Variable Area And Thrust-reversing Nozzle

Abstract

A variable area, convergent-divergent, propulsion nozzle is disclosed which comprises a hooplike carrier having flaps pivoted thereon. For forward propulsion, the carrier is positioned at the outlet of a duct from which a motive fluid stream is discharged. The flaps are pivoted to form a discharge nozzle of a desired area. For reverse thrust, the carrier is spaced from the end of the duct, the flaps are swung inwardly and tabs, pivoted on the flaps, are also swung inwardly to provide substantially complete blockage of the motive fluid stream which is discharged laterally and forwardway through open blow-in doors.

Description

The invention described and claimed in the United States patent application herein resulted from work done under United States Government contract FA-SS-66-6. The United States Government has an irrevocable, nonexclusive license under said application to practice and have practiced the invention claimed herein, including the unlimited right to sublicense others to practice and have practiced the claimed invention for any purpose whatsoever.

The present invention relates to improvements in propulsive nozzles.

To obtain thrust for the propulsion of an aircraft, a motive fluid stream may be discharged from a propulsive nozzle. Such nozzles take many forms dependent on the engine generating the motive fluid stream and the mission of the aircraft.

The mission of commercial, supersonic aircraft imposes challenging requirements on the propulsive nozzles that are to be used therefor. In order to attain supersonic flight, the nozzles must be of the convergent-divergent type. For economical operation at different flight speeds, including subsonic flight, the area relationships of the nozzle must be variable. Commerical airports have relatively short runway lengths and, therefore, such nozzles must also have reverse thrust capabilities which are also necessary for ground maneuvering and may be utilized in flight. Reverse thrust can also be desirable, at times, in in-flight operation.

The provision of reverse thrust capabilities has been a challenge in subsonic aircraft and is an even greater challenge in supersonic aircraft. The requisites to be met include reliability, light weight, simplicity and high aerodynamic efficiency.

There have been several prior proposals of nozzles which have the functional capability of providing reverse thrust in a supersonic nozzle. However, these proposals have been deficient in one or more of the requisites noted above to the extent that they are not adequate for the demanding overall requirements of a commercial supersonic aircraft.

Accordingly, one object of the invention is to provide an improved nozzle having both supersonic and reverse thrust capabilities which are particularly suited to the requirements of commercial aircraft.

Another and broader object of the invention is to provide an improved nozzle having reverse thrust capability.

These ends are attained, in accordance with the broader aspects of the invention, by employing a hooplike carrier on which flap means are pivotally mounted with tab means pivotally mounted on the free ends of the flap means. This assembly is disposed at the discharge end of a duct for motive fluid and the flaps are pivoted to form a nozzle having a discharge area of a desired size for forward propulsion. For reverse thrust, this assembly is spaced from the end of the duct and the flap and tab means are swung inwardly to form a blocker which deflects the motive fluid stream laterally.

More specifically, for supersonic propulsion, an outer casing is utilized which supports a divergent nozzle extending downstream of the nozzle provided by the flap means. The motive fluid stream diverted by the blocker is discharged through open blow-in doors which also admit ambient or tertiary air into the nozzle during selected portions of forward flight.

The assembly is supported and its movement controlled by a unique linkage system which, among other things, efficiently transmits force loadings into the outer casing.

The above and other related objects and features of the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawings and the novelty thereof pointed out in the appended claims.

In the drawings:

FIG. 1 is a schematic representation, partially in section, of a gas turbine engine embodying the present invention;

FIG. 2 is an enlarged longitudinal section of a portion of the propulsive nozzle seen in FIG. 1, the nozzle being positioned for subsonic flight operation;

FIG. 3 is a section similar to FIG. 2 illustrating the position of the nozzle for supersonic propulsion;

FIG. 4 is a section similar to FIG. 2 illustrating the thrust reverse position of the nozzle;

FIG. 5 is a section taken generally on line V--V in FIG. 4; and

FIG. 6 is a section taken generally on line VI--VI in FIG. 2;

FIG. 7 is an enlarged illustration similar to FIG. 2.

