GB2119857A

GB2119857A - Ducted fan gas turbine engine

Info

Publication number: GB2119857A
Application number: GB08212768A
Authority: GB
Inventors: Leonard John Rodgers
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1982-04-30
Filing date: 1982-04-30
Publication date: 1983-11-23

Abstract

The engine is supported from an aircraft wing by a pylon 34 having a beam 36 which projects a relatively long way in front of the pylon and, rather than being thickened to resist the increased bending loads, is supported by a link 38 extending from the pylon 34 to a position near the extremity of the beam 36. The latter is connected directly or via link 42 to an annular box structure 40 dividing supporting struts 18 and 28. A peg 46 protruding from beam 36 is received in a socket 48 in the core engine casing 16. <IMAGE>

Description

SPECIFICATION Ducted fan gas turbine engine This invention relates to a ducted fan gas turbine power plant having a mounting structure for mounting it on an aircraft. More specifically, the invention relates to a ducted fan gas turbine engine which has affront mounted ducted fan and is supported on fixed aircraft structure e.g. a wing mounted pylon.

A known ducted fan gas turbine powerplant comprises a ducted fan, mounted at the upstream end of a core gas generator for co-axial rotation with the compressor of the core gas generator.

It is a common practice to suspend the front portion of the power plant from a pylon, which in turn is fastened to and projects forwardly of an aircraft wing, via a beam fixed only to the underside of the pylon and linked to the compressor casing of the core gas generator.

The invention seeks to provide a ducted fan gas turbine power plant including an improved front mounting structure.

According to the present invention, a ducted fan gas turbine engine comprises a core gas generator, a fan mounted at the front of the core gas generator for coaxial rotation with the compressor of the core gas generator, a rigid annular box structure which is positioned at the upstream end of the compressor of the core gas generator, a rigid pylon arranged for fixing to an aircraft structure, a beam fixed to the pylon and projecting forwardly thereof, and having nieans for connection to the annular box structure, a link having one end connected to the upstream end of the pylon and the other end connected to the projecting extremity of the beam which extremity is connected to the annular box structure.

Preferably the beam extremity is connected to the annular box structure via a pair of links which are positioned so as to straddle the axis of the core gas generator.

The invention will now be described by way of example and with reference to the accompanying drawings in which: 'Fig. 1 is a cross sectional part view of a ducted fan gas turbine engine incorporating an embodiment of the invention.

Fig. 2 is a view on line 2-2 of fig. 1.

Fig. 3 is a part view of an alternative embodiment of the invention.

Referring to fig. 1. A core gas generator 10 of a ducted fan gas turbine engine 12 includes a compressor 14 which is surrounded by a casing 16.

A plurality of radial struts 18 are arranged radially of the axis 20 of the engine 12 and support an air intake 22 for the compressor 14.

A fan 24 is mounted upstream of the compressor 1 4 for coaxial rotation with the compressor 14 and is enclosed in a fan casing 26.

A plurality of radial struts 28 support the fan casing 26 in coaxial relationship with the compressor air intake 22.

A streamlined cowl and air intake structure 30 is fastened to the casing 26 via a flanged joint 32.

A rigid pylon 34 of which only the upstream end is shown, is arranged for fixing to the wing (not shown) of an aircraft (not shown). A beam 36 is rigidly fastened to the underside of the pylon 34 and has a portion which extends forwardly of the pylon 34.

A link 38 has or;e end connected to the end face of the pylon 34 and the other end connected to the upper surface of the free end of the projecting extremity 36.

A rigid, annular box structure 40 divides supporting struts 1 8 and 28 and further provides anchor points for an end of each of two other links 42 and 44. Only link 42 is shown in fig. 1. The remaining ends of links 42 and 44 are connected to the underside of the beam 36, at its free end.

Reference to fig. 1 shows that link 42 and link 44 which in Fig. 1 is directly behind link 42; are in alignment with the link 38.

