Deformable Seal Runner for Stable Turbine Engine Seal Gaps
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Solution Overview
Problem
Gas turbine engines face a decrease in sealing efficiency due to thermal growth and centrifugal forces affecting the controlled gap between the seal runner and the sealing ring, leading to increased leakage and efficiency penalties.
Innovation Solution
A resiliently deformable seal runner is used, which changes shape from an at-rest to a pre-loaded configuration under axial compression, increasing its outer diameter and maintaining a consistent gap height despite thermal growth and centrifugal forces, by adjusting its curvature and axial width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a controlled gap seal is used with a seal runner and sealing ring, then lubricant leakage is limited through compressed air circulation, but thermal growth and centrifugal force cause the gap dimension to change, decreasing sealing efficiency
Solution Approach 1:
The seal runner is designed with a resiliently deformable structure that can dynamically adjust its shape in response to operating conditions. The curved inner face allows the seal runner to deform elastically under thermal growth and centrifugal force, maintaining a consistent gap dimension between the seal runner outer face and sealing ring inner face despite changes in temperature and rotational speed.
Solution Approach 2:
The invention changes the physical parameters of the seal runner by introducing a curved inner face geometry. This curvature allows the seal runner to undergo controlled elastic deformation, changing its outer diameter and gap dimension in response to thermal and centrifugal loads, thereby maintaining sealing efficiency across varying operating conditions.
2Reliability
If the seal runner is made resiliently deformable with a curved inner face, then the gap height is maintained consistent despite thermal growth and centrifugal forces, but the structural complexity of the seal runner increases
Solution Approach 1:
The seal runner incorporates a curved inner face that acts as a flexible element, allowing elastic deformation under load. This curved geometry enables the seal runner to adapt its shape in response to thermal growth and centrifugal force, maintaining a consistent gap dimension without requiring complex active control systems or multiple adjustable components.
3Reliability
If axial compression force is applied to pre-load the seal runner, then the outer diameter increases and gap consistency is improved, but additional loading on the shaft and bearing is introduced
Solution Approach 1:
The seal runner is pre-loaded with an axial compression force during assembly to establish an initial curved configuration. This preliminary action positions the seal runner in a state where its outer diameter is optimized for gap consistency at a specific operating condition (e.g., takeoff). As operating conditions change, the seal runner deforms elastically from this pre-set configuration, maintaining sealing effectiveness across the operating range.
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
This solution maintains a consistent radial height of the gap between the seal runner and the sealing ring, reducing leakage and maintaining sealing efficiency across varying operating conditions, including takeoff and cruise phases.
Implementation Method 1
the seal runner resiliently deformable from an at-rest shape where no axial compression force is exerted on the seal runner to a pre-loaded shape where the seal runner is axially clamped on the shaft by an axial compression force
Implementation Method 2
thermal growth and centrifugal force affect a dimension of this controlled gap
Implementation Method 3
thermal growth and centrifugal force affect a dimension of this controlled gap
Data Source
AI summary
An aircraft engine, has: a shaft rotatable about a central axis; a housing mounted around the shaft; and a seal assembly disposed radially between the shaft and the housing relative to the central axis, the seal assembly having: a sealing ring mounted to the housing, and a seal runner secured to the shaft, the seal runner extending radially relative to the central axis from an inner face facing the shaft to an outer face facing the sealing ring and being radially spaced apart from the sealing ring by a gap, the seal runner resiliently deformable from an at-rest shape where no axial compression force is exerted on the seal runner to a pre-loaded shape where the seal runner is axially clamped on the shaft by an axial compression force, an outer diameter of the outer face greater in the pre-loaded shape than in the at-rest shape.