FIG. 1 briefly illustrates a gas turbine engine having supersonic propulsion capability. Air enters an inlet 10 comprising an axisymmetrical spike 12. The majority of this air is further pressurized by a compressor 14. A small percentage of the air bypasses the compressor as "secondary air" flowing through the space between the engine compressor casing 16 and an outer casing or pod 18. The secondary air flows downstream to be employed for purposes later referenced. The air pressurized by the compressor 14 supports combustion of fuel in a combustor 19 in the generation of a hot gas stream. A portion of the energy of this hot gas stream drives a turbine 20 which is connected to the rotor of the compressor 14 by a shaft 21. The hot gas stream discharged from the turbine 20 may be augmented by the combustion of further fuel in an afterburner 22. The hot gas stream (motive fluid stream) is then discharged through a propulsion nozzle 24 which comprises a convergent, primary nozzle 26 and a divergent, secondary nozzle 28. The primary and secondary nozzles 26, 28 are of the variable geometry type and will be described in greater detail later.

In operation the hot gas stream is usually augmented only during periods where a relatively high thrust output is required. The discharge areas of the primary and secondary nozzles are varied in area to match the performance conditions of the engine in operation. Further, in subsonic propulsion, particularly, it is desirable that ambient air be introduced into the interior of the nozzle. This is provided for by blow-in doors 30 which are spaced around the exterior of the pod 18 adjacent the upstream end of the secondary nozzle 28. When it is desired to introduce ambient or tertiary air into the nozzle, the doors swing inwardly for the introduction of such air.

Reference will now be made to FIGS. 5, 6 and 7 for a more detailed description of the propulsion nozzle 24. The primary nozzle 26 comprises a convergent duct section 32 of the engine casing 16 and a plurality of pivotal flaps 35, 36. These flaps are supported from a carrier ring 38 by brackets 40 which have legs 48. Pins 50 pivotally mount the flaps 34 and 36 on the bracket legs 48. The brackets 40 further include ribs 42 spanning the lower ends of the legs 48 and an outwardly spaced baffle 44. The baffles 44 guide secondary air over the outer surfaces of the flaps 34, 36 to provide a cooling effect.

This ring and flap assembly is supported by links 52 which are, respectively, pivotally connected to the flaps 34 by pins 54. The links 52 extend outwardly to lugs 56 projecting from an actuation ring 58 and are pivotally connected thereto by pins 60. The actuation ring 58 is connected to the rods 62 of a plurality of longitudinally extending actuators 64 (FIG. 1) (only one of which is shown, the remainder being angularly spaced around the nozzle). The cylinders of these actuators are mounted on the frame structure of the pod or outer casing 18. The primary nozzle 26 is thus mounted in bicycle spoke fashion for axial movement in a fashion later described.

The flaps 36 overlap the inner surfaces of the flaps 34 and are normally held thereagainst by the pressure of the hot gas stream. This pressurized engagement provides an effective seal between adjacent flaps. In order to prevent uncontrolled movement of the flaps 34, hooks 63 (FIG. 3) are provided on their outer surfaces. These hooks overlie extensions of the shafts 54 from the adjacent flap 34.

THe pod or outer casing 18 comprises triangular beams 66 extending between the blow-in doors 30 to structural elements which form and support the secondary nozzle 24.

Ramps 70 angle inwardly from the downstream ends of the openings 71 for the blow-in doors 30 and blend with a surface of revolution 72 forming the throat of the secondary nozzle 28. When the doors 30 are swung inwardly, this structure provides a passageway between the exterior of the nozzle and the juncture between the primary and secondary nozzles.