A peg 46 protrudes from the underside of beam 36 and is received in a complementary socket 48 in the compressor casing 1 6. This feature positionally locates the engine 12 in the fore and aft direction with respect to the pylon 34 and so eases connection and disconnection of link 38 with the front face of pylon 34. It is arranged however, so as to transmit to pylon 34 only those loads which are exerted upon it in a direction axially of engine 10.

Referring now to fig. 2. The links 42 and 44 straddle the axis 20 of engine 12 and lie tangentially of the mean diameter of annular box 40. With such an arrangement, links 42 and 44 pass vertical loads and fore and aft loads to pylon 34.

The pylon 34 and the beam 36 are enclosed in a stream-lined fairing 50, shown in chain dotted lines in both fig. 1 and fig. 2, which though not shown to its full extent, extends in a downstream direction for most of the length of the fan duct 52.

Referring back to fig. 1. By arranging the engine mounting links 38, 42 and 44 such that they lie at an angle of less than 900 to a plane normal to the axis of engine 12, more space 56 is provided between the struts 28 and the pylon 34. The length of the fan cowl 26 may thus be increased in a downstream direction from the trailing edge of struts 28. Such components as accessory drive shafts 54 may then be arranged to project from the engine interior and through the space 56 and the extended portion of can cowl 26, without disrupting the airflow which leaves the trailing edges of the struts 28 during operation of the engine.

When it is required to remove the core gas generator 10, fan 24 and fan cowl 26 is an entity, leaving behind the remainder of the cowling and the pylon 34, so far as the front mounting is concerned, only two connections need be broken.

The first is that end of link 38 which is fastened to beam 36. When that end is released, the link 38 will hang against the end of the pylon 34, as shown in chain dotted lines in fig. 1.

The second connection to be broken is the fastening which holds beam 36 to the underside of the pylon 34. When these two connections have been broken the engine 12 can be lowered on a sling (not shown) in known manner, onto a suitable support.

The fan cowl 26 terminates sufficiently far away from the pylon 34, to pass the link 38 which as has been explained, lies against the end of pylon 34.

An alternative embodiment of the invention is depicted in fig. 3 wherein like parts are given like numerals. Links 42 and 44 are obviated and the beam 36 is fastened directly to the annular box 40 by a spherical joint 41.

If it is desired to maintain a spacing between the fan cowl and the pylon similar to that achieved in the embodiment of fig. 1, the beam 36 will have to extend further beyond the pylon 34 (not shown in fig. 3).

Beam 36 need not be unduly thickened in order to support the extra loads generated by its increased length, provided that link 38 is again connected to, or adjacent its extremity.

Claims

1. A ducted fan gas turbine engine comprising a core gas generator, a fan mounted at the front of the compressor of the core gas generator for coaxial rotation with the compressor of the core gas generator, a rigid annular box structure which is positioned at the upstream end of the compressor of the core gas generator, a rigid pylon adapted for fixing to aircraft structure, a beam fixed to the pylon and projecting forwardly thereof and having means for connection to the annular box structure, a link having one end connected to the pylon and the other end connected to the projecting extremity of the beam, which extremity is connected to the annular box structure by said means.

2. A ducted fan gas turbine engine as claimed in claim 1 wherein the means connecting the beam extremity to the annular box structure comprises a pair of links which are positioned so as to straddle the axis of the core gas generator.

3. A ducted fan gas turbine engine as claimed in claim 1 wherein the means for connecting the projecting extremity of the beam to the annular box structure comprises a spherical joint formed at the extremity of the beam and on the annular box structure.

4. A ducted fan gas turbine engine as claimed in any previous claim wherein the annular box structure includes radially projecting struts which maintains the fan cowl of the ducted fan in radially spaced relationship with the core gas generator.

5. A ducted fan gas turbine engine substantially as described in this specification with reference to figs. 1 and 2 of the drawings.

6. A ducted fan gas turbine engine substantially as described in this specification with reference to fig. 3 of the drawings.