Abstract:
A variable area nozzle comprising a concentric support and a plurality of convexly contoured self sealing vanes is disclosed and claimed. The vanes are circumferentially and rotatably mounted to the concentric support forming a nozzle infinitely positionable between a first position corresponding to a minimum area nozzle and a second position corresponding to a maximum area nozzle. A closer, which is preferably a shape memory alloy (SMA), urges the nozzle toward the first position corresponding to a minimum area nozzle. Periodically spaced openers act between adjacent vanes to urge the nozzle to a second position corresponding to a maximum area nozzle.

Description:
ORIGIN OF THE INVENTION 
   The invention described herein was made by employees of the United States Government, and may be manufactured and used by the government for government purposes without the payment of any royalties therein and therefor. 

   FIELD OF THE INVENTION 
   The field of the invention is variable area nozzles for use in connection with gas turbine engines. However, the invention may be used on other applications where dynamic flow control is needed, for example, hydraulic applications. 
   Background of the Invention 
   U.S. Pat. No. 6,318,070 B1 issued Nov. 20, 2001 to Rey et al. entitled Variable Area Nozzle For Gas Turbine Engines Driven By Shape Memory Actuators discloses a variable area nozzle having a plurality of flaps actuated by shape memory alloy (SMA) actuators to vary fan exit nozzle area. See,  FIGS. 1 and 2 . The plurality of flaps are sealed therebetween by a seal (not illustrated) to minimize air leakage. See, col. 6, lns. 53-55 of the &#39;070 patent to Rey et al. As the flaps of the &#39;070 patent are moved from the cruise position (i.e., nozzle has the minimum cross-sectional area) to the landing position (i.e., nozzle has the maximum cross-sectional area) the opening between the flaps increases and sealing becomes a more difficult problem as the gap between the flaps increases. 
   The &#39;070 patent to Rey et al. includes a good discussion of conventional gas turbine engines. Referring to  FIG. 3 , conventional gas turbine engines include a fan section and core section (core engine). The core engines provide the primary thrust of turbojet engines whereas the bypass provides the primary thrust in turbofan engines. Still referring to  FIG. 3 , reference numeral  302  represents flow of air through the fan section and reference numeral  303  represents flow of combustion products through the core engine. The fans section and the core engine are disposed sequentially about a longitudinal axis and are enclosed in a nacelle. An annular path of air passes through the fan section of the gas turbine engine and exits through the fan nozzle formed by the nacelle and the core engine. Fan nozzles of conventional gas turbine engines have fixed geometry. The &#39;070 patent to Rey et al. addresses a modification to the fixed geometry. 
   Requirements for take-off and landing conditions are different from requirements for the cruise condition. It is desirable to have a smaller diameter fan nozzle for increasing cruise efficiency and performance. Take-off and landing conditions require a larger diameter fan nozzle. Fixed geometry nozzles represent compromises between the requirements for take-off and landing in an attempt to satisfy both conditions. 
   Referring to  FIG. 1 , a partial cross-sectional cut away view  100  of the Rey et al &#39;070 patent gas turbine engine  10  taken from the &#39;070 patent  FIG. 1  is illustrated. Fan section  12  and core engine  14  are illustrated as being disposed sequentially along a longitudinal axis  16 . Reference numeral  18  indicates the outer housing of the gas turbine which is known as the nacelle  18 . Primary air flow  20  passes through the core section and generates primary thrust  22 . Fan exit nozzle  36  is illustrated as being a variable area nozzle  30  located in a downstream portion of the nacelle. A plurality of flaps  38  are illustrated. An annular path of fan flow  24 , disposed radially outward of the path of the primary air flow  20 , bypasses the core engine  14  and flows through the fan section  12 , generating fan thrust  26 . See, the &#39;070 patent, col. 3 lns. 20 et seq. 
   Referring to  FIG. 2 , a partial cross-sectional view  200  taken from the prior art &#39;070 patent to Rey et al., “each actuating mechanism  40  includes a four bar linkage [ ] comprising a drive or output arm  54  pivotally connected by means of pivots  56 ,  58  to the flap actuating portion  48  and to a link  60 , respectively. The four bar linkage [ ] also includes a fixed member  62  that extends from the nacelle  18 . The flap actuating portion  48  and the link  60  are pivotally attached to the fixed member  62  by means of pivots  64 ,  66 , respectively. Pivot  64  functions as a hinge for the flap  38 . The actuating mechanism  40  also includes a SMA actuator  68  engaging the drive arm  54  of the four bar linkage [ ]. In the preferred embodiment of the [ ] [Rey et al &#39;070 patent] the SMA actuator  68  comprises a plurality of strands [ ] forming an array [ ].” See, col. 3 lns. 49 et seq. 
   Still referring to  FIG. 2 , “each return mechanism  42 , according to one embodiment of the present invention, comprises a spring  84  disposed about a shaft  86  which is anchored to the spring  84  disposed about a shaft  86  which is anchored to the spring  84  disposed about a shaft  86  which is anchored to the nacelle  18  on one end thereof and pivotally attaching to a first bracket  88  on the other end thereof by means of a pivot  90 . The first bracket  88  is pivotally affixed to the nacelle  18  and to a second bracket  92  by means of pivots  94 ,  96 , respectively. The flap actuating arm  48  is also pivotally attached to the second bracket  92  by means of a pivot  98 .” See, col. 4, lns. 21 et seq. 
