In exemplary embodiments, the cascade assembly 208 includes one or more cascade vanes 210 that are circumferentially spaced around a circumference of the nacelle assembly 150. The cascade vanes 210 are disposed between or at the juncture of the fan cowl 204 and the transcowl 206 which are selectively uncovered upon axial translation of the transcowl 206 upon reaching the position C or become uncovered as the transcowl 206 moves aft from the position A to the position C. In exemplary embodiments of the present disclosure, the cascade vanes 210 remain covered in positions A and B. In exemplary embodiments, one or more actuation assemblies 212 are mounted to the nacelle assembly 150. The actuation assemblies 212 may be circumferentially spaced apart and coupled to at least one of the transcowl 206 or the thrust reverser assembly 200. The actuation assemblies 212 are configured to move or translate the transcowl 206 in an axial direction forward and aft with respect to the fan cowl 204. The actuation assemblies 212 can be of any suitable type such as, by way of non-limiting example, rails, gliding elements, carriages, threaded rods, linkages or link assemblies, ball-screw or screw jack actuators, rotary actuators, etc., and can be driven by, e.g., pneumatic, hydraulic, or electric motors.

The thrust reverser assembly 200 also includes one or more blocker doors 214 pivotally mounted to the transcowl 206 that border the bypass airflow passage 156 when stowed. The blocker doors 214 are selectively deployed when the transcowl 206 is translated aft to the position C as depicted in FIG. 4C. In exemplary embodiments, one or more drag links 216 are operatively coupled to the blocker doors 214 for moving the blocker doors 214 between a stowed position (positions A and B) and a deployed position (position C). In the exemplary embodiments, a radially inward end 218 of the drag link 216 is pivotally coupled to the core cowl 118, and a radially outward end 220 of the drag link 216 is pivotally coupled to an intermediate portion of a respective blocker door 214. The blocker doors 214 are also pivotally coupled to the transcowl 206 at or near a forward or upstream end of the transcowl 206 so that the blocker doors 214 may pivot into the bypass airflow passage 156 (i.e., deployed) as the transcowl 206 translates in the aft direction from the position B to the position C.

Referring to FIGS. 4A and 4B, the fan cowl 204 includes an inner wall 222, and an outer wall 224 disposed radially outward and spaced apart from the inner wall 222. The inner wall 222 and the outer wall 224 define an interior area 226 of the fan cowl. The transcowl 206 also includes an inner wall 228, and an outer wall outer 230 disposed radially outward and spaced apart from the inner wall 228. In exemplary embodiments, in at least one or more of the positions A and B, at least a portion of the transcowl 206 is positioned within the fan cowl 204 or at least partially within the interior area 226 of the fan cowl 204. In other words, in at least one or more of the positions A and B, at least a portion of the outer wall 224 of the fan cowl 204 is disposed radially outward from and overlaps at least a portion of the outer wall 230 of the transcowl 206, and at least a portion of the inner wall 222 of the fan cowl 204 is disposed radially inward from and overlaps at least a portion of the inner wall 228 of the transcowl 206. In the illustrated embodiment, the overlapped position of the outer wall 224 with respect to the outer wall 230 causes an aft-facing step 231 at the radially outward interface of the fan cowl 204 with the transcowl 206, and the overlapped position of the inner wall 222 with respect to the inner wall 228 causes an aft-facing step 233 at the radially inward interface of the fan cowl 204 with the transcowl 206 within the bypass airflow passage 156. In exemplary embodiments, in at least one or more of the positions A and B, at least a portion of the transcowl 206 is positioned within the fan cowl 204 or at least partially within the interior area 226 of the fan cowl 204 such that the steps 231 and 233 are aft-facing to avoid airflow separation in at least the bypass airflow passage 156. In exemplary embodiments, one or more seals 232 may be disposed between the fan cowl 204 and the transcowl 206 in the overlapping portion or at another suitable interface of the fan cowl 204 and the transcowl 206 to seal against undesirable airflow leakage radially outwardly from the bypass airflow passage 156 such as, by way of non-limiting example, when the transcowl 206 is located in at least one or more of the positions A and B. The seal 232 may be any conventional seal or sealing mechanism such as, by way of non-limiting example, a compressible sealing material, seals as used in bleed air applications, seals as used in ducting applications, or various types of thrust reverser door seals.

