Abstract:
Aspects of the disclosure are directed to a system associated with a thrust reverser of an aircraft, comprising: a plurality of cascade vanes configured in accordance with a substantially arc-tangent profile, where a leading edge of a first of the cascade vanes has a first width, and a trailing edge of the first of the cascade vanes has a second width that is different from the first width.

Description:
BACKGROUND 
       [0001]    Referring to  FIG. 1 , on an aircraft a typical cascade-style thrust reverser system  100  for a turbofan propulsion system includes a circumferential array of cascades/cascade vanes  104 . The cascades  104  are frequently grill- or grate-like structures through which the majority of a fan bypass air  108  from the propulsion system passes through during reverse thrust operation. This bypass air  108  is redirected through the cascades  104  during reverse thrust operation via a deployment of a blocker door  112 . During flight when the thrust reverser is stowed, the cascades  104  are concealed/blocked from the external environment via a sleeve  116 . During landing/descent of the aircraft when the thrust reverser is deployed, the sleeve  116  is translated aft to expose/unblock the cascades  104 . The thrust reverser system  100  provides the exhaust area required by an engine of the aircraft in reverse thrust operation. Additionally, the thrust reverser system  100  is frequently designed to realize a cascade efflux plume vectoring pattern to meet engine re-ingestion and aircraft stability and control requirements. 
         [0002]    Each of the cascade vanes  104  includes a leading edge and a trailing edge, such as for example leading edge  114   a  and trailing edges  114   b  and  114   c . As the nomenclature implies, a leading edge is the portion of a cascade vane  104  that initially interfaces to the bypass flow/air  108 , whereas a trailing edge is the portion of the cascade vane  104  that interfaces to the external environment and is the last portion of the cascade vane  104  to interface to the (redirected) bypass air  108 . 
         [0003]    Conventional design practice has dictated that the cascade vanes  104  have a constant thickness/dimension over the length/span of the cascade  104 , in progressing from the leading edge to the trailing edge. Such practice may facilitate ease in manufacture and assembly of the cascade  104 . For example, cascades have typically been fabricated using carbon fiber, where sheets of material of a same/common dimension are layered. However, a price is paid in using such design practices in terms of performance/efficiency of the thrust reverser system  100 . For example, the reverse thrust that is produced is sub-optimal for a thrust reverser system  100  of a given size/footprint. 
       BRIEF SUMMARY 
       [0004]    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. 
         [0005]    Aspects of the disclosure are directed to a system associated with a thrust reverser of an aircraft, comprising: a plurality of cascade vanes configured in accordance with a substantially arc-tangent profile, where a leading edge of a first of the cascade vanes has a first width, and a trailing edge of the first of the cascade vanes has a second width that is different from the first width. In some embodiments, the second width is less than the first width. In some embodiments, the second width is approximately 0.5 times the width of the first width. In some embodiments, the leading edge is associated with an arc-portion of the arc-tangent profile, and the trailing edge is associated with a tangent-portion of the arc-tangent profile. In some embodiments, a second leading edge of a second of the cascade vanes has a third width, and a second trailing edge of the second of the cascade vanes has a fourth width. In some embodiments, the second of the cascade vanes is located aft of the first of the cascade vanes. In some embodiments, the fourth width is different from the second width. In some embodiments, the system further comprises a blocker door configured to redirect a portion of a bypass flow towards the cascade vanes when the thrust reverser is deployed. In some embodiments, the second width is different from the first width in an amount greater than a first threshold such that a rearward acting force imposed on the thrust reverser structure is greater than a second threshold. In some embodiments, the second width is different from the first width in an amount greater than a first threshold, and the first threshold is based on an amount of deviation in an exiting air flow angle that can be tolerated before an impact on at least one of engine efflux re-ingestion or aircraft impingement performance is realized in an amount greater than a second threshold. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. 
           [0007]      FIG. 1  illustrates a thrust reverser system in a deployed state in accordance with the prior art. 
