US20040083713A1 - Jet blade ejector nozzle - Google Patents
Jet blade ejector nozzle Download PDFInfo
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- US20040083713A1 US20040083713A1 US10/691,956 US69195603A US2004083713A1 US 20040083713 A1 US20040083713 A1 US 20040083713A1 US 69195603 A US69195603 A US 69195603A US 2004083713 A1 US2004083713 A1 US 2004083713A1
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- Prior art keywords
- flow
- jet engine
- voids
- rotor
- engine assembly
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02K—JET-PROPULSION PLANTS
- F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
- F02K1/38—Introducing air inside the jet
- F02K1/386—Introducing air inside the jet mixing devices in the jet pipe, e.g. for mixing primary and secondary flow
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02K—JET-PROPULSION PLANTS
- F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
- F02K1/40—Nozzles having means for dividing the jet into a plurality of partial jets or having an elongated cross-section outlet
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/60—Efficient propulsion technologies, e.g. for aircraft
Definitions
- the present invention relates generally to flow mixing methods and devices for jet engines and more particularly to a device and method for mixing flows to attenuate noise and augment thrust.
- Flow mixing devices have attracted significant attention since the invention of the jet engine.
- One application for these devices is related to the attenuation of the noise that is produced by the exhaust during the operation of the jet engine. Since noise generation is proportional to the velocity of the jet engine taken to the sixth or eighth power depending upon the pressure ratio of the nozzle, reductions in the velocity of the exhaust have the potential to significantly attenuate noise.
- Static mixers and steady flow ejectors have been employed to breakup the exhaust flow into smaller jets to enhance the rate with which the exhaust flow is mixed with the ambient flow field.
- these devices create large shear areas between the jets and the ambient flow field, causing the streams to interact at their interfaces and exchange shear force and momentum.
- the operation of these devices substantially reduced the efficiency of the engine. Consequently, it was possible to achieve a similar degree of noise attenuation by simply omitting the flow mixer and reducing the power level of the jet engine.
- the present invention provides a jet engine assembly having a turbofan jet engine and an unsteady flow ejector.
- the turbofan jet engine has an engine core for powering a fan.
- the engine core produces an engine core flow and the fan producing a fan flow.
- the unsteady flow ejector has a multi-bladed rotor which is disposed within the engine core flow and rotates in response to a transfer of momentum from the engine core flow. Rotation of the rotor within the engine core flow generates a plurality of high velocity, low density rotating jets and a plurality of low pressure voids, with each of the voids being spaced between two of the jets. Each of the voids entrains a portion of the fan flow which then mixes with the jets and produces a mixed flow having a relatively higher flow rate and a relatively lower velocity than the engine core flow.
- the present invention provides a jet engine assembly having an inlet, a turbojet engine and an unsteady flow ejector.
- the inlet provides an inlet flow of air to the turbojet engine.
- the turbojet engine receives at least a portion of the inlet flow, employing it to generate a propulsive primary flow.
- the unsteady flow ejector includes a multi-bladed rotor that is disposed within the primary flow and rotates in response to a transfer of momentum from the primary flow.
- the rotor employs the primary flow to generate a plurality of high velocity, low density rotating jets and a plurality of low pressure voids, with each of the voids being spaced between two of the jets and being selectively employable to entrain a secondary flow of air into voids.
- the jet engine assembly can be operated in a first mode wherein the secondary flow is a flow of ambient air that is introduced directly into the unsteady flow ejector to mix the primary and secondary flows so as to attenuate the noise level of the air exiting the turbojet engine.
- the present invention provides a method for reducing the noise emitted by a flow of exhaust from an outlet of a jet propulsion engine.
- the method includes the steps of segregating the exhaust flow into a plurality of rotating high velocity, low density jets and a plurality of rotating low pressure voids; and employing the low pressure voids to entrain at least a portion of a secondary flow of air, the jets and the entrained secondary flow mixing to produce a mixed flow having a relatively higher flow rate and a relatively lower velocity than the exhaust flow.
- FIG. 1 is a schematic illustration of an ejector constructed in accordance with the teachings of a preferred embodiment of the present invention
- FIG. 2A is a perspective view of a portion of the ejector of FIG. 1 illustrating the ejector rotor;
- FIG. 2B is a perspective view similar to that of FIG. 2A but illustrating another rotor configuration
- FIG. 3A is a schematic illustration of the ejector of the present invention in operative association with a short-duct turbofan engine
- FIG. 3B is a schematic illustration of the ejector of the present invention in operative association with a long-duct turbofan engine
- FIG. 4A is a schematic cross-sectional view of a jet engine assembly equipped with the ejector of the present invention, the jet engine assembly being configured in a take-off mode;
- FIG. 4B is a schematic cross-sectional view similar to that of FIG. 4A but illustrating the jet engine assembly as configured in a transonic mode;
- FIG. 4C is a schematic cross-sectional view similar to that of FIG. 4A but illustrating the jet engine assembly as configured in a supersonic mode;
- FIG. 5 is a schematic illustration of an ejector constructed in accordance with the teachings of an alternate embodiment of the present invention.
- an unsteady flow ejector constructed in accordance with the teachings of the present invention is generally indicated by reference numeral 10 .
- the unsteady flow ejector 10 is operable for mixing a high velocity primary air flow 12 , such as an exhaust stream 14 produced by a turbojet engine 16 , and a lower velocity secondary air flow 18 to produce a mixed flow 20 having a lower velocity than that of the primary air flow 12 .
- Operation of the unsteady flow ejector 10 in this manner may be employed to attenuate the noise that is generated by the primary air flow 12 and/or to extract work to augment engine thrust.
- the unsteady flow ejector 10 is illustrated to include a rotor 30 which is disposed at least partially in a primary air flow 12 .
- the rotor 30 is illustrated to be free-spinning, but could be coupled for rotation with another component, such as the final turbine stage of a jet engine (not shown).
- Rotation of the rotor 30 in the primary air flow 12 generates a plurality of rotating high pressure, high velocity jets 32 and a plurality of rotating low pressure voids 34 , with each of the voids 34 being spaced between two of the jets 32 .