As described above, the bypass airflow passage 156 is configured to provide a converging flow area which terminates near a trailing edge 234 of the transcowl 206 corresponding to the fan exit nozzle 158. As depicted in FIGS. 4A-4C, the core cowl 118 has a contoured portion 240 that slopes radially inward as the core cowl 118 extends aft in the axial direction such that the core cowl 118 and the transcowl 206 define the fan exit nozzle 158. As depicted in FIGS. 4A and 4B, axial translation of the transcowl 206 between the positions A and B, respectively, varies a throat area 250 of the fan exit nozzle 158. The throat area 250 may be defined as a minimum flow area defined by the fan exit nozzle 158 measured along a line 252 extending perpendicular to and radially outward from contoured portion 240 of the core cowl 118. Thus, axial movement or translation of the transcowl 206 also causes the axial movement or translation of the trailing edge 234 of the transcowl 206 with respect to the core cowl 118 and the contoured portion 240. Accordingly, the variable positioning of the trailing edge 234 of the transcowl 206 with respect to the contoured portion 240 causes a change in a length of the line 252 and, correspondingly, a size of the throat area 250. In exemplary embodiments, for the turbofan engine 100 depicted in FIGS. 4A and 4B configured as a short duct separate flow exhaust system, the throat area 250 at the position A (FIG. 4A) is greater than the throat area 250 at the position B (FIG. 4B).

In exemplary embodiments, a sensor 254 may be used to sense or detect the axial position of the transcowl 206. The sensor 254 may be communicatively coupled to the controller 72 (FIG. 1). The actuation assembly 212 may be automatically controlled, such as by the controller 72 (FIG. 1), based on information communicated by the sensor 254. Thus, the controller 72 (FIG. 1) may be used to vary the throat area 250 of the fan exit nozzle 158 based on the sensed or detected position of the transcowl 206. The controller 72 may be configured similar to exemplary computing devices of the computing system 300 described below with reference to FIG. 7.

In exemplary embodiments, the ends 220 of the drag links 216 are pivotally coupled to the respective blocker doors 214 via one or more slot joints 260. The one or more slot joints 260 extend axially (when the blocker doors 214 are in a stowed position, such as in positions A and B) such that the transcowl 206 is movable forward and aft without deploying the blocker doors 214. In other words, the ends 220 of the drag links 216 are axially movable within the slot joints 260 resulting from axial movement of the transcowl 206. FIGS. 5A-5C depict the position of the end 220 of the drag link 216 within the slot joint 260 corresponding to respective positions A-C of respective FIGS. 4A-4C. As depicted in FIG. 5A, in the position A, the end 220 of the drag link 216 is medially positioned within the slot joint 260. In FIG. 5B, the transcowl 206 has been translated axially forward (FIG. 4B) such that the end 220 of the drag link 216 is positioned at or near an aft end 262 of the slot joint 260. In FIG. 5C, the transcowl 206 has been translated axially aft (FIG. 4C) such that the end 220 of the drag link 216 has reached a forward end 264 of the slot joint 260 such that the end 220 is prevented or restrained from further axial movement within the slot joint 260. Accordingly, when the end 220 reaches forward end 264 of the slot joint 260, further axial rearward movement of the transcowl 206 causes the blocker doors 214 (FIG. 4C) to be pivoted radially inward into a deployed position as depicted in the position C (FIG. 4C).

In exemplary embodiments, one or more stop mechanisms 270 may be included and configured to prevent movement of the transcowl 206 to the position C in flight (FIGS. 4C and 5C) without sensing the aircraft 10 (FIG. 1) has landed by use of a sensor such as, by way of non-limiting example, a weight on wheels indication or, in other words, to prevent deployment of the blocker doors 214 (FIGS. 4A-4C) in a flight phase of the aircraft 10 (FIG. 1). In exemplary embodiments, the one or more stop mechanisms 270 may include a hydraulically or electromechanically actuatable mechanism that limits aft movement of the transcowl 206 (FIGS. 4A-4C) until a weight on wheels sensor (not shown) is engaged due to the aircraft 10 (FIG. 1) being on the ground. In exemplary embodiments, the one or more stop mechanisms 270 may include a pin, track stop, motor limit stop, or other type of mechanism configured to limit aft movement of the transcowl 206.

