초록 ▼

A combined-cycle engine having at least one core engine and at least one ramjet engine. The ramjet utilizes a novel swirl generator for rapidly and efficiently atomizing, vaporizing, as necessary, and mixing a fuel into an oxidant. The swirl generator converts an oxidant flow into a turbulent, three

A combined-cycle engine having at least one core engine and at least one ramjet engine. The ramjet utilizes a novel swirl generator for rapidly and efficiently atomizing, vaporizing, as necessary, and mixing a fuel into an oxidant. The swirl generator converts an oxidant flow into a turbulent, three-dimensional flowfield into which the fuel is introduced. The swirl generator effects a toroidal outer recirculation zone and an inner central recirculation zone, both of which are configured in a backward-flowing manner that carries heat and combustion byproducts upstream where they are employed to continuously ignite a combustible fuel/oxidizer mixture in adjacent shear layers, which accelerate flame propagation throughout the core flowfield. The swirl generator provides smooth combustion with no instabilities and minimum total pressure losses and enables significant reductions in the L/D ratio of the combustor. Other benefits include simplicity, reliability, wide flammability limits, high combustion efficiency and high specific thrust performance.

대표청구항 ▼

1. A combined-cycle engine for producing propulsive thrust, the combined-cycle engine comprising:a core engine operable for producing all of the propulsive thrust when the combined-cycle engine has a velocity that is less than a predetermined transition velocity; andat least one ramjet engine for pr

