Abstract:
A thrust reverser door provides in one aspect a separation of structural and aerodynamic functions through the provision of individual structures. In some embodiments, an aerodynamic element is adjustable in position, while in other embodiments, the relative positions are fixed. An exemplary aerodynamic element extends radially into the reverser flow to redirect the flow away from the door surface.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a thrust reverser for a turbofan gas turbine engine, and in particular to a thrust reverser door. 
       BACKGROUND 
       [0002]    The length of a thrust reverser&#39;s door is one of the design parameters which is important, as it plays a direct role in the thrust reverser&#39;s effectiveness and efficiency. The deployed doors deflect air to create a drag force for slowing down the aircraft, and the size of the deployed door therefore tends to affect the amount of drag generated (i.e. braking performance). However, a trade-off exists, as larger doors tend to be heavier and introduce more losses when stowed, and so it is generally required to optimize door length to obtain acceptable performance and efficiency. It is therefore desirable to, among other things, have a thrust reverser door which provides improved performance while decreasing losses. 
       SUMMARY 
       [0003]    In one aspect, the present concept provides a thrust reverser having at least one thrust reverser door, the door comprising a transverse leading edge having a first, second and third frames axially spaced apart from one another and disposed circumferentially adjacent said leading edge, the first, second and third frames projecting inwardly from an interior side of the door, the third frame mounted to the first and second frames, the third frame extending inwardly beyond inward terminal edges of the first and second frames. 
         [0004]    In another aspect, the present concept provides a thrust reverser for a turbofan gas turbine engine, the thrust reverser having at least one door movable between a stowed position and a deployed position for deflecting engine thrust, the at least one door having a leading edge with a deflector wall adjustable in position, the wall generally parallel to the leading edge and extending generally radially inwardly of the at least one door to, in use, redirect engine thrust. 
         [0005]    In another aspect, the present concept provides a thrust reverser comprising at least one door for deflecting engine thrust, the door having a leading edge and a single skin in a vicinity of the leading edge, the door having at least a first bulkhead extending radially inwardly from the skin, the first bulkhead defining a first member extending generally parallel to the leading edge of the door and being sized and configured relative to the skin to structurally stiffen the skin, the door also having at least a second member extending radially relative to the skin and disposed adjacent the first member, the second member having a radial height relative to the skin which is greater than a radial height of the first member. 
         [0006]    In another aspect, the present concept provides a method of adjusting an effective length of a thrust reverser door, the method comprising: mounting a substantially radially projecting member inside the thrust reverser door generally parallel and adjacent to a leading edge of the door; deflecting gases with the member during a thrust reversal mode; and changing a position of the member relative to the door to thereby change an aerodynamic effective length of the door. 
         [0007]    Further details of these and other aspects of the improvements presented herein will be apparent from the detailed description and appended figures. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0008]      FIG. 1  is a side view of an example of a nacelle provided with a thrust reverser, its doors being shown in a stowed position; 
           [0009]      FIG. 2  is a schematic view showing an example of the present thrust reverser doors in a stowed position around a jet pipe; 
           [0010]      FIG. 3  is a view similar to  FIG. 2 , showing the doors in a deployed position; 
           [0011]      FIG. 4  is a schematic cross-sectional view showing one embodiment of a door; 
           [0012]      FIG. 5  is a view similar to  FIG. 4 , showing another embodiment of a door; 
           [0013]      FIG. 6  is a schematic cross-sectional view of one example of a kicker frame mounted to a door; 
           [0014]      FIG. 7  is a view similar to  FIG. 6 , showing another example of a kicker frame mounted to a door; 
           [0015]      FIG. 8  is a schematic elevation view illustrating another embodiment of the kicker frame; and 
           [0016]      FIGS. 9 to 12  show alternate embodiments of the present concept. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to  FIG. 1 , there is shown an example of a nacelle  20  including a target/bucket door type thrust reverser  22  in the aft section  20   a  of the nacelle  20 . The turbofan gas turbine engine is located within the nacelle  20  and the nacelle  20  is attached under the wings or on the fuselage of the aircraft using an appropriate arrangement (not shown). The thrust reverser  22  comprises two opposite pivoting doors  24 ,  26  forming most of the exhaust nozzle of the nacelle  20  when they are in their stowed position. In the example illustrated in  FIG. 1 , one door  24  is at the upper side and the other door  26  is at the bottom side. 