In FIGS. 5A-5C, the one or more stop mechanisms 270 include one or more pins 272 coupled to or movably positionable with respect to the one or more slot joints 260. The one or more pins 272 may be coupled to one or more actuators 274 that are actuatable to cause movement of the one or more pins 272 with respect to the one or more respective slot joints 260. The one or more actuators 274 may be part of the actuation assembly 212 or may be independent or stand-alone actuators. In exemplary embodiments, at least a portion of the one or more pins 272 may reside within at least a portion of the slot joint 260, such as depicted in FIGS. 5A and 5B, to prevent axial travel of the end 220 of the drag link 216 to the forward end 264 of the slot joint 260. In FIGS. 5A and 5B, the pin 272 may be considered in an actuated position such that the pin 272 prevents axial travel of the end 220 of the drag link 216 to the forward end 264 of the slot joint 260. In response to a weight on wheel indication, the actuators 274 may be actuated to move or withdraw the one or more pins 272 from the slot joint 260, as depicted in FIG. 5C, to enable movement of the end 220 of the drag link 216 to the forward end 264 of the slot joint 260 to deploy the blocker doors 214 (FIGS. 4A-4C).

Thus, in FIG. 5C, the pin 272 is in a de-actuated position with respect to the slot joint 260. Accordingly, the one or more stop mechanisms 270 may be actuated or de-actuated to respectively prevent or enable axial translation of the transcowl 206 into the deploy position of the thrust reverser assembly 200 as depicted in position C (FIG. 4C). It should be understood that the one or more stop mechanisms 270 may also be part of or formed as part of the actuation assembly 212 (FIGS. 4A-4C) such that the actuation assembly 212 (FIGS. 4A-4C) is configured to limit axial aft travel of the transcowl 206 to the position C to deploy the blocker doors 214 (FIGS. 4A-4C) without a weight on wheel indication. The actuation assembly 212 (FIGS. 4A-4C), the actuator 274 (FIGS. 5A-5B), or both, may be automatically controlled, such as by the controller 72 (FIG. 1). It should also be understood that other types of mechanisms or linkage assemblies may be used to enable in-flight forward and aft movement of the transcowl 206 (FIGS. 4A-4C) such as, by way of non-limiting example, a slider mechanism on the drag links 216 (FIGS. 4A-4C) to effectively create a slider crank mechanism.

In exemplary embodiments, the controller 72 (FIG. 1) may be configured to control the throat area 250 of the fan exit nozzle 158 (FIGS. 4A and 4B) via the actuation assembly 212 (FIGS. 4A-4C) to correspondingly control a maximum or minimum fan pressure ratio (FPR) variation as a function of an operating condition of the turbofan engine 100 (FIG. 2). The FPR is a ratio between a first volume of air passing through the bypass airflow passage 156 (FIG. 2) and a second volume of air passing through the core air flowpath 137 (FIG. 2). By controlling the axial movement of the transcowl 206 (FIGS. 4A and 4B) between the respective positions A and B (FIGS. 4A and 4B) and, correspondingly, the throat area 250 of the fan exit nozzle 158 (FIGS. 4A and 4B), variations in the FPR can be controlled during different flight phases of the aircraft 10 (FIG. 1). In exemplary embodiments, the controller 72 (FIG. 1) may be configured to control the throat area 250 of the fan exit nozzle 158 (FIGS. 4A and 4B) via the actuation assembly 212 (FIGS. 4A-4C) based on a percentage of a maximum thrust of the turbofan engine 100 (FIG. 2). For example, in exemplary embodiments, a ratio of the percentage of maximum thrust of the turbofan engine 100 (FIG. 2) with respect to the rotational speed of the LP spool 136 (FIG. 2) may be used to define or control the throat area 250 of the fan exit nozzle 158 (FIGS. 4A and 4B) via the actuation assembly 212 (FIGS. 4A-4C). It should also be understood that the controller 72 (FIG. 1) may be configured to automatically control the throat area 250 of the fan exit nozzle 158 (FIGS. 4A and 4B) via the actuation assembly 212 (FIGS. 4A-4C) based on other detected parameters of the turbofan engine 100 (FIG. 2), based on different flight phases of the aircraft 10 (FIG. 1), and/or based on user instructions, such as from a pilot of the aircraft 10 (FIG. 1).

