Patent Application
20140263737
The invention generally relates to variable area exhaust nozzles for variable cycle gas turbine engines, and more particularly to a compact system and process for actuating the variable area exhaust nozzles.
Gas turbine engines may have variable area exhaust nozzles with a convergent/divergent configuration for providing multiple nozzle positions to manage flow or control the thrust produced by the gas turbine engines. In a variable cycle engine, it might be necessary to accommodate multiple area changes in separate flow paths. The exit aperture may also be fixed, to allow for better aircraft integration. These gas turbine engines may include somewhat large and complex systems for actuating the variable area exhaust nozzles.
Therefore, a need exists for a variable internal area exhaust nozzle for a gas turbine engine that has a simple construction configured to improve overall engine performance.
While the claims are not limited to a specific illustration, an appreciation of the various aspects is best gained through a discussion of various examples thereof. Referring now to the drawings, exemplary illustrations are shown in detail. Although the drawings represent the illustrations, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of an example. Further, the exemplary illustrations described herein are not intended to be exhaustive or otherwise limiting or restricted to the precise form and configuration shown in the drawings and disclosed in the following detailed description. Exemplary illustrations are described in detail by referring to the drawings as follows:
Referring to the Figures, one exemplary exhaust nozzle (hereinafter “nozzle”) may have a three-stream variable internal flow area and fixed overall exit aperture for a high performance gas turbine engine. The nozzle may utilize a fluid circuit to operate multiple flap trains and provide a combination of flow streams to accommodate various flight operating conditions while maintaining the fixed exit aperture. While the exemplary illustration of the fluid circuit is a pneumatic circuit, the nozzle may be operated by other non-pneumatic systems, such as hydraulic circuit, and integrated in other suitable applications. Furthermore, the nozzle may include a variable exit aperture.
Referring to
As best shown in
The fixed overall exit area 116 may be sized based on a diffusion factor from the maximum area of the throat 118 to provide, for example, maximum power afterburning conditions. Therefore, this exit area may result in overexpansion of the nozzle 100 during most other operating conditions. However, the third stream may act like a supersonic ejector at these conditions, filing the plenum and minimizing the overexpansion that the primary stream would otherwise see. The result may be higher performance across vastly different flight conditions while keeping a fixed exit area. The fixed exit area may provide a clean external surface and therefore decrease drag.
The variable internal area nozzle 100 with fixed exit area 116 may be capable of high performance during various flight conditions by actuating internal nozzle geometry by the use of two sets of flaps. Furthermore, the nozzle 100 may use the engine third stream flow as a supersonic ejector at conditions where the nozzle 100 would otherwise be over expanded to minimize nozzle losses. This may alleviate the trade between cruise and after burning performance that would otherwise be expected for a fixed exit area nozzle.
The convergent and divergent flaps 108, 110 may be disposed in the variable area third stream passage 120 and configured to at least control the stream that bypasses the heat exchanger. In particular, these flaps can include one or more chambers for receiving a working fluid from a pneumatic circuit 114, which is configured to pivot the respective flaps radially inward or radially outward so as to control flow of the primary stream and the variable area third stream. For instance, each convergent flap 108 may include an opening pressure chamber 124 selectively communicating with an opening portion 126 of the pneumatic circuit 114, and the convergent flap 108 may be configured to move the convergent flap 108 radially inward in response to the opening pressure chamber 124 receiving a working fluid from the pneumatic circuit 114. Moreover, the convergent flap 108 may also have a closing pressure chamber 128 selectively communicating with a closing portion 130 of the pneumatic circuit 114, and the convergent flap is configured to move radially outward in response to the closing chamber 132 receiving a working fluid from the closing portion 130 of the pneumatic circuit 114. Each of the opening and closing pressure chambers may be configured to selectively vent working fluid when the other chamber receives working fluid from the pneumatic circuit 114. In one example, the opening chamber of the convergent flap 108 or the divergent flap 110 may be configured to vent working fluid in response to the flap moving radially outward. Moreover, the closing chamber 132 of the flaps may be configured to vent working fluid in response to the flaps moving radially inward to permit movement of the flap.
