The present disclosure relates generally to seals for rotary machines and, more particularly, to a seal strip for a seal assembly and methods to form the same.
In many rotary machines, such as a multi-stage centrifugal compressor or pump, a fluid is compressed by successive stages, or in turbines, a fluid is expanded in successive stages. Turbine and compressor stage(s) have stationary or non-rotating components, e.g., vanes, cooperating with rotating components, e.g., blades, for compressing and expanding the operational fluid. The operational fluids change in pressure through the machine and a variety of seals are provided to preserve the differential pressures where necessary to maximize machine efficiency and performance. An illustrative seal may be provided between a turbine or compressor rotor and a cooperating stator or stator body so the rotor may be pressurized to provide thrust balance relative to the rearwardly directed force generated by the equipment.
In the above-described settings, the seals used must address the close operating clearances required in machinery of this type. Rotary machine seal design also depends on, e.g., relative motion between components produced by the differential thermal expansion and system pressure that occurs during operation. For example, thermal expansion of various system components, at all times, must comply with clearance requirements, transient rotor dynamic displacements, etc., as the components operate at high temperatures, pressures, speeds, etc.
Conventional seal assemblies such as those described in U.S. Pat. Nos. 6,644,667 and 7,578,509 specify multiple leaf layers to block leakage flow. These layers of leaves may be bent at an angle and wrapped onto a cylindrical support with essentially no gap between leaf layers to eliminate leakage paths through the seal. This intimate nesting, i.e., fit of one leaf layer with the next, also is required to prevent vibration of seal leaves. Forming multiple layers of seal leaves while also mounting each layer onto the cylindrical support has proven to be a technical challenge associated with seal leaf assemblies. Other types of seal assemblies, which may not employ leaf seal structures, may introduce competing concerns and/or other technical challenges not appropriate for some implementations and/or systems.
Aspects of the disclosure provide a seal strip for a seal assembly for a turbomachine, the seal strip includes: a retaining portion for fixed coupling within a recess in a stationary component of the turbomachine; and a plurality of leaf members extending from the retaining portion, a slit extending between adjacent leaf members of the plurality of leaf members, wherein each leaf member includes a first stepped edge and an opposing, second stepped edge, and wherein the first stepped edge and the second stepped edge of adjacent leaf members are configured to sealingly mesh in a mounted state of the seal strip in the turbomachine.
Further embodiments of the disclosure provide a seal strip having a length sized for placement within a circumferential recess formed between a rotating component and a stationary component of a turbomachine, the seal strip including: a retaining portion for fixed coupling the stationary component; a plurality of leaf members extending from and structurally continuous with the retaining portion; and a plurality of slits extending partially inwardly from a single side of the seal strip, and substantially perpendicularly to the length of the seal strip, to separate each of the plurality of leaf members from an adjacent leaf member; wherein each leaf member includes a first stepped edge and an opposing, second stepped edge, and wherein the plurality of leaf members are moveable between: a non-mounted state in which each leaf member is free of contact with an adjacent leaf member, and a mounted state in the circumferential recess in which the first stepped edge of each leaf member sealingly meshes with the second stepped edge of a respective adjacent leaf member.
Still further embodiments of the disclosure provide a method to form a seal strip for a seal assembly, the method including: forming a first plurality of recesses within a strip of sealing material, each of the plurality of first recesses extending at most partially into a first surface of the strip of sealing material, and at most partially inward from a longitudinal edge of the strip of sealing material; and forming a second plurality of recesses within the strip of sealing material, the second plurality of recesses extending at most partially into a second surface of the strip of sealing material opposite the first surface, and at most partially inward from the longitudinal edge of the strip of sealing material, wherein each of the second plurality of recesses connects to a respective one of the first plurality of recesses to form a plurality of slits within the strip of sealing material, the plurality of slits separating remaining portions of the strip of sealing material into a plurality of leaf members, wherein each of the plurality of leaf members includes a first stepped edge and an opposing, second stepped edge.
The foregoing and other features and advantages of the disclosure will be apparent from the following more particular description of preferred embodiments of the disclosure.
The preferred embodiments of this disclosure will be described in detail, with reference to the following figures, wherein like designations denote like elements, and wherein:
Embodiments of the disclosure provide a seal strip for a seal assembly of a turbomachine. The seal strip in some cases may be a unitary component (i.e., free of separable or mechanically distinct subcomponents) structured to fluidly sealing a recess between two elements of a turbomachine, e.g., a stationary component and a rotating component of the turbomachine. Embodiments of a seal strip according to the disclosure, in some applications, may be suitable for use without mounting additional seal strips and/or leaf members into the same location. Embodiments of the disclosure thus eliminate the need to nest and/or otherwise correspondingly mount multiple sealing components into the same location, and eliminate the need for additional alignment and/or nesting steps.
An example of a turbomachine configured to receive a seal strip according to embodiments of the disclosure may include any currently known or later developed power generation system, e.g., a gas turbine, steam turbine, water turbine, etc., having rotary components such as a compressor or turbine therein. Such rotary components may include any currently known or later developed machinery that includes a non-rotating component (e.g., a stator) and a rotating component (e.g., a rotor and/or set of rotor-mounted blades) having a longitudinal axis, e.g., a centrifugal compressor, a pump or a steam turbine, etc. For description purposes, embodiments of the present disclosure will be described in terms of a centrifugal compressor or steam turbine having a stationary body or stator, and a rotating component, or rotor. Operating fluid of the turbine flows through the machine from a high pressure area to a lower pressure area. Pressure from higher pressure area is exerted against at least part of seal assembly located between the two areas. Embodiments of a seal strip according to the disclosure are operable to seal fluids in higher pressure area from the lower pressure area.