- Each of the jets 32 flows through the unsteady flow ejector 10 in the thrust direction so as not to require the use of additional flow momentum to re-direct the mixed flow 20 .
- flow velocity is directed axially in the thrust direction.
- Each of the voids 34 is operable for entraining a portion 18 a of the secondary air flow 18 .
- the low static pressure of each of the voids 34 causes a portion 18 a of the secondary flow 18 to rush into and fill each of the voids 34 .
- Entrainment of the secondary flow 18 is dominated by static pressure momentum interchange which occurs in an essentially isentropic manner. Accordingly, the losses that result from the mixing process are relatively small as compared to other known mixing devices and ejectors which employ shear forces to mix flows.
- the temperature and density differentials between the jets 32 and the entrained portion 18 a of the secondary flow 18 set up a phenomenon known as Taylor Instability, which causes the primary air flow 12 and the entrained portion 18 a of the secondary flow 18 to mix. Mixing occurs when the interface instability causes the jets 32 and the entrained portion 18 a of the secondary flow 18 to breakup as the low-density jets 32 push through the higher density entrained portion 18 a of the secondary flow 18 .
- the unsteady flow ejector 10 In order to place the unsteady flow ejector 10 behind the turbojet engine 16 , the unsteady flow ejector 10 must be able to entrain the secondary flow 18 from the ambient by turning it from the free stream direction radially down into an ejector-mixer and then turn it back into the thrust direction. This turning must be done as efficiently as possible. There must be no flow separation. Furthermore, the jets 32 must be smoothly formed from the primary flow 12 with minimum losses. These jets 32 must flow in the thrust direction so that no additional flow momentum will be needed to align them in the thrust direction.
- the rotor 30 is illustrated to have a plurality of blades 40 and a hub 42 .
- Each of the blades 40 has a face portion 44 and an end portion 46 and is fixedly coupled to the hub 42 .
- the face portion 44 has an airfoil shape which guides the primary flow 12 in an efficient manner to the exit of the unsteady flow ejector 10 .
- the rotor 30 has four blades 40 , with the rotor face angle being about 60° and having an open area ratio for the jets 32 of about 33%.
- the configuration of the rotor 30 e.g., the quantity of the blades 40 , the shape of the blades 40 and the rotational speed of the rotor 30 ) must allow enough time and room for the entrained portion 18 a of the secondary flow 18 to move into the low pressure voids 34 .
- the end portion 46 is uniform in the circumferential direction so that no torque, other than that which results from surface skin friction, is applied to the rotor 30 as it rotates.
- the end portion 46 has a conical downstream face 48 .
- Configuration of the rotor 30 in this manner causes the free-spinning rotor 30 to rotate at a speed which balances the static pressure in the circumferential direction between the suction and pressure surfaces of the blades 40 . Accordingly, the speed of the rotor 30 is directly related to the flow rate of the primary flow 12 and no runaway conditions are possible.
- each of the blades 40 of the rotor 30 may additionally include a relieved portion 50 .
- each of the relieved portions 50 includes a cavity 52 that emanates from a point on the outer surface 54 of a respective one of the blades 40 and tapers both downwardly toward the hub 42 and outwardly toward the end portion 46 .
- the cavity 52 operates as a flow channel for the secondary flow 18 to increase the rate with which the secondary flow 18 is entrained.
- FIG. 3A illustrates a jet engine assembly 60 having a turbofan jet engine 62 and the unsteady flow ejector 10 .
- the turbofan jet engine 62 is conventional and includes a turbojet engine core 64 having a combuster 66 and a turbine 68 with a plurality of turbine stages 70 .
- the turbine 68 is employed to operate a relatively large fan 72 that is mounted forwardly of the turbojet engine core 64 .
- the fan 72 adds energy to the air that is taken in through the inlet 74 of the jet engine assembly 60 , causing the air to be expelled from the jet engine assembly 60 at a rate of speed that is relatively faster than the speed with which it enters the jet engine assembly 60 .
- the unsteady flow ejector 10 replaces the conventional nozzle (not shown) that is typically mounted aft of the turbojet engine core 64 .
- the rotor 30 is mounted in a free-spinning manner preferably on one of the engine shafts 76 , although a dedicated shaft arrangement (not shown) could also be employed.
- the unsteady flow ejector 10 is also mounted outside of the generally hollow duct 78 in which the turbofan engine 62 is disposed.
- the particular embodiment illustrated is not intended to be limiting in any manner and that the unsteady flow ejector 10 may alternatively be mounted inside the duct 78 as illustrated in FIG. 3B.
- the turbojet engine core 64 produces an engine core flow 80 and the fan 72 produces a propulsive fan flow 82 .
- the rotor 30 of the unsteady flow ejector 10 is disposed within the engine core flow 80 (i.e., the primary flow), causing the rotor 30 to rotate in response to a transfer of momentum from the engine core flow 80 .
- Rotation of the rotor 30 within the engine core flow 80 generates the plurality of high velocity, low density rotating jets 32 and the plurality of low pressure voids 34 in the manner that is discussed above.
- the voids 34 then entrain a portion of the fan flow 82 (i.e., the secondary flow), causing the engine core flow 80 and the fan flow 82 to mix and produce a mixed flow 86 having a relatively higher flow rate and a relatively lower velocity than the engine core flow 80 .
- operation of the unsteady flow ejector 10 attenuates the noise produced by the operation of the turbojet engine core 64 .
- FIG. 4A illustrates a jet engine assembly 90 having a turbo jet engine 92 , the unsteady flow ejector 10 , a conventional inlet 94 and a conventional variable geometry nozzle 96 .
- the turbojet engine 92 is conventional and includes a compressor 98 , a combuster 100 and a turbine 102 with a plurality of turbine stages 104 . Air is directed from the inlet 94 through the compressor 98 and into the combuster 100 where it is mixed with fuel and the mixture is burned. The hot gasses that exit the combuster 100 are expanded through the turbine 102 and exit the turbojet engine 92 as a propulsive exhaust flow 106 .
- the unsteady flow ejector 10 is mounted aft of the turbojet engine 92 .
- the rotor 30 is mounted in a free-spinning manner preferably on one of the engine shafts 108 forward of a cowling assembly 110 that has a cowling member 112 that defines at least one inlet aperture 114 .
