Annular Face Seal Counterface System for Gas Turbine Engines
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Solution Overview
Problem
Gas turbine engine face seals experience deformation due to thermal gradients caused by uneven heat distribution, leading to coning and gas leakage, which existing solutions like external cooling or ceramic materials either complicate the design or introduce brittleness.
Innovation Solution
An annular face seal arrangement with a mounting ring, mounting member, stator, and rotor featuring specific geometric configurations and biasing segments to manage thermal expansion and minimize coning, including an 'E' shaped rotor design with varying leg and segment widths to control thermal expansion and maintain a planar seal surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If external cooling or internal cooling passages are provided in the counterface, then coning deformation is prevented, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent converts the harmful thermal expansion that causes coning into a beneficial effect by pre-biasing the mounting member. The mounting member is designed with intentional initial curvature or pre-stress that creates a counteracting force against the thermal expansion, so that when heating occurs, the combined effect maintains planarity rather than creating coning deformation.
Solution Approach 2:
The patent changes the physical parameters of the mounting member by introducing pre-biasing forces or initial geometric configurations. The mounting member is designed with specific pre-stress conditions or initial curvature parameters that compensate for the expected thermal expansion, allowing the system to maintain stability without adding complex cooling infrastructure.
2Stability of the object's composition
If the counterface is made from ceramic material, then coning deformation is prevented, but brittleness and reliability issues are introduced
Solution Approach 1:
The patent employs a composite structure consisting of the counterface material combined with a mounting member having elastic or compliant properties. This composite system allows the counterface to maintain dimensional stability while the mounting member provides stress distribution and compensation, avoiding the need for purely ceramic constructions that would be brittle and unreliable.
Solution Approach 2:
The mounting member acts as an intermediary between the counterface and the sealing system. It mediates the thermal stresses by providing compliant mounting that distributes loads and compensates for expansion, thereby preventing coning without requiring the counterface itself to be made of brittle ceramic material.
3Stability of the object's composition
If the counterface is made thicker to resist deformation, then coning is reduced, but the axial space required increases and seal performance deteriorates
Solution Approach 1:
The patent segments the sealing system into distinct functional components: the counterface and the mounting member. By separating these functions, the counterface can remain thin for optimal sealing performance while the mounting member provides the necessary structural support, stress distribution, and thermal compensation, thereby achieving rigidity without increasing the counterface thickness.
Solution Approach 2:
The patent addresses the rigidity requirement by transitioning from a single-dimensional solution (thicker counterface) to a multi-dimensional solution. The mounting member introduces additional structural dimensions and support mechanisms that provide the necessary rigidity and stability without increasing the axial thickness of the counterface itself, maintaining compact seal geometry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces coning and wear by thermally expanding in a controlled manner, maintaining a stable seal surface and preventing gas leakage, while avoiding the complexity and brittleness issues of prior approaches.
Implementation Method 1
a mounting member (18) including a clamp portion (40) and a biasing portion (42)
Implementation Method 2
The portion of the counterface proximate the seal surface will, as a result, experience greater thermal expansion than the aft surface
Data Source
Figure 1~2
Figure 3A~3B
Figure 4~5
AI summary
According to the present invention, an annular face seal arrangement (10) for a gas turbine engine is provided that includes a mounting ring (16), a mounting member (18), a rotor (22), and a stator (20). The mounting ring has a width (31) extending between a first axial end (32) and a second axial end (34). The mounting member has a clamp portion (40) and a biasing portion (42). The clamp portion extends axially between a first clamping surface (50) and a second clamping surface (52). The biasing portion includes a first segment (46) and a second segment (48) The second segment has a width (47) and a rotor contact surface (54). The rotor has a rotor seal surface (68) and a clamp portion (56) having a width (53). The stator has a stator seal surface (76) 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.