Abstract:
The thrust reverser is used with a gas turbine engine and includes first and second doors pivotable between a stowed position and a deployed position. When deployed, pivoting fairings on the first door are moved so as to give room to the second door as its trailing edge moves within the first door. When stowed, the second door preferably provides the locking mechanism to the pivoting fairings of the first door.

Description:
TECHNICAL FIELD 
   The invention relates to thrust reversers for gas turbine engines. 
   BACKGROUND 
   Thrust reversers on gas turbine engines have to fulfill two functions: while stowed, to provide an exhaust nozzle for the direct thrust generated by the engine; and while deployed, to redirect the engine thrust in order to provide a decelerating force after landing. Since almost the entire flight sequence occurs with the thrust reverser in the stowed position, it is desirable that the presence of the thrust reverser does not degrade the direct thrust performance of the engine. 
   While many thrust reverser models have been used successfully for a number of years, there is always a need to provide further improved arrangements. 
   SUMMARY 
   In one aspect, the present concept provides a thrust reverser for a nacelle of a gas turbine engine, the thrust reverser comprising a first reverser door and a second reverser door defining a portion of an aft section of the nacelle, the doors having a respective trailing edge adjacent to a propulsive jet outlet of the nacelle and being pivotable simultaneously between a stowed position and a deployed position, the trailing edge of the first door being positioned behind the trailing edge of the second door in the deployed position, the thrust reverser comprising a pair of pivoting fairings, each having a respective trailing edge adjacent to the propulsive jet outlet and being pivotally connected to a respective side of the first door, the pivoting fairings being in a stowed position when the doors are in a stowed position and being in an outwardly pivoted position when the doors are in a deployed position. 
   In another aspect, the present concept provides a fairing for a thrust reverser door, the fairing comprising a wall defining an outer surface and being pivotable around a pivot axis located adjacent to an edge of the wall, the wall being pivotally connected to a side at a rear end of a door, the wall being outwardly biased around the pivot axis. 
   In another aspect, the present concept provides method of pivoting doors of a thrust reverser, the method comprising the simultaneous steps of: pivoting the doors from a stowed position to a deployed position in such a way that a trailing edge of a first one of the doors moves behind the trailing edge of a second one of the doors; and outwardly pivoting a pair of opposite fairings that are connected to corresponding sides of the first door and adjacent to its trailing edge so as to provide clearance for the trailing edge of the second door in the deployed position. 
   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 
       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; 
       FIG. 2A  is a schematic view showing an example of the present thrust reverser doors in a deployed position around a jet pipe, and  FIG. 2B  is an enlarged view of the indicated portion of  FIG. 2A ; 
       FIG. 3  is a rear view of the trust reverser doors shown in  FIG. 2A ; 
       FIG. 4  is a schematic and enlarged view showing one of the pivoting fairings at the rear side of the upper thrust reverser door of  FIG. 2A , both doors being shown as transparent; 
       FIG. 5  is a view similar to  FIG. 4 , showing the pivoting fairing at the beginning of the deployment of the doors; and 
       FIG. 6  is a view similar to  FIGS. 4 and 5 , showing the doors during the transit to their deployed position, the pivoting fairing being pivoted further outwards. 
   

   DETAILED DESCRIPTION 
   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 propulsive jet outlet  28  of the nacelle  20  when they are in a stowed position. One door  24  of the illustrated example is at the upper side and the other door  26  is at the bottom side. The doors  24 ,  26  are generally semi-circular. 
   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 thrust reverser nozzle  22  is active in direct thrust as it forms the exhaust nozzle of the engine. The trailing edges  24   a ,  26   a  cooperate with the trailing edge of side arms  32  of a jet pipe  30  ( FIG. 2A ) located inside the aft section  20   a  of the nacelle  20  and to which the doors  24 ,  26  are pivotally connected. The leading edges  24   b ,  26   b  of the doors  24 ,  26  and their outer wall form a smooth continuity with the upstream parts of the nacelle  20  when the doors  24 ,  26  are in the closed position. 
     FIG. 2A  schematically shows an example of the interior side of the fixed structure  30  of the thrust reverser  22 . The jet pipe  30  and its side arms  32  are concealed inside the aft section  20   a  of nacelle  20  when the doors  24 ,  26  are in their stowed position, as in  FIG. 1 . 
   The engine is in a thrust reversal mode in  FIG. 2A . This mode is generally used immediately after landing an aircraft on a runway. The doors  24 ,  26  are pivoted to that position simultaneously using actuators (not shown). The arrows in  FIG. 2A  indicate the main flow path of the efflux coming out of the engine when operated during the thrust reversal. As can be seen, a large portion of the 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 increased aerodynamic decelerating force, thus more braking. 
     FIGS. 2A and 3  show that the trailing edge  24   a  of the upper door  24  is pivoted behind the trailing edge  24   a  of the lower door  26  when the doors  24 ,  26  are deployed. This can result from the asymmetrical positioning of the door&#39;s pivots with reference to the horizontal center plane of the jet pipe  30  as disclosed, for instance, in applicant&#39;s co-pending application Ser. No. 11/534,202, filed Sep. 21, 2006.  FIG. 3  shows the deployed doors of  FIG. 2  from the rear. 