   In the Rey et al. &#39;070 patent, the variable area nozzle uses a mechanical device with a locking pin which may be prone to binding to hold the rotating vanes in position. This design places a pair of SMA wire ropes (one used for opening and the other for closing) at the hinge point which translates into more SMA wire rope needed to overcome the hinge moment and thus added weight. Finally, the vanes are not self sealing but use an elastomeric seal between the vanes. At wide degrees of opening sealing is more difficult. 
     FIG. 3  is a prior art representation  300  of a gas turbine engine. Nacelle  301  is illustrated and fixed bypass nozzle area  302  is illustrated. Reference numeral  303  represents hot core engine gases exiting the core engine nozzle. 
   United States Patent Application Publication No. US 2002/0125340 A, inventors Birch et al., discloses a gas turbine engine exhaust nozzle having tabs extendable between a first deployed position and a second non-deployed position. United States Patent Application Publication No. US 2002/0125340 A at page 1 thereof discusses many exhaust noise problems associated with jet engine operation. 
   UK Patent Application GB 2355766, inventors Strange et al., applicant Rolls-Royce plc, discloses angle tabs having V-shaped nozzles therebetween. 
   There is a need for a lighter weight, self sealing variable area nozzle for use in connection with aircraft. Further, there is a need for fail safe operation such that the variable area nozzle fails in the open (largest area diameter) position. Finally, there is a need for a variable area nozzle whose concentricity is mechanically controlled and whose position is reliably controlled and/or reliably locked. 
   Further, there is a need for a variable area nozzle having a minimum number of vanes. Further is a need for a variable area nozzle closer which maximizes the counter hinge moment. 
   A better understanding of the invention will be had when reference is made to the SUMMARY OF THE INVENTION, BRIEF DESCRIPTION OF THE DRAWINGS, DESCRIPTION OF THE INVENTION and CLAIMS which follow hereinbelow. 
   SUMMARY OF THE INVENTION 
   The present invention is a variable area nozzle which utilizes vanes which are self sealing. The present variable area nozzle includes (1) rigid, self sealing interengaging vanes which form the nozzle; (2) magneto-rheological dampers, brakes and holding devices for positioning the nozzle; (3) closers including SMA wire actuation closers; and, (4) openers including fail-safe opening devices. 
   Vanes 
   A plurality of 18 vanes are rotatably and circumferentially mounted on a concentric support which may be mounted on a nacelle of a gas turbine engine or some other device. It will readily be recognized by those having skill in the art that a different number of vanes may be used without departing from the spirit and the scope of the claims which are set forth below. The invention as disclosed herein may employ fewer or more vanes as the situation requires. 
   Vanes composed of lightweight material for example Aluminum, DRA (Discontinuous Reinforced Aluminum), PMC (Polymeric Matrix Composite), MMC (Metal Matrix Composite), and CMC (Ceramic Matrix Composite) vanes may be used in gas turbine engine applications. Other flow control applications may use substantially different material. Although this invention is primarily directed toward use in connection with gas turbine engines, the principles taught herein are equally applicable to several and varied engineering disciplines. 
   Each vane interengages its neighboring vane in its range of motion which varies between a first position corresponding to a nozzle having a minimum cross-sectional area to a second position corresponding to a nozzle having a maximum cross-sectional area. The vanes have interior and exterior surfaces with interior surfaces defined as those facing the interior of the gas turbine engine within which they are mounted. Exterior surfaces are those facing outwardly from the gas turbine engine. Each surface of the vane includes a convex contour which contributes to the concentricity of the vanes and hence the nozzle over its full range of opening and closing. Convex is determined from the orientation outside (to the exterior of) the variable area nozzle. Each vane includes two tongues and two grooves which coact with reciprocal tongues and grooves of the adjacent vanes. Male vanes include a uniform interior surface (i.e., a surface without grooves) and female vanes include a uniform exterior surface (i.e., a surface without grooves). Male vanes each include an exterior surface which has two grooves and female vanes each include an interior surface which has two grooves. All of the grooves are generally arranged as non parallel legs of a trapezoid. 
   Those skilled in the art will readily recognize that various types and geometries of tongue and groove interengaging vanes may be used without departing from the spirit and scope of the invention. 
   Each vane is supported by a tapered stiffener and includes a leading edge and a trailing edge. All of the tapered stiffeners are generally arranged as non parallel legs of a trapezoid. The leading edge of the vane is thicker than the trailing edge of the vane. Interior and exterior surfaces of the vanes are affixed to the tapered stiffeners within the vanes. Alternatively, the vanes including the tapered stiffeners may be cast using the lost wax investment casting process or some other casting process. There are preferably two to four tapered stiffeners within the vanes although different numbers of tapered stiffeners may be used. 
