 16 via a coolant conduit 42 (e.g., a pipe, a tubing, etc.).

[0023] The heat exchanger 38 is carried 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 (e.g., gas, 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 (e.g., a pipe, a tubular object, etc.).

[0024] The turbine 40 is carried on the second stage rocket 12 and includes an inlet 46, a shaft 48, and an outlet 50. The inlet 46 receives a heating fluid that is output from the heat exchanger 38 via a main heating fluid conduit 52 (e.g., a pipe, a tube, etc.). In some embodiments, there will be excess energy in the heating fluid, which will bypass around the turbine 40 via a bypass conduit 54 (e.g., a pipe, a tube, etc.) and be used to pressurize or power an auxiliary system 56 (e.g., a tank, a gas thruster, an evaporative cooling system, an auxiliary power unit (APU), etc.). The shaft 48 of the turbine 40 is coupled (e.g., directly coupled, indirectly coupled via a coupling, etc.) to the pump 16 and includes turbine blades (not shown) mounted on the shaft 48. When the heating fluid received from the heat exchanger 38 acts on the turbine blades (not shown), the shaft 48 rotates and thereby powers the pump 16. The outlet 50 of the turbine 40 outputs the heating fluid. In some embodiments, the second stage rocket 12 includes an exhaust conduit 58 through which the heating fluid exits the second stage rocket 12 (e.g., for providing thrust). In addition or alternatively, the heating fluid output from the outlet 50 of the turbine 40 can be used to pressurize or power auxiliary systems (e.g., tanks, gas thrusters, evaporative cooling systems, APUs, etc.). The heating fluid output from the outlet 50 of the turbine 40 will have a pressure and energy that is less than the pressure and energy of the heating fluid diverted through the bypass conduit 54 to the auxiliary systems 56. In some embodiments, the heat shield system 10 also 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 heat shield system 10, pressurized coolant enters the heat exchanger 38 (e.g., into a channel or other conduit formed in the heat shield 34) and picks up heat at a rate (i.e., heat flux) that is typical for hypersonic and reentry vehicles and may be, for example, in the range of 0.01-10 BTU / in. 2 -s. The heat exchanger 38 serves the dual purpose of cooling the windward side 22 of the second stage rocket 12 and adding energy to the coolant, which is used to drive the turbine 40 and then power the pump 16. The pressure of the coolant decreases, while the overall enthalpy increases along the heat exchanger 38 until the coolant leaves the heat exchanger 38 as a heating fluid. The main flow of the heating fluid enters the turbine 40, where energy is extracted. The heating fluid leaving the turbine 40 is discharged from the second stage rocket 12 into the external environment 14 or used for another purpose (e.g., re-refrigerated 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 alone provides sufficient energy to begin spinning the turbine 40 and the pump 16, thereby creating increased pressure and increased power available to the turbine 40. In other embodiments, the pressure of the coolant in the tank 36 does not provide sufficient energy to begin spinning the turbine 40 and the pump 16. In some such embodiments, the heat shield system 10 also includes an external starting source, such as a motor connected to the turbine shaft 48 or high pressure gas directed to the turbine 40.

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

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

[0029] Once operation of the heat shield system 10 begins, the thermal energy added to the coolant is sufficient to maintain operation. Specifically, the energy added to the coolant is sufficient to supply the turbine 40 with the power required to drive the pump 16 after accounting for all losses in the system 10, including inefficiencies of the pump 16 and turbine 40, pressure losses in the heat exchanger 38, and other losses from friction and other mechanisms.

[0030] As the second stage 12 traverses a severe thermal environment (e.g., as the second stage 12 reenters the atmosphere), coolant flowing through the heat exchanger 38 integrated into the windward side 22 of the second stage 12 is sufficient to maintain acceptable temperatures on the heat shield 34 and other walls of the second stage 12. Thus, the heat shield system 10 enables the second stage 12 to execute a base-first re-entry trajectory. This provides several key advantages over other proposed nose-first or body-first (known as belly flop) strategies: (i) it eliminates the need for challenging intra-atmospheric redirection maneuvers required for nose-first or body-first (known as belly flop) reentry vehicles with vertical landing envelopes; (ii) it maintains the primary load paths in the axial direction during all phases of flight, allowing for more efficient structural solutions; (iii) the common vertical orientation during ascent and reentry simplifies cryogenic fluid management challenges by minimizing sloshing and associated boil-off; and (iv) it minimizes the heat shield surface area while also maintaining a low ballistic coefficient, thereby minimizing the overall heat loads managed by the vehicle during reentry.

