Abstract:
Aspects of the disclosure are directed to a thrust reverser of an aircraft, comprising: a wall having a first surface that partially forms a flow channel associated with an air flow, a blocker door having a second surface that partially forms the flow channel, and a dielectric elastomeric device that is configured to selectively expand and contract within a cavity formed between the wall and the blocker door where the cavity is substantially radially adjacent to the flow channel when the thrust reverser is in a stowed state.

Description:
BACKGROUND 
       [0001]    On an aircraft, a nacelle is used to house an engine and a thrust reverser which can be of the cascade or pivoting type, among other types.  FIGS. 1A-1B  illustrate a typical gas turbine engine inside a nacelle  22 , which is attached via a pylon  21  to an aircraft wing  20 . The nacelle  22  includes a forward fixed structure  23  and an aft fixed structure  12 . The aft fixed structure  12  includes a thrust reverser. 
         [0002]    A main jet stream F 1  flows through the nacelle  22  from an approximate right-to-left direction in  FIGS. 1A-1B . Whereas  FIG. 1A  shows the thrust reverser operating in a stowed state/mode,  FIG. 1B  illustrates the thruster reverser operating in a deployed state/mode with a radially outward deflected jet F 1 ′ exiting doors  1  which pivot on two pivot bearings  27  ( FIG. 1A ), provided in lateral side beams  2  ( FIG. 1A ) which bound an opening  26  ( FIG. 1B ). 
         [0003]      FIG. 1C  provides additional details regarding a portion of a thrust reverser  82  (which may be incorporated in the nacelle  22  of  FIGS. 1A-1B ). As shown in  FIG. 1C  (which is representative of a thrust reverser operating in a stowed state/mode), a flow channel  53  is formed between a first wall (e.g., an inner wall)  51  and a second wall (e.g., an outer wall)  52 . Arrows  54  represent a flow of air in the flow channel  53 ; the air flow  54  is generally in a left-to-right direction in  FIG. 1C  and may correspond to the main jet stream F 1  of  FIGS. 1A-1B . The wall  52  has associated therewith an inner surface  55  that is proximate/adjacent to the flow channel  53 . The thrust reverser  82  includes a blocker door  56  (which may correspond to the doors  1  of  FIGS. 1A-1B ). An axis of rotation for the blocker door  56  is shown as reference character  57 . An actuator  58  is used to control/drive the deploying or stowing of the blocker door  56 . The blocker door  56  includes a front deflector  59  and an inner surface  60 . The components/devices that have been described form a flow line  61  of the channel  53  and also form a flow cavity  62 . Superimposed in  FIG. 1C  are reference characters  70 ,  71 , and  72 ; reference character  70  is representative of an articulation point for the actuator  58 , reference character  71  is representative of a fixed connection/coupling between the actuator  58  and the blocker door  56 , and reference character  72  is representative of a resting lip for the front deflector  59 . 
         [0004]    The contour/shape of the flow channel  53  has a significant impact on operational parameters. For example, it is generally desirable to have a smooth flow line  61 . However, the cavity  62  has been shown to contribute to total pressure losses, due at least in part to secondary flows recirculating behind the blocker door  56 . The pressure losses lead to degraded performance in terms of, e.g., specific fuel consumption (SFC). 
       BRIEF SUMMARY 
       [0005]    The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosure. The summary is not an extensive overview of the disclosure. It is neither intended to identify key or critical elements of the disclosure nor to delineate the scope of the disclosure. The following summary merely presents some concepts of the disclosure in a simplified form as a prelude to the description below. 
         [0006]    Aspects of the disclosure are directed to a thrust reverser of an aircraft, comprising: a wall having a first surface that partially forms a flow channel associated with an air flow, a blocker door having a second surface that partially forms the flow channel, and a dielectric elastomeric (DE) device that is configured to selectively expand and contract within a cavity formed between the wall and the blocker door where the cavity is substantially radially adjacent to the flow channel when the thrust reverser is in a stowed state. In some embodiments, the dielectric elastomeric device is in a first state when the thruster reverser is operated in the stowed state and in a second state when the thrust reverser is operated in a deployed state. In some embodiments, a first size of the dielectric elastomeric device in the first state is larger than a second size of the dielectric elastomeric device in the second state. In some embodiments, the dielectric elastomeric device comprises an elastomer located between two electrodes. In some embodiments, the dielectric elastomeric device is in an energized state when the thruster reverser is operated in the stowed state and in a de-energized state when the thrust reverser is operated in a deployed state. In some embodiments, the energized state and the de-energized state are based on a voltage that is applied to the electrodes. In some embodiments, the voltage is based on a 28 Volt direct current aircraft power source. In some embodiments, the thrust reverser further comprises a shutter plate coupled to the dielectric elastomeric device, wherein the shutter plate partially forms the flow channel. In some embodiments, the shutter plate is formed from at least one of aluminum, titanium, or a composite material. In some embodiments, a first end of the shutter plate is hinged to the blocker door, and wherein a second end of the shutter plate couples to a protrusion formed in a deflector when the thrust reverser is operated in the stowed state. In some embodiments, the dielectric elastomeric device is configured to completely fill the cavity when the thrust reverser is operated in the stowed state. In some embodiments, the thrust reverser system further comprises an actuator configured to control a deployment or stowing of the blocker door. In some embodiments, the dielectric elastomeric device is wedge-shaped. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. 
