Patent Application
20210040860
The application relates generally to turbine rotors for gas turbine engines, and more particularly to turbine blades.
Turbine blades spin at very high speeds and must be reliably retained on the turbine disc. As well, because of the high temperatures to which they are exposed, turbine blades are often cooled. This is typically done using cooling air, which may be directed into cooling inlets formed in the blades. Sealing of the turbine blades is therefore also an important consideration, as excessive leakage of cooling air is undesirable.
There is accordingly provided a turbine blade, comprising: an airfoil; a root connected to the airfoil and having lobed edges being spaced apart on laterally opposed sides of an axis extending axially through the root; an air passage extending through the airfoil and the root; a first tab extending at least partially along and laterally outward from a first edge of the laterally opposed lobed edges; and a second tab extending at least partially along and laterally outward from a second edge of the laterally opposed lobed edges.
The turbine blade may also include, one or more of the following elements/features, in whole or in part, and in any combination.
The first tab includes a plurality of first tabs extending along the first edge, and the second tab includes a plurality of second tabs extending along the second edge.
The first tabs are spaced from each other along the first edge and the second tabs are spaced from each other along the second edge.
The lobed edges are disposed on an upstream-facing surface of the root.
A seal at a bottom of a downstream-facing surface of the root, the downstream-facing surface being opposite the upstream-facing surface.
A seal including a plurality of projections extending downward from a rest of the root, and the seal is defined in part by the downstream-facing surface.
Each of the first and second tabs conforms in shape to a portion of the corresponding one of the first and second edges along which that first tab extends.
The lobed edges are fir-tree shaped.
A turbine rotor, comprising a disc rotatable about a rotation axis and the turbine blade as defined above, the disc defining an axially-extending lobed slot therein, the root being lobed and being received in the lobed slot, the airfoil portion of the turbine blade extending radially outward from the lobed slot and the disc relative to the rotation axis.
The air passage is a first air passage, the root, the seal, and the disc define a second air passage between the root, the seal, and the disc, the first air passage being fluidly connected to the second air passage.
A cover plate attached to an upstream-facing surface of the disc, the cover plate and the upstream-facing surface of the disc defining a third air passage between the cover plate and the upstream-facing surface of the disc, the third air passage being fluidly connected to the second air passage.
The lobed edges of the root and opposed surfaces of the disc define gaps between the lobed edges and corresponding ones of the opposed surfaces of the disc, and the first and second tabs fluidly block at least parts of corresponding ones of the gaps.
The first and second tabs are disposed between the root and the cover plate.
The lobed slot is a fir-tree-shaped slot, a plurality of the fir-tree-shaped slots defined in the disc at circumferentially distributed locations about a periphery of the disc , and a plurality of turbine blades each having the root thereof received in a corresponding one of the fir-tree-shaped slots.
There is also provided, in accordance with another aspect of the present disclosure, a turbine rotor for a gas turbine engine, comprising: a disc rotatable about a rotation axis and having a circumferential array of slots therein, slots extending generally axially in the disc relative to the rotation axis; a plurality of turbine blades received in the slots, the blades having a fir-tree-shaped roots configured with the slot to for a mating connection between the disc and the turbine blades; the turbine blades having one or more tabs extending laterally from a lateral outer edge of the fir-tree-shaped roots on circumferentially opposite sides of fir-tree-shaped roots, the one or more tabs extend over a surface of the disc thereby sealing a lateral portion of a gap defined between the fir-tree-shaped roots and the disc.
The turbine rotor may also include, one or more of the following elements/features, in whole or in part, and in any combination.
Thee one or more tabs are integrally formed with the fir-tree-shaped roots.
The one or more tabs include a plurality of tabs spaced apart from each other and conforming in shape to the lateral outer edges of the fir-tree-shaped roots.
A cover plate connected to an upstream-facing side of the disc and defining a first air passage between the cover plate and the disc, and wherein the disc and the given turbine blade define a second air passage fluidly connected to the first air passage and extending through the root of the given turbine blade to an airfoil portion of the given turbine blade.