         [0018]    Each door  24 ,  26  has a trailing edge  24   a ,  26   a  adjacent to the propulsive jet outlet  28 . The arrows in  FIG. 1  show the direct thrust operation of the engine. The trailing edges  24   a ,  26   a  cooperate with the trailing edge of side arms  32  of a jet pipe  30  located inside the aft section  20   a  of the nacelle  20  and to which the doors  24 ,  26  are pivotally connected. The jet pipe  30  and the side arms  32  are shown in  FIGS. 2 and 3 . The jet pipe  30  is concealed inside the aft section  20   a  of nacelle  20  when the doors  24 ,  26  are in their stowed position, as in  FIG. 1 . 
         [0019]      FIG. 2  schematically shows an example of the interior side of the thrust reverser  22 .  FIG. 3  shows the doors of  FIG. 2  being in a deployed position. These figures show the relative position of the jet pipe  30  with reference to the nacelle  20 .  FIG. 2  shows that the leading edges  24   b ,  26   b  of the doors  24 ,  26  and their outer wall  44  form a smooth continuity with the upstream parts of the nacelle  20  when in the closed position. 
         [0020]    The arrows in  FIG. 3  indicate the main flow path when the engine is operated during the thrust reversal. As can be seen, gases coming out of the engine are deviated substantially toward the front. The gases exit the doors  24 ,  26  in the vicinity of their leading edges  24   b ,  26   b . These edges are located at the front of the doors  24 ,  26  and are referred to as “leading” edges with reference to the travel path of the aircraft. The deviation of the gases creates a resulting horizontal retarding force opposing the forward movement of the aircraft. Increasing the output thrust generated by the engine creates an increasing aerodynamic decelerating force. In the illustrated example seen in  FIG. 3 , the trailing edge  24   a  of the upper door  24  is pivoted behind the trailing edge  26   a  of the lower door  26 , this resulting from the asymmetrical positioning of the pivots with reference to the horizontal center plane of the jet pipe  30  as disclosed in applicant&#39;s co-pending application Ser. No. 11/534,202, filed Sep. 21, 2006. The operation of the presently-described concept, however, is not dependent on such a door and pivot configuration, and any suitable arrangement may be employed. 
         [0021]    It should be noted that although the doors  24 ,  26  are described herein and shown in the drawings as being an upper reverser door  24  and a lower reverser door  26  movable in a vertical plane, doors can also be configured as left and rights door movable in a horizontal plane. Likewise, the skilled reader will appreciate that it is possible to provide an arrangement using the present invention in which the trailing edge  26   a  of the lower door  26  opens behind the trailing edge  24   a  of the front door  24 , as mentioned above, and other arrangements of the trailing edges  24   a ,  26   a  are also available. Other door arrangements employing the present invention are possible, as well, and therefore this description is not to be understood as limited to the door mounting orientation and configuration depicted, nor the target/bucket type depicted. 
         [0022]    Doors  24 ,  26  have an outer skin  44  extending from their leading edge to their trailing edge, and a partial inner skin  45  extending from the door&#39;s trailing edge to a point roughly halfway intermediate the leading and trailing edges. This construction results in a single skin  44  being present in the vicinity of the door leading edge. The skilled reader will appreciate that double-skin doors provide structural advantages, but are correspondingly heavier than single skin designs. The presently-described “hybrid” single-and-double skin construction thus has advantages over other constructions, including permitting control of airflow in the vicinity of the trailing edge, as will now be further described. 
