Blade Outer Air Seal Mount Spring Re-centering
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Solution Overview
Problem
Disparate thermal growth between rotor assemblies and outer cases in gas turbine engines causes interference with blade outer air seals, leading to performance degradation, and existing solutions like increased gaps or abradable materials are ineffective in maintaining optimal seal alignment under varying pressure loads.
Innovation Solution
A blade outer air seal assembly featuring spring elements between block mounts and the seal section ends, which counteracts reaction forces and maintains centering, using materials like nickel-based or cobalt-based alloys to accommodate thermal growth and pressure loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gap between rotor blade tips and blade outer air seal is increased to avoid interference from thermal growth, then interference is avoided, but engine performance deteriorates due to increased leakage
Solution Approach 1:
The blade outer air seal is designed with spring elements that allow it to dynamically adjust its position relative to the rotor blade tips. The spring-mounted configuration enables the seal to move axially and radially to maintain optimal clearance under varying thermal and pressure conditions, rather than using a fixed gap design.
Solution Approach 2:
The sealing system utilizes changes in physical parameters (spring compression, material thermal expansion) to adapt to thermal growth. The spring elements compress or expand based on thermal conditions and pressure loads, automatically adjusting the seal position to maintain effective sealing without requiring a larger fixed gap.
2Manufacturing precision
If abradable material is used in blade outer air seal to encourage abrading and create customized clearance, then optimal clearance can be achieved, but unequal pressure loads cause rotational forces that push the seal out of alignment
Solution Approach 1:
The spring elements are positioned and configured to counteract the rotational forces generated by unequal pressure loads across the seal surface. The springs provide a restoring force that opposes the destabilizing moments, maintaining the seal's alignment and preventing it from rotating out of position.
Solution Approach 2:
The seal transitions from a static abradable material design to a dynamic spring-mounted system that can actively respond to and compensate for unequal pressure loads. The springs allow the seal to maintain stable alignment while accommodating the forces that would otherwise cause rotational displacement.
3Ease of manufacture
If rigid mounting is used for blade outer air seal, then manufacturing is simpler, but the seal cannot accommodate thermal growth and pressure loads, leading to interference or misalignment
Solution Approach 1:
The mounting system replaces rigid fixed-position mounting with dynamic spring-mounted support. The springs provide compliance that allows the seal to accommodate thermal growth and pressure-induced deformations while maintaining proper alignment, eliminating the need for complex adjustable mechanisms.
Solution Approach 2:
The spring-mounted design explicitly accommodates thermal expansion of the rotor assembly. As the rotor and seal experience different thermal growth, the springs compress or expand to maintain proper clearance and alignment, preventing interference while keeping the manufacturing process relatively simple.
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 maintains the blade outer air seal's alignment and performance by tolerating thermal and pressure variations, reducing leakage and enhancing engine efficiency.
Implementation Method 1
a first spring element disposed between the blade outer air seal section first end and the first block mount; a second spring element disposed between the blade outer air seal section second end and the second block mount
Data Source
AI summary
The present disclosure relates generally to blade outer air seal section mount including a resilient spring element that acts to provide re-centering forces to the blade outer air seal section when non-uniform forces applied to the blade outer air seal section causing it to move away from its nominal position.