   Closers 
   Fluid flow though a nozzle converts the energy of the fluid to kinetic energy. Pressure is exerted outwardly on the nozzle and the closer must counteract this pressure. Since the vanes of the nozzle are rotatably mounted to a support mounted to the gas turbine engine, a moment is created by the pressure applied to the vanes. The closer counteracts this moment and is responsible for narrowing the variable area nozzle. Many different materials may be used as the closer. Preferably the closer is an SMA (shape memory alloy) rope which is laced through apertures in the individual vanes which comprise the nozzle. Apertures are radially spaced in the tapered stiffeners of the vanes to enable counteraction of the moment created by the opening forces. The opening forces include the wind or outward pressure on the nozzle coupled with the force of the spring or other opener (discussed hereinbelow). 
   The SMA (shape memory alloy) may be a wire, a plurality of wires, or a rope which extends through each and every one of the vanes circumferentially mounted on the support. Electrically nonconductive standoffs or insulators are used to secure the SMA (shape memory alloy) inside the vanes. A plurality of 18 vanes extend 360 degrees around the circumference of a support which is concentric with a nacelle of a gas turbine engine. 
   Alternatively, the support may itself be pivotably attached to the nacelle enabling vectoring of the engine thrust. This alternative may also be effected in the application of the invention to the core engine. 
   Optionally, vanes adapted for cooling may be used on the engine core. Optionally, vanes having extenders to change the length of the vanes may be employed. Optionally, vanes having different lengths may be employed. 
   The SMA wires or ropes extend 360 degrees within the vanes and function to close the nozzle when the SMA wires or ropes are heated. Heating of the SMA material is accomplished by applying a voltage (DC or AC) to it causing it to contract. Other means of heating the SMA material may be used. Although SMA wire ropes are the preferred material for the closer, other materials such as an ordinary metallic, polymeric, or synthetic wire or plastic rope may be used. 
   Optionally, a hydraulically based or a mechanically based device may close the vanes of the nozzle. Such a device is not necessary on every vane as the contoured vanes each include tongues and grooves on respective vanes which urge adjacent vanes closed. Thus uniform and concentric closing occurs. 
   Openers 
   An opener, a leaf or coil spring, is employed between the tapered stiffeners of the individual vanes to assure fail-safe opening. Opener must be able to open in a dynamic or static situation. One portion of a leaf spring may be welded or otherwise secured to the outer portion of a stiffener of a vane and the other portion of the spring acts against the outer portion of the stiffener of the adjacent vane. Another embodiment includes a coil spring secured to the outer portions of stiffeners of adjacent vanes. Selection, sizing and placement of the spring are dependent upon the particular application of the variable area nozzle. 
   Springs are fail-safe openers which position the nozzle in the maximum open position. Springs may be employed between all vane to vane interfaces or they may be employed periodically around the circumference of the nozzle. Since the entire nozzle is comprised of interengaging contoured vanes each having tongues and grooves, the spring force between two vanes has the tendency to open vanes adjacent to those two vanes. Thus with sufficient sizing and placement of the springs, uniform concentric opening of the nozzle occurs. 
   Another embodiment of the invention includes the use of hydraulic actuators for opening the vanes. 
   Brakes and Dampers 
   A magneto-rheological brake/device acting primarily in compression is preferably mounted about the pivot axis of one or more of the vanes of the nozzle. The magneto-Theological device further acts as a damper as the viscosity of the fluid is varied as the magnetic field about the brake is increased or decreased. The magneto-rheological brake/device further acts as a locking device to maintain the vanes in the desired position such as at cruise altitude or in a cruise condition. 
   It is an object of the present invention to provide a concentric self sealing variable area nozzle. 
   It is an object of the present invention to provide self-sealing interengaging vanes which form the variable area nozzle. 
   It is a further object of the present invention to provide a variable area nozzle which includes a magneto-rheological damping, brake and/or holding device for position control of the nozzle. 
   It is a further object of the present invention to provide a closer for varying the position of the nozzle against the force of an opening device and/or internal fluid pressure. It is a further object of the present invention to preferably provide a SMA (shape memory alloy) closer comprised of wires or ropes for weight advantage. 
   It is a further object of the present invention to provide a fail safe opener. 
   It is a further object to provide a process for controlling the positioning of the variable area nozzle. 
   It is a further object of the present invention to provide a smart, self-sealing variable area nozzle. 
   It is a further object of the present invention to provide a variable cross-section area nozzle which allows dramatic dynamic flow changes. 
   It is a further object of the present invention to reduce gas turbine engine noise and increase gas engine turbine thrust. 
   It is an object of the present invention to protect the actuating system (i.e, SMA wires) from external damage. 
   It is a further object of the present invention to enable placement of the SMA actuator (closer) at a position that maximizes the hinge moment thus minimizing the required actuation force (i.e., the number of SMA wires within the rope/bundle) thereby decreasing weight while still maintaining a specified life requirement. 
   It is a further object of the present invention to provide a variable area nozzle which is concentric with each vane opening and closing in unison with the other vanes. 