         [0023]    The leading edges  24   b ,  26   b  of the door  24 ,  26  comprise a first and a second arc-shaped radial frame  40 ,  42  disposed across the interior side of single-skin wall  44  and extending circumferentially along the leading edges  24   b ,  26   b . The first and second frames  40 ,  42  are spaced apart from each other and project substantially radially relative to a curvature of the doors  24 ,  26 . These radial frames  40 ,  42  have a structural function, to stiffen skin  44 , and, in this example, preferably have substantially the same height, as in many of the illustrated examples. A third arc-shaped radial frame member  50  is provided, in this embodiment, extending between the first and second radial frames  40 ,  42 . This third frame, referred to hereinbelow as the kicker frame  50 , has a height greater than the first and second radial frames  40 ,  42  when kicker frame  50  mounted to the door  24 ,  26 . Thus, the distal edge of the kicker frame  50  extends beyond the first and second radial frames  40 ,  42 . The kicker frame  50  is preferably mounted to the door  24 ,  26  in any suitable fashion, such as being connected to the other radial frames  40 ,  42  using any appropriate arrangement. Also preferably, the kicker frame  50  is mounted in a manner allowing its axial position relative to the door to be selectively adjusted with reference to the first and second radial frames  40 ,  42 , as described below. 
         [0024]    As can be appreciated, and as best shown in  FIG. 3 , the position of the kicker frame  50  affects the “effective” or aerodynamic length of their respective door  24 ,  26  since each kicker frame  50  redirects the flow of gases closer to the horizontal. The kicker frame  50  has an aerodynamic function, namely to intercept the reverse efflux and deflect it in a more forward thrust direction—i.e. as if the door were geometrically longer than it in fact is, and thus improves the overall efficiency of the thrust reverser. The kicker frame  50  is preferably mechanically connected to the two radial frames  40 ,  42 , and thus it also serves to a structural function. 
         [0025]      FIG. 2  also shows that the first and second radial frames  40 ,  42  of the upper door  24  are separated from each other by a distance “d”. The two radial frames  40 ,  42  have height that is substantially equal to a value that is consistent with the required structural rigidity of the thrust reverser door  24 . The distance “d” can be, for example, between 50 mm and 100 mm. The door length can be characterized by its geometric length L 1  and by the so-called “effective length” L 2 . The length L 1  is the geometrical length of the door between its leading and trailing edges  24   a ,  24   b . The effective length L 2  is the length between the trailing edge  24   a  of the door  24  and the second radial frame  42 . Adjusting the position of the kicker frame  50  allows varying the effective length between a minimum value up to a maximum value within the range “d”. The same principle applies to the lower door  26 . 
         [0026]      FIG. 4  schematically shows an example of the first and second radial frames  40 ,  42  made integral with the wall  44  of the door  24 , such as by casting or machining from solid (kicker frame  50  is not depicted, for clarity). Providing the radial frame integrally with the outer skin tends to result in better containment of the reverse efflux as it attaches to the outer skin, although this feature is not critical to operation of the presently-described concept.  FIG. 5  is a similar view (also shown without kicker frame  50 , for clarity), showing another example where the first and second radial frames  40 ,  42  are part of an element  46  having a U-shaped section and that is connected to the wall  44  of the door  24  using an appropriate arrangement, such as bolts, rivets, welding, etc. Other suitable arrangements are possible as well, and it is understood that the invention is not limited to the connection means shown.  FIGS. 4 and 5  show that the first and second radial frames  40 ,  42  may deviate by a small angle with reference to a perpendicular extending from the wall  44  of the door  24 . When the doors  24 ,  26  are deployed, as in  FIG. 3 , the reverse efflux is then deflected further toward the front of the engine. 
         [0027]      FIG. 6  is a schematic view showing an example of how the kicker frame  50  may be connected between the first and second radial frames  40 ,  42 .  FIG. 6  shows the kicker frame  50  adjustably mounted using a plurality of threaded rods  52  (only one is seen in the figure) longitudinally extending between the first and second radial frames  40 ,  42 . The kicker frame  50  in this arrangement may have a threaded hole, or maybe connected to a follower engaged on the threaded rods  52 , or have other suitable means keying the axial position of the rod to the threaded rods. As mentioned, a plurality of rods  52  are provided circumferentially along the kicker frame  50 , to adequately mount the kicker  50  to frames  40 ,  42 . Rotation of the rods  52  will move the kicker frame  50  axially between radial frames  40 ,  42  which allows, for example, adjusting the effective length of the reverser doors, for example, during development tests of the thrust reverser. 
