1. Technical Field
This disclosure relates generally to a sealing system for use in a gas turbine engine and, more particularly, to a distortion resistant face seal counterface system for use in a gas turbine engine.
2. Background Information
A typical prior art mechanical face seal arrangement within a gas turbine engine (sometimes referred to as a carbon face seal arrangement) includes a stationary seal member disposed in contact with, and sealing against, a rotating seal counterface (also referred to as the seal plate). The counterface is locked into place relative to a rotating engine shaft by an axially directed compressive force that may, depending upon the application, be several thousands of pounds in magnitude. In some applications, the compressive force is applied non-uniformly around the circumference of the shaft. As a result, the seal counterface may warp and assume a “wavy” configuration wherein the seal surface of the counterface is not planar; i.e., the axial position of the seal surface varies as a function of circumferential position.
It is known that rubbing between the counterface and the stationary seal member can generate significant amounts of heat, and consequent thermal gradients within the counterface. The thermal gradient forms because the surface (i.e., the seal surface) of the counterface in contact with the seal member rises to a much higher temperature during operation, than an aft surface on the opposite side of the counterface. The portion of the counterface proximate the seal surface will, as a result, experience greater thermal expansion than the aft surface. The difference in thermal expansion causes the seal surface to diverge from its original planar orientation, away from the stationary seal member, resulting in the counterface assuming a cone-like geometry. This deformation is typically referred to as “coning”. Coning can create an undesirable gas leakage path between the seal surface of the seal counterface and the seal member. Coning can also lead to excessive wear of the members that are in running contact.
One prior art approach to preventing the deformation of the counterface caused by coning has been to provide external or internal cooling of the counterface in the form of oil jets, cooling fins, or cooling passages. However, this approach adds significant complexity to the design of the counterface and is expensive. Another approach to preventing the deformation of the counterface has been to make the counterface from a ceramic. However, ceramics may cause other problems due to their brittleness.
According to an aspect of the present invention, an annular face seal arrangement for a gas turbine engine is provided that includes a mounting ring, a mounting member, a rotor, and a stator. The mounting ring has a width extending between a first axial end and a second axial end opposite the first axial end. The mounting member has a clamp portion and a biasing portion. The clamp portion extends axially between a first clamping surface and a second clamping surface. The biasing portion includes a first segment and a second segment. The second segment has a width and a rotor contact surface. The rotor has a rotor seal surface and a clamp portion having a width. The stator has a stator seal surface that is aligned with the rotor seal surface. The mounting ring is disposed radially inside of the rotor and radially inside of at least part of the biasing portion, and is disposed in contact with the second clamping surface of the clamp portion. The rotor contact surface of the biasing portion is disposed in contact with the rotor. The sum of the second segment and clamp portion widths is greater than the width of the mounting ring, thereby causing the biasing portion to be biased against the rotor.
According to another aspect of the present invention, an annular face seal arrangement for a gas turbine engine is provided that includes a mounting ring, a mounting member, a rotor, and a stator. The mounting member has a clamp portion and a biasing portion. The stator has a seal surface. The rotor has an outer connecting segment disposed between an outer leg and a middle leg, an inner connecting segment disposed between an inner leg and the middle leg, and a seal surface. Each of the legs has a width, and each of the connecting segments has a width, and the widths of the legs are greater than the widths of the connecting segments. The rotor seal surface aligns with the stator seal surface.
Now referring to
Now referring to
In some embodiments, the mounting member 18 includes a plurality of optional slots 64. The slots 64 are disposed circumferentially around the biasing portion 42 of the mounting member 18. Each slot has a length 57, a width 59, and is disposed at a slot angle λslot between 0° and 90° relative to the axial centerline 14. One or both ends of each slot may be terminated with an aperture 66 that reduces the potential of a crack propagating into the second segment 48 from a slot 64. The geometry of the slots 64 and/or the number of the slots 64 disposed around the circumference (i.e., the pitch) of the mounting member 18 can be varied to adjust the spring load-deflection properties of the mounting member 18, as will be discussed below.