- At least one closure member 116 is movably coupled to the cowling member 112 and is selectively positionable between an open position and a closed position.
- cowling assembly 110 will be discussed below in greater detail.
- the rotor 30 may be mounted to a dedicated shaft arrangement (not shown) or to one of the turbine stages 104 (FIG. 5).
- the rotor 30 may be coupled to the turbine stage 104 so that it rotates at the same rotational speed as that of the turbine stage 104 or, with additional gearing, so that it rotates at a rotational speed that is different than that of the turbine stage 104 .
- the jet engine assembly 90 is operable in a first mode during take-off situations, for example, wherein the closure member 116 is positioned in the open position, exposing the unsteady flow ejector 10 to a flow of ambient air 120 (i.e. a secondary flow).
- the rotor 30 of the unsteady flow ejector 10 is disposed within the exhaust flow 106 (i.e., the primary flow), causing the rotor 30 to rotate in response to a transfer of momentum from the exhaust flow 106 .
- Rotation of the rotor 30 within the exhaust flow 106 generates the plurality of high velocity, low density rotating jets 32 and the plurality of low pressure voids 34 in the manner that is discussed above.
- the voids 34 then entrain a portion of the ambient air flow 120 (i.e., the secondary flow), causing the exhaust flow 106 and the ambient air flow 120 to mix and produce a mixed flow 128 having a relatively higher flow rate and a relatively lower velocity than the exhaust flow 106 .
- amount of air contained in the ambient air flow 120 was about 110% of the amount of air contained in the exhaust flow 106 .
- the mixed flow 128 is then discharged through the variable geometry nozzle 96 . Operation of the unsteady flow ejector 10 attenuates the noise produced by the operation of the turbojet engine 92 , as well as reduces the temperature of the air flowing out of the variable geometry nozzle 96 .
- the unsteady flow ejector 10 is operated with the closure member 116 in the open position until the speed of the aircraft to which the jet engine assembly 90 is coupled exceeds a predetermined flight speed (e.g., about Mach 0.8). After this point, the aerodynamic drag associated with the direction of the ambient air flow 120 into the unsteady flow ejector 10 becomes sufficiently large so as to outweigh the noise attenuation benefits of the unsteady flow ejector 10 as operated in the first mode. Accordingly, the closure member 116 may thereafter be positioned in the closed position.
- a predetermined flight speed e.g., about Mach 0.8
- the jet engine assembly 90 is illustrated to be operable in a second mode during transonic situations.
- the closure member 116 is positioned in the closed position so that the unsteady flow ejector 10 is not exposed to the ambient air flow 120 .
- the transfer of momentum from the exhaust flow 106 causes the rotor 30 to rotate and generate the plurality of high velocity, low density rotating jets 32 and the plurality of low pressure voids 34 .
- the second mode utilizes a flow of bypass air 130 which is directed from the inlet 94 around the combuster 100 and into the unsteady flow ejector 10 .
- the bypass flow 130 is generated from a flow mismatch between a supersonic inlet flow 122 and an engine intake flow 124 , with the bypass air flow 130 being the difference between the supersonic inlet flow 122 and the engine intake flow 124 .
- the voids 34 then entrain a portion of the bypass flow 130 (i.e., the secondary flow), causing the exhaust flow 106 and the bypass flow 130 to mix and produce a mixed flow 132 having a relatively higher flow rate and a relatively lower velocity than the exhaust flow 106 .
- the mixed flow 132 is then discharged through the variable geometry nozzle 96 .
- Operation of the unsteady flow ejector 10 in the second mode reduces the temperature of the air flowing out of the variable geometry nozzle 96 and provides an augmented level of thrust. This later benefit stems in part from a reduction in drag that is normally associated with the bypass flow 130 as the bypass flow 130 is normally ejected without having had any work extracted from it.
- variable geometry nozzle 96 allow for a shallower boat tail angle and as such, achieve lower aerodynamic drag.
- An additional benefit of this use of the bypass flow 130 is that it may be used to cool portions of the unsteady flow ejector 10 and the variable geometry nozzle 96 since the temperature of the bypass flow 130 is much cooler than that of the exhaust flow 106 .
- the secondary flow that is directed to the unsteady flow ejector 10 during the operation of the jet engine assembly 90 in the second mode also includes a component that is associated with a boundary-layer bleed flow 134 .
- the boundary-layer bleed flow 134 results from the process of decelerating all or a portion of the supersonic inlet flow 122 prior to its entering the compressor 98 via a Series of oblique shocks. The low momentum flow in the boundary layer interacts with these shocks, growing in thickness, which in some situations, can lead to flow separation.
- the boundary-layer bleed flow 134 is employed to reduce the mass and thickness of the boundary layer to help maintain a uniform flow to the compressor 98 .
- the boundary-layer bleed flow 134 is combined with the bypass flow 130 to permit work to be extracted from it prior to its ejection from the jet engine assembly 90 .
- the amount of air in the secondary flow i.e., the bypass flow 130 and the boundary-layer bleed flow 134 ) was about 30% of the amount of air in the exhaust flow 106 .
- the jet engine assembly 90 is illustrated to be operable in a third mode during supersonic situations.
- the closure member 116 is positioned in the closed position so that the unsteady flow ejector 10 is not exposed to the ambient air flow 120 .
- the transfer of momentum from the exhaust flow 106 causes the rotor 30 to rotate and generate the plurality of high velocity, low density rotating jets 32 and the plurality of low pressure voids 34 .
- the third mode utilizes the boundary-layer bleed flow 134 as the primary constituent of the secondary flow.
- the voids 34 entrain a portion of the boundary-layer bleed flow 134 , causing the exhaust flow 106 and the boundary-layer bleed flow 134 to mix and produce a mixed flow 138 having a relatively higher flow rate and a relatively lower velocity than the exhaust flow 106 .
- the mixed flow 138 is then discharged through the variable geometry nozzle 96 .
- Operation of the unsteady flow ejector 10 in the third mode reduces the temperature of the air flowing out of the variable geometry nozzle 96 and provides an augmented level of thrust. This later benefit stems from a reduction in drag that is normally associated with the boundary-layer bleed flow 134 as the boundary-layer bleed flow 134 is normally ejected without having had any work extracted from it.
