Abstract:
A thrust reverser assembly includes a first cowl member and a second cowl member repositionable relative to the first cowl member and operable to open a gap between the first cowl member and the second cowl member. A movable member is in supported connection with the second cowl member. The movable member is passively actuatable to move between a generally axially extending disposition and a generally radially extending disposition to direct bypass airflow of a turbofan engine.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims priority to U.S. Provisional Patent Application No. 61/388,360 filed Sep. 30, 2010, which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    Exemplary embodiments disclosed herein relate generally to turbofan engine assemblies, and more particularly to a thrust reverser assembly that may be utilized with a turbofan engine. 
         [0003]    Turbofan engine assemblies may include a fan assembly, a core gas turbine engine enclosed in an annular core cowl, and a fan nacelle that surrounds a portion of the core gas turbine engine. The fan nacelle is generally spaced radially outward from the annular core cowl such that the core cowl and the fan nacelle form a fan duct terminating in a fan exit nozzle. 
         [0004]    Some turbofan engine assemblies include a thrust reverser assembly. The thrust reverser assembly may include a first fixed cowl and a second cowl that is axially translatable with respect to the first cowl. 
         [0005]    In blocker-door type thrust reversers, doors or panels are actively moved into the fan duct as the thrust reverser is deployed through drag links or other mechanical means to block or impede the flow of fan air through the fan exit nozzle. Fan air may be diverted to provide reverse thrust for example through a series of turning vanes disposed in a cascade box. 
         [0006]    Blocker-door-less type thrust reversers are typically used for small commercial engines with moderate bypass ratios. In blocker-door-less type thrust reversers, the geometry of the core cowl cooperates with a surface of the translatable cowl to block or impede the flow of fan air through the exit nozzle when the thrust reverser is deployed. 
         [0007]    Current blocker-door-less thrust reversers are not practical for turbofan engines having increased bypass ratios. Blocker-door type thrust reversers incur weight and performance penalties through the use of drag links or other mechanisms. Accordingly, it would be desirable to have a hybrid design that provides thrust-reversing capability for a bypass turbofan engine that incorporates mechanical simplicity. 
       BRIEF DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0008]    The above-mentioned need or needs may be met by exemplary embodiments described herein. 
         [0009]    In one aspect, a thrust reverser assembly includes a first cowl member and a second cowl member repositionable relative to the first cowl member and operable to open a gap between the first cowl member and the second cowl member. The thrust reverser further includes a movable member in supported connection with the second cowl member, wherein the movable member is passively actuatable to move between a generally axially extending disposition and a generally radially extending disposition. 
         [0010]    In another aspect, an assembly includes a thrust reverser assembly including a first cowl member and a second cowl member repositionable relative to the first cowl member and operable to open a gap between the first cowl member and the second cowl member, and a movable member in supported connection with the second cowl. The movable member is passively actuatable to move between a generally axially extending disposition and a generally radially extending disposition. The assembly further includes a core cowl for a gas turbine engine. The core cowl has an outer surface having a geometry adapted to cooperate with the thrust reverser assembly to define at least a portion of a fan duct, wherein the movable member is operable to move radially into the fan duct to inhibit air flow therethrough. 
         [0011]    In yet another aspect, a method includes repositioning a second cowl member relative to a first cowl member from a stowed position to a fully translated position to form a gap between the first and second cowl members. The second cowl member forms at least a portion of a fan duct. The method includes passively actuating a movable member mounted in supported connection with the second cowl member from a generally axially extending disposition to a generally radially extending disposition to inhibit air flow through the fan duct. The method further includes directing the air flow through the gap formed between the first and second cowl members to provide reverse thrust when the moveable member is in the generally radially extending disposition. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present disclosure may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures. 
           [0013]      FIG. 1  is a schematic view, either plan or side depending on installation, of an exemplary turbofan engine assembly including an exemplary thrust reverser assembly. 
           [0014]      FIG. 2  is a side schematic view showing an exemplary thrust reverser assembly in a stowed disposition. 
           [0015]      FIG. 3  is a side schematic view showing an exemplary thrust reverser assembly in a fully deployed disposition. 
           [0016]      FIG. 4  is a schematic representation of certain features of an exemplary thrust reverser assembly illustrating a movement of the translatable cowl and a movable member. 