   It is a further object of the invention to provide a smart material torsional or axial magneto-rheological braking system that can be either a fail-safe or non-fail safe braking system. The torsional brake is described in our copending patent application filed simultaneously with this patent application. The purpose of the magneto-rheological braking system is to enable position control and nozzle opening speed by using the variable viscosity magneto-rheological fluid within the braking system. 
   These and other objects will be best understood when reference is made to the BRIEF DESCRIPTION OF THE DRAWINGS, DESCRIPTION OF THE INVENTION, AND CLAIMS which follow hereinbelow. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a prior art illustration taken from the &#39;070 patent to Rey et al. of a gas turbine engine. 
       FIG. 2  is a prior art illustration taken from the &#39;070 patent to Rey et al. of a flap on the nacelle of a gas turbine engine. 
       FIG. 3  is a prior art representation of a gas turbine engine. 
       FIG. 4  is a schematic representation of a nacelle of a gas turbine engine and a schematic representation of the present invention mounted to the nacelle.  FIG. 4  illustrates the vanes in first position of minimum cross-sectional area. 
       FIG. 4A  is an end view of  FIG. 4  taken along the lines  4 A- 4 A. 
       FIG. 4B  is an enlarged schematic of one embodiment of the present invention mounted to a nacelle. 
       FIG. 4C  is a schematic of a second embodiment of the present invention mounted to a nacelle. 
       FIG. 4D  is a schematic of the second embodiment of the present invention mounted to a nacelle taken along the lines  4 D- 4 D of  FIG. 4C . 
       FIG. 4E  is a schematic of a third embodiment of the present invention mounted to a nacelle. 
       FIG. 4F  is a schematic of a fourth embodiment of the present invention illustrating a piston actuator in combination with a vane having 4 tapered stiffeners. 
       FIG. 5  is a schematic representation of a nacelle of a gas turbine engine and a schematic representation of the present invention mounted to the nacelle.  FIG. 5  illustrates the vanes in the second position of maximum cross-sectional area. 
       FIG. 5A  is an end view taken along the lines  5 A- 5 A of  FIG. 5 . 
       FIG. 5B  is an illustration of the exterior of two adjacent vanes in the fully closed position, namely, when the nozzle has minimum cross sectional area. 
       FIG. 5C  is a perspective view of a leaf spring. 
       FIG. 5D  is an illustration of two adjacent vanes similar to  FIG. 5B  employing a coil spring as the opener. 
       FIG. 5E  is a schematic illustration of the invention used in the core exhaust stream. 
       FIG. 6  is an illustration of three adjacent self-sealing vanes. 
       FIG. 6A  is an enlargement of a portion of  FIG. 6  illustrating the vanes in a relatively open position. 
       FIG. 6B  is an enlargement of a portion of  FIG. 6  illustrating the vanes in a relatively closed position. 
       FIG. 6C  is an illustration of asymmetric sealed vanes. 
       FIG. 6D  illustrates a metal to metal seal arrangement. 
       FIG. 6E  illustrates a supplemental brush seal arrangement. 
       FIG. 6F  illustrates a supplemental hydrostatic seal arrangement. 
       FIG. 6G  illustrates a supplemental elastomeric seal arrangement. 
       FIG. 7  is a perspective view of the exterior side of the male vane. 
       FIG. 7A  is a perspective view of the exterior side of the male vane similar to that illustrated in  FIG. 7  with an optional access window. 
       FIG. 7B  is a perspective view of the interior side of the male vane. 
       FIG. 7C  is a side view of the male vane illustrated in  FIG. 7 . 
       FIG. 7D  is a schematic illustration of an insulated conductor (i.e., an SMA wire). 
       FIG. 8  is a view of the leading edge of the male vane taken along the lines  8 - 8  of  FIG. 7  illustrating the inner or inside portion of the male vane. 
       FIG. 8A  is an enlargement of a portion of  FIG. 8 . 
       FIG. 9  is a view of the trailing edge of the male vane taken along the lines  9 - 9  of  FIG. 7 . 
       FIG. 9A  is an enlargement of a portion of  FIG. 9 . 
       FIG. 10  is a perspective view of the exterior of a female vane. 
       FIG. 10A  is a perspective view of the exterior of a female vane similar to that illustrated in  FIG. 10  with an optional access window. 
       FIG. 10B  is a perspective view of the interior of a female vane. 
       FIG. 11  is a view of the leading edge of the female vane taken along the lines  11 - 11  of  FIG. 10  illustrating the inner or inside portion of the female vane. 
       FIG. 11A  is an enlargement of a portion of  FIG. 11 . 
       FIG. 12  is a view of the trailing edge of the female vane taken along the lines  12 - 12  of  FIG. 10 . 
       FIG. 12A  is an enlargement of a portion of  FIG. 12 . 
       FIG. 13  is a schematic representation of a vane extender used to enhance noise reduction. 
       FIG. 14  is a block diagram of a control system for the controlling the variable area nozzle of the present invention. 
   

   A better understanding of the invention will be had when reference is made to the following DESCRIPTION OF THE INVENTION and CLAIMS. 