- the secondary flow that is directed to the unsteady flow ejector 10 during the operation of the jet engine assembly 90 in the third mode also includes a component that is associated with an engine cooling air flow 140 .
- the engine cooling air flow 140 is employed when the turbojet engine 92 is operating at supersonic speeds; the engine cooling air flow 140 is a flow of air that is directed through the jet engine assembly 90 to extract heat.
- the engine cooling air flow 140 is combined with the boundary-layer bleed flow 134 to permit work to be extracted from it prior to its ejection from the jet engine assembly 90 .
- the amount of air in the secondary flow i.e., the boundary-layer bleed flow 134 and the cooling air flow 140
- the unsteady flow ejector 10 may be operated in the second and third modes without the benefit of the secondary flow (i.e., without the bypass flow 130 or the boundary-layer bleed flow 134 in the second mode and without the boundary-layer bleed flow 134 and the cooling air flow 140 in the third mode). Operation of the jet engine assembly 90 in this manner would, however, necessitate that the various flows be spilled or dumped overboard to the ambient air flow and their ram drag would be simply unrecovered.
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Abstract
A jet engine assembly having a jet engine and an unsteady flow ejector. The unsteady flow ejector segregates the exhaust flow from the jet engine into a plurality of rotating high velocity, low density jets and a plurality of rotating low pressure voids. The low pressure voids are employed to entrain at least a portion of a secondary flow of air which is mixed with the jets to produce a mixed flow having a relatively higher flow rate and a relatively lower velocity than the exhaust flow. A method for attenuating the noise that is produced by the exhaust flow of a jet engine is also provided.
Description
- 1. Technical Field
- The present invention relates generally to flow mixing methods and devices for jet engines and more particularly to a device and method for mixing flows to attenuate noise and augment thrust.
- 2. Background Art
- Flow mixing devices have attracted significant attention since the invention of the jet engine. One application for these devices is related to the attenuation of the noise that is produced by the exhaust during the operation of the jet engine. Since noise generation is proportional to the velocity of the jet engine taken to the sixth or eighth power depending upon the pressure ratio of the nozzle, reductions in the velocity of the exhaust have the potential to significantly attenuate noise.
- Static mixers and steady flow ejectors have been employed to breakup the exhaust flow into smaller jets to enhance the rate with which the exhaust flow is mixed with the ambient flow field. In operation, these devices create large shear areas between the jets and the ambient flow field, causing the streams to interact at their interfaces and exchange shear force and momentum. As this process is irreversible in nature, the operation of these devices substantially reduced the efficiency of the engine. Consequently, it was possible to achieve a similar degree of noise attenuation by simply omitting the flow mixer and reducing the power level of the jet engine.
- Flow mixing devices have also been investigated due to their potential to augment the thrust that is produced by the engine. Several problems have been noted, however, when these devices have also been employed to attenuate noise. In the case of steady flow ejectors, the ram drag that results from the drawing of ambient air into the ejector for mixing with the exhaust flow overtakes the level of augmented thrust that is produced when the jet engine is operated at a relatively low speed (i.e., approximately Mach 0.3 to Mach 0.4). As such, it has not been possible to employ these steady flow ejectors in an efficient manner, particularly where the jet engine is to operate at a supersonic speed.
- In view of the drawbacks of steady flow ejectors, a second kind of ejector has been proposed to take advantage of the unsteady flow physics. The known unsteady flow ejectors produce a primary jet having a relatively large radial velocity component that must be turned back to the axial direction in order to provide thrust. This turning must be done by the secondary flow at a cost of its axial momentum, thereby generating a substantial loss of the available propulsive energy.
- In one preferred form, the present invention provides a jet engine assembly having a turbofan jet engine and an unsteady flow ejector. The turbofan jet engine has an engine core for powering a fan. The engine core produces an engine core flow and the fan producing a fan flow. The unsteady flow ejector has a multi-bladed rotor which is disposed within the engine core flow and rotates in response to a transfer of momentum from the engine core flow. Rotation of the rotor within the engine core flow generates a plurality of high velocity, low density rotating jets and a plurality of low pressure voids, with each of the voids being spaced between two of the jets. Each of the voids entrains a portion of the fan flow which then mixes with the jets and produces a mixed flow having a relatively higher flow rate and a relatively lower velocity than the engine core flow.
- In another preferred form, the present invention provides a jet engine assembly having an inlet, a turbojet engine and an unsteady flow ejector. The inlet provides an inlet flow of air to the turbojet engine. The turbojet engine receives at least a portion of the inlet flow, employing it to generate a propulsive primary flow. The unsteady flow ejector includes a multi-bladed rotor that is disposed within the primary flow and rotates in response to a transfer of momentum from the primary flow. The rotor employs the primary flow to generate a plurality of high velocity, low density rotating jets and a plurality of low pressure voids, with each of the voids being spaced between two of the jets and being selectively employable to entrain a secondary flow of air into voids. The jet engine assembly can be operated in a first mode wherein the secondary flow is a flow of ambient air that is introduced directly into the unsteady flow ejector to mix the primary and secondary flows so as to attenuate the noise level of the air exiting the turbojet engine.
- In another preferred form, the present invention provides a method for reducing the noise emitted by a flow of exhaust from an outlet of a jet propulsion engine. The method includes the steps of segregating the exhaust flow into a plurality of rotating high velocity, low density jets and a plurality of rotating low pressure voids; and employing the low pressure voids to entrain at least a portion of a secondary flow of air, the jets and the entrained secondary flow mixing to produce a mixed flow having a relatively higher flow rate and a relatively lower velocity than the exhaust flow.
- Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, wherein:
- FIG. 1 is a schematic illustration of an ejector constructed in accordance with the teachings of a preferred embodiment of the present invention;
- FIG. 2A is a perspective view of a portion of the ejector of FIG. 1 illustrating the ejector rotor;
- FIG. 2B is a perspective view similar to that of FIG. 2A but illustrating another rotor configuration;
- FIG. 3A is a schematic illustration of the ejector of the present invention in operative association with a short-duct turbofan engine;
- FIG. 3B is a schematic illustration of the ejector of the present invention in operative association with a long-duct turbofan engine;
- FIG. 4A is a schematic cross-sectional view of a jet engine assembly equipped with the ejector of the present invention, the jet engine assembly being configured in a take-off mode;
- FIG. 4B is a schematic cross-sectional view similar to that of FIG. 4A but illustrating the jet engine assembly as configured in a transonic mode;
- FIG. 4C is a schematic cross-sectional view similar to that of FIG. 4A but illustrating the jet engine assembly as configured in a supersonic mode; and
- FIG. 5 is a schematic illustration of an ejector constructed in accordance with the teachings of an alternate embodiment of the present invention.
- With reference to FIG. 1 of the drawings, an unsteady flow ejector constructed in accordance with the teachings of the present invention is generally indicated by
reference numeral 10. Theunsteady flow ejector 10 is operable for mixing a high velocityprimary air flow 12, such as anexhaust stream 14 produced by aturbojet engine 16, and a lower velocitysecondary air flow 18 to produce a mixedflow 20 having a lower velocity than that of theprimary air flow 12. Operation of theunsteady flow ejector 10 in this manner may be employed to attenuate the noise that is generated by theprimary air flow 12 and/or to extract work to augment engine thrust. - The
unsteady flow ejector 10 is illustrated to include arotor 30 which is disposed at least partially in aprimary air flow 12. Therotor 30 is illustrated to be free-spinning, but could be coupled for rotation with another component, such as the final turbine stage of a jet engine (not shown). Rotation of therotor 30 in theprimary air flow 12 generates a plurality of rotating high pressure,high velocity jets 32 and a plurality of rotatinglow pressure voids 34, with each of thevoids 34 being spaced between two of thejets 32. Each of thejets 32 flows through theunsteady flow ejector 10 in the thrust direction so as not to require the use of additional flow momentum to re-direct the mixedflow 20. Stated another way, although the pattern of total temperature, pressure and other scalar properties tends to move in a spiral manner, flow velocity is directed axially in the thrust direction. - Each of the
voids 34 is operable for entraining aportion 18 a of thesecondary air flow 18. Essentially, the low static pressure of each of thevoids 34 causes aportion 18 a of thesecondary flow 18 to rush into and fill each of thevoids 34. Entrainment of thesecondary flow 18 is dominated by static pressure momentum interchange which occurs in an essentially isentropic manner. Accordingly, the losses that result from the mixing process are relatively small as compared to other known mixing devices and ejectors which employ shear forces to mix flows. - The temperature and density differentials between the
jets 32 and the entrainedportion 18 a of thesecondary flow 18 set up a phenomenon known as Taylor Instability, which causes theprimary air flow 12 and the entrainedportion 18 a of thesecondary flow 18 to mix. Mixing occurs when the interface instability causes thejets 32 and the entrainedportion 18 a of thesecondary flow 18 to breakup as the low-density jets 32 push through the higher density entrainedportion 18 a of thesecondary flow 18. - In order to place the
unsteady flow ejector 10 behind theturbojet engine 16, theunsteady flow ejector 10 must be able to entrain thesecondary flow 18 from the ambient by turning it from the free stream direction radially down into an ejector-mixer and then turn it back into the thrust direction. This turning must be done as efficiently as possible. There must be no flow separation. Furthermore, thejets 32 must be smoothly formed from theprimary flow 12 with minimum losses. Thesejets 32 must flow in the thrust direction so that no additional flow momentum will be needed to align them in the thrust direction. - In FIG. 2A, the
rotor 30 is illustrated to have a plurality ofblades 40 and a hub 42. Each of theblades 40 has aface portion 44 and anend portion 46 and is fixedly coupled to the hub 42. Theface portion 44 has an airfoil shape which guides theprimary flow 12 in an efficient manner to the exit of theunsteady flow ejector 10. In the example provided, therotor 30 has fourblades 40, with the rotor face angle being about 60° and having an open area ratio for thejets 32 of about 33%. Those skilled in the art will understand, however, that the configuration of the rotor 30 (e.g., the quantity of theblades 40, the shape of theblades 40 and the rotational speed of the rotor 30) must allow enough time and room for the entrainedportion 18 a of thesecondary flow 18 to move into the low pressure voids 34. - The
end portion 46 is uniform in the circumferential direction so that no torque, other than that which results from surface skin friction, is applied to therotor 30 as it rotates. In the particular embodiment illustrated, theend portion 46 has a conicaldownstream face 48. Configuration of therotor 30 in this manner causes the free-spinningrotor 30 to rotate at a speed which balances the static pressure in the circumferential direction between the suction and pressure surfaces of theblades 40. Accordingly, the speed of therotor 30 is directly related to the flow rate of theprimary flow 12 and no runaway conditions are possible. - As illustrated in FIG. 2B, each of the
blades 40 of therotor 30 may additionally include arelieved portion 50. In the example provided, each of therelieved portions 50 includes acavity 52 that emanates from a point on theouter surface 54 of a respective one of theblades 40 and tapers both downwardly toward the hub 42 and outwardly toward theend portion 46. During the operation ofrotor 30, thecavity 52 operates as a flow channel for thesecondary flow 18 to increase the rate with which thesecondary flow 18 is entrained. - FIG. 3A illustrates a
jet engine assembly 60 having aturbofan jet engine 62 and theunsteady flow ejector 10. Theturbofan jet engine 62 is conventional and includes aturbojet engine core 64 having acombuster 66 and aturbine 68 with a plurality of turbine stages 70. Theturbine 68 is employed to operate a relativelylarge fan 72 that is mounted forwardly of theturbojet engine core 64. Thefan 72 adds energy to the air that is taken in through theinlet 74 of thejet engine assembly 60, causing the air to be expelled from thejet engine assembly 60 at a rate of speed that is relatively faster than the speed with which it enters thejet engine assembly 60. Theunsteady flow ejector 10 replaces the conventional nozzle (not shown) that is typically mounted aft of theturbojet engine core 64. Therotor 30 is mounted in a free-spinning manner preferably on one of theengine shafts 76, although a dedicated shaft arrangement (not shown) could also be employed. In the particular example provided, theunsteady flow ejector 10 is also mounted outside of the generallyhollow duct 78 in which theturbofan engine 62 is disposed. Those skilled in the art will understand, however, that the particular embodiment illustrated is not intended to be limiting in any manner and that theunsteady flow ejector 10 may alternatively be mounted inside theduct 78 as illustrated in FIG. 3B. - During the operation of the