In exemplary embodiments, in response to detecting a failure indication corresponding to the thrust reverser assembly 200 (FIGS. 4A-4C), the actuation assembly 212 is configured to move the transcowl 206 to the position A depicted in FIG. 4A. For example, in exemplary embodiments, in response to detecting a failure indication corresponding to the thrust reverser assembly 200 (FIGS. 4A-4C), the controller 72 (FIG. 1) may actuate the actuation assembly 212 to translate the transcowl 206 to the position A depicted in FIG. 4A to obtain a largest possible throat area 250 of the fan exit nozzle 158 as depicted in FIG. 4A.

FIG. 6 provides a flow diagram of an exemplary method (280) for varying a size of the throat area 250 of the fan exit nozzle 158 in accordance with exemplary embodiments of the present disclosure. It should be appreciated that the method (280) is discussed herein only to describe exemplary aspects of the present subject matter and is not intended to be limiting.

At (282), the method (280) includes, during a flight phase of the aircraft 10, moving the transcowl 206 forward to reduce an area of the fan exit nozzle 158. As described above, movement of the transcowl 206 forward may be automatically controlled such as, by way of non-limiting example, by the controller 72 based on a percentage of a maximum thrust of the turbofan engine 100, based on a particular phase of a flight condition of the aircraft 10, or by pilot control. At (284), the method (280) includes, during a flight phase of the aircraft 10, moving the transcowl 206 aft to increase an area of the fan exit nozzle 158. Similarly, movement of the transcowl 206 aft may be automatically controlled such as, by way of non-limiting example, by the controller 72 based on a percentage of a maximum thrust of the turbofan engine 100, based on a particular phase of a flight condition of the aircraft 10, or by pilot control. At (286), the method (280) includes determining whether the aircraft 10 has landed such as, by way of non-limiting example, detecting a weight on wheels indication, such as by the controller 72. At (288), the method (280) includes, responsive to detecting that the aircraft 10 has landed, de-actuating the stop mechanism 270 restricting or limiting aft travel of the transcowl 206. De-actuation of the stop mechanism 270 may also be automatically controlled such as, by way of non-limiting example, by the controller 72 in response to detecting that the aircraft 10 has landed. At (290), the method (280) includes, responsive to de-actuating the stop mechanism 270, moving the transcowl 206 aft to deploy the blocker doors 214. The aft movement of the transcowl 206 to deploy the blocker doors 214 may also be automatically controlled, such as by the controller 72.

FIG. 7 provides an example computing system 300 according to example embodiments of the present disclosure. The computing devices or elements described herein, such as the controller 72 (FIG. 1), may include various components and perform various functions of the computing system 300 described below, for example.

As shown in FIG. 7, the computing system 300 can include one or more computing device(s) 302. The computing device(s) 302 can include one or more processor(s) 302A and one or more memory device(s) 302B. The one or more processor(s) 302A can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and/or other suitable processing device. The one or more memory device(s) 302B can include one or more computer-executable or computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and/or other memory devices.

The one or more memory device(s) 302B can store information accessible by the one or more processor(s) 302A, including computer-readable instructions 302C that can be executed by the one or more processor(s) 302A. The computer-readable instructions 302C can be any set of instructions that when executed by the one or more processor(s) 302A, cause the one or more processor(s) 302A to perform operations. In some embodiments, the computer-readable instructions 302C can be executed by the one or more processor(s) 302A to cause the one or more processor(s) 302A to perform operations, such as any of the operations and functions for which the computing system 300 and/or the computing device(s) 302 are configured, such as controlling operation of actuation assembly 212, the actuators 274, or both. The computer-readable instructions 302C can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the computer-readable instructions