           [0017]      FIG. 5  is a cross-sectional view of an exemplary damper structure. 
           [0018]      FIG. 6  is a side schematic representation comparing certain features of an exemplary thrust reverser assembly with features of another thrust reverser. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Description of exemplary embodiments disclosed herein is made with reference to the accompanying  FIGS. 1-6 . In the exemplary embodiments disclosed herein, it will be understood by those with skill in the art that an exemplary translatable cowl member  102  is supported in movable relationship to slider tracks or the like, that are not further described herein. 
         [0020]      FIG. 1  shows an exemplary turbofan engine assembly  10 . In an exemplary embodiment, turbofan engine assembly  10  includes a core gas turbine engine  20 . In an exemplary embodiment, turbofan engine assembly  10  includes an annular core cowl  22  that extends around core gas turbine engine  20  and includes a radially outer surface  15 . Turbofan engine assembly  10  also includes an inlet  30 , a first outlet  29 , and a second outlet  34 . 
         [0021]    In one embodiment, fan cowl, or turbofan nacelle,  24  surrounds fan assembly  16  and is spaced radially outward from core cowl  22 . Nacelle  24  includes a radially outer surface  23  and a radially inner surface  25 . A fan duct  26  is generally defined between radially outer surface  15  of core cowl  22  and radially inner surface  25  of nacelle  24 . 
         [0022]    During operation, airflow enters inlet  30 , flows through fan assembly  16 , and is discharged downstream. A first portion of the airflow is channeled through core gas turbine engine  20 , compressed, mixed with fuel, and ignited for generating combustion gases which are discharged from core gas turbine engine  20  through second outlet  34 . In forward thrust operations, a second portion of the airflow  28  is channeled downstream through fan duct  26  and is discharged from fan duct  26  through first outlet  29 , also referred to as a fan exit nozzle. In an exemplary embodiment, nacelle  24  includes a thrust reverser assembly  100  as described in greater detail below. 
         [0023]    With reference to  FIGS. 2-4 , in an exemplary embodiment, thrust reverser assembly  100  includes a translatable cowl member  102  that defines a portion of nacelle  24 . In the exemplary embodiment, translatable cowl member  102  is movably coupled to a stationary first cowl member  104 .  FIG. 2  shows a partial sectional side view of an exemplary embodiment having the translatable cowl member  102  in a first operational position (i.e., a stowed position).  FIG. 3  is a partial sectional side view of an exemplary embodiment showing the translatable cowl member  102  in a second operational position (i.e., fully translated), wherein a movable member  152  is oriented generally radially. As illustrated in  FIG. 3  in an exemplary manner, when translatable cowl member  102  is disposed in the fully translated operational position, a gap  154  is opened up between the first cowl member  104  and the translatable cowl member  102 . 
         [0024]    When the translatable cowl member  102  is fully translated, the movable member  152  is able to passively extend radially into the fan duct  26  to block or impede fan air from flowing through fan exit nozzle  29  (see  FIG. 1 ) so that fan air is directed through thrust reverser member  140  and is turned by turning vanes  142  to provide reverse thrust (i.e., full deployment of thrust reverser assembly). 
         [0025]    In an exemplary embodiment, an actuator assembly  110  is coupled to translatable cowl member  102  to selectively translate cowl member  102  in a generally axial direction relative to first cowl member  104 . In the exemplary embodiment, actuator assembly  110  is positioned within a portion of the area defined by nacelle  24 . In the exemplary embodiment, actuator assembly  110  may be electrically, pneumatically, or hydraulically powered in order to translate cowl member  102  between the operational positions. 
         [0026]    An exemplary embodiment includes a first cowl member  104  including an aft portion  114  and a translatable cowl member  102  including a forward portion  112  sized and/or configured to be telescopingly received within the aft portion  114  of the first cowl member  104 . Embodiments employing movable member  152  do not necessarily require a telescoping engagement between first cowl member  104  and translatable cowl member  102 . For example, first cowl member  104  and translatable cowl member  102  may incorporate other joint or abutting means as an alternative to the telescoping engagement. 