jet engine assembly 60, theturbojet engine core 64 produces anengine core flow 80 and thefan 72 produces apropulsive fan flow 82. Therotor 30 of theunsteady flow ejector 10 is disposed within the engine core flow 80 (i.e., the primary flow), causing therotor 30 to rotate in response to a transfer of momentum from theengine core flow 80. Rotation of therotor 30 within theengine core flow 80 generates the plurality of high velocity, lowdensity rotating jets 32 and the plurality of low pressure voids 34 in the manner that is discussed above. Thevoids 34 then entrain a portion of the fan flow 82 (i.e., the secondary flow), causing theengine core flow 80 and thefan flow 82 to mix and produce amixed flow 86 having a relatively higher flow rate and a relatively lower velocity than theengine core flow 80. As such, operation of theunsteady flow ejector 10 attenuates the noise produced by the operation of theturbojet engine core 64. - FIG. 4A illustrates a
jet engine assembly 90 having aturbo jet engine 92, theunsteady flow ejector 10, aconventional inlet 94 and a conventionalvariable geometry nozzle 96. Theturbojet engine 92 is conventional and includes acompressor 98, acombuster 100 and aturbine 102 with a plurality of turbine stages 104. Air is directed from theinlet 94 through thecompressor 98 and into thecombuster 100 where it is mixed with fuel and the mixture is burned. The hot gasses that exit thecombuster 100 are expanded through theturbine 102 and exit theturbojet engine 92 as apropulsive exhaust flow 106. - The
unsteady flow ejector 10 is mounted aft of theturbojet engine 92. Therotor 30 is mounted in a free-spinning manner preferably on one of theengine shafts 108 forward of acowling assembly 110 that has acowling member 112 that defines at least oneinlet aperture 114. At least oneclosure member 116 is movably coupled to thecowling member 112 and is selectively positionable between an open position and a closed position. The operation ofcowling assembly 110 will be discussed below in greater detail. Alternatively, therotor 30 may be mounted to a dedicated shaft arrangement (not shown) or to one of the turbine stages 104 (FIG. 5). In this latter arrangement, therotor 30 may be coupled to theturbine stage 104 so that it rotates at the same rotational speed as that of theturbine stage 104 or, with additional gearing, so that it rotates at a rotational speed that is different than that of theturbine stage 104. - Returning to FIG. 4A, the
jet engine assembly 90 is operable in a first mode during take-off situations, for example, wherein theclosure member 116 is positioned in the open position, exposing theunsteady flow ejector 10 to a flow of ambient air 120 (i.e. a secondary flow). Therotor 30 of theunsteady flow ejector 10 is disposed within the exhaust flow 106 (i.e., the primary flow), causing therotor 30 to rotate in response to a transfer of momentum from theexhaust flow 106. Rotation of therotor 30 within theexhaust flow 106 generates the plurality of high velocity, lowdensity rotating jets 32 and the plurality of low pressure voids 34 in the manner that is discussed above. Thevoids 34 then entrain a portion of the ambient air flow 120 (i.e., the secondary flow), causing theexhaust flow 106 and theambient air flow 120 to mix and produce amixed flow 128 having a relatively higher flow rate and a relatively lower velocity than theexhaust flow 106. In the particular example provided, amount of air contained in theambient air flow 120 was about 110% of the amount of air contained in theexhaust flow 106. Themixed flow 128 is then discharged through thevariable geometry nozzle 96. Operation of theunsteady flow ejector 10 attenuates the noise produced by the operation of theturbojet engine 92, as well as reduces the temperature of the air flowing out of thevariable geometry nozzle 96. - Preferably, the
unsteady flow ejector 10 is operated with theclosure member 116 in the open position until the speed of the aircraft to which thejet engine assembly 90 is coupled exceeds a predetermined flight speed (e.g., about Mach 0.8). After this point, the aerodynamic drag associated with the direction of theambient air flow 120 into theunsteady flow ejector 10 becomes sufficiently large so as to outweigh the noise attenuation benefits of theunsteady flow ejector 10 as operated in the first mode. Accordingly, theclosure member 116 may thereafter be positioned in the closed position. - In FIG. 4B, the
jet engine assembly 90 is illustrated to be operable in a second mode during transonic situations. In the second mode, theclosure member 116 is positioned in the closed position so that theunsteady flow ejector 10 is not exposed to theambient air flow 120. As with the operation of theunsteady flow ejector 10 in the first mode, the transfer of momentum from theexhaust flow 106 causes therotor 30 to rotate and generate the plurality of high velocity, lowdensity rotating jets 32 and the plurality of low pressure voids 34. In contrast to the first mode, the second mode utilizes a flow ofbypass air 130 which is directed from theinlet 94 around thecombuster 100 and into theunsteady flow ejector 10. Thebypass flow 130 is generated from a flow mismatch between a supersonic inlet flow 122 and anengine intake flow 124, with thebypass air flow 130 being the difference between the supersonic inlet flow 122 and theengine intake flow 124. - The
voids 34 then entrain a portion of the bypass flow 130 (i.e., the secondary flow), causing theexhaust flow 106 and thebypass flow 130 to mix and produce amixed flow 132 having a relatively higher flow rate and a relatively lower velocity than theexhaust flow 106. Themixed flow 132 is then discharged through thevariable geometry nozzle 96. Operation of theunsteady flow ejector 10 in the second mode reduces the temperature of the air flowing out of thevariable geometry nozzle 96 and provides an augmented level of thrust. This later benefit stems in part from a reduction in drag that is normally associated with thebypass flow 130 as thebypass flow 130 is normally ejected without having had any work extracted from it. Furthermore, the extra flow through the internal parts of thevariable geometry nozzle 96 allow for a shallower boat tail angle and as such, achieve lower aerodynamic drag. An additional benefit of this use of thebypass flow 130 is that it may be used to cool portions of theunsteady flow ejector 10 and thevariable geometry nozzle 96 since the temperature of thebypass flow 130 is much cooler than that of theexhaust flow 106. - Preferably, the secondary flow that is directed to the
