Angled Retention Hook for Blade Outer Air Seal Thermal Growth
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Solution Overview
Problem
Existing blade outer air seal (BOAS) designs in gas turbine engines face inefficiencies due to thermal growth of the engine case, leading to gaps between the blade tip and the BOAS, which can reduce engine efficiency.
Innovation Solution
The BOAS incorporates angled retention features with a slidable interface using tapered components that interface with retention blocks mounted to the engine case, allowing the BOAS to move radially inboard during thermal growth, maintaining a tight clearance with the blade tip and enhancing engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the BOAS is rigidly mounted to the engine case, then the structure is simple and stable, but gaps form between the blade tip and BOAS during thermal growth, reducing engine efficiency
Solution Approach 1:
The retention hook is designed with an angled interface that allows the BOAS to move dynamically relative to the retention block during thermal growth. The angled surface enables the BOAS to slide radially inboard as the engine case expands thermally, maintaining seal contact with the blade tip while accommodating thermal deformation. This dynamic adjustment mechanism resolves the contradiction by allowing structural simplicity while achieving reliable seal consistency through controlled movement.
2Productivity
If the BOAS maintains tight clearance with the blade tip, then engine efficiency is improved, but the BOAS cannot accommodate engine case thermal growth
Solution Approach 1:
The retention hook utilizes an angled interface geometry that changes the positional parameter of the BOAS relative to the retention block. As thermal growth occurs, the angled surface converts thermal expansion into radial inboard movement of the BOAS, maintaining optimal clearance with the blade tip. This parameter change mechanism allows the system to adapt to thermal growth while preserving engine efficiency through consistent seal contact.
3Ease of manufacture
If the retention hook is perpendicular to the BOAS, then manufacturing is simple, but thermal growth causes gap formation and seal failure
Solution Approach 1:
The retention hook employs an asymmetric angled interface rather than a symmetric perpendicular connection. The angled surface creates a directional sliding path that accommodates thermal growth forces. This asymmetric geometry, while slightly more complex to manufacture, provides reliable seal performance by enabling the BOAS to adjust its position during thermal expansion, preventing gap formation and maintaining contact with the blade tip.
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 design improves engine efficiency by maintaining a consistent seal between the blade tip and the BOAS, minimizing the impact of engine case thermal growth and reducing energy losses.
Implementation Method 1
Movement of the BOAS relative to the retention block along the slidable interface in response to thermal growth of the engine case
Data Source
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AI summary
A blade outer air seal (BOAS) according to an exemplary aspect of the present disclosure includes, among other things, a ceramic body having a radially inner face and a radially outer face and a retention feature that extends from the radially outer face. The retention feature includes at least one angled hook that extends at a transverse angle relative to the radially outer face.