[0031] Although several embodiments have been disclosed, it will be apparent to those of ordinary skill in the art that aspects of the present invention include many more embodiments. Therefore, aspects of the present invention are not limited except in accordance with the appended claims and their equivalents. It will also be apparent to those of ordinary skill in the art that variations and modifications may be made without departing from the true scope of the present disclosure. For example, in some cases, one or more features disclosed in conjunction with one embodiment may be used alone or in combination with one or more features of one or more other embodiments.

Claims

1. A vehicle, comprising: Front end; a rear end portion opposite to the front end portion; a heat shield at the rear end portion and defining a windward side of the vehicle during travel of the vehicle in an atmospheric reentry trajectory; a tank configured to store a coolant; a pump configured to receive coolant from the tank and output pressurized coolant; a heat exchanger 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; as well as A turbine is configured to receive the heating fluid output from the heat exchanger, extract energy from the heating fluid, and power the pump using the energy extracted from the heating fluid.

2. The carrier according to claim 1, characterized in that: The vehicle is an upper-stage rocket of a multi-stage rocket system.

3. The carrier according to claim 1, characterized in that: The heat exchanger and the heat shield are configured such that coolant flow through the heat exchanger maintains an acceptable temperature on the heat shield during travel of the vehicle in the atmospheric re-entry trajectory.

4. The carrier according to claim 1, characterized in that: At least the heat exchanger, the turbine and the pump are configured such that, once operation of the pump has begun, the amount of energy extracted from the heating fluid by the turbine alone is sufficient to continue operation of the pump.

5. The carrier according to claim 1, characterized in that: wherein the heat shield, the tank, the pump, the heat exchanger, and the turbine are components of a heat shield system; and The heat shield system is configured such that once operation begins, the amount of energy transferred from the heat exchanger to the coolant is at least sufficient to maintain operation.

6. The carrier according to claim 1, characterized in that: The heat shield, the tank, the pump, the heat exchanger, and the turbine are components of a heat shield system; and Wherein the heat shield, the tank, the pump, the heat exchanger, and the turbine are configured such that an amount of energy transferred from the heat exchanger to the coolant is at least sufficient to maintain operation of the heat shield system.

7. The carrier according to claim 1, characterized in that: The heat shield, the tank, the pump, the heat exchanger, and the turbine are configured such that an amount of energy transferred to the coolant by the heat exchanger is at least sufficient to supply the turbine with an amount of power required to drive the pump.

8. The carrier according to claim 1, characterized in that: The pressure of the coolant in the tank alone provides enough energy to begin spinning the turbine and the pump, thereby creating increased pressure and increased power available to the turbine.

9. The carrier according to claim 1, characterized in that: The turbine includes a shaft coupled to the pump and turbine blades mounted on the shaft; and Wherein, when the heating fluid received from the heat exchanger acts on the turbine blades, the shaft is configured to rotate and thereby power the pump.

10. The carrier according to claim 9, characterized in that: The turbine comprises an outlet configured to output the heating fluid.

11. The vehicle of claim 10, further comprising an exhaust conduit through which at least a portion of the heating fluid output from the turbine exits the vehicle.

12. The vehicle of claim 1 further comprising a propulsion engine at a rear end of the vehicle.

13. The carrier according to claim 12, characterized in that: The heat shield is a heat shield of the propulsion engine.

14. The carrier according to claim 12, characterized in that: The tank is a fuel tank.

15. The carrier according to claim 12, characterized in that: The pump is a fuel pump of the propulsion engine.

16. The carrier according to claim 12, characterized in that: The heat exchanger is a heat exchanger of the propulsion engine.

17. The carrier according to claim 12, characterized in that: The turbine is the turbine of the propulsion engine.

18. The carrier according to claim 1, further comprising: a main heating fluid conduit configured to transfer the heating fluid from the heat exchanger to an inlet of the turbine; as well as A bypass conduit is configured to bypass excess energy in the heating fluid from at least a portion of the main heating fluid conduit for use in power for use by auxiliary systems onboard the vehicle.

19. The carrier according to claim 18, characterized in that: The auxiliary system is a tank.

20. The carrier according to claim 18, characterized in that The auxiliary system is a gas thruster.

21. The carrier according to claim 18, characterized in that The auxiliary system is an evaporative cooling system.

22. The carrier according to claim 18, characterized in that The auxiliary system is an auxiliary power unit.

23. The carrier according to claim 1, characterized in that The coolant is an active coolant.

24. The carrier according to claim 1, characterized in that The coolant is a liquid coolant.

25. The carrier according to claim 1, characterized in that The coolant is a low temperature coolant.

26. The carrier according to claim 1, characterized in that The heating fluid is gas.

27. The carrier according to claim 1, characterized in that The heating fluid is a supercritical fluid.

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