APPARATUS AND METHOD FOR ACCELERATING AN OBJECT VIA AN EXTERNAL FREE JET

• US 20200132403A1
• Filed: 10/23/2019
• Published: 04/30/2020
• Est. Priority Date: 10/24/2018
• Status: Active Grant

• Current Assignee: Wave Motion Launch Corporation
• Original Assignee: Finn Van Donkelaar
• Inventors: VAN DONKELAAR, Finn
• Granted Patent: US 10,928,146 B2
• Time in Patent Office: Days
• CPC Class Codes: F41A 1/04 Missile propulsion using the combustion of a liquid, loose powder or gaseous fuel, e.g. hypergolic fuel
• CPC Class Codes: F41B 11/60 characterised by the supply of compressed gas
• CPC Class Codes: F41B 11/70 Details not provided for in F41B11/50 or F41B11/60
• CPC Class Codes: F41B 11/80 specially adapted for particular purposes
• CPC Class Codes: F42B 14/064 Sabots enclosing the rear end of a kinetic energy projectile, i.e. having a closed disk shaped obturator base and petals extending forward from said base

Abstract

An apparatus includes an energy source and an expansion structure. The energy source is configured to convey an amount of energy operable to increase a pressure of a compressible gas disposed in a chamber. The expansion structure is configured to be placed in fluid communication with the chamber and to receive a flow of the compressible gas in response to the increase in pressure. The expansion structure includes an inlet having a first diameter and an outlet having a second diameter greater than the first diameter and is configured to allow the compressible gas to expand as the compressible gas flows from the inlet to the outlet such that a supersonic free jet of the compressible gas exits the outlet. In some instances, the supersonic free jet of the compressible gas can accelerate, relative to the expansion structure, a projectile disposed outside of the expansion structure.

Claims

1. An apparatus, comprising:

an energy source, the energy source configured to convey an amount of energy to a volume of a compressible gas disposed in a chamber and operable to increase a pressure associated with the volume of the compressible gas; and

an expansion structure configured to be placed in fluid communication with the chamber to receive a flow of the compressible gas in response to the increase in pressure, the expansion structure including an inlet having a first diameter and an outlet having a second diameter greater than the first diameter, the expansion structure allowing the compressible gas to expand as the compressible gas flows from the inlet to the outlet such that a supersonic free jet of the compressible gas exits the outlet,

the supersonic free jet of the compressible gas configured to accelerate a projectile disposed outside of the expansion structure.

2. The apparatus of claim 1, wherein the supersonic free jet is an underexpanded supersonic free jet.

3. The apparatus of claim 1, wherein the expansion structure is substantially stationary when the supersonic free jet exits the outlet, the supersonic free jet configured to accelerate the projectile relative to the expansion structure.

4. The apparatus of claim 1, wherein the energy source is a thermal energy source configured to convey thermal energy to the volume of the compressible gas disposed in the chamber, the thermal energy conveyed to the volume of the compressible gas operable to increase the pressure of the volume of the compressible gas disposed in the chamber.

5. The apparatus of claim 1, wherein the compressible gas includes a propellant, the energy source is an ignition source configured to initiate a combustion of the propellant, and the combustion of the propellant is operable to increase the pressure associated of the volume of the compressible gas.

6. The apparatus of claim 1, wherein the chamber includes a closure member configured to transition from a first state to a second state in response to the pressure associated with the compressible gas exceeding a threshold pressure between 0.2 megapascals (MPa) and 600.0 MPa,

the closure member fluidically isolates the chamber from the inlet of the expansion structure when in the first state and allows fluid communication between the chamber and the inlet of the expansion structure when in the second state.

7. The apparatus of claim 1, wherein the energy source is a kinetic energy source, the kinetic energy source configured to compress the volume of the compressible gas.