           [0008]      FIGS. 1A-1C  illustrate components and devices associated with an aircraft nacelle thrust reverser in accordance with the prior art. 
           [0009]      FIG. 2A  illustrates a thrust reverser incorporating a shutter plate and a dielectric elastomeric (DE) device when a pivot-door-type thrust reverser is in a stowed state. 
           [0010]      FIG. 2B  illustrates the thrust reverser of  FIG. 2A  when the pivot-door-type thrust reverser is in a deployed state. 
           [0011]      FIG. 3A  illustrates a thrust reverser incorporating a DE device that fills a cavity when a pivot-door-type thrust reverser is in a stowed state. 
           [0012]      FIG. 3B  illustrates the pivot-door-type thrust reverser of  FIG. 3A  when the thrust reverser is in a deployed state. 
           [0013]      FIG. 4  illustrates a portion of an aircraft nacelle thrust reverser, including a nozzle assembly incorporating a DE device that provides for a sealing of a gap between edges of blocker doors of a cascade type thrust reverser. 
           [0014]      FIG. 5  illustrates a nozzle assembly incorporating a DE device that provides for a sealing of a side-length of blocker doors when a cascade type thrust reverser is operated in a stowed state. 
           [0015]      FIG. 6  illustrates a DE device in accordance with aspects of this disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. 
         [0017]    In accordance with various aspects of the disclosure, apparatuses, systems and methods are described for utilizing a dielectric elastomeric device in connection with a thrust reverser. As one skilled in the art would appreciate, a DE device may belong to a family of electroactive polymers which are capable of large strains (e.g., on the order of 100% to 300%) that are produced in response to one or more inputs or conditions, such as for example an electric current, an electric field, etc. Referring to  FIG. 6 , a DE-based actuator  600  may use an elastomer (e.g., a plastic film)  602  located between two electrodes  604 - 1  and  604 - 2 . Upon application of a voltage (V)  606  across the electrodes  604 - 1  and  604 - 2 , the elastomer  602  is deformed due to electrostatic pressure resulting from the Coulomb forces between the electrodes  604 - 1  and  604 - 2 . 
         [0018]    The DE device may be used to increase/maximize forward mode (stowed reverser) thrust reverser performance by reducing/minimizing total pressure losses. The DE device may be used to control a selective filling of a pit/cavity (e.g., cavity  62  of  FIG. 1C ) of a thrust reverser. 
         [0019]      FIG. 2A  illustrates a thrust reverser  200  operating in a stowed state. The thrust reverser  200  includes many of the components and devices described above in connection with  FIG. 1C , and so, a complete re-description of those components and devices is omitted for the sake of brevity. 
         [0020]    The thrust reverser  200  includes a shutter plate  210  (having an axis of rotation denoted by a reference character  210 - 1 ) and a DE device  213 . The shutter plate  210  is coupled (e.g., attached or hinged) to the blocker door  56  at the first end  210 - 1  of the shutter plate  210 . A second end  210 - 2  of the shutter plate  210  may couple to, or rest on, a protrusion/lip  52 - 1  formed in the wall  52  or the front deflector  59 . The shutter plate  210  may be formed from one or more materials, such as aluminum, titanium, or a composite material. 
         [0021]    In  FIG. 2A , the DE device  213  is shown in a first state (e.g., an energized state). In this first state, the DE device  213  may act as a locking mechanism with respect to the shutter plate  210 , preventing the shutter plate  210  from rotating due to air flow buffeting in either reverse mode or forward mode about the end  210 - 1  in a clockwise direction in  FIG. 2A . 
         [0022]      FIG. 2B  illustrates the thrust reverser  200  operating in a deployed state. In  FIG. 2B , the DE device  213  is shown in a second state (e.g., a de-energized state). The smaller size/profile of the DE device  213  in the second state (relative to the first state of the DE device  213  shown in  FIG. 2A ) may allow/enable the shutter plate  210  to be forced open or rotate in a clockwise direction about the end  210 - 1 . 