The secondary nozzle may be of the aerodynamically positioned type comprising an outer set of flaps pivotally mounted on the pod 18 and an inner set of flaps. The inner set of flaps would be pivotally connected to the downstream ends of the outer flaps and extend toward the throat of the secondary nozzle for guided movement in a known fashion. The described structure also defines an annular chamber or interior within which the actuators 64 are mounted.

Reverting back to the primary nozzle 26, it will be seen (FIG. 5) that the links 52 extend through slots 73 in the surface 72 and that alternate links 52 are extended outwardly of the pins 60. Rolls 74 are mounted on these extensions and ride in a fixed cam track 76 which is secured to the pod 18. The cam track 76 controls movement of the flaps 34, 36 as will be later described.

A triangular tab 78 is pivotally mounted at the free end of each flap 34 by a pin 80. The tabs 78 are respectively connected to the supporting links 52 by links 82 which are pivotally connected thereto at their opposite ends.

A final linkage arrangement comprises links 84, pivotally connected to the ring 38 and to closure flaps 86. The latter are pivotally mounted on posts 88 secured to the beams 66.

In subsonic and supersonic operation, the bracket ribs 42 sealingly engage a flange 90 at the downstream end of the fixed duct portion 32. This position of the carrier ring 38 will be maintained through a substantial range of the synchronized travel of the actuator rods 62. As such travel occurs, the gas stream pressure on the flaps 34, 36 acts outwardly forcing the primary nozzle assembly against the flange 90 as the flaps 34, 36 are pivoted to vary the discharge area of the primary nozzle in accordance with the requirements of the engine's operating conditions.

As the primary nozzle area is varied between the described subsonic and supersonic positions, the tabs 78 are angled toward the throat of the secondary nozzle so as to have a minimal effect on the aerodynamic performance of the hot gas stream. The angular spacing of the tabs 78 also facilitates entry of tertiary air when the blow-in doors 30 are open.

Further retraction of the actuator rods 62 from the supersonic position of FIG. 3 causes the primary nozzle to be deployed in its reverse thrust position of FIG. 4. In traveling to this position, the cam rolls 74 engage the lower surfaces of the cams 76 to pivot the links 52 in a counterclockwise direction. This in turn pivots the flaps 34, 36 inwardly against the pressure of the hot gas stream. At the same time the support ring 38 is displaced in a downstream direction until projections 92 extending therefrom, engage stops 75. After the travel of the support ring 38 is thus limited, the rods 62 displace the actuation ring 58 a slight distance further in a downstream direction. This spaces the rolls 74 from the surfaces of cams 76 so that the sustained loadings of reverse thrust are carried into the structural elements of the pod 18 through the actuators 64.

It will also be apparent that when the primary nozzle is deployed in its reverse thrust position, the tabs 78 are swung inwardly so that they provide, in combination with the flaps 34 and 36, substantially complete blockage of the hot gas stream. The hot gas stream is thus deflected laterally and discharged forwardly through the openings 71 of selected blow-in doors which are swung inwardly by means not shown.

In the reverse thrust position, it will also be seen that the closures 86 are swung into the openings 73. Further, a circumferential seal 94, on the ring 38, engages the surface 72 and the closures 86. All of this minimizes leakage of the hot gas stream, particularly into the interior of the secondary nozzle where the actuators 64 are mounted.

When the rods 62 are extended to return the primary nozzle to its supersonic and subsonic positions, the rolls 74 engage the upper surface of cam 76, initially to swing the links 52 in displacing the support ring in an upstream direction. The cam 76 has primary control of the position of the links 52 only when the ring 38 is being displaced to and from its extreme positions. However, the cams are coextensive with the full paths of movement of the rolls 34 maintaining control of the flap system in the event of a loss of gas pressure on the flaps.

Various modifications of the described embodiment will be apparent to those skilled in the art with the scope of the present inventive concepts which is therefore to be derived solely from the following claims.