8. The apparatus of claim 7, wherein the kinetic energy source is a piston.

9. A method, comprising:

disposing a projectile in a desired position adjacent to and outside of an outlet of a nozzle;

increasing a pressure of a compressible gas disposed in a chamber;

establishing fluid communication between the chamber and an inlet of the nozzle when a pressure of the volume of the compressible gas exceeds a threshold pressure;

expanding at least a portion of the compressible gas as the compressible gas flows from the inlet to the outlet such that a supersonic free jet exits the outlet of the nozzle; and

accelerating the projectile relative to the outlet of the nozzle in response to the supersonic free jet stagnating against a surface of the projectile.

10. The method of claim 9, wherein the supersonic free jet is an underexpanded supersonic free jet.

11. The method of claim 9, wherein the nozzle is substantially stationary when the supersonic free jet exits the outlet.

12. The method of claim 9, wherein the increasing the pressure of the compressible gas disposed in the chamber includes conveying at least one of electrical energy to the compressible gas, thermal energy to the compressible gas, or kinetic energy to the compressible gas.

13. The method of claim 9, wherein the nozzle is a divergent nozzle.

14. The method of claim 9, wherein the nozzle is a convergent-divergent nozzle.

15. The method of claim 9, wherein the supersonic free jet exiting the outlet of the expansion structure has an axial flow direction, the supersonic free jet stagnating against a concave base surface of the projectile to accelerate the projectile in the axial flow direction.

16. The method of claim 15, wherein the concave base surface is configured to redirect a portion of the supersonic free jet after stagnating against the concave base surface of the projectile toward the remaining portion of the supersonic free jet flowing in the axial flow direction, the redirecting of the portion of the supersonic free jet is operable to increase a recovery temperature of the supersonic free jet.

17. A method, comprising:

disposing a projectile in a desired position adjacent to and outside of an outlet of a nozzle;

increasing a pressure of a volume of a compressible gas disposed in a chamber, the chamber configured to be in fluid communication with an inlet of the nozzle;

introducing incompressible particles into the volume of the compressible gas;

expanding the volume of the compressible gas as the compressible gas flows from the inlet of the nozzle to the outlet of the nozzle;

producing a first free jet from the outlet of the nozzle as a result of the expanding, the first free jet having a first velocity and a first Mach number;

producing a second free jet from the outlet of the nozzle as a result of the expanding, the second free jet having a second velocity lower than the first velocity and a second Mach number greater than the first Mach number, the second free jet being a substantially annular free jet circumferentially surrounding the first free jet; and

accelerating the projectile relative to the outlet of the nozzle in response to a thrust associated with first free jet stagnating against a base surface of the projectile.

18. The method of claim 17, further comprising:

establishing fluid communication between the chamber and the inlet of the nozzle when the pressure of the volume of the compressible gas exceeds a threshold pressure.

19. The method of claim 17, wherein the second free jet circumferentially surrounding the first free jet results in an elongated barrel shock region of the first free jet relative to a barrel shock region of a non-surrounded free jet having a velocity and a Mach number similar to the first velocity and the first Mach number, respectively, of the first free jet.

20. The method of claim 17, wherein the first Mach number is in a range of supersonic Mach numbers and the second Mach number is in a range of hypersonic Mach numbers.

21. The method of claim 17, wherein the first free jet and the second free jet have a common axial flow direction, and

the base surface of the projectile is concave base surface, the concave base surface is configured to redirect a portion of the first free jet after stagnating against the concave base surface of the projectile and toward the remaining portion of the first free jet flowing in the axial flow direction, the redirecting of the portion of the first free jet results in an increase of an amount of thrust associated with a recovery temperature of the first free jet.

22. The method of claim 17, further comprising:

separating the volume of the compressible gas during the expanding into a first volume of the compressible gas having a first density and a second volume of the compressible gas having a second density greater than the first density, the second volume of the compressible gas including the incompressible particles.

23. The method of claim 21, wherein the producing the first free jet includes producing the first free jet as a result of expanding the first volume of the compressible gas and the producing the second free jet includes producing the second free jet as a result of expanding the second volume of the compressible gas.