   As can be seen in  FIG. 1 , the doors  24 ,  26  are separated on each side by longitudinal fairings  34 ,  36 . The fairings  34 ,  36  cover the actuators, the various linkages and other parts in that area. They complete the outer mold line (OML) of the nacelle  20  when the doors  24 ,  26  are stowed. The front fairings  34  are fixed and the rear fairings  36  are pivotable. The pivoting fairings  36  have trailing edges  36   a  that meet the trailing edge of the jet pipe  30  for minimization of the base area. The trailing edges  36   a  of the pivoting fairings  36  also form a substantially continuous outline with the trailing edges  24   a ,  26   a  of the doors  24 ,  26 , which outline surrounds the propulsive jet outlet  28 . 
   There are two pivoting fairings  36  on the thrust reverser  22 . One is inboard and the other is outboard. They are preferably mirror images of each other. The pivoting fairings  36  provide clearance for the ends of the trailing edge of the door that goes into the other door when they are deployed. This way, in the case of the illustrated example, the trailing edge  26   a  of the lower door  26  can move into the upper door  24  without interference.  FIGS. 4 to 6  illustrate various stages of the movement of one of the pivoting fairings  36 . The other parts are not shown in these figures for the sake of clarity. 
   The pivoting fairing  36  is outwardly biased to its opened position and is pivotally connected at the rear of the upper door  24 . A torsion spring  40 , shown in  FIG. 2B , can be used to generate the bias. Other kinds of springs or arrangements are possible. The upper door  24  supports the spring  40  and devises (not shown) on which is hinged the pivoting fairing  36 . There are two supporting devises per pivoting fairing  36  and each fairing  36  is fitted with two associated hinges  42 ,  44 , one located upstream the other one downstream of the fairing  36 . 
   As shown in  FIG. 4 , the pivot axis of the pivoting fairing  36  of the illustrated embodiment defines an angle with reference to the central longitudinal axis of the nacelle  20 . The exact shape of the wall of the pivoting fairing  36  depends on the width required for the clearance of the lower door  26  in the deployed position. 
   The hinge  44  located downstream is fitted with a follower arm  50  that can be on or off an inclined ramp  52  installed on the outer surface of a fixed structure, in this case the jet pipe arm  32  of the jet pipe  30 . The illustrated pivoting fairing  36  is also fitted with a locking tab  54  that engages the surface under the upper longitudinal edge  26   c  of the lower door  26  for locking the pivoting fairing  36  in a stowed position when the doors  24 ,  26  are stowed. The lower door  26  is consequently part of the locking mechanism of the pivoting fairing  36 . 
     FIG. 4  shows the doors  24 ,  26  immediately before moving from their stowed position to their deployed position. The pivoting fairing  36  is urged to outwardly pivot around its own pivot axis under the action of its spring  40 . However, the pivoting fairing  36  is retained by its locking tab  54  that has not yet disengaged from the upper longitudinal edge  26   c  the of lower door  26 .  FIG. 4  also shows that the arm  50  of the pivoting fairing  36  is above but not yet engaged on the ramp  52  of the jet pipe  30 . 
     FIG. 5  shows the doors  24 ,  26  when in transit to their deployed position, and the locking tab  54  of the pivoting fairing  36  is now disengaged from the lower door  26  while the arm  50  is now engaging the ramp  52  on the jet pipe  30 . Since the pivoting fairing  36  is spring loaded to its opened position and the spring  40  maintains the arm  50  in contact with the inclined surface of the ramp  52  that is fixed, the pivot angle of the fairing  36  is dictated by the relative position of the arm  50  on the ramp  52 . The ramp  52  has a decreasing height toward the rear and accordingly, the pivot angle of the fairing  36  increases as the doors  24 ,  26  move closer to their deployed position. 
     FIG. 6  shows that the doors  24 ,  26  are continuing their movement toward the deployed position, and the arm  50  is still resting on the ramp  52  but will eventually leave the ramp  52  at one point. A stop or another means can be provided to maintain the same pivot angle when the arm  50  leaves the ramp  52 . The trailing edge at the end of the ramp  52  can otherwise be inclined for redirecting the arm  50  on its surface when the doors  24 ,  26  are moved back to the stowed position. 
   It should be noted that the same figures can be used for explaining how the pivoting fairing  36  moves back to its locking position and is locked once again by the lower door  26 . As the doors  24 ,  26  move from their deployed to their stowed positions, the pivoting fairing  36  stays opened until the arm  50  meets and rests on the ramp  52  of the jet pipe  30 , as in  FIG. 6 . As the doors  24 ,  26  continue to transit toward their stowed position, the ramp  52  of the jet pipe  30  forces the pivoting fairing  36  to return progressively towards its stowed position, as in  FIG. 5 . At one point, the locking tab  54  of the pivoting fairing  36  engages the surface underneath the lower door  26  while the arm  50  of the pivoting fairing  36  moves off the ramp  52  but stays above it, as in  FIG. 4 . From this position to the fully stowed position of the doors  24 ,  26 , the lower door  26 , via the locking tab  54  of the pivoting fairing  36 , drives it to its fully stowed position. Locking the pivoting fairing  36  using the lower door  26  prevents it from fluttering during direct thrust. 
   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 exact shape of the illustrated elements (nacelle, doors, etc.) may be different. Although the doors are described herein and shown in the figures as being an upper reverser door and a lower reverser door 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 in which the trailing edge of the lower door opens behind the trailing edge of the front door, as mentioned above, and other arrangements of the trailing edges 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. The pivoting fairings can be attached to the lower door instead of the upper door in a thrust reverser designed so that the upper door goes into the lower door. Other locking mechanisms can be devised than the one shown and described herein. 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.