Referring to
Seal strip 100 may include, e.g., a retaining portion 102 for fixed coupling within a recess (e.g., a circumferential recess) of a stationary component. Such recesses may appear directly between a stator and a rotating component of a turbomachine, or similar junctions between interconnected components (e.g., multiple rotating components, or between subcomponents of a single rotating component). A plurality of leaf members 104 may extend from retaining portion 102, thereby defining one or more slits S between adjacent leaf members 104. Retaining portion 102 and leaf members 104 may be formed from a single piece of raw material, e.g., by removing selected portions of a single metal strip, as described elsewhere herein. Thus, retaining portion 102 and leaf members 104 may together form portions of a single, unitary seal strip 100 according to embodiments of the disclosure. Although retaining portion 102 and leaf members 104 are described separately throughout the disclosure, it is understood that the material composition and properties of seal strip 100 may be uniform within retaining portion and leaf members 104. Despite differences in the geometrical profile and/or position of each component of seal strip 100, seal strip 100 may not have any physical interfaces, boundaries, etc., where retaining portion 102 meets leaf members 104. Each leaf member, as shown, may include a set of stepped edges 106 on opposing edges thereof. Stepped edges 106 may allow leaf members to mesh and form a seal when seal strip 100 is in a mounted state, e.g., when leaf members form a seal ring at a predetermined location. Each leaf member 104 may include, e.g., one stepped edge 106 adjacent a first slit S between adjacent leaf members 104. Each leaf member also may include a second, opposed stepped edge 106 adjacent another slit S and another adjacent leaf member 104. Several slits S optionally may have a substantial V-shape, as shown in
Leaf members 104 of seal strip 100 may be formed in the shape of one or more predetermined geometries, e.g., by modifying the shape of slits S formed therebetween. Multiple geometries for leaf member(s) 104 may be included together in one seal strip 100. For example, a substantially rectangular leaf member 104a may be located adjacent a substantially trapezoidal leaf member 104b. Rectangular leaf members 104a in one example may be positioned between adjacent trapezoidal leaf members 104b in the embodiment shown in
Referring to
Stepped edges 106 may include a variety of geometrical profiles. For example, stepped edges 106 may feature rounded corners 107 (
Turning now to
A further embodiment of seal strip 100 in a non-mounted state, and with another example set of leaf member geometries is shown in
Referring now to
Referring to
Referring to
Process P0 according to the disclosure may include forming one or more strips of material, e.g., by direct manufacture or subtractive manufacture from a larger sheet of material. The strips formed in process P0 may be rectangular, or otherwise may be capable of being separated into distinct units having a desired geometry (e.g., a rectangular shape, arcuate shape, and/or any other desired geometry in plane X-Y). However, embodied, the formed strip may have the same material composition as seal strip 100, or otherwise may include material capable of being processed into one or more seal strip 100 materials.
Process P1 according to the disclosure may include forming a plurality of first recesses within one surface, e.g., first surface S1, of the formed strip. According to an example, forming the first plurality of recesses may include a photo chemical etching of the strip material. The plurality of recesses formed in process P1 may extend partially, or in some cases at most approximately halfway through, the thickness of the strip material. The strip material may not include any slits after process P1 concludes.
Process P2 according to the disclosure may include forming a plurality of second recesses within the strip material. The second plurality of recesses may be formed to extend partially into second surface S2 of the strip material, opposite surface S1. Similar to process P1, the second plurality of recesses in some cases may extend approximately halfway through the thickness of the strip material. The second plurality of recesses may be formed, e.g., by another instance of photo chemical etching of the strip material. One or more recesses in the second plurality of recesses may formed in a positional horizontally distal to a corresponding one of the first plurality of recesses. However, at least a portion of the second recess may interconnect with the first recess, thereby forming slits within the strip material as discussed elsewhere herein. Any portion(s) of the strip without slits or recesses formed therein may serve as retaining portion(s) 102. At this stage, seal strip 100 may be formed according to embodiments of the disclosure, and the method may conclude (“Done”) or optionally may proceed to further processes.
Process P3 according to the disclosure includes mounting retaining portion 102 within a turbomachine, e.g., at recess R (
In further implementations, the mounting of seal strip 100 may be implemented by process P3.1 of deforming seal strip 100 in-plane, e.g., as shown in
While embodiments of this disclosure are discussed herein in connection with a turbomachine such as a steam or gas turbine, it is understood that embodiments of this disclosure are also applicable to any situation where a seal is needed between a stationary component and a rotating component or another stationary component. In addition, embodiments of this disclosure are especially applicable to any situation with extreme variations of speeds or operating conditions, such as start-up conditions for a turbomachine, a compressor, such as a centrifugal compressor, that operates at a range of speeds (part load or over load), or aircraft applications. In aircraft applications, effective seals are especially important given the extreme conditions and very high pressures involved in transient conditions, such as take-off.
It should also be recognized that seal assemblies in accordance with the present disclosure may be combined with one or more labyrinth seals and/or one or more brush seals (not shown) to provide further sealing capacity.
The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context, (e.g., includes the degree of error associated with measurement of the particular quantity). The suffix “(s)” as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the metal(s) includes one or more metals). Ranges disclosed herein are inclusive and independently combinable (e.g., ranges of “up to about 25 wt %, or, more specifically, about 5 wt % to about 20 wt %”, is inclusive of the endpoints and all intermediate values of the ranges of “about 5 wt % to about 25 wt %,” etc).
While various embodiments are described herein, it will be appreciated from the specification that various combinations of elements, variations or improvements therein may be made by those skilled in the art, and are within the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.
Number | Date | Country | |
---|---|---|---|
62844429 | May 2019 | US |