           [0008]      FIG. 2  illustrates a thrust reverser system in a deployed state in accordance with aspects of this disclosure. 
           [0009]      FIG. 3  illustrates the thrust reverser system of  FIG. 2 , with the cascade vanes  204  of  FIG. 2  superimposed against conventional cascade vanes. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    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. 
         [0011]    Referring to  FIG. 2 , a thrust reverser system  200  is shown. The system  200  incorporates some of the components and devices described above in connection with the system  100 . As such, a complete re-description is omitted herein for the sake of brevity. 
         [0012]    The system  200  may include one or more cascades/cascade vanes  204 . The cascade vanes  204  may adhere to one or more shapes/profiles, such as for example a substantially arc-tangent profile. The portion of the cascade vanes  204  below (superimposed) reference line  224  may adhere to the arc-portion of the arc-tangent profile. The portion of the cascade vanes  204  above the reference line  224  may adhere to the tangent-portion of the arc-tangent profile. 
         [0013]    Each of the cascade vanes  204  may include a leading edge and a trailing edge, such as for example leading edges  214   a  and  214   d , and trailing edges  214   b  and  214   c . The leading edges may be associated with the arc-portion of the arc-tangent profile. The trailing edges may be associated with the tangent-portion of the art-tangent profile. 
         [0014]    The edges  214   a - 214   d  may have associated widths/dimensions. For example, a first of the edges (e.g., leading edge  214   a ) may have a first width/thickness and a second of the edges (e.g., trailing edge  214   b ) may have a second width. In this example, the second width may be the same as, or different from, the first width. The second width may be less than (e.g., approximately 0.5 times the width of) the first width. In some embodiments, the first and second widths may be specified in terms of one or more thresholds. As the second width is decreased relative to the first width, the exit flow area of the cascade  204  increases. As the air flow rate is increased, the amount of rearward force acting on the thrust reverser structure is increased. The increased effective flow area and the increased rearward force together improve the reverse thrust performance. However, as the second width is decreased relative to the first width, the deviation in the flow angle of the exiting air flow increases relative to a configuration having a constant vane thickness throughout the chord (e.g., the system  100  of  FIG. 1 ). The choice of the second width may be determined by the amount of deviation in the exiting air flow angle that can be tolerated before a detrimental impact on the engine efflux re-ingestion and/or aircraft impingement performance is realized in an amount greater than a threshold. 
         [0015]    In some embodiments, a width associated with a first trailing edge (e.g., trailing edge  214   b ) may be the same as, or different from, a width associated with a second trailing edge (e.g., trailing edge  214   c ). 
         [0016]    Referring now to  FIG. 3 , a closer view of the system  200  of  FIG. 2  is shown. In particular, in  FIG. 3  each of the cascade vanes  204  are superimposed against a conventional cascade vane  104 . For example, the portion of the cascade vane  104  between the superimposed reference lines  304   a  and  304   b  in  FIG. 3  (at the trailing edge of the cascade vane) might not be present in the cascade vane  204 . 
         [0017]    In view of the examples described above, aspects of the disclosure may provide for a modification (e.g., a reduction) in terms of thicknesses associated with a trailing edge of a cascade vane. Such a modification may result in a change in the effective flow exit area of the thrust reverser cascade array and thereby the rearward acting force on the thrust reverser structure. In this manner, the performance/efficiency of a thrust reverser system may be increased/maximized for a thrust reverser system of a given size/footprint. 
         [0018]    The modification of the trailing edge thicknesses may change (e.g., increase) an exit area associated with the cascades/cascade vanes. This change in exit area may result in a change (e.g., an increase) in terms of cascade mass flow. The vector of the exiting cascade flow may remain largely unchanged, despite the modification to the trailing edge thicknesses, such that the engine re-ingestion and stability/control aspects might not be appreciably impacted. Aspects of the disclosure may be used to modify (e.g., increase) the effective flow area of the cascade/cascade vanes. 
         [0019]    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.