1. A combined-cycle engine for producing propulsive thrust, the combined-cycle engine comprising:a core engine operable for producing all of the propulsive thrust when the combined-cycle engine has a velocity that is less than a predetermined transition velocity; andat least one ramjet engine for producing at least a portion of the propulsive thrust after the velocity of the combined-cycle engine is greater than or equal to the predetermined transition velocity, the ramjet engine including a combustor and a swirl generator, the combustor having a combustor inlet, the swirl generator having an inlet housing, a swirl vane pack, a centerbody assembly, and a plurality of groups of fuel injectors, the inlet housing being coupled to the combustor inlet and defining a hollow interior volume therein, the inlet housing serving as a conduit through which an oxidizer flow is conducted, the hollow interior volume intersecting the combustor inlet at a dump step wherein the inlet housing has an inner dimension that is smaller than that of the combustor, the swirl vane pack being disposed within the hollow interior volume and having a plurality of vanes, the vanes cooperating to change the velocity of the oxidizer flow so that the velocity includes a substantial tangential velocity component, the centerbody assembly being disposed in the hollow interior volume and being coupled to the swirl vane pack so as to extend rearwardly therefrom, the centerbody assembly including an aft bluff body, an aft-most portion of the aft bluff body being sized relatively larger than an adjacent upstream portion of the centerbody assembly, and the plurality of groups of fuel injectors being coupled to at least one of the inlet housing, the swirl vane pack and the centerbody assembly and dispensing a fuel therefrom directly into the oxidizer flow for at least partially mixing the fuel and oxidizer prior to entering the combustor;wherein the swirl generator converts the oxidizer flow received therein into a swirling, three-dimensional flowfield;wherein a first portion of the flowfield flows over the dump step to form an outer recirculation zone;wherein a second portion of the flowfield forms a central recirculation zone that is anchored by an aft end of the centerbody assembly;wherein a first portion of the fuel mixes with the first portion of the flowfield to fuel the outer recirculation zone;wherein a second portion of the fuel mixes with the second portion of the flowfield to fuel the central recirculation zone;and wherein a remaining portion of the fuel enters and fuels a core flow.2. The combined-cycle engine of claim 1, wherein the combustor has a length-to-diameter ratio that is less than about 2.0.3. The combined-cycle engine of claim 2, wherein the length-to-diameter ratio is less than about 1.6.4. The combined-cycle engine of claim 3, wherein the length-to-diameter ratio is about 1.0.5. The combined-cycle engine of claim 1, wherein the core engine is selected from a group of engines consisting of turbojet engines and rocket engines.6. The combined-cycle engine of claim 5, further comprising at least one forward movable element, the forward movable element being selectively positionable for diverting the oxidizer flow to the ramjet engine or turbojet engine.7. The combined-cycle engine of claim 6, wherein the forward movable element is further selectively positionable to divert a first portion of the oxidizer flow to the turbojet engine and a second portion of the oxidizer flow to the ramjet engine.8. The combined-cycle engine of claim 5, further comprising a bypass duct and a bypass valve, the bypass duct interconnecting the turbojet engine and the ramjet engine, the bypass valve being operable for selectively closing the bypass duct, wherein when the bypass valve is opened, air is bled from the turbojet engine and fed into the ramjet engine.9. The combined-cycle engine of claim 8, wherein the bypass duct intersects the turbojet engine aft of a high-pressure compressor.10. The combined-cycle engine of claim 5, further comprising at least one aft movable element, the aft movable element being selectively positionable for at least partially closing off an outlet of the ramjet engine or an outlet of the turbojet engine.11. The combined-cycle engine of claim 10, wherein a surface of the aft movable element forms a portion of a nozzle of the ramjet engine when the aft movable element is positioned to at least partially close off the outlet of the turbojet engine.12. The combined-cycle engine of claim 10, wherein a surface of the aft movable element forms a portion of an expansion nozzle of the turbojet engine when the aft movable element is positioned to at least partially close off the outlet of the ramjet engine.13. The combined-cycle engine of claim 5, wherein the ramjet engines are circumferentially spaced apart from one another and disposed radially outwardly of the turbojet engine.14. The combined-cycle engine of claim 5, wherein the ramjet engines are arranged such that their longitudinal axes are contained in a common plane and the common plane is generally parallel to a longitudinal axis of the turbojet engine.15. The combined-cycle engine of claim 5, wherein at least a portion of the rocket engines are circumferentially spaced apart from one another radially outwardly of the swirl generator.16. The combined-cycle engine of claim 15, wherein the portion of the rocket engines are mounted in one of a backward facing wall of one of a dump step and a quarl.17. The combined-cycle engine of claim 5, wherein the rocket engine is housed in the centerbody assembly.18. The combined-cycle engine of claim 5, wherein the combustor further comprises a nozzle, wherein at least a portion of the nozzle is at least one of ejectable, frangible and consumable, the portion being employed only during operation of the rocket engine.19. The combined-cycle engine of claim 5, wherein the combustor further comprises a variable area nozzle.20. The combined-cycle engine of claim 19, wherein the variable area nozzle includes a plurality of throat closure elements that are movable between a first position and a second position, the variable area nozzle having a first outlet area when the throat closure elements are positioned in the first position, and a second outlet area that is smaller than the first outlet