Claims

Having thus described the invention, what is claimed as novel and desired to be protected by Letters Patent of the United States is:

1. A propulsion nozzle system comprising:

a duct having an outlet from which a motive fluid stream is discharged,

a ringlike carrier engageable with the outlet of said duct,

flap means pivotally mounted around said carrier and extending generally in a downstream direction,

tab means pivotally mounted on said flap means,

means for selectively positioning said carrier (a) in engagement with the duct outlet and pivoting the flap means so that they function as a nozzle having a discharge area of a desired size and (b) in spaced relation from the duct outlet and pivoting said flap and tab means inwardly to form a blocker which deflects the motive fluid stream laterally.

2. A propulsion nozzle system as in claim 1 wherein

the positioning and pivoting means include means for angling the tab means outwardly of the hot gas stream when the carrier is in engagement with the casing outlet.

3. A propulsion nozzle as in claim 1 wherein

the flap means comprise a plurality of overlapping, generally rectangular flaps, and

the tab means comprise triangular tabs pivotally mounted, respectively, on alternate flaps.

4. A propulsion nozzle as in claim 1 which is of the convergent-divergent type with the nozzle formed by the flaps being the primary nozzle, and further comprising

an outer casing surrounding the engine, casing,

a secondary nozzle mounted on said outer casing and extending downstream of the primary nozzle,

blow-in doors mounted on said outer casing, and

passageway means, from the juncture of said nozzles to said blow-in doors for the introduction of tertiary air into the nozzle and discharge of the hot gas stream when it is deflected laterally by the flap and tab means.

5. A propulsion nozzle as in claim 4 wherein:

said passageway means includes an inner surface of revolution leading to the throat of the secondary nozzle and defining, in part, chamber means on said casing, and

the positioning and pivoting means include linkage means supporting the carrier and flap assembly and actuators mounted on said outer casing.

6. A propulsion nozzle as in claim 5 wherein:

the surface of revolution has longitudinal slots through which a portion of the linkage means extend and the actuators are mounted in said outer casing chamber, and

further including a circumferential seal on said ring engaging said surface of revolution when the flaps and tabs form a blocker,

closures for said slots, and

means for swinging said closures into said slots between the upstream ends thereof and said circumferential seal when the flaps and tabs form a blocker,

thereby sealing the hot gas stream, in reverse thrust flow, from the casing chamber.

7. A propulsion nozzle as in claim 5 wherein:

the linkage means comprise a plurality of supporting links pivotally connected at their inner ends to the flap means and extending radially outwardly and an actuation ring with said outer casing chamber, said supporting links being pivotally connected to the actuation ring and said actuators also being connected to said actuation ring as well as the outer casing.

8. A propulsion nozzle as in claim 7 wherein:

the flap means comprise a plurality of overlapping, generally rectangular flaps,

the tab means comprise triangular tabs pivotally mounted, respectively, on alternate flaps,

the supporting links are, respectively, connected to each alternate flap,

the linkage means comprise a link extending from each supporting link to the associated tab.

9. A propulsion nozzle as in claim 8 wherein:

the linkage means include cam means cooperating with at least some of the supporting links for imparting pivotal movement thereto and swinging the flaps and tabs relative to the carrier as the carrier is moved to and from its extreme positions.

10. A propulsion nozzle as in claim 9 wherein:

the surface of revolution has longitudinal slots through which said supporting links extend and the actuators are mounted in said outer casing chamber, and

further including a circumferential seal on said ring engaging said surface of revolution when the flaps and tabs form a blocker,

closures for said slots, and

means for swinging said closures into said slots between the upstream ends thereof and said circumferential seal when the flaps and tabs form a blocker,

thereby sealing the hot gas stream, in reverse thrust flow, from the casing chamber, and

projections on said carrier engageable with abutments on the outer casing to limit the travel of said carrier and space the carrier a predetermined distance from the duct outlet,

said actuators having a travel sufficient to continue displacement of said actuation ring and disengage the supporting links from the cam means when the carrier is so positioned.