The subject matter disclosed herein relates to a rotary machine and, more particularly, to a tie bolt and stacked wheel assembly for the rotors of such machines.
The rotors of rotary machines, such as turbines and compressors, are typically formed of axially stacked wheels, which hold individual blades about their periphery. For example, compressor rotors include a series of individual compressor wheels stacked together with a set of tie bolts extending generally axially through the stack. The wheels mount the blades which, together with stator blades, form the compressor stages. The tie bolts are typically elongated studs threaded at both ends for receiving nuts to maintain the wheels in stacked, assembled relation relative to one another. Loosening of the nuts on the tie bolts reduces the tension on the bolts, thereby lowering the torque carrying capability of the rotor, eventually to unacceptable levels.
Traditionally, nuts are designed as hollow cylinders with internal threads. The circular face of the nut is pressed against a rotor surface to transfer a clamp load in a substantially axial direction. Positioning of the cylindrical nuts against the rotor surfaces requires additional space, thereby leading to an undesirable effect of the presence of a kink or step in the rotor midsection structure. The kink or step reduces the overall bending stiffness of the rotor and may lead to high gravity sag and high cycle fatigue stress.
According to one aspect of the invention, a stacked wheel assembly for a rotor of a rotary machine includes a plurality of stacked wheels for rotation about a common axis and forming a portion of the rotor. Also included is a tie bolt passing through aligned bolt holes of the plurality of stacked wheels for retaining the plurality of stacked wheels in axially stacked relation, the tie bolt extending out of a forward end of a forward wheel of the plurality of stacked wheels and out of an aft end of an aft wheel of the plurality of stacked wheels. Further included is a rotor component disposed adjacent the aft end of the aft wheel. Yet further included is a nut mounted within a forward face of the rotor component, the nut configured to be in threaded engagement with the tie bolt to exert a clamping force on the plurality of stacked wheels.
According to another aspect of the invention, a nut for a rotary machine includes a threaded hole configured to engage a tie bolt passing through aligned bolt holes of a plurality of stacked wheels. Also included is a dovetail region for engaging a slot of a rotor component disposed adjacent an aft end of an aft wheel of the plurality of stacked wheels, the slot comprising a corresponding geometry for receiving the nut therein, wherein the dovetail region of the nut axially retains the nut within the rotor component.
According to yet another aspect of the invention, a rotary machine includes a compressor section, a combustor assembly, and a turbine section. Also included is a rotor operatively coupling the compressor section and the turbine section. Further included is a plurality of stacked wheels for rotation about a common axis and forming a portion of the rotor within the compressor section. Yet further included is a tie bolt passing through aligned bolt holes of the plurality of stacked wheels for retaining the plurality of stacked wheels in axially stacked relation, the tie bolt extending out of an aft end of an aft wheel of the plurality of stacked wheels. Also included is a rotor component disposed adjacent the aft end of the aft wheel. Further included is a nut mounted within a forward face of the rotor component, the nut configured to be in threaded engagement with the tie bolt to exert a clamping force on the plurality of stacked wheels.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
The terms “axial” and “axially” as used in this application refer to directions and orientations extending substantially parallel to a center longitudinal axis of a turbine system. The terms “radial” and “radially” as used in this application refer to directions and orientations extending substantially orthogonally to the center longitudinal axis of the turbine system. The terms “upstream” and “downstream” as used in this application refer to directions and orientations relative to an axial flow direction with respect to the center longitudinal axis of the turbine system.
Referring to
Referring to
The tie bolt 24 is a mechanical fastener and may be characterized as an elongated stud having a first end 26 and a second end 28. As shown, the first end 26 protrudes slightly and extends out of a forward end 30 of a forward wheel 32 of the plurality of wheels 20. The second end 28 protrudes slightly and extends out of an aft end 34 of an aft wheel 36 of the plurality of stacked wheels 20. The tie bolt 24 is locked in place, thereby axially clamping the plurality of stacked wheels 20, with respective locking components at the first end 26 and the second end 28. In particular, the locking components include a forward nut 27 and an aft nut 29 that are each threaded and configured to engage threaded regions of the tie bolt 24 proximate the first end 26 and the second end 28. The nuts may be different in structure and the aft nut 29 is configured to engage the second end 28 of the tie bolt 24, which will be described in detail below. As shown, the aft wheel 36 of the tie bolt 24 is disposed adjacent a rotor structure 38 that may be referred to as a “mid-section structure” of the rotor 18. The rotor structure 38 is located at the aft end 34 of the plurality of stacked wheels 20 and is disposed between, and operatively couples, the compressor section 12 and the turbine section 16. The aft nut 29 is mounted within a forward face 40 of the rotor structure 38.
Referring now to
Referring to
Referring to
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
Number | Name | Date | Kind |
---|---|---|---|
4405285 | Surdi | Sep 1983 | A |
4488844 | Baubles | Dec 1984 | A |
6784597 | Hess | Aug 2004 | B1 |
20130034402 | Ferslew et al. | Feb 2013 | A1 |
Number | Date | Country | |
---|---|---|---|
20150128611 A1 | May 2015 | US |