area when the throat closure elements are positioned in the second position.21. The combined-cycle engine of claim 20, wherein the throat closure elements are operated in opposed pairs so as to minimize rotational torques on the combined cycle engine when the throat closure elements are moved between the first and second positions.22. A combined-cycle engine for producing propulsive thrust, the combined-cycle engine comprising:at least one core engine operable for producing all of the propulsive thrust when the combined-cycle engine has a velocity that is less than a predetermined transition velocity, the core engine being selected from a group consisting of rocket engines and turbojet engines; andat least one ramjet engine, each ramjet engine including a combustor and a swirl generator, the combustor having an inlet, the swirl generator being coupled to the inlet of the combustor and operable for converting an oxidizer flow into a three-dimensional flowfield that includes a substantial tangential velocity component, the swirl generator including a flow defining means and a fueling means, the flow defining means including swirl vanes and a centerbody with an aft bluff body, at least an aft-most portion of the aft bluff body being sized relatively larger than an adjacent upstream portion of the centerbody, the flow defining means being operable for effecting both an outer recirculation zone and a central recirculation zone in the combustor, the outer recirculation zone being toroidal in shape, the central recirculation zone being disposed inwardly of the outer recirculation zone, the fueling means being operable for fueling the outer recirculation zone, the central recirculation zone and a core flow and including a Plurality of groups of fuel injectors for injecting the fuel directly into the oxidizer flow for at least partially mixing the fuel and the oxidizer prior to entering the combustor;wherein heat and combustion by-products produced during combustion are carried upstream by the outer and central recirculation zones where the heat and combustion by-products are employed to continuously ignite a combustible fuel/oxidizer mixture in a shear layer adjacent to each of the outer and central recirculation zones, which accelerate flame propagation into the core flow.23. The combined-cycle engine of claim 22, further comprising an inlet structure coupled to the swirl generator opposite the combustor, the inlet structure including a plurality of flow guide vanes for mitigating oxidizer flow distortions and flow separations in the oxidizer flow before the oxidizer flow enters the swirl generator.24. The combined-cycle engine of claim 22, wherein the flow defining means includes a swirl vane pack having a plurality of vanes and wherein the vanes are configured to provide the swirl vane pack with a swirl number that is less than about 2.0.25. The combined-cycle engine of claim 24, wherein the swirl number of the swirl vane pack is about 0.4 to about 1.2.26. The combined-cycle engine of claim 22, wherein the combustor has a length-to-diameter ratio that is less than about 2.0.27. The combined-cycle engine of claim 26, wherein the length-to-diameter ratio is less than about 1.6.28. The combined-cycle engine of claim 27, wherein the length-to-diameter ratio is about 1.0.29. The combined-cycle engine of claim 22, further comprising an inlet for selectively controlling an amount of air directed to the at least one core engine and the at least one ramjet engine.30. The combined-cycle engine of claim 29, wherein the inlet employs variable geometry flow control using at least one of a hinged component and a translating component to control the amount of air directed to the at least one core engine and the at least one ramjet engine.31. The combined-cycle engine of claim 22, further comprising a bypass duct and a bypass valve, the bypass duct interconnecting the turbojet engine and the ramjet engine, the bypass valve being operable for selectively closing the bypass duct, wherein when the bypass valve is opened, air is bled from the turbojet engine and fed into the ramjet engine.32. The combined-cycle engine of claim 31, wherein the bypass duct intersects the turbojet engine aft of a high-pressure compressor.33. The combined-cycle engine of claim 22, further comprising at least one aft movable element, the aft movable element being selectively positionable for at least partially closing off an outlet of the ramjet engine or an outlet of the turbojet engine.34. The combined-cycle engine of claim 33, wherein a surface of the aft movable element forms a portion of a nozzle of the ramjet engine when the aft movable element is positioned to at least partially close off the outlet of the turbojet engine.35. The combined-cycle engine of claim 33, wherein a surface of the aft movable element forms a portion of an expansion nozzle of the turbojet engine when the aft movable element is positioned to at least partially close off the outlet of the ramjet engine.36. The combined-cycle engine of claim 22, wherein the portion of the rocket engines are mounted in one of a backward facing wall of one of a dump step and a quarl.37. The combined-cycle engine of claim 22, wherein the rocket engine is housed in the centerbody assembly.38. The combined-cycle engine of claim 22, wherein the combustor further comprises a nozzle, wherein at least a portion of the nozzle is at least one of ejectable, frangible and consumable, the portion being employed only during operation of the rocket engine.39. The combined-cycle engine of claim 22, wherein the combustor further comprises a variable area nozzle.40. The combined-cycle engine of claim 39, wherein the variable area nozzle includes a plurality of throat closure elements that are movable between a first position and a second position, the variable area nozzle having a first outlet area when the throat closure elements are positioned in the first position, and a second outlet area that is smaller than the first outlet area when the throat closure elements are positioned in the second position.41. The combined-cycle engine of claim 40, wherein the throat closure elements are operated in opposed pairs so as to minimize rotational torques on the combined cycle engine when the throat closure elements are moved between the first and second positions.