Patent Application
20130156584
This application relates to a rotor that is provided with a stiffening element.
Gas turbine engines are known, and typically include a fan delivering air into a compressor section. The air is compressed in the compressor section and delivered downstream into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors, driving the turbine rotors to rotate. The turbine rotors in turn rotate the fan and compressor sections.
Typically the compressor sections are formed of a plurality of rotor stages, with each of the rotor stages carrying compressor blades. The compressor rotors may have removal blades, or may be formed integrally with their blades.
The compressor rotors and blades are subject to a number of stresses, and must have sufficient stiffness to address those stresses.
Typically, to provide required stiffness, the prior art has made the rotors thicker. Often, the rotors are formed of titanium. The use of the additional thickness to provide additional stiffness increases the weight and expense of the rotor.
An embodiment addresses a rotor, including a hub at a radially outer location, with a leg extending from an inner ring at a radially inner location to the hub. The hub has an inner bore at a location spaced from the leg. A stiffening ring is forced to fit into the inner bore of the hub.
In another embodiment, the leg extends from the inner ring to the hub in a direction having an axial component and a radial component such that its axial component extends along the direction that will be downstream when the rotor is mounted in a gas turbine engine. The stiffening ring is positioned in the inner bore at a location that will be upstream of the location where the leg connects into the hub but when the rotor is mounted in a gas turbine engine.
In another embodiment of either of the foregoing embodiments, an axial location of the stiffening ring is such that a plane defined perpendicularly to a central axis of the rotor and passing through the stiffening ring, will also pass through a portion of the leg.
In another embodiment of either of the foregoing embodiments, the stiffening ring is formed of a distinct material from the hub.
In yet another embodiment , the hub material may contain aluminum and the stiffening ring may be formed of nickel.
In yet another embodiment, the hub material may contain titanium and the stiffening ring may be formed of aluminum.
In yet another embodiment of any of the foregoing embodiments, the inner bore has a surface which receives the stiffening ring, and a ledge extends radially inwardly of a portion of the inner bore to provide a stop for the stiffening ring.
In another embodiment of any of the foregoing embodiments, the ledge may have a radially innermost extent, with the stiffening ring extending radially inwardly of the radially innermost extent of the ledge.
In yet another embodiment, the rotor may be a compressor rotor.
In yet another embodiment, a gas turbine engine includes a compressor section, a combustor section and a turbine section, with the turbine section driving a shaft to drive the compressor section. The compressor section and the turbine section include at least one rotor. The rotor of at least one of the compressor and turbine sections includes a hub at a radially outer location and a leg extending to an inner ring at a radially inner location. The hub has an inner bore at a location spaced from the leg, and a stiffening ring is force-fit into the inner bore.
In another embodiment, the leg extends from the inner ring to the hub in a direction having an axial component and a radial component such that its axial component extends along the direction that will be downstream when the rotor is mounted in a gas turbine engine. The stiffening ring is positioned in the inner bore at a location that will be upstream of the location where the leg connects into the hub when the rotor is mounted in a gas turbine engine.
In another embodiment of either of the foregoing embodiments, an axial location of the stiffening ring is such that a plain defined perpendicularly to a central axis of the rotor and passing through the stiffening ring will also pass through a portion of the leg.
In another embodiment of either of the foregoing embodiments, the stiffening ring is formed of a distinct material from the hub.
In yet another embodiment, the hub material may contain aluminum and the stiffening ring may be formed of nickel.
In yet another embodiment, yet another material may contain titanium and the stiffening ring may be formed of aluminum.
In yet another embodiment of any of the foregoing embodiments, the inner bore has a surface which receives the stiffening ring, and a ledge extends radially inwardly of the portion of the inner bore to provide a stop for the stiffening ring.
In another embodiment of any of the foregoing embodiments, the ledge may have a radially inner most extent, with the stiffening ring extending radially inwardly of the radially innermost extent of the ledge.
In yet another embodiment, the rotor may be a compressor rotor.
These and other features can be best understood from the following specification and drawings, the following of which is a brief description.
A gas turbine engine 10, such as a turbofan gas turbine engine, circumferentially disposed about an engine centerline 11, is shown in
To provide additional stiffness, a ring 56 is force fit into an inner bore or internal surface 52. In this embodiment, an axial end of the ring 56 abuts a ledge 54 on the hub 144. As shown, a radially inner end 58 of the ledge is spaced radially outwardly of a radially inner end 60 of the ring 56.
The stiffening ring 56 is positioned in inner bore 52 at a location that will be upstream of a location where leg 48 connects into hub 144 when the rotor is mounted in a gas turbine engine. An axial location of ring 56 is such that a plane defined perpendicularly to a central axis 11 of rotor 44 and passing through ring 56 would also pass through a portion of leg 48.
The ring 56 is selected to provide stiffening properties, and is typically formed of a distinct material from the rotor 44. On the other hand, in some embodiments, the stiffening ring may be formed of the same material as the rotor.
As one example, the rotor 44 may be formed of titanium or a titanium alloy, while the ring 56 may be formed of aluminum. An aluminum stiffening ring may be selected if bending stiffness is most important. In such a situation, thickness of the ring is more important than the material properties.
On the other hand, if hoop stiffness is desired, and design space is limited, nickel may be best suited for the stiffening ring.
The use of the force fit between the outer periphery of the ring and the inner periphery of the hub also provides preload which will increase the stiffness.
While this application discloses a compressor rotor, its teachings extend to other gas turbine engine rotors, such as a turbine rotor.
While an embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modification would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content.