         [0027]    As illustrated, the translatable cowl member  102  is operably movable with respect to the first cowl member  104  between a fully stowed position (e.g., as shown in  FIG. 2 ) and a fully translated position (e.g., as shown in  FIG. 3 ). In an exemplary embodiment, the translatable cowl member  102  is sized and/or configured to cooperate with the core cowl  22  to define at least a portion of a fan duct  26  having an exit nozzle  29 . 
         [0028]    With particular reference to  FIG. 2 , an exemplary translatable cowl member  102  includes a radially inner panel  132  and a radially outer panel  134  being arranged and configured to define a space  138  therebetween. The exemplary embodiment also includes a thrust reverser member  140  positioned relative to the space  138  between the radially inner and outer panels  132 ,  134 , respectively, so as to be selectively covered and uncovered by the translatable cowl member  102 . Thus, when the translatable cowl member  102  is disposed in the stowed operational position, the thrust reverser member  140  is covered, and when the translatable cowl member  102  is in the fully translated operational position, the thrust reverser member  140  is uncovered. Appropriate flow directing members and seals may be utilized in the exemplary embodiments to provide a sealing (e.g., air tight) engagement among components. In an exemplary embodiment, thrust reverser member  140  is a fixed cascade structure including a plurality of cascade turning vanes  142  ( FIG. 3 ). 
         [0029]    In operation, when the translatable cowl member  102  is in the stowed operational position, air in the fan duct  26  is generally directed out of exit nozzle  29  in a forward thrust operation. To provide reverse thrust, the translatable cowl member  102  may be moved into the fully translated operational position whereby the thrust reverser member  140  is uncovered and airflow is directed through the turning vanes  142 . 
         [0030]    With particular reference to  FIG. 4 , in an exemplary embodiment, movable member  152  is carried in hinged relationship at the forward portion of radially inner panel  132 . Spring/cam mechanism  164  cooperates with bracket  168  to hold movable member  152  in a stowed position that may be adjacent a fixed structure  160  forming a part of the thrust reverser assembly  100 . In an exemplary embodiment, a fixed structure  160  such as a torque box or diverter fairing is sized and configured to provide a recess  174  for seating at least an end portion of the movable member  152  in the stowed position. When the thrust reverser assembly  100  is deployed, translatable cowl member  102  moves aft. The movable member  152  is disengaged from the fixed structure  160 . Upon sufficient air loading, member  152  moves into a substantially radially extending disposition. 
         [0031]    Member  152  is operable to move radially by turning about hinge  166  when acted upon by sufficient air load when the thrust reverser assembly is fully deployed and the engine power and airflow is increased. As illustrated in  FIG. 4  in an exemplary manner, movable member  152  cooperates with radially outer surface  15  to block or impede airflow through the fan exit nozzle, and instead the airflow is directed through the thrust reverser structure  140  and is turned by turning vanes  142  to provide reverse thrust ( FIG. 3 ). Thus, movable member  152  is passively activated (e.g., by airflow) rather than being actively rotated by a mechanical actuator or other mechanism. 
         [0032]    An exemplary embodiment includes a damper structure  180 , such as the spring damper mechanism  80  and  180  illustrated in  FIGS. 2 ,  3  and  5 . The damper structure  180  may be utilized to provide snubbing and avoid aero-elastic instability in the movable member  152 . The illustrated spring damper mechanism is exemplary only and other mechanisms able to perform similar functions may be utilized. For example pneumatic, visco-fluid, electric, or friction mechanisms may be employed as those having skill in the art will readily appreciate. 
         [0033]    When the thrust reverser assembly is returned to a stowed position (i.e., forward translation of the translatable cowl member  102 ), spring/cam mechanism  164  carried on movable member  152  engages with one or more brackets  168  on fixed structure  160  to flip the movable member  152  to the stowed orientation. 
         [0034]      FIG. 4  illustrates movement of an exemplary translatable cowl member  102  along path  172 . Movable member  152  may be in a stowed position adjacent structure  160  along recess  174 , it may be in an aft, unloaded position, or it may be rotated radially by the air load to substantially block the fan duct. 
         [0035]    In one embodiment, damper structure  180  is sized and/or configured to return movable member  152  to the axial position at low fan flow (e.g., reverse idle) and allow the movable member to seek the radial position at high fan flow (e.g., maximum reverse fan flow). 