There is further provided, in accordance with another aspect of the present disclosure, a method of constructing a rotor assembly for a gas turbine engine, comprising: constructing a disc of a rotor for the gas turbine engine for rotation about a rotation axis, including defining an axially-extending fir-tree-shaped slot in a periphery of the disc, mating a fir-tree-shaped root of a blade to the fir-tree-shaped slot, the mating leaving a fir-tree-shaped gap between the root and the disc, fluidly sealing at least a part of the fir-tree-shaped gap, and attaching a cover plate to the upstream-facing side of the disc over the root.
In the method as defined herein, the step of fluidly sealing may include fluidly sealing at least the part of the fir-tree-shaped gap at the upstream-facing side of the disc.
Reference is now made to the accompanying figures in which:
The turbine section 18 may include multiple turbine rotors 20 which may be implemented according to the present technology. While the present technology is illustrated with regard to a low pressure turbine rotor 20, the present technology may be implemented in one or more high pressure turbine rotors of the engine 10, instead of or in addition to being implemented with the low pressure turbine rotor 20. Also, while the present technology is illustrated with regard to turbine rotors, the present technology may also be implemented with regard to a compressor rotor for example.
As schematically shown in
For the purposes of this document, the terms “laterally”, “axially”, “radially” and “circumferentially” used in relation to the turbine rotor 20 and its components, including the blades 24, are in reference to the rotation axis (X) of the turbine rotor 20. For the purposes of this document, the terms upstream and downstream and corresponding upstream and downstream directions are used relative to the direction of the flow of air through the turbine rotor 20 when the turbine rotor 20 is rotating to propel the engine 10 forward. For example, and “upstream-facing side” of a component would face the airflow through the turbine rotor 20.
The airfoil portion 24A is connected to, and in this embodiment integral with, a root 24B of the blade 24. The blade 24 defines air passages 24D therethrough, which extend from the root 24B into the airfoil portion 24A and terminate at openings 240 defined in an outer surface of the airfoil portion 24A. The number and arrangement of the air passages 24D and the openings 240 may be any number and arrangement selected to suit each particular embodiment and application of the turbine rotor 20.
As shown in
In other embodiments, the surface(s) of the root 24B and corresponding surface(s) of the disc 22 defining the slot 22SL receiving the root 24B may be selected differently while still defining the corresponding mating fir-tree shapes of the root 24B and the slot 22SL. As shown in
Although the slots 22SL are defined herein as being “generally axially”, it is to be understood that they may in fact be inclined slightly (e.g. about 15 degrees to axial). For the sake of simplicity of explanation, the slots 22SL in the disc 22 will be said to be generally axially extending, despite this small angular inclination/skew angle.
Referring back to
Still referring to
Further in this embodiment, as shown in
As shown, in this embodiment the root 24B has two laterally opposed lobed edges 24E, which in this embodiment are fir-tree-shaped and are defined by the upstream-facing surface 24US of the root 24B and respective ones of the sinusoidal lateral surfaces 24S of the root 24B. Even more particularly in this embodiment, the tabs 28 extend along, or stated otherwise follow the respective portion of the curve of, the respective ones of the curved fir-tree-shaped edges 24E. That is, in this embodiment each of the tabs 28 is shaped to conform to a corresponding portion of the one of the fir-tree-shaped edges 24E along which that tab 28 extends. As an example, since in this embodiment and as shown in
Referring to
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As shown in
To supply air to the air passage 36, the cover plate 32 defines therein one or more inlets 32IN. These inlet(s) may be connected, when the turbine rotor 20 is in use, to one or more suitable sources of air. As a non-limiting example, and as shown with dashed line 38 in
When the rotor 20 is in use, the sealed interface 34 provided by the cover plate 32 directs air to the air passages 24D and 30, and-or stated otherwise prevents or at least limits air from escaping the air passages 30, 36 via the interface 34. In turn, the tabs 28 fluidly block at least parts of the gaps 26 as described above, between the disc 22 and the roots 24B of the blades 24. The tabs 28 may thus help limit or prevent air from escaping the air passages 30, 36 via the gaps 26 and hence help direct more air from the air passage 36 to the air passages 30 and 24D. In yet another aspect, in the present embodiment the tabs 28 of each of the blades 24, by engaging the upstream-facing surface 22US of the disc 22, may provide a retention feature and-or an axial positioning feature of that blade 24 with respect to the disc 22. The retention feature may help prevent the roots 24B from exiting the slots 22SL in the downstream axial direction (DD).