   DESCRIPTION OF THE INVENTION 
     FIG. 4  is a schematic representation  400  of a nacelle  405  of a gas turbine engine and a schematic representation of the present invention mounted to the nacelle  405 .  FIG. 4  illustrates vanes  401 ,  402 ,  403  and  406  in first position of minimum cross-sectional area D 1 . Support  404  is affixed to the nacelle  405 . Optionally, support  404  may pivot to enable vectoring of the thrust of the engine. Vanes  401  etc. are rotatably mounted to support  404 .  FIG. 4A  is an end view  400 A of  FIG. 4  taken along the lines  4 A- 4 A of  FIG. 4  illustrating, among other things, the interior  407  of the nozzle. In  FIGS. 4 and 4A , the tongues and grooves of each vane are fully engaged with the respective tongues and grooves of the adjacent vanes. 
     FIG. 4B  is an enlarged schematic  400 B of one embodiment of the present invention mounted to a nacelle  405  by support  404 . Seal  420  is diagrammatically illustrated in  FIG. 4B  for sealing the interengaging vanes  401 ,  402 ,  403  and  406 . Hinge pairs  408  and  409  on the vanes coact with hinge pairs  410  and  411  on support  404 . Shafts  412  are fixed to hinges  408  and  409  on the vanes. Torsional magneto-rheological brake  415  operates on one of the shafts  412 . Preferably there are 6 magneto-rheological brakes  415  equally spaced around the 360 degree circumference of the support  404 . However, depending upon the application there may be fewer or more brakes. 
     FIG. 4C  is a schematic  400 C of a second embodiment of the present invention mounted to a support  404 A which in turn is affixed to a nacelle  405 A.  FIG. 4D  is a schematic  400 D of the second embodiment of the present invention mounted to a support  404 A which in turn is affixed to a nacelle  405 A taken along the lines  4 D- 4 D of  FIG. 4C . A magneto-rheological brake  425  of the type disclosed in our copending application filed simultaneously with this application operates on shaft  443  which is secured to adapters  442  and  444  by set screws  422 . Adapters  442  and  444  pass through hinges  441  and  445  affixed to support  404 A and are rotatable with respect to said hinges  441  and  445 . Shaft  443 , which may be splined, could alternatively be directly connected to hinges  440 ,  440 A. 
   Adapter  444  may be connected to another shaft or another adapter  450  as set forth in  FIG. 4D  by union  446 . Also illustrated in  FIG. 4D  are hinges  448  and  449 . Referring still to  FIGS. 4C and 4D , reference numeral  430  schematically illustrates vane  430  and elastomeric seals  420 A,  460  which prevent the escape of fluid (i.e. air, hot gases etc.) upon rotation of the vane  430 . Exterior portion  430 A and interior portion  430 B of vane  430  are illustrated in  FIGS. 4C and 4D . In  FIG. 4D  the curvature of the vane  430  is illustrated in phantom. 
     FIG. 4E  is a schematic  400 E of a third embodiment of a vane  430  of the present invention mounted to a nacelle  405 A through support  404 A. Actuator  451  may be a linear magneto-rheological brake or it may be a hydraulic actuator. In the embodiment of  FIG. 4E , a pivot  454  is affixed to the vane  430  and another pivot  452  is affixed to the nacelle  405 A. Actuator  451  includes corresponding pivot  455  for coaction with pivot  454  and corresponding pivot  453  for coaction with pivot  452 . Arm  456  variably extends to deploy the infinitely positionable variable area nozzle to the desired position between minimum cross-sectional area and maximum cross sectional area. 
     FIG. 4F  is a schematic  400 F of a fourth embodiment of the present invention illustrating a piston actuator  465  in combination with a vane  430  having 4 tapered stiffeners,  466 ,  467 ,  468 , and  469 . The stiffeners  467 ,  468  are parallel with respect to each other while stiffeners  466 ,  469  are oriented as non parallel legs of a trapezoid. Positioned within vane  430  is a support  462  which includes a pivot  463  connected to piston  465 . Piston  465  may be a hydraulically actuated piston or it may be a axial magneto-rheological device. Piston  465  includes a moveable and pivotable rod  461  as described in connection with  FIG. 4E . 
     FIG. 5  is a schematic representation  500  of a nacelle  405  of a gas turbine engine and a schematic representation of the variable area nozzle of the instant invention mounted to the nacelle  405 .  FIG. 5  illustrates the vanes  401 ,  402 ,  403  etc. in the second position of maximum cross-sectional area D 2 . In this position, the gas turbine engine is not operating as efficiently as possible but noise is reduced by enlarging the cross-section of the bypassed flow, that is the flow through the bypass nozzle area. Reference numerals  561 ,  562  illustrate the interengagement sealing of vanes  402  and  403  viewed from outside the nozzle. Although the nozzle is illustrated in its fully open position of maximum cross sectional area D 2 , it is completely sealed. In fact, it is self sealing as will described in greater detail hereinbelow. Referring to  FIG. 5A , similarly, reference numerals  563  and  564  illustrate the interengagement of vanes  402  and  403  viewed from inside the nozzle. 
     FIG. 5A  is an end view  500 A taken along the lines  5 A- 5 A of  FIG. 5 . D 2  as illustrated in  FIG. 5A  is larger than D 1  as illustrated in  FIG. 4A . 