         [0023]      FIG. 3A  illustrates a thrust reverser  300  operating in a stowed state. The (components/devices and operation of the) thrust reverser  300  may be similar to the thrust reverser  200  described above, and so, a complete re-description is omitted for the sake of brevity. Differences between the thrust reverser  300 , relative to the thrust reverser  200 , are described below. 
         [0024]    Whereas in  FIG. 2A  the DE device  213  is shown as consuming/filling a portion of the cavity  62 , in  FIG. 3A  a DE device  313  fills an entirety of the cavity  62  when the DE device  313  is operated in a first state (e.g., an energized state). In  FIG. 3A , the DE device  313  may be aligned with the inner surface  55  of the wall  52  and with the inner surface  60  of the blocker door  56 , providing for an overall surface for the flow channel  53  that is substantially smooth/continuous and substantially free of steps/discontinuities. 
         [0025]      FIG. 3B  illustrates the thrust reverser  300  operating in a deployed state. In  FIG. 3B , the DE device  313  is shown in a second state (e.g., a de-energized state). The smaller size/profile of the DE device  313  in the second state (relative to the first state of the DE device  313  shown in  FIG. 3A ) may allow/enable air flow  54  to fill the cavity  62  ( FIG. 3A ) below the blocker door  56 , thus allowing the blocker door  56  to open (based in part on actuation via the actuator  58 ). 
         [0026]    Aspects of the disclosure may be applied in connection with a variable area nozzle. For example, aspects of the disclosure may be applied near the exit of a nacelle where a thrust reverser deploys. Embodiments that optimize the operational characteristics of modern high bypass ratio (BPR) turbofan engines may include varying the exit nozzle area around an engine core and the circumscribing nacelle. 
         [0027]      FIG. 4  illustrates a variable area nozzle assembly  400 . The assembly  400  includes a nacelle  418 , an engine core cowl  419 , an upstream exit  460 , a ring actuator  470 , a thrust reverser  480 , a first sleeve section  482 , cascade vanes  488 , a sleeve actuator  490 , and a pressure seal  492 . The first sleeve section  482  may be axially translatable in the direction of the bidirectional arrow  482 ′. 
         [0028]    The assembly  400  may include one or more blocker doors  456  (which may correspond to the blocker doors  56  described above). The blocker doors  456  may pivot in the direction of the arrow  456 ′. 
         [0029]    The assembly  400  includes a DE device  413 . The DE device  413  may seal a small gap between one or more edges of the blocker doors  456  when the blocker doors  456  are stowed. 
         [0030]      FIG. 5  illustrates a variable area nozzle assembly  500 . The (components/devices and operation of the) assembly  500  may be similar to the assembly  400  described above, and so, a complete re-description is omitted for the sake of brevity. Differences between the assembly  500 , relative to the assembly  400 , are described below. 
         [0031]    In  FIG. 5 , a DE device  513  is used to seal a portion or an entire side-length of the blocker doors  456  in their stowed position resting on the inner surface of the nacelle  418 . This eliminates/reduces any flow recirculation (shown via the circled arrow  523 ) behind the blocker doors  456  across the cascade vanes  488 . 
         [0032]    The shapes (e.g., triangular/wedge) and dimensions of the DE devices (e.g., DE devices  213 ,  313 ,  413 ,  513 ) described herein are illustrative. One skilled in the art would appreciate, based on a review of this disclosure, that other shapes/geometrical modes of the DE devices may be used. 
         [0033]    Technical effects and benefits of this disclosure include, as a result of the use of DE devices, compact size/form factors, elimination or reduction of mechanical moving parts, accurate continuous control due to precise adjustment of surrounding fields (e.g., electric fields), a capability to fill a door pit cavity of conventional thrust reversers, an exposed kicker plate/blocker door during landing upon thrust reverser deployment, a reduction of total pressure loss, high levels of deformation (e.g., actuation) of the DE devices before returning to an “original” shape, and fast response times (e.g., during rapid aerodynamic transients), low power consumption from available power sources already on-board an aircraft (e.g., 28 Volts direct current (DC)). The use of DE devices provides for enhanced durability/reliability, particularly when confronted by sources of foreign object damage (FOD), such as for example rain, sleet, snow, ice, and hail. Aspects of the disclosure may be applied/retrofitted to an existing fleet of aircraft or incorporating into a newly-designed aircraft model. 
         [0034]    Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional in accordance with aspects of the disclosure. One or more features described in connection with a first embodiment may be combined with one or more features of one or more additional embodiments.