The divergent flaps 112 may have a configuration of chambers similar to the configuration of the convergent flaps 108. In particular, each divergent flap 110 may include an opening pressure chamber 124 selectively communicating with an opening portion 126 of the pneumatic circuit 114, and the divergent flap may be configured to move radially inward in response to the opening pressure chamber 124 receiving a working fluid from the pneumatic circuit 114. Moreover, the divergent flap 110 may also have a closing pressure chamber 132 selectively communicating with a closing portion 130 of the pneumatic circuit 114, and the divergent flap may be configured to move radially outward in response to the closing pressure chamber 128 receiving a working fluid from the pneumatic circuit 114. Each of the opening and closing pressure chambers may receive a partition 134 extending from the engine body that bifurcates the flaps between respective opening and closing pressure chambers. Moreover, the flaps may be configured to selectively vent the working fluid when the other chamber receives working fluid from the pneumatic circuit 114. Continuing with the previous example, the working fluid may be air vented to ambient to permit movement of the flap. It is likely that a controlled leak path in each chamber will be required to prevent overheating. However, one or both of the convergent and divergent flaps may have other suitable configurations.
Each flap may further include one or more seals 138, gaskets, O-rings or other suitable sealing mechanisms adjacent to the respective chambers to prevent the working fluid from leaking out of those chambers. The working fluid may be compressor bled air. By receiving the working fluid and changing the area of the streams, the flaps 108, 112 may act as both flow surfaces and moveable pistons. In particular, pivoting the flaps using regulated compressor bleed air may provide the ability to vary the throat and internal exit areas of the primary and third stream nozzles. The actuated flaps may be segregated from each other by, for example, pivotally attaching the convergent flaps 108 to one location in the nozzle 100 and divergent flaps 112 to another separate location in the nozzle 100. In this example, third stream flow may flow over the convergent flaps 108 that set the area for the primary stream, and the throat 118 for the primary flow area may be dictated by divergent flaps 112 hinged further downstream of the nozzle 100.
Referring to
As shown in
The convergent or primary flaps 108 may be configured to define the minimum throat area 118 of the primary stream. The divergent or secondary flaps 112 may be configured to control the area of the third stream. At maximum power takeoff conditions or afterburning conditions, the convergent flaps 108 and the divergent flaps 112 can be pivoted radially outward to substantially block the third stream to increase the jet thrust through the primary stream. The shaping of these flaps may increase the overall performance of the combined flows.
One non-limiting exemplary advantage of the nozzle 100 is that it permits immediate installation in a gas turbine engine and provides smooth fairing into the fuselage or wing that has spacing constraints. This arrangement may reduce a base drag on an aircraft and reduce complexity in the aircraft. Yet another advantage may be that the nozzle 100 may have flap trains including separate chambers configured to be efficiently sealed and further enable the use of engine air to actuate the flaps thereby eliminating the need for a separate hydraulic system and the accompanying weight. Still another advantage may be that the nozzle having a pneumatic system with conventional hydraulic actuators. Yet another advantage may be that the pneumatic circuit can use compressor bleed or fan air to purge the sealed cavities on the outboard or inboard side of each flap and thus help pressure balance between the chambers of the flap thus reducing actuator load and weight.
The nozzle may include external shaping, a shroud or other housing, which surrounds the convergent flaps and the divergent flaps and is configured to provide the fixed exit aperture of the nozzle. In this respect, the number of convergent and divergent flap pairs may be changed along with their corresponding geometric positions, while maintaining the fixed exit aperture. In one embodiment, the nozzle may have an 8-flap cyclic-symmetric configuration in which all flap hinge normal intersect at a common center. As shown in
The nozzle may have several different configurations based on the actuation and quantity of the variable area flap system.
Referring back to
It will be appreciated that the aforementioned method and devices may be modified to have some components and steps removed, or may have additional components and steps added, all of which are deemed to be within the spirit of the present disclosure. Even though the present disclosure has been described in detail with reference to specific embodiments, it will be appreciated that the various modifications and changes can be made to these embodiments without departing from the scope of the present disclosure as set forth in the claims. The specification and the drawings are to be regarded as an illustrative thought instead of merely restrictive thought.
This application claims priority to U.S. Provisional Patent Application No. 61/780,807, filed Mar. 13, 2013, and U.S. Provisional Patent Application No. 61/786,055, filed Mar. 14, 2013, now U.S. patent application No. Ser. ______, titled “COMPACT ACTUATION SYSTEM FOR FLOW NOZZLE,” and U.S. Provisional Patent Application No. 61/780,772, filed Mar. 13, 2013, now U.S. patent application Ser. No. ______, titled “THREE STREAM, VARIABLE AREA, VECTORABLE NOZZLE,” the contents of which are hereby incorporated in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61786055 | Mar 2013 | US | |
| 61780807 | Mar 2013 | US | |
| 61780772 | Mar 2013 | US |
