Patent Application
20120027573
The present invention relates generally to a seal assembly, and more particularly to a seal assembly including seal teeth having protrusions to reduce swirl and leakage in rotary machines.
Ideally, a rotary machine, such as a turbine, consists of a rotating component positioned within a stationary component. The fluid path inside the rotary machine consists of a primary fluid path and a secondary fluid path. Fluid leakage, either into the primary fluid path from the secondary fluid path or out of the primary fluid path into the secondary fluid path, may adversely affect the operating efficiency of the turbine. In order to minimize leakage, seal assemblies, such as labyrinth seals, typically including arcuate packing rings, are placed between the stationary component and the rotary components of the turbine.
These labyrinth seals conventionally include a plurality of axially spaced, circumferentially extending seal teeth that are used to reduce leakage in the rotary machine.
In operation, with high rotor rotational velocity, fluid axially entering the fluid path of a rotary machine can acquire a significant tangential velocity component (also called “steam swirl”). For example, as the fluid moves through the labyrinth seal, the fluid may flow between the axially spaced seal teeth and circumferentially around the rotating component. This causes the fluid to acquire the significant tangential velocity component, which can induce rotor instabilities in turbomachines. The magnitude of this rotor instability is a function of the circumferential flow component of fluid within the labyrinth seal.
A first aspect of the invention provides a seal assembly for a rotating element, the seal assembly comprising: a plurality of arcuate packing rings configured to form an annulus proximately surrounding the rotating element; and a plurality of radially and circumferentially extending seal teeth coupled to each of the plurality of arcuate packing rings, wherein at least one of the plurality of seal teeth includes a plurality of axially extending protrusions.
A second aspect of the invention provides a turbomachine comprising: a rotating element; a stationary component substantially surrounding the rotating element; and a seal assembly coupled to the stationary component, the seal assembly including: a plurality of arcuate packing rings configured to form an annulus proximately surrounding the rotating element; and a plurality of radially and circumferentially extending seal teeth coupled to each of the plurality of arcuate packing rings, wherein at least one of the plurality of seal teeth includes a plurality of axially extending protrusions.
These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which:
It is noted that the drawings of the invention are not to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.
Turning to
Machine 100 may include a rotating element 120 and a stationary component 130. Stationary component 130 may substantially surround rotating element 120. Machine 100 may also include a seal assembly 150 coupled to stationary component 130. As shown, seal assembly 150 may be coupled to stationary component 130 by fitting a mounting portion 151 of an arcuate packing ring 152 within a groove 132 of stationary component 130.
Referring now to
Referring now to
Although plurality of protrusions 156 are shown to extend in one axial direction of rotating element 120 (towards the right in
Plurality of axially extending protrusions 156 may be configured to be any shape that prevents fluid from circumferentially flowing, between each of the plurality of seal teeth 154, around rotating element 120. As shown in
As mentioned above, seal assembly 150 may be configured to form an annulus that proximately surrounds rotating element 120. Referring back to
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
This written description uses examples to disclose the various embodiments of the present invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments of the present invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
