Gas turbine engine
A fan containment system has a fan case having an annular casing element for encircling an array of fan blades and a hook projecting generally radially inwardly from the annular casing element. An annular fan track liner is positioned substantially coaxial to the annular casing element, and positioned such that a forward end of the fan track liner is axially spaced from the hook so that there is a gap between the hook and the fan track liner. A bridge member spans the gap between the hook and the fan track liner, wherein the bridge member is connected to the hook and contacts a radially inner surface of the forward end of the fan track liner. The bridge member fails when impacted by a fan blade released from a hub so that the released fan blade can impact the hook and be contained by the fan containment system.
1. A fan containment system for fitment around an array of radially extending fan blades mounted on a hub in an axial gas turbine engine, the fan containment system comprising:
a fan case having an annular casing element for encircling an array of fan blades and a hook projecting in a generally radially inward direction from the annular casing element and positioned axially forward of an array of fan blades when the fan containment system is fitted around said fan blades;
an annular fan track liner positioned substantially coaxial to the annular casing element, and positioned such that a forward end of the fan track liner is axially spaced from the hook so that there is a gap between the hook and the fan track liner; and
a bridge member spanning the gap between the hook and the fan track liner;
wherein the bridge member is configured to fail when impacted by a fan blade released from a hub so that the released fan blade can impact the hook and be contained by the fan containment system, wherein the bridge member is connected to the hook and contacts a radially inner surface of the forward end of the fan track liner.
2. The fan containment system according to claim 1 , wherein the bridge member is connected to the hook via a fastener.
3. The fan containment system according to claim 1 , wherein the bridge member is arranged so that the bridge member applies a preload to the fan track liner.
4. The fan containment system according to claim 1 , wherein a voidal region is provided radially between the bridge member and the annular casing element.
5. The fan containment system according to claim 1 , wherein the bridge member comprises a series of arcuate plates arranged to form an annular member.
6. The fan containment system according to claim 5 , wherein the annular plate comprises a plurality of adjacent arcuate plates.
7. The fan containment system according to claim 5 , wherein the bridge member comprises a stiffening member.
8. The fan containment system according to claim 7 , wherein the stiffening member is provided radially outward from the annular plate.
9. The fan containment system according to claim 7 , wherein the stiffening member comprises a plurality of spaced plate elements.
10. The fan containment system according to claim 7 , wherein the stiffening member connects the bridge member to the hook.
11. The fan containment system according to claim 10 , wherein the stiffening member is arranged so as to be pivotable about the fastener at the hook when a fan blade impacts the bridge member.
12. The fan containment system according to claim 1 , wherein the bridge member includes a crushable forward portion.
13. The fan containment system according to claim 12 , wherein the bridge member includes an annular or arcuate plate and a stiffening member and the stiffening member is connected to the plate at a position spaced from the hook so as to define the crushable forward portion.
14. The fan containment system according to claim 12 , wherein weakening features are provided in the forward portion to promote crushing of the forward portion.
15. The fan containment system according to claim 1 , wherein the bridge member includes a deformable rear portion.
16. The fan containment system according to claim 15 , wherein weakening features are provided in the rear portion to promote deformation of the rear portion when impacted by a released fan blade.
17. The fan containment system according to claim 1 , wherein an anti-wear material is positioned between the bridge member and the fan track liner.
18. The fan containment system according to claim 17 , wherein at least a rear portion of the bridge member is coated with an anti-wear material.
19. A fan containment system for fitment around an array of radially extending fan blades mounted on a hub in an axial gas turbine engine, the fan containment system comprising:
a fan case having an annular casing element for encircling an array of fan blades and a hook projecting in a generally radially inward direction from the annular casing element and positioned axially forward of an array of fan blades when the fan containment system is fitted around said fan blades;
an annular fan track liner positioned coaxial to the annular casing element, and positioned such that a forward end of the fan track liner is spaced from the hook so that there is a gap between the hook and the fan track liner; and
an annular member spanning the gap between the hook and the fan track liner;
wherein the annular member is connected to the hook via a fastener and contacts a radially inner surface of the fan track liner.
20. A gas turbine engine comprising the fan containment system according to claim 1 .