     FIG. 5B  is an illustration  500 B of the exterior of two adjacent vanes  501 ,  502  in the fully closed position, namely, when the nozzle has minimum cross sectional area D 1 . In other words,  FIG. 5B  is an illustration of a portion of the nozzle as viewed from outside the nozzle. A leaf spring  504  is employed as an opener.  FIG. 5C  is a perspective view  500 C of a leaf spring  504 . Another leaf spring is illustrated affixed to stiffener  523  which operates between vane  502  and the adjacent vane which is not shown. 
   Vane  501  is a female vane and vane  502  is a male vane as defined by the extent of their interior surfaces as will be discussed below in connection with  FIGS. 7 and 10 . It will be noticed that the exterior of vane  501  is substantially trapezoidally shaped as indicated by lines  580 ,  580 A. Vane  502  is substantially trapezoidally shaped as well as indicated by line  505 . The left most extent of vane  502  resides near line  506  which indicates a stiffener in phantom. The left most extent of vane  502  is not illustrated in FIG.  5 B so as to enhance the clarity of the illustration. All vanes employed are substantially trapezoidally shaped. Those skilled in the art will readily recognize that other vane profiles may be used other than a profile which is substantially trapezoidally shaped. For instance, vanes which are substantially rectangularly shaped may be employed. 
   Leaf spring  504  is affixed  503  to tapered stiffener  522  and includes an end portion which engages stiffener  521  which is illustrated in phantom. Springs between each and every vane are not necessary in all nozzle applications and as such they may be placed between every other vane or every third vane or spaced in some other fashion. 
   Reference numerals  580  and  580 A define the extent of the exterior surface of female vane  501 . Reference numerals  580 A and  580 B define the extent of the exterior surface of male vane  502 . 
   Vane  501  includes support rails  520  and  521  which are tapered support rails or stiffeners arranged in the configuration of non parallel legs of a trapezoid. They are illustrated in  FIG. 5B  in phantom as they reside between the exterior and interior surfaces of the vane  501 . Preferably vanes  501 ,  502  are made of Aluminum but they can be made of different materials. 
   Vane  502  includes support rails  522  and  523  which are tapered support rails or stiffeners arranged in the configuration of non parallel legs of a trapezoid. The exteriors and interiors of the vanes are permanently and non-movably affixed to the stiffeners. Reference numerals  505  and  506  indicate the extent of the interior surface of vane  502 . The vanes  501  and  502  are interleaved, self-sealing tongue and groove vanes. One exterior groove  580 B is illustrated in male vane  502 . 
   Still referring to  FIG. 5B , SMA rope or wire  525 ,  526 ,  527  can be placed radially as desired. Since vanes  501  and  502  are hollow, SMA wire is laced therethrough and can be positioned radially away from the pivot points. In this way, as the SMA wire or rope is heated, less force is required for the SMA wire to be placed through eyelets  530 ,  532 ,  534  and  535  to counteract a given moment created by pressure from within the nozzle. The SMA wire is insulated by nonconductive SMA standoffs placed in the eyelets. A DC voltage may be applied to the SMA as indicated by the symbols V+ and V− in  FIG. 5B . Alternatively, AC voltage or some other energy source may be employed to heat and contract the SMA wire or SMA rope. To ensure uniform heating, a DC voltage is applied to the SMA wire which is laced through a plurality of vanes. It is also within the scope of the invention to employ an SMA closer through additional eyelets such as eyelets  529 ,  531 ,  533  and  536 . If required, additional eyelets  528 ,  539 ,  540  and  541  may be laced with SMA wire radially closer to the pivot points. 
   Closers other than SMA wire or SMA rope may be employed. For example, a metallic or synthetic wire may be mounted in the eyelets and mechanically contracted. Alternatively, the magnetorheological device may be replaced by a pulley driven motor. In this way, the motor/pulley can open or close the vanes of the driving shaft  510  (for instance) directly. 
   Pivot pairs  508 ,  509  and  512 ,  513  are schematically illustrated for rotating vane  501  about shaft or axis  510 . A magneto-rheological brake  511  is employed to brake, dampen and lock motion of the shaft  510 . Similarly, pivot pairs  514 ,  515  and  517 ,  518  are diagrammatically illustrated for rotating vane  502  about shaft or axis. Each vane includes two pivots, however, one pivot or greater than two pivots may be used without departing from the spirit and scope of the invention as claimed below. 
     FIG. 5D  is an illustration  500 D of adjacent vanes  501 ,  502  similar to  FIG. 5B  employing coil springs  590 ,  591  and  592  as openers. The coil springs and leaf springs illustrated in  FIGS. 5B and 5D  may be placed between the stiffeners of adjacent vanes at any radial position. 
     FIG. 5E  is a schematic illustration  500 E of the variable area nozzle of the instant used on the core engine  571 . Vanes  574  are rotatably mounted at pivot  576  to the core engine  571  and bypass air is routed through the vane as indicated by arrow  575 . The inner surfaces  573  of the vane  572  may be constructed from a material having low thermal conductivity, i.e., a thermal insulator, so as to protect the vanes from destruction. 