         [0028]    Referring again to  FIG. 3 , in use, the doors  24 ,  26  are deployed to redirect engine thrust, as indicated by arrows A 1 . As the reverse efflux flow flows along the inner side of doors  24 ,  26 , it eventually reaches kicker frame  50 , and is then redirected (as indicated by arrows A 2  in  FIG. 3 ), more forwardly than it otherwise would have been by the skin  44  of doors  24 ,  26  or by the frames  42 . It will be understood that the height and axial position of kicker frame  50  on the doors  24 ,  26  will affect the direction of reverse efflux exiting the thrust reverser. It will also be understood that, while kicker frame  50  could be positioned axially just about anywhere along doors  24 ,  26 , the positioning of kicker frame  50  in the vicinity of the door&#39;s leading edge allows better optimization and adjustment of the reverser door effective length. Adjustment of the kicker frame permits optimizing of the reverser door effective length and reversing efficiency without having to change the geometrical length of the doors. 
         [0029]      FIG. 7  schematically shows an example of a fixed spacer arrangement  54  for holding in desired position the kicker frame  50 . In this case, the kicker frame  50  is in a fixed position relative to frames  40 ,  42 . This arrangement allows the relative position of the kicker to be fixed on the doors  24 ,  26 , for instance in a final desired state on the thrust reverser  22  as certified for flight on a particular aircraft. Spacers of different widths can be used on different aircrafts, which facilitates the use of doors  24 ,  26  of a particular configuration on more than one thrust reverser design (i.e. allows commonality of doors between designs on multiple aircraft designs employing the same engines). This provides many advantages for manufacturing and maintenance, etc, such as part count reduction, etc. 
         [0030]      FIG. 8  schematically illustrates an example of a variable height profile for the kicker frame  50 , as viewed from beyond the edge of the first or the second kicker radial frame  40 ,  42 . This figure shows that the height of the kicker frame  50 , with reference to the interior wall of a given door, may be varied so as to orient the gases coming out of the thrust reverser  22  in a specific direction, and thus provide an asymmetric reverse efflux which permits optimization of the thrust reverser&#39;s performance. In the illustrated example, the height h 1  is larger than the height h 3 , which is larger than the height h 2  at the center of the kicker frame  50 . For optimization of the direction of the reverse efflux, other suitable configurations (for example, h 1 &gt;h 2 &gt;h 3 , not shown, or h 1 =h 3 &gt;h 2 , not shown, etc.) and kicker frame shapes are possible, as well. It will also be understood that a kicker frame  50  may have a substantially constant height (h 1 =h 2 =h 3 ), but be mounted off-centre relative to frames  40 ,  42 , thus yielding a similar aerodynamic effect on the reverse efflux flow. 
         [0031]    Overall, as can be appreciated, the length of the doors  24 ,  26  can now be modified in a given range to fit the requirements and it does so without the need of remanufacturing the doors. 
         [0032]    The above description is meant to be exemplary only, and one skilled in the art will recognize that many changes may also be made to the embodiments described without departing from the inventions disclosed. For instance, the kicker frame  50  need not be located between frames  40 ,  42 , but may be located in any suitable fashion. Also, as described above, rather than (or in addition to) adjusting an axial position of the kicker frame  50 , the kicker frame  50  may be configured to be adjustably extended into the reverse efflux flow, such as by mounting it higher with respect to frames  40 ,  42 . Referring to  FIGS. 11 and 12 , the function of kicker frame  50  may be integrated with one of the radial structural frames  40 ,  42 . In the embodiments of  FIGS. 11 and 12 , it will be understood that the axial position of the kicker frame  50  is not adjustable, per se, as in previous embodiments, however the height h 2  (not indicated in  FIGS. 9 to 12 ) may be “adjusted” such as through grinding or other mechanical means, or in any suitable fashion, by removing portions  50 ′ and  50 ″. The shapes of the doors and the configuration of these doors with reference to each other may be different to what is shown. The first and the second radial frames can be differently shaped and/or positioned relative to one another. One or both of the first and the second radial frames may be omitted, or supplemental members may be provided, as it will be understood that many other suitable arrangements to support the kicker frame are available, and that the present concept is not limited to the exemplary frames described. Although the kicker frame is preferably mounted to the first and second frames, the kicker frame may be mounted to the door in any suitable manner. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.