Now referring to
The relative geometries of the legs 78, 80, 82 and the connecting segments 84 and 86 give the rotor its “E” shaped configuration. Within that configuration, however, the relative dimensions can be relatively varied to produce a geometry that thermally expands in a predetermined manner for a given set of operating conditions; e.g., radially neutral coning away from the stator 20, coning toward the stator 20, etc.
In the example shown in
The specific relative dimensions of the legs 78, 80, 82 and the connecting segments 84, 86 within the “E” configuration can be adjusted to create the desired operational rotor 22 configuration for the application at hand. For example, the relative dimensions of the “E” shaped rotor 22 can be configured such that during operation the rotor seal surface 68 is biased towards the stator seal surface 76. Alternatively, the rotor 22 can be configured to reduce wear between the rotor seal surface 68 and the stator seal surface 76 by decreasing rotor bias towards the stator 20. Thermal expansion is a function of the temperature of the material. A rotor 22 configuration that has a plurality of different size sections (e.g., an “E” shaped configuration) will have different amounts of thermal expansion in the different sections because the certain sections (e.g., smaller sections, and/or sections closer to the thermal energy source) will be at a higher temperature (and therefore subject to greater expansion) than other sections (e.g., larger sections and/or sections farther away from the thermal energy source). The desired amount of coning (toward, away, neutral) can be achieved by the selective sizing and positioning of the different legs and segments.
Now referring to
Now referring to
In the embodiment shown in
During operation of the gas turbine engine, the shaft 12 rotates about the axial centerline 14. The rotor 22 rotates relative to the stator 20 and thermal energy is developed by the frictional interaction between the rotor seal surface 68 and the stator seal surface 76. The thermal energy causes the rotor 22 to thermally expand. Depending upon the configuration of the rotor 22, as described above, the rotor 22 will cone toward or away from the stator 20, or will thermally expand in an axially neutral direction.
While various embodiments of the distortion resistant face seal counterface system have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the method. For example, the mounting ring 16, mounting member 18, the rotor 22, and the stator 20 are described above as having annular configurations. In some embodiments, the annular configurations may be a single annular body. In other embodiments, one or more of the mounting ring 16, mounting member 18, the rotor 22, and the stator 20 may be formed in sections that collectively form an annular body.
Number | Name | Date | Kind |
---|---|---|---|
2586739 | Summers | Feb 1952 | A |
2761712 | Ecker | Sep 1956 | A |
2802679 | Taltavall | Aug 1957 | A |
2992842 | Shevchenko et al. | Jul 1961 | A |
3819191 | Voitik | Jun 1974 | A |
4020910 | Peterson et al. | May 1977 | A |
4087097 | Bossens et al. | May 1978 | A |
4415165 | Martini | Nov 1983 | A |
4519719 | Burr | May 1985 | A |
4659092 | Wallace et al. | Apr 1987 | A |
4695063 | Schmitt et al. | Sep 1987 | A |
4872767 | Knapp | Oct 1989 | A |
5024451 | Borowski | Jun 1991 | A |
5135235 | Parmar | Aug 1992 | A |
5137284 | Holder | Aug 1992 | A |
5183270 | Alten et al. | Feb 1993 | A |
5244216 | Rhode | Sep 1993 | A |
5464227 | Olson | Nov 1995 | A |
5544896 | Draskovich et al. | Aug 1996 | A |
5626347 | Ullah | May 1997 | A |
5639096 | Ullah | Jun 1997 | A |
6322081 | Ullah et al. | Nov 2001 | B1 |
6530573 | Merkin et al. | Mar 2003 | B1 |
6655695 | Sund et al. | Dec 2003 | B1 |
Number | Date | Country |
---|---|---|
1805245 | Jul 2006 | CN |
2182730 | May 1987 | GB |
1213296 | Mar 1986 | SU |
1643834 | Apr 1991 | SU |
Number | Date | Country | |
---|---|---|---|
20100244385 A1 | Sep 2010 | US |