Now referring to
In some embodiments, the method 40 may also include mating, such as described above for example, a fir-tree-shaped root 24B of a turbine blade 24 to the fir-tree-shaped slot 22SL, the mating leaving a fir-tree-shaped gap 26 between the root 24B and the disc 22. In some embodiments, the method 40 may also include fluidly sealing at least a part, such as a lateral portion for example, of the fir-tree-shaped gap 26. As seen above for example, in some embodiments the sealing may include sealing at least that part of the gap 26 at the upstream-facing side 22US of the disc 22. In some embodiments, the method 40 may also include attaching one or more cover plates 32 to the disc 22, such as to the upstream-facing side 22US of the disc 22 for example, over the roots 24 of the turbine blades 24.
In some embodiments, one or more cover plates 32 may be attached in this way to both the upstream-facing surface 22US of the disc 22 and to a downstream-facing surface of the disc 22. Understandably, the downstream-facing surface of the disc 22 may be opposite the upstream-facing surface 22US of the disc 22. As seen above, in some embodiments, the attaching of the cover plate(s) 32 may help axially secure the blades 24 to the disc 22. In embodiments where the cover plate(s) 32 is-are made of multiple components, the attaching the cover plate(s) 32 may correspondingly include correspondingly attaching each of the multiple components to each other and-or to the disc 22 for example, as may be applicable in each given possible embodiment.
In some embodiments, the method 40 may continue with steps similar to those described above with respect to one or more of the other blade(s) 24 and slot(s) 22SL of the disc 22 to complete a given rotor, such as the turbine rotor 20 for example, from the turbine rotor assembly. Understandably, in at least some such cases, the cover plate(s) 32 may be attached to the disc 22 after the rest of the blade(s) 24 have been mated to the disc 22 as described above.
In some embodiments, such as for example where the method 40 is used to make a turbine rotor 20, the method 40 may also include defining an air passage, such as defined by air passages 36, 30, 24D for example, extending as shown in
The embodiments described above may be manufactured using material(s) and manufacturing and assembly methods, such as conventional material(s) and manufacturing and assembly methods, which may be selected to suit each particular embodiment and application of the engine 10 and turbine rotor 20. The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the technology disclosed.
For example, while the tabs 28 of the root 24B of each blade 24 in the embodiments described above are attached to the root 24B, in other embodiments one or more of the tabs 28 may be attached to the cover plate 32 at corresponding locations that may provide for the positioning of the one or more tabs 28 over at least parts of corresponding one or more of the gaps 26 as described above. As another example, the tabs 28 in the illustrated embodiments may be made of the same material as the respective ones of the roots 24B. In other embodiments, this need not be the case.
As another example, while the air passages 24D, 30, 36 are described above as separate interconnected air passages, the air passages 24D, 30, 36 may also be referred to as a single air passage extending through the turbine rotor 20 as described above with regard to each of the air passages 24D, 30, 36 separately. As yet another example, while the tabs 28 described above may help axially position and axially secure the blades 24 relative to the disc 22, in other embodiments the disc 22 may have features to provide this functionality, in addition to or instead of the tabs 28.
Still other modifications which fall within the scope of the present technology will be apparent to those skilled in the art, in light of a review of this disclosure.
