Patent Application
20090217643
The present invention relates generally to gas discharge techniques for vehicle engines, and more particularly, but not exclusively, to signature suppression for gas turbine engines of airborne vehicles.
Signature suppression remains an area of significant interest for both homeland security and military purposes. Unfortunately, some existing systems have various shortcomings relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology.
One embodiment of the present application is a unique discharge technique for a vehicle engine. Other embodiments include unique apparatus, systems, devices, hardware, methods, and combinations for signature suppression. Further embodiments, forms, objects, features, advantages, aspects, and benefits of the present invention shall become apparent from the following description and drawings.
For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the illustrated device, and any further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
One embodiment of the present application is a gas turbine engine that includes an s-shaped conduit having an ejector formed therein. The s-shaped conduit is configured downstream of the outlet of the gas turbine engine and serves to radially displace an exhaust flow generated by the engine to alter the line of sight angles from which infrared radiation may be detected. The ejector additionally serves to reduce total emitted infrared radiation by entraining non-exhaust flow air into the exhaust flow to create a cooled flow mixture. The ejector may be located at a point upstream of an inflection point in the s-shaped conduit. As used herein, the term “inflection point” means a point where a tangent line to such point reverses direction. A nacelle may be attached near the gas turbine engine to house the s-shaped conduit and may have an inlet that is in fluid communication with the ejector.
For another embodiment,
In this nonlimiting example, the nozzle system 50 is shown located beneath the wing 65 of the aircraft 55 downstream of the gas turbine engine 60. The nozzle system 50 includes an s-shaped discharge duct 90 (alternatively designated an s-shaped conduit 95) as well as a nacelle 100. The system 50 is structured to suppress the infrared (IR) signature that would otherwise result from the discharge of hot exhaust therethrough. In operation, hot exhaust from the gas turbine engine 60 is routed through the s-shaped duct 90 and out the downstream end of the nacelle 100. The s-shaped character of the s-shaped duct 90 forces the exhaust flow to be radially displaced while still preserving the axial direction of the exhaust flow that existed prior to entering the s-shaped duct 90. However, in other forms, the axial flow direction may not be entirely or substantially preserved. The s-shaped duct 90 has a sinuous shape 105, the nature of which is described further hereinbelow.
The S-shaped duct 90 includes a first segment 110 and a second segment 115 and further includes an ejector 120 formed by the relative orientation between the first segment 110 and the second segment 115. The s-shaped duct 90 is shaped to reduce, if not eliminate any line of sight to the turbines 85 by an external observer looking through the discharge end thereof; thus reducing the detectable emitted infrared radiation from gas turbine engine 60. In addition, external air, as represented by the arrow designated with reference numeral 121, is provided to the s-shaped duct 90 through the action of the ejector 120 and thereafter mixed with hot exhaust flow. Mixing exhaust flow with external flow reduces the temperature of the flow traveling through the s-shaped duct 90 and therefore further reduces the signature of emitted radiation. As used herein, the terms “external flow” or “external air” means air flow that is external to the flow path through the gas turbine engine core, i.e. the air flow along a path through compressor 75, combustor 80 and turbines 85; that is typically cooler in temperature than the core flow. As an example, air flow downstream of the propeller 70 is one form of “external air.” In addition, air flow at ambient conditions upstream of the propeller 70 is also included in the meaning of such terms.
The first segment 110 of the s-shaped duct 90 is attached to an outlet 122 of the gas turbine engine 60 to receive hot exhaust flow. In one form, the first segment 110 is permanently attached to the gas turbine engine 60, but in other forms may be releasably attached. In yet other forms, the first segment 110 may be an integral part of the gas turbine engine 60. The first segment 110 defines a first segment inlet opening 125 and a first segment exit opening 130 in fluid communication with one another to via first segment passage 111 to provide a first segment flow path therethrough. As exhaust flow exits the gas turbine engine 60, it is substantially captured by the first segment 110 through the opening 125 so that it may be conveyed further downstream through the passage 111. As the exhaust flow is conveyed downstream through passage 111, it is radially displaced by the geometry of the first segment 110. In the illustrated embodiment, the first segment 110 only partially provides for the final radial displacement of exhaust flow downstream of the nozzle system 50, but in other embodiments the first segment 110 may be configured to provide all or none of the final radial displacement. In addition to radial displacement, in some implementations the first segment 110 may be oriented at an angle relative to the longitudinal axis of the gas turbine engine 60. The first segment opening 125 substantially conforms in shape to the outlet 122 and may provide for an efficient flow path transition from the gas turbine engine 60 to the first segment 110. The opening 125 can be approximately circular in shape, but other shapes are also contemplated. Although not depicted in the illustrated embodiment, the interface between the first segment 110 and the outlet 122 of gas turbine engine 60 may or may not have an additional seal to prevent the escape of hot exhaust flow.
