Abstract:
Gas turbine engine systems involving flexible panels are provided. In this regard, a representative flexible panel assembly for a gas turbine engine includes: a flexible panel operative to define at least one of a throat area and an exit area of a nozzle of a gas turbine engine, the panel being further operative to selectively exhibit a range of positions to regulate exhaust of the engine.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The disclosure generally relates to gas turbine engines. 
         [0003]    2. Description of the Related Art 
         [0004]    Varying the nozzle exhaust area of a gas turbine engine can affect engine performance. By way of example, varying the nozzle exhaust area can alter propulsive efficiency, fan stability, noise output, and/or fuel consumption. 
       SUMMARY 
       [0005]    Gas turbine engine systems involving variable nozzles with flexible panels are provided. In this regard, an exemplary embodiment of a flexible panel assembly for a gas turbine engine comprises: a flexible panel operative to define at least one of a throat area and an exit area of a nozzle of a gas turbine engine, the panel being further operative to selectively exhibit a range of positions to regulate exhaust of the engine. 
         [0006]    An exemplary embodiment of a nozzle assembly for a gas turbine engine comprises: a nozzle having a throat area and an exit area; and a flexible panel operative to variably alter at least one of the throat area and the exit area to regulate exhaust flow of the nozzle. 
         [0007]    An exemplary embodiment of a gas turbine engine comprises: a compressor; a turbine operative to drive the compressor; and a nozzle assembly positioned downstream of the turbine, the nozzle assembly defining a throat area and an exit area and having a flexible panel operative to selectively move between an open position and a closed position such that gas flowing through the nozzle is regulated. 
         [0008]    Other systems, methods, features and/or advantages of this disclosure will be or may become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features and/or advantages be included within this description and be within the scope of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0010]      FIG. 1  is a schematic diagram depicting an exemplary embodiment of a gas turbine engine. 
           [0011]      FIG. 2  is a cross-sectional perspective diagram of the gas turbine engine of  FIG. 1 . 
           [0012]      FIG. 3  is a perspective diagram depicting an exemplary embodiment of a nozzle assembly. 
           [0013]      FIG. 4  is a schematic diagram depicting the flexible panel of the embodiment of  FIG. 3  in a planar view. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Gas turbine engine systems involving variable nozzles with flexible panels are provided, several exemplary embodiments of which will be described in detail. In some embodiments, such a flexible panel is deflected in a gas turbine engine to create a desired shape in order to vary the nozzle exhaust area of the engine dynamically. Varying the nozzle exhaust area in a gas turbine engine can alter engine performance characteristics such as increasing fuel efficiency. 
         [0015]    As shown in  FIGS. 1 and 2 , gas turbine engine  100  includes a compressor section  102 , a combustion section  104 , a turbine section  106 , and an exhaust section  108 . Engine  100  also includes a nozzle assembly  10 , located at the aft end of the exhaust section  108 , that defines a nozzle throat area  12  and a nozzle exit area  14 , which is located downstream of the throat area. A duct  16  interconnects the gas path from the compressor section to the nozzle assembly  10 . As such, duct  16  routes a gas stream  26  to the nozzle assembly, which then discharges the gas stream through the throat area and exit area. Notably, performance of engine  100  can be affected by regulating gas stream  26  by varying the nozzle assembly  10  at nozzle throat area  12  and/or nozzle exit area  14 . 
         [0016]    In this regard, reference is made to the perspective diagram of  FIG. 3 , which depicts an exemplary embodiment of a nozzle assembly  10  that incorporates a flexible panel  34 . As shown in  FIG. 3 , flexible panel  34  is positioned at nozzle throat area  12  and nozzle exit area  14  to influence gas stream  26  exiting through the nozzle assembly  10 . In some embodiments, the nozzle assembly  10  can be a third stream exhaust nozzle regulating a third stream ducted from the compressor section of a gas turbine engine. 
         [0017]    The flexible panel  34  is configured to be variably deflected along a range of positions between a full open position, at which the nozzle assembly  10  exhibits a maximum exit area, and a full closed position, at which the nozzle assembly  10  exhibits a minimum exit area. As the flexible panel  34  is variably positioned, gas stream  26  (entering from a duct  16  of the nozzle assembly  10 ) is regulated. 