         [0036]      FIG. 6  provides a comparison of the area of a fan duct defined by translatable cowl member  102  and the radially outer surface  15  of the core cowl. This area, illustrated by Arrow  161 , extends between radially inner surface  25  and radially outer surface  15 . Typical blocker-door type thrust reverser arrangements may provide a fan duct area illustrated by arrow  162  which extends between an ordinary radially inner surface  25 ′ and ordinary radially outer surface  15 ′, as shown in  FIG. 6 . In an exemplary embodiment, arrow  161  represents a fan duct area substantially the same, or generally comparable in size, to the fan duct area represented by arrow  162 . 
         [0037]    Core cowl offset, in an exemplary embodiment, is illustrated by arrow  170 . The term “core cowl offset” is used in this context to reference the maximum radial height of the outer surface  15  of the core cowl. Those with skill in the art will appreciate that the offset is provided by the core cowl. The exemplary core cowl offset is generally greater than the core cowl offset found in typical blocker-door type thrust reverser arrangements, but generally less than known blocker-door-less thrust reverser arrangements. 
         [0038]    Those having skill in the art will appreciate that provision and operation of one movable member  152  has been described herein. However, exemplary embodiments include a plurality of movable members  152  spaced in circumferential orientation along the translatable cowl member  102 , with each movable member  152  having corresponding spring damper mechanisms and brackets. 
         [0039]    Further, those with skill in the art will appreciate that the exemplary embodiments disclosed herein provide desired mechanical simplicity while incorporating the benefits of fixed cascade type translating cowl thrust reversers. Technical effects of the present disclosure include passive actuation of the movable member(s)  152  to provide the ability to eliminate drag links required in blocker door type thrust reversers. The partial fan duct offset allows low duct Mach numbers and minimal nacelle diameters. The exemplary embodiments disclosed herein may be adapted to accommodate various by-pass ratios in turbofan engines. 
         [0040]    In some embodiments, the systems and method disclosed herein may be facilitated by a computer or stored on a computer readable medium. 
         [0041]    The embodiments described herein are not limited to any particular system controller or processor for performing the processing of tasks described herein. The term controller or processor, as used herein, is intended to denote any machine capable of performing the calculations, or computations, necessary to perform the tasks described herein. The terms controller and processor also are intended to denote any machine that is capable of accepting a structured input and of processing the input in accordance with prescribed rules to produce an output. It should also be noted that the phrase “configured to” as used herein means that the controller/processor is equipped with a combination of hardware and software for performing the tasks of embodiments of the invention, as will be understood by those skilled in the art. The term controller/processor, as used herein, refers to central processing units, microprocessors, microcontrollers, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), logic circuits, and any other circuit or processor capable of executing the functions described herein. 
         [0042]    The embodiments described herein embrace one or more computer readable media, including non-transitory computer readable storage media, wherein each medium may be configured to include or includes thereon data or computer executable instructions for manipulating data. The computer executable instructions include data structures, objects, programs, routines, or other program modules that may be accessed by a processing system, such as one associated with a general-purpose computer capable of performing various different functions or one associated with a special-purpose computer capable of performing a limited number of functions. Aspects of the disclosure transform a general-purpose computer into a special-purpose computing device when configured to execute the instructions described herein. Computer executable instructions cause the processing system to perform a particular function or group of functions and are examples of program code means for implementing steps for methods disclosed herein. Furthermore, a particular sequence of the executable instructions provides an example of corresponding acts that may be used to implement such steps. Examples of computer readable media include random-access memory (“RAM”), read-only memory (“ROM”), programmable read-only memory (“PROM”), erasable programmable read-only memory (“EPROM”), electrically erasable programmable read-only memory (“EEPROM”), compact disk read-only memory (“CD-ROM”), or any other device or component that is capable of providing data or executable instructions that may be accessed by a processing system. 
         [0043]    A computer or computing device such as described herein has one or more processors or processing units, system memory, and some form of computer readable media. By way of example and not limitation, computer readable media comprise computer storage media and communication media. Computer storage media include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically embody computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism and include any information delivery media. Combinations of any of the above are also included within the scope of computer readable media. 
         [0044]    This written description uses various embodiments to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.