The second segment 115 is positioned downstream of the first segment 110 and is configured to receive exhaust flow traveling out of an exit opening 130 from first segment 110. The second segment 115 defines a second segment inlet opening 135 and a second segment exit opening 140 in fluid communication with one another via second segment passage 115 to provide a second segment flow path therethrough. The inlet opening 135 of the second segment 115 can be larger in size but typically conforms in shape to the exit opening 130 of the first segment 110. In some forms, the inlet opening 135 may not conform in shape to the exit 130. The inlet opening 135 may be approximately circular in some forms, but other shapes are also contemplated. The second segment 115 provides for the final radial displacement of the exhaust flow from the gas turbine engine 60. In some forms, the second segment 115 may provide none or all of the radial displacement of the s-shaped duct 90. A vector angle in the exhaust flow aft of the second segment 115 may be provided in some implementations.
The ejector 120 is formed when the inlet opening 135 receives the exit opening 130. Although the second segment 115 is shown oriented symmetrically from top to bottom about the first segment 110, other forms contemplate offsets in the configuration. For example, the inlet opening 135 may be oriented such that its top edge is coincident with the top edge of the exit opening 130, thus leaving a large and asymmetric gap created between the bottom of the inlet opening 135 and exit opening 130. The ejector 120 is configured to entrain an external flow of air with the exhaust flow traversing through s-shaped duct and is sized to accommodate a broad range of mass flows both in the internal hot exhaust flow and the pumped external air.
The nacelle 100 includes a nacelle inlet 145 opposite a nacelle outlet 150, a nacelle flow director 155, and a nacelle connector 160. The nacelle 100 is configured to substantially enclose the conduit 95, but in some implementations nacelle 100 may only partially enclose it. An outer surface 165 of the nacelle 100 provides an aerodynamic fairing for the nozzle system 50 such that aerodynamic drag is reduced. The nacelle 100 is connected to the wing 65 by the nacelle connector 160 and may be permanently or releasably connected. The nacelle flow director 155 is configured to be in fluid communication with the nacelle inlet 145 and the ejector 120, and may be configured as a ramp or other suitable structure for directing airflow. In some implementations, the flow director 155 may not be included such as when a nacelle is not provided, to name one possibility. During operation of the nozzle system 50, the airflow that is channeled to the ejector 120 by the flow director 155 is thereafter entrained with exhaust flow traversing the conduit 95. Mixed exhaust flow and external air flow are discharged from the nacelle outlet 150. In some implementations, the nacelle outlet 150 may be coincident with the second segment exit opening 140 such as when the outer surface 165 of the nacelle 100 converges at the second segment exit opening 140. Correspondingly, the outlet 150 is not defined separately from the opening 140. In other implementations, the nacelle outlet 150 may be axially and/or radially displaced from the second segment exit 140.
The duct segment support 175 is used to connect at least part of the s-shaped duct 90 to the nacelle 100, and may be permanently or releasably connected to either or both the s-shaped duct 90 and the nacelle 100. In the illustrated embodiment, the duct segment support 175 is configured to support the second segment 115 and suspend it aft of the first segment 110. The second segment 115 is not supported by the first segment 110, but in other forms the second segment 115 may be supported solely by the first segment 110 or via a combination of the first segment 110 and the duct segment support 175.
An ejector 215 is formed by the relative orientation of the second segment 195 and the first segment 190 and includes an ejector lip 220 that defines an inlet 225 of the ejector 215 in cooperation with the second segment 195. Airflow, as represented by the arrow designated by reference numeral 230, enters the inlet 225 at the bottom of the s-shaped conduit 180, but in other forms may also enter the ejector 215 substantially around the entire circumferential periphery of the s-shaped conduit 180. In other forms, the airflow 230 may enter at the top or sides of the ejector 215. In still other forms, the airflow 230 may be bifurcated into two streams or further divided into multiple streams before entering the ejector 215. The airflow 230 entering the ejector 215 is entrained in the exhaust flow 235 traversing from the first segment 190 thus creating a mixed flow.
A third segment 240 is provided and is oriented aft of the second segment 195 to also form an ejector 250. Airflow, as represented by the arrow designated by reference numeral 245, enters the bottom of the ejector 250, but may also enter around the entire circumferential periphery of the s-shaped conduit 180. In other forms, the airflow 245 may enter at the top or sides of the ejector 250, or be divided into two or more streams. The airflow 245 entering the ejector 250 is entrained in the mixed flow traversing from the second segment 195.
The relative orientation of the first segment 190, the second segment 195, and the third segment 240 creates an s-shaped pathway 255 that includes two reversals of curvatures denoted by the inflection points 260 and 265. It will be understood that the first segment 190, the second segment 195, and the third segment 240 may be arranged to provide any number of inflection points, including only one as would be defined by a literal s-shaped. In this way, the term “s-shaped” includes a sinuous shape of a conduit that has at least one inflection point, and also includes a sinuous shape that has more than one inflection point such that it defines more than a single s-shaped portion. It will also be understood that either or both ejectors may be located upstream or downstream of an inflection point as suits a particular application.
