GB2252279A

GB2252279A - Thrust reverser

Info

Publication number: GB2252279A
Application number: GB9102205A
Authority: GB
Inventors: Leonard John Rodgers; Norman Roberts
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1991-02-01
Filing date: 1991-02-01
Publication date: 1992-08-05
Also published as: DE4200645A1; FR2672339A1; GB9102205D0

Abstract

A thrust reverser, for a gas turbine engine 10 having a jet pipe (13), comprises two deflector doors 16 and 18 having scarfed downstream edges (24 and 26) (Fig. 1). The deflector doors 16 and 18 are mounted so they can pivot from a stowed position, in which they define a nozzle (14) through which the engine efflux flows, to the operative position shown when they lie substantially transverse to the jet pipe (13) to redirect the engine efflux. A conical or frusto conical member 20 abuts the scarfed downstream edges (24 and 26) of the deflector doors 16 and 18 when they are in the stowed position. The member 20 acts as a seal to prevent spillage of the engine efflux from between the scarfed edges (24 and 26) of the defector doors 16 and 18 when in the stowed position. When thrust reversal is required the member 20 translates axially from the position where it abuts the doors 16 and 18 to a position which allows the doors to pivot to the operative position. <IMAGE>

Description

225. - -);,9 1 THRUST REVERSER The present invention relates to a thrust

reverser and in particular to a thrust reverser for a gas turbine engine.

It is known to use a thrust reverser consisting of two opposed rounded doors in a jet pipe of a gas turbine engine. The doors are pivotally mounted for movement between two positions. In a stowed position they constitute a rearward extension of the jet pipe and define a nozzle through which the hot gases efflux from the jet pipe. The doors pivot from this position to an operative position in which they lie transverse to the jet pipe. The downstream edges of the doors are scarfed so that when the doors are deployed into the operative position they act to direct the engine efflux forwards to redirect thrust of the engine.

A problem with this type of thrust reverser is that when the doors are in the stowed positions the efflux can spill sideways through the cut away region between the scarfed edge of the doors. Further the provision of a hinge to allow pivoting movement of the doors increases the thickness of the nozzle adjacent the hinge which results in an increase in the basic drag effect on the trailing edge of the nozzle.

The present invention seeks to provide an improved thrust reverser having scarfed doors in which the spillage and base drag effects are substantially eliminated.

According to the present invention a thrust reverser for a gas turbine engine having a jet pipe, the thrust reverser comprises a plurality of deflector doors having scarfed downstream edges and being mounted for pivotable movement from a stowed position, in which they form part of the jet pipe wall and cause substantially no blockage to flow of gas therethrough, to an operative position in which they lie substantially transverse to the jet pipe to cause substantially complete blockage to flow of gas therethrough, there being further provided a sealing member, of annular cross section, which abuts the downstream edges of the deflector doors so as to seal between the scarfed 2 downstream edges of the deflector doors when in the stowed position, the sealing member being mounted so that it is axially translatable from a position where it abuts the deflector doors to a position which allows pivotable movement of the deflector doors to the operative position.

Preferably pivotable movement of the deflector doors is mechanically actuated by a ram mechanism.

The sealing member may be axially translated by connecting means between the deflector doors and the sealing member, so that movement of the deflector doors actuates axial movement of the sealing member.

The connecting means comprises a plurality of pivotable links between the deflector doors and the sealing member, there being further provided a plurality of guides which permit axial movement of the sealing member whilst preventing vertical movement.

The pivotable links between the deflector doors and sealing member are preferably U shaped.

In the preferred embodiment of he present invention the guides are moved axially rearward to permit movement of the sealing member by the means of actuating the deflector doors.

The guides are provided with pins which locate in slots in the sealing member, the pins permit axial movement of the sealing member relative to the guide but prevents any vertical movement therebetween.

The present invention will now be described by way of example with reference to the accompanying drawings in which, Figure 1, is a diagrammatic view of a gas turbine engine incorporating a thrust reverser in accordance with the present invention, Figure 2, is a pictorial view of a nozzle of a gas turbine engine showing a thrust reverser in accordance with the present invention in a stowed position, Figure 3, is a pictorial view of a nozzle of a gas turbine engine showing a thrust reverser in accordance with the present invention in an operative position.

3 In Figure 1 a gas turbine engine 10 is enclosed in a casing 12. The gas turbine engine 10 has a jet pipe 13 which terminates at its downstream end in an exhaust nozzle 14. The exhaust nozzle 14 is defined by a pair of rounded doors 16 and 18 and a member 20 of annular cross-section. The member 20 may be cylindrical or frusto-conical and is located downstream of the doors 16 and 18.

Each of the pair of rounded doors 16 and 18 is mounted so that it is pivotable about an axis 22. The downstream edges 24 and 26 of the pair of rounded doors, 16 and 18 respectively, are scarfed. The member 20 abuts the scarfed edges 24 and 26 and is connected to the doors 16 and 18 by links 28 which allow axial movement of the member 20 relative to the doors 16 and 18.