unsteady flow ejector 10 during the operation of thejet engine assembly 90 in the second mode also includes a component that is associated with a boundary-layer bleed flow 134. The boundary-layer bleed flow 134 results from the process of decelerating all or a portion of the supersonic inlet flow 122 prior to its entering thecompressor 98 via a Series of oblique shocks. The low momentum flow in the boundary layer interacts with these shocks, growing in thickness, which in some situations, can lead to flow separation. The boundary-layer bleed flow 134 is employed to reduce the mass and thickness of the boundary layer to help maintain a uniform flow to thecompressor 98. In the particular embodiment illustrated, the boundary-layer bleed flow 134 is combined with thebypass flow 130 to permit work to be extracted from it prior to its ejection from thejet engine assembly 90. In the example provided, the amount of air in the secondary flow (i.e., thebypass flow 130 and the boundary-layer bleed flow 134) was about 30% of the amount of air in theexhaust flow 106. - In FIG. 4C, the
jet engine assembly 90 is illustrated to be operable in a third mode during supersonic situations. In the third mode, theclosure member 116 is positioned in the closed position so that theunsteady flow ejector 10 is not exposed to theambient air flow 120. As with the operation of theunsteady flow ejector 10 in the first mode, the transfer of momentum from theexhaust flow 106 causes therotor 30 to rotate and generate the plurality of high velocity, lowdensity rotating jets 32 and the plurality of low pressure voids 34. In contrast to the first mode, the third mode utilizes the boundary-layer bleed flow 134 as the primary constituent of the secondary flow. Thevoids 34 entrain a portion of the boundary-layer bleed flow 134, causing theexhaust flow 106 and the boundary-layer bleed flow 134 to mix and produce amixed flow 138 having a relatively higher flow rate and a relatively lower velocity than theexhaust flow 106. Themixed flow 138 is then discharged through thevariable geometry nozzle 96. Operation of theunsteady flow ejector 10 in the third mode reduces the temperature of the air flowing out of thevariable geometry nozzle 96 and provides an augmented level of thrust. This later benefit stems from a reduction in drag that is normally associated with the boundary-layer bleed flow 134 as the boundary-layer bleed flow 134 is normally ejected without having had any work extracted from it. - Preferably, the secondary flow that is directed to the
unsteady flow ejector 10 during the operation of thejet engine assembly 90 in the third mode also includes a component that is associated with an enginecooling air flow 140. The enginecooling air flow 140 is employed when theturbojet engine 92 is operating at supersonic speeds; the enginecooling air flow 140 is a flow of air that is directed through thejet engine assembly 90 to extract heat. In the particular embodiment illustrated, the enginecooling air flow 140 is combined with the boundary-layer bleed flow 134 to permit work to be extracted from it prior to its ejection from thejet engine assembly 90. In the example provided, the amount of air in the secondary flow (i.e., the boundary-layer bleed flow 134 and the cooling air flow 140) was about 9% of the amount of air in theexhaust flow 106. - Those skilled in the art will understand that the
unsteady flow ejector 10 may be operated in the second and third modes without the benefit of the secondary flow (i.e., without thebypass flow 130 or the boundary-layer bleed flow 134 in the second mode and without the boundary-layer bleed flow 134 and the coolingair flow 140 in the third mode). Operation of thejet engine assembly 90 in this manner would, however, necessitate that the various flows be spilled or dumped overboard to the ambient air flow and their ram drag would be simply unrecovered. - While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the foregoing description and the appended claims.
Claims (13)
1. A jet engine assembly comprising:
a turbofan jet engine, the turbofan jet engine having an engine core for powering a fan, the engine core producing an engine core flow and the fan producing a fan flow; and
an unsteady flow ejector having a multi-bladed rotor, the rotor being disposed within the engine core flow and rotating in response to a transfer of momentum therefrom;
wherein rotation of the rotor within the engine core flow generates a plurality of high velocity, low density rotating jets and a plurality of low pressure voids, each of the voids being spaced between two of the jets, each of the voids entraining a portion of the fan flow, the jets and the entrained portion of the fan flow mixing to produce a mixed flow having a relatively higher flow rate and a relatively lower velocity than the engine core flow.
2. The jet engine assembly of claim 1 , wherein the rotor includes a hub and a plurality of blades, each of the blades being fixed to the hub and having a face portion, an end portion and a relieved portion, each of the relieved portions having a cavity, each of the cavities emanating from a point on an outer surface of a respective one of the blades and tapering downwardly toward the hub and outwardly toward the end portion, wherein the cavity operates a flow channel for the fan flow to increase a rate with which the fan flow is entrained.
3. The jet engine assembly of claim 1 , further comprising a duct having a hollow cavity, the turbofan engine being coupled to the duct and at least partially disposed within the hollow cavity.
4. The jet engine assembly of claim 1 , wherein the turbofan engine and the unsteady flow ejector are disposed within the duct.
5. A noise suppressor for attenuating noise associated with a high-velocity discharge flow, the noise suppressor comprising:
an unsteady flow elector having a multi-bladed rotor that is adapted to be disposed in the discharge flow and rotate in response to a transfer of energy therefrom, the rotor having a blade spacing that generates a plurality of high-velocity, low density rotating jets and a plurality of low pressure voids, each of the voids being spaced between an associated pair of the jets, the low pressure voids operably entraining a secondary flow of air.
6. A jet engine assembly comprising:
an inlet for providing an inlet flow of air;
a turbojet engine having a turbine and a combuster, the turbojet engine receiving at least a portion of the inlet flow of air and generating a propulsive primary flow; and
an unsteady flow ejector having a multi-bladed rotor, the rotor being disposed within the primary flow and rotating in response to a transfer of momentum therefrom, the rotor employing the primary flow to generate a plurality of high velocity, low density rotating jets and a plurality of low pressure voids, each of the voids being spaced between an associated pair of the jets, the unsteady flow ejector being selectively operable for entraining a secondary flow of air into voids;
the jet engine assembly being operable in a first mode wherein the secondary flow is a flow of ambient air that is introduced directly into the unsteady flow ejector, each of the voids entraining a portion of the ambient flow, the jets and the entrained portion of the secondary flow mixing to attenuate a noise level of an exhaust flow of air exiting the turbojet engine.