The s-shaped conduit 180 may vary smoothly between the shapes of the projected exhaust inlet 270 and the projected exhaust outlet 285, or may be discontinuous at some point along the length of the duct. For example, the cross section of the s-shaped duct 180 may be held substantially circular for the length of the first segment 190 and then abruptly change to a different cross sectional shape for the length of the second segment 195. In another form, the cross section may change along one segment but be held substantially constant across another. In yet another form the cross section of both segments may be substantially the same.
Referring to
A second segment 340 is located aft of the first segment 310 and includes support channels 345 and 350 and mount bosses 355 and 360. The second segment 340 also includes a forward flow blocker 365 that extends in the space defined between the s-shaped conduit 305, the nacelle 100, and a bottom surface 367 of the wing 65. The forward flow blocker 365 impedes airflow from flowing in the nacelle 100 from one side of the forward flow blocker 365 to the other side. The forward flow blocker 365 substantially surrounds the s-shaped conduit 305 in the illustrative embodiment, but in other embodiments may only partially surround the conduit s-shaped conduit 305. A heat shield 370 is located between the first segment 310 and the second segment 340 to provide for thermal management of the s-shaped conduit 305. An ejector 375 is formed by the relative orientation of the second segment 340 and the heat shield 370. In addition, an ejector 377 is also formed between the first segment 310 and heat shield 370. Both ejectors 375 and 377 operate in the same manner as the previously described ejectors.
Many different embodiments are envisioned, for example in some embodiments the nacelle and second segment may be formed as an integrated suppression apparatus. In still other implementations, the nacelle second segment, and first segment may be formed in an integrated assembly that may be capable of attachment directly to the wing. Additionally and/or alternatively, an integrated assembly may be mounted to the exhaust outlet of gas turbine engine.
In one particular form, a suppression device is provided to that can be retrofit to the engines of pre-existing aircraft. This form may include a nacelle that carries a multisegment s-shaped conduit that can be connected to the pre-existing exhaust outlet of an engine. One implementation of such form is used to retrofit underwing turboprop engines, such as those of a C-130 fixed wing aircraft.
In another embodiment, an ejector formed by a third segment and second segment can have a configuration independent of the configuration of an ejector formed by a first segment and second segment. For example, a bifurcated stream may be configured to enter a first ejector and a peripheral stream may enter a second ejector.
Still another embodiment of the present application includes a nozzle system having an s-shaped duct. Two segments comprise the s-shaped duct wherein a margin of one segment is at least partially nested in the margin of another segment. The relative orientation of the two segments defines an ejector configured to mix a secondary flow stream with a primary flow stream.
In still another embodiment, a fixed wing aircraft powered by a gas turbine engine includes an s-shaped duct to receive and discharge an exhaust flow. An ejector is formed along the length of the s-shaped duct to mix air with the exhaust flow before being discharged through the outlet.
In yet another embodiment, an s-shaped duct is provided having an inlet with a first aspect ratio and an outlet with a second aspect ratio. The first aspect ratio is taken from a cross section of the duct near the inlet end and the second aspect ratio is taken from a cross section of the duct near the outlet. Both aspect ratios are determined by dividing a maximum distance by a minimum distance of the cross section. The cross sections may be transverse to a flow from a gas turbine engine. The first cross section may be circular in shape thus having a near unity aspect ratio while the outlet aspect ratio may be rectangular in shape, thus resulting in a greater than unity aspect ratio.
Another embodiment includes: providing a gas turbine powered aircraft having a turbine exhaust, connecting a first duct segment to the turbine exhaust, and installing a nacelle having a second duct segment such that the relative orientation of the first duct segment and the second duct segment create an s-shaped conduit having an ejector with an ejector lip.
In a further embodiment, the present invention provides means for ducting an exhaust flow in an s-shape and providing an ejector therein. The ducting is comprised of two segments wherein one segment nestingly receives another segment. An ejector means is formed by the relative orientation of the first segment to the second segment wherein a secondary flow stream is entrained in a primary flow stream. The relative orientation of the two segments provides at least one inflection point.
In a still further embodiment, means for ducting the exhaust from a gas turbine powered aircraft are provided, including an s-shaped means and an ejector means. The ejector means is capable of mixing air with an exhaust flow from the gas turbine engine.
In a still another embodiment, means for ducting the exhaust from a gas turbine powered aircraft are provided, including an s-shaped means and an ejector means. The s-shaped means having an inlet aspect ratio less than an outlet aspect ratio.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. It should be understood that while the use of the word preferable, preferably or preferred in the description above indicates that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one,” “at least a portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.