Figure 2 shows the position of the doors 16 and 18 when the engine 10 is operating under forward thrust. The doors 16 and 18 are stowed so that they cause substantially no blockage to the flow of gases therethrough and constitute a rearward extension of the jet pipe 13. The doors 16 and 18 are locked in the stowed position so that the gas pressure in the jet pipe 13 can not deploy them. In this position the doors define a nozzle through which efflux passes.

The annular cross section member 20, abuts the scarfed edges 24 and 26 of the doors 16 and 18 respectively, to prevent efflux spillage sideways through the region 25 between the scarfed edges 24 and 26. The links 28, which connect the member 20 to the doors 16 and 18, are located in recesses (not shown) in the outer surface of the doors 16 and 18. The member 20 is tapered to provide minimum thickness at the trailing edge 15 of the nozzle 14. The member 20 thus forms a smooth extension of the doors 16 and 18 in the forward thrust condition. Tapering of the member 20 reduces the basic drag effect experienced at the trailing edge 15 of the nozzle 14.

When thrust reversal is required the doors 16 and 18 are unlocked and move to the operative position shown in Figure 3. The doors 16 and 18 are pivoted by the rearward 4 movement of a pair of rods 30. The rods 30 are moved rearward by an actuator crosshead (not shown) located in a recess 32 in the casing 12. The actuator crosshead can be driven by, for example, a hydraulic piston, air mixer or a lead screw.

Pivotable movem ent of the doors 16 and 18 causes the member 20 to move axially rearwards. Axial movement of the member 20 is permitted by the links 28 which connect the member 20 to the doors 16 and 18. The links 28 are of rectangular U-shape and are hinged at each end. The hinges provide restraint in the axial and sideways direction and avoids rotation about the pitch, roll and jaw axes.

Two guides 34 are provided to prevent vertical movement of the member 20 as it moves axially rearward. The guide 34 forms part of the external surface of the casing 12 and are located on either side of the engine casing 12. One end 35 of each of the side guides 34 is mounted on the actuator cross head (not shown) which moves the rods 30 rearwards to display two doors 16 and 18.

The other end 36 of each of the guides 34 is provided with a pin 38 which locates in a slot 40 in the side of the member 20. The guides 34 move rearward with the actuator crosshead when the doors 16 and 18 are displayed. Axial movement of the member 20 is permitted by the pin 38 on the end 36 of each of the guides 34 sliding in the slot 40 in the member 20. The pins 38 on the guides 34 therefore allow axial movement of the member 20 relative to the doors 16 and 18 but prevent any vertical movement.

The doors 16 and 18 pivot about axis 20 until the scarfed edges, 24 and 26 respectively, abut on the centre line of the engine 10. The doors 16 and 18 are then transverse to the jet pipe 13 and cause substantially complete blockage of the gas flow therethrough to reverse the thrust of the engine 10.

Claims

Claims: -

1. A thrust reverser for a gas turbine engine having a jet pipe, the thrust reverser comprising a plurality of deflector doors having scarfed downstream edges and being mounted for pivotable movement from a stowed position, in which they form part of the jet pipe wall and cause substantially no blockage to flow of gas therethrough, to an operative position in which they lie substantially transverse to the jet pipe to cause substantially complete blockage to flow of gas therethrough, there being further provided a sealing member, of annular cross section, which abuts the downstream edges of the doors so as to seal between the scarfed downstream edges of the deflector doors when in stowed position, the sealing member being mounted so that it is axially translatable from a position where it abuts the downstream edges of the deflector doors to a position which allows pivotable movement of the deflector doors to the operative position.

2. A thrust reverser as claimed in claim 1 in which pivotable movement of the deflector doors is mechanically actuated.

3. A thrust reverser as claimed in claim 2 in which the pivotable movement of the deflector doors is mechanically actuated by a ram mechanism.

A thrust reverser as claimed in claim 2 or claim 3 in which the sealing member is axially translated by connecting means between the deflector doors and the sealing member, so that movement of the deflector doors actuates axial movement of the sealing member.

5. A thrust reverser as claimed in claim 4 in which the connecting means comprises a plurality of pivotable links within the deflector doors and the sealing member, there being further provided a plurality of guides which permit axial movement of the sealing member whilst preventing vertical movement.

6. A thrust reverser as claimed in claim 5 in which the pivotable links between the deflector doors and sealing member are U shaped.

7. A thrust reverser as claimed in claim 5 or claim 6 in which guides are moved axially rearward to permit movement 4 - Ap 6 of the sealing member by the means of actuating their deflector doors.

8. A thrust reverser as claimed in claim 7 in which the guides are provided with pins which locate in slots in the sealing member, the pins permit axial movement of the sealing member relative to the guide but prevents any vertical movement therebetween.

9. A thrust reverser as hereinbefore described by way of example and as shown in Figures 1-3.

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