7. The jet engine assembly of claim 6 , wherein the jet engine assembly is further operable in a second mode wherein the secondary flow includes a flow of bypass air, the bypass air being directed from the inlet around the combuster and into the unsteady flow ejector, each of the voids entraining a portion of the secondary flow, the jets and the entrained portion of the secondary flow mixing to augment a level of thrust produced by the turbojet engine.
8. The jet engine assembly of claim 7 , wherein the secondary flow also includes a boundary-layer bleed flow when the jet engine assembly is operating in the second mode.
9. The jet engine assembly of claim 7 , wherein the jet engine assembly is further operable in a third mode wherein the secondary flow includes a boundary-layer bleed flow, the boundary-layer bleed flow being directed from the turbojet engine into the unsteady flow ejector, each of the voids entraining a portion of the secondary flow, the jets and the entrained portion of the secondary flow mixing to augment a level of thrust produced by the turbojet engine.
10. The jet engine assembly of claim 9 , wherein the secondary flow also includes an engine cooling air flow when the jet engine assembly is operating in the third mode.
11. The jet engine assembly of claim 9 , further comprising a variable geometry nozzle.
12. The jet engine assembly of claim 6 , wherein the rotor is mounted for rotation on a turbine shaft that rotatably supports the turbine.
13. The jet engine assembly of claim 6 , wherein the rotor includes a hub and a plurality of blades, each of the blades being fixed to the hub and having a face portion, an end portion and a relieved portion, each of the relieved portions having a cavity, each of the cavities emanating from a point on an outer surface of a respective one of the blades and tapering downwardly toward the hub and outwardly toward the end portion, wherein the cavity operates a flow channel for the secondary flow to increase a rate with which the secondary flow is entrained.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/691,956 US20040083713A1 (en) | 2000-09-27 | 2003-10-23 | Jet blade ejector nozzle |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/671,870 US6662548B1 (en) | 2000-09-27 | 2000-09-27 | Jet blade ejector nozzle |
US10/691,956 US20040083713A1 (en) | 2000-09-27 | 2003-10-23 | Jet blade ejector nozzle |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US09/671,870 Division US6662548B1 (en) | 2000-09-27 | 2000-09-27 | Jet blade ejector nozzle |
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US20040083713A1 true US20040083713A1 (en) | 2004-05-06 |
Family
ID=24696206
Family Applications (2)
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US09/671,870 Expired - Lifetime US6662548B1 (en) | 2000-09-27 | 2000-09-27 | Jet blade ejector nozzle |
US10/691,956 Abandoned US20040083713A1 (en) | 2000-09-27 | 2003-10-23 | Jet blade ejector nozzle |
Family Applications Before (1)
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US09/671,870 Expired - Lifetime US6662548B1 (en) | 2000-09-27 | 2000-09-27 | Jet blade ejector nozzle |
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US (2) | US6662548B1 (en) |
EP (1) | EP1320674B1 (en) |
AU (1) | AU2001296227A1 (en) |
GB (1) | GB2384029B (en) |
WO (1) | WO2002027177A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US20100150705A1 (en) * | 2008-12-12 | 2010-06-17 | Rolls-Royce Plc | Gas turbine engine |
US8776527B1 (en) | 2008-06-17 | 2014-07-15 | Rolls-Royce North American Technologies, Inc. | Techniques to reduce infrared detection of a gas turbine engine |
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US7644888B2 (en) * | 2002-05-15 | 2010-01-12 | The Boeing Company | High-speed aircraft and methods for their manufacture |
US20040260585A1 (en) * | 2003-06-20 | 2004-12-23 | Spangenberg Glynn Alan | Method and apparatus for measuring benefits of business improvements |
US20060157613A1 (en) * | 2005-01-19 | 2006-07-20 | Adamson Eric E | Supersonic aircraft with active lift distribution control for reducing sonic boom |
US20070000234A1 (en) * | 2005-06-30 | 2007-01-04 | Anderson Jack H | Jet nozzle mixer |
FR2975135B1 (en) * | 2011-05-12 | 2016-07-22 | Snecma | REVERSE CONE OF MICROJETS TURNOVER TURNOVER |
US20130087632A1 (en) * | 2011-10-11 | 2013-04-11 | Patrick Germain | Gas turbine engine exhaust ejector nozzle with de-swirl cascade |
US8690097B1 (en) * | 2012-04-30 | 2014-04-08 | The Boeing Company | Variable-geometry rotating spiral cone engine inlet compression system and method |
US10544755B2 (en) * | 2016-09-20 | 2020-01-28 | Rolls-Royce North American Technologies, Inc. | Variable infrared suppression system in a gas turbine engine |
US11828248B1 (en) * | 2022-06-27 | 2023-11-28 | Pratt & Whitney Canada Corp. | Rotatably driven exhaust mixer |
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- 2001-08-30 WO PCT/US2001/027349 patent/WO2002027177A1/en active IP Right Grant
- 2001-08-30 EP EP01977080A patent/EP1320674B1/en not_active Revoked
- 2001-08-30 GB GB0308817A patent/GB2384029B/en not_active Expired - Lifetime
- 2001-08-30 AU AU2001296227A patent/AU2001296227A1/en not_active Abandoned
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- 2003-10-23 US US10/691,956 patent/US20040083713A1/en not_active Abandoned
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US8413418B2 (en) | 2008-12-12 | 2013-04-09 | Rolls-Royce Plc | Gas turbine engine |
Also Published As
Publication number | Publication date |
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GB0308817D0 (en) | 2003-05-21 |
EP1320674B1 (en) | 2006-10-18 |
EP1320674A1 (en) | 2003-06-25 |
US6662548B1 (en) | 2003-12-16 |
GB2384029A (en) | 2003-07-16 |
GB2384029B (en) | 2004-09-15 |
AU2001296227A1 (en) | 2002-04-08 |
WO2002027177A1 (en) | 2002-04-04 |
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