   Springs are used as openers and fail safe devices. In the event of power failure to the SMA rope, springs push the interleaved vane apart opening the variable area nozzle to the second open position. Similarly, the magnetorheological device employed may be configured to be fail in its last position such that power is required to reposition the brake. 
     FIG. 6  is an illustration  600  of the interior side of three adjacent self-sealing vanes  601 ,  604  and  601 A. Vanes  601  and  601 A are male vanes and their interiors have no grooves. Vane  604  is female vane having grooves  608  and  638 .  FIG. 6  illustrates the vanes in their fully open position and self sealed. Referring to  FIG. 6A , an enlargement  600 A of a portion of  FIG. 6  illustrating the vanes in the full open position, tongues  602  and  603  of male vane  601  slidingly and sealingly interengage grooves  606  and  608  of female vane  604 . Similarly, tongues  605 ,  607  of female vane  604  slidingly and sealingly interengage grooves  609  and  639  of the male vane  601 . 
   Still referring to  FIGS. 6 and 6A , groove  606  of female vane  604  is formed by the exterior portion  607  and interior portion  605  of the female vane  604  and it extends downward and is oriented as a non parallel trapezoidal leg toward the leading edge of the female vane  604 . Groove  608  is a shoulder which extends downward and is oriented as a non parallel trapezoidal leg toward the leading edge of the female vane  604 . Similarly groove  609  is formed in male vane  601  by interior portion  603  and exterior portion  602 . Groove  639  or shoulder  639  on the exterior of the male vane  601  is similar to groove  606  of the female vane  604 . Grooves  609  and  639  extend downwardly toward the leading edge of the male vane  601  and are oriented as non parallel trapezoidal legs.  FIG. 6B  is an enlargement  600 B of a portion of  FIG. 6  illustrating the vanes in a relatively closed position.  FIGS. 6-6B  illustrate the interengagement of the respective tongues and grooves of the male and female vanes. 
     FIG. 6C  is an illustration  600 C of asymmetric sealed vanes  621 ,  624 . In other words, the vanes employed in  FIG. 6C , for example, have only one groove  628  in its interior and one groove  622  in its exterior. Vane  624  includes tongues  625 ,  627  and grooves  626  and  628 . 
     FIG. 6D  is an illustration  600 D of a metal to metal seal arrangement between two vanes  610 ,  614 . Gaps  611 ,  613  as well as an interior space  612  are a labyrinth which seals the vanes. When the vanes are pressurized, the tongues of one vane will engage the grooves of the adjacent vanes.  FIG. 6E  is an illustration  600 E of supplemental brush seals  615  and  616  residing in spaces between the tongues and their respective grooves.  FIG. 6F  is an illustration  600 F of a supplemental hydrostatic seal  617  residing in the interior space between the vanes. 
     FIG. 6G  illustrates a supplemental elastomeric seal  619  between the vanes. 
     FIG. 7  is a perspective view  700  of the exterior side  701  of the male vane. The exterior surface of the male vane includes a convex curvature. Tapered stiffener  706  is illustrated as being wider at the leading edge  750  than at the trailing edge  751 . Tapered stiffener  706  extends in a trapezoidal non parallel fashion from the leading edge  750  to the trailing edge  751 . Exterior surface  701  and interior surface  705  are welded or otherwise permanently affixed to tapered stiffener  706 . Preferably there are two tapered stiffeners but there may be one or four as illustrated in  FIG. 4F . 
   Shoulder or groove  702  also extends as a non parallel leg of a trapezoid being wider at the trailing edge  751  than at the leading edge  750 . The direction of flow with respect to the vane is from the leading edge toward the trailing edge. 
   Apertures or eyelets  708 ,  720 , and  721  in tapered stiffener  706  are illustrated in  FIG. 7 . One or more of these eyelets may receive a shape memory alloy wire or rope depending on the specific need. Wire or ropes extending through eyelet  721  will produce a larger counter moment than a wire of the same dimension extended through eyelet  708 . Eyelets include a nonconductive insulator  761  or standoff illustrated in  FIG. 7D  so that an electric current may pass through the wire or rope without grounding to the metal of the nozzle. 
     FIG. 7  further illustrates a land  703  formed by shoulder  702  in exterior surface  701  of the male vane. Land  703  and shoulder  702  extend the length of the vane such that there is a narrow land portion  703 A proximate the leading edge  750  of the vane. Reference numeral  712  indicates a groove or slot which receives a reciprocal tongue of a female vane. Land  703  receives a reciprocal tongue of a female vane. Pivot  710  and opening  711  are illustrated in  FIG. 7 . 
   Still referring to  FIG. 7 , trailing edge  751  of the male vane includes a space or gap  707  formed by the termination of the interior  705  and exterior surface  701  which are affixed to the tapered stiffeners. 