         [0018]    The nozzle assembly  10  also incorporates a support structure  32  located within a lower cavity  36 . The support structure  32  is configured to provide alignment and structural support to the flexible panel  34  from the underside (i.e., the non-gas path side) as the flexible panel  34  is variably positioned. In some embodiments (such as in  FIG. 3 ), the support structure  32  is a truss structure including multiple triangular units constructed with beam members whose ends are connected at joints. 
         [0019]    The flexible panel  34  incorporates stiffening stays  30  to maintain the throat profile of the nozzle assembly  10 . The stiffening stays  30  are structural stiffeners tailored to provide a desired aerodynamic shaping of the flexible panel  34  at key performance locations over the entire range of motion of the flexible panel  34 . In this embodiment, the stiffening stays  30  are formed of elongated strips of semi-rigid material extending across the width of the panel, although various other shapes, orientations and/or materials can be used in other embodiments. 
         [0020]    In some embodiments, the flexible panel  34  may be all or partially comprised of a flexible elastomeric material, such as a fluorosilicone elastomer composite. Such a panel can be particularly well adept at sealing undesirable cracks and gaps. Metallics, organic composites, and ceramic composite materials are also envisioned to be suitable panel materials depending on placement within the panel structure and engine application. In higher temperature applications, for example, edge sealing could be performed with flexible metallic elements to cover cracks and gaps. Additionally, the relatively low translation and deflection requirements of the flexible panel  34  to vary the nozzle throat area  12  and/or nozzle exit area  14  can result in reduced actuation load requirements for positioning the panel. 
         [0021]    In some embodiments, a nozzle assembly can incorporate a pressurized plenum. The pressurize plenum can be located in a lower cavity  36 , for example, on a side of the panel opposite the gas path. Such a pressurized plenum is configured to provide pressure balancing of the panel to reduce actuation loads. 
         [0022]      FIG. 4  is a schematic diagram depicting the nozzle assembly  10  of  FIG. 3 . As shown in  FIG. 4 , the gas stream  26  passes through duct  16  and nozzle throat area  12  and exits nozzle assembly  10  at nozzle exit area  14 . As the gas stream  26  passes over the flexible panel  34 , the gas stream is regulated by the nozzle throat area  12  and the nozzle exit area  14 , the shape of each of which can be affected by positioning of the flexible panel  34 . 
         [0023]    Notably, the embodiment of  FIG. 4  incorporates stiffening ribs (e.g., rib  44 ) on the underside of the flexible panel  34 . The stiffening ribs are configured to deflect the flexible panel  34  to a desired shape in order to regulate the gas stream  26  and affect engine performance. As the flexible panel  34  is deflected by the stiffening ribs, the nozzle throat area  12  and nozzle exit area  14  are varied to operatively regulate the gas stream  26 . The stiffening ribs are configured to be actuated via an actuator  42  that is coupled to the ribs at actuation point  40 . In this embodiment, actuator  42  moves the stiffening ribs  44  about actuation point  40  to vary the shape of the flexible panel  34 . By way of example, the actuator  42  is mechanically coupled to the flexible panel  34 . In this regard, actuator  42  can be a hydraulic motor, for example. The actuator  42  can be located in the lower cavity  36  of the nozzle assembly  10 . 
         [0024]    The actuation mechanism between the actuator  42  and flexible panel  34  can be optimized for expected operating conditions and can incorporate one or more of a variety of linkages, levers, gears, and/or cam designs, chosen to facilitate reduced actuator loading yet increase operating speed. 
         [0025]    It should be emphasized that the above-described embodiments are merely possible examples of implementations set forth for a clear understanding of the principles of this disclosure. Many variations and modifications may be made to the above-described embodiments without departing substantially from the spirit and principles of the disclosure. By way of example, in some embodiments, a flexible panel  34  can be configured to alter a nozzle throat asymmetrically in order to affect yaw vectoring of the flow. In some embodiments, this can be accomplished by the use of differential actuation of multiple actuators. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the accompanying claims.