     FIG. 7A  is a perspective view  700 A of the exterior side of the male vane similar to that illustrated in  FIG. 7  with an optional access window  730 . The access window  730  enables attachment, lacing and/or maintenance of the SMA wire  731 ,  732 , and  733  through the vane. Another support stiffener  716  is illustrated in  FIG. 7A  together with apertures or eyelets  708 A,  720 A and  721 A for easy assembly and disassembly. 
     FIG. 7B  is a perspective view  700 B of the interior side  705  of the male vane of  FIG. 7  illustrating interior side  705  as not having any grooves and being substantially trapezoidally shaped.  FIG. 7C  is a side view  700 C of the male vane illustrated in  FIG. 7  with the curvature of the exterior surface illustrated. 
     FIG. 8  is a view  800  of the leading edge  750  of the male vane taken along the lines  8 - 8  of  FIG. 7  illustrating the inner or inside portion  801  of the male vane.  FIG. 8  does not illustrate the pivots so as to increase clarity of the illustration. Tapered stiffeners  706  and  716  are also illustrated in  FIG. 8 .  FIG. 8A  is an enlargement  800 A of a portion of  FIG. 8 . 
     FIG. 9  is a view  900  of the trailing edge  751  of the male vane taken along the lines  9 - 9  of  FIG. 7 .  FIG. 9A  is an enlargement  900 A of a portion of  FIG. 9  which better illustrates the tongues  705 ,  705 A and grooves  702 ,  712 . The convex curvature of the exterior surface  701  is illustrated in  FIGS. 7-9A . 
     FIG. 10  is a perspective view  1000  of the convexly shaped exterior  1001  of a substantially trapezoidally shaped female vane having a leading edge  1050  and a trailing edge  1051 . Surface  1001  forms tongues  1007  and  1009  which interengage with corresponding grooves in the exterior of adjacent male vanes. Grooves  1011 ,  1014  and  1013 ,  1012  interengage corresponding tongues of adjacent male vanes. Lands  1008 ,  1010  are formed in the interior surface  1002  of the female vane by grooves  1011  and  1012 . Opening or space  1006  is illustrated in the trailing edge  1051 . 
   Still referring to  FIG. 10 , tapered stiffener  1003  supports exterior surface  1001  and interior surface  1002 . Both surfaces  1001  and  1002  are affixed to the tapered stiffeners. Eyelets or apertures  1004 ,  1020 ,  1021  are illustrated in stiffener  1003  for receiving SMA or other type wire or rope for lacing the 9 pairs of male and female vanes together. As previously indicated, fewer or less vanes may be used about the 360 degree circumference of the gas turbine engine. 
     FIG. 10A  is a perspective view  1000 A of the exterior  1001  of a female vane similar to that illustrated in  FIG. 10  with an optional access window  1030 . Tapered stiffener  1003 A is illustrated in  FIG. 10A .  FIG. 10B  is a perspective view  1000 B of the interior of a female vane illustrating grooves  1011  and  1012  in surface  1002  as well as lands  1008  and  1010 . 
     FIG. 11  is a view of the leading edge  1050  of the female vane taken along the lines  11 - 11  of  FIG. 10  illustrating the inner or inside portion  1101  of the female vane as well as the tapered stiffeners  1003  and  1003 A.  FIG. 11  does not illustrate the pivots so as to increase clarity of the illustration.  FIG. 12  is a view of the trailing edge  1050  of the female vane taken along the lines  12 - 12  of  FIG. 10  which illustrate the tongues  1007 ,  1009 ,  1015 ,  1016  and grooves  1008 ,  1012 ,  1014 ,  1016 .  FIG. 12A  is an enlargement of a portion of  FIG. 12 . The convex curvature of surface  1001  is illustrated in  FIGS. 10-12A . 
     FIG. 13  is a schematic representation  1300  of a vane extender (vortex generator)  1306  for reducing noise from a gas turbine fan and/or engine exhaust. Tracks  1301  and  1302  reside within vane  1305 . In this application vane  1306  is extended through the opening  1304  in the trailing edge of vane  1305 . Leading edge  1303  and the remaining structure is similar to that described above. Vane extender  1306  is illustrated in and its extended position  1307  in  FIG. 13 . A drive mechanism be it mechanical or smart (not shown) drives and retracts the vane between its two positions. 
     FIG. 14  is a block diagram  1400  of a control system for controlling the position of the variable area nozzle  1410  of the present invention. Set point  1401  is inputted to controller  1403  and compared to a position feedback signal  1412  which is sensed by sensor  1413  and fed to the controller by line  1402 . The controller  1403  outputs a position signal to the SMA actuator  1407  dictating the length and, hence, the position of the smart, self-sealing variable area nozzle  1410 . The controller compensates for nonlinearities in the SMA actuator and the hardware including the spring openers in the variable area nozzle  1410 . In parallel with the SMA actuator  1407  is magneto-rheological brake  1406  which locks the nozzle in a specified position, dampens mechanical vibrations in the nozzle, and controls the rate of change of position of the nozzle. 
   The SMA brake is fail safe such that loss of power to the brake renders it ineffectual. 
   The invention has been described herein by way of example only. Those skilled in the art will readily recognize that structural changes, method changes and material changes may be made to those disclosed herein without departing from the spirit and scope of the appended claims.