Outer Air Seal Geometry for First Stage Casing Sealing
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Solution Overview
Problem
Existing gas turbine engines face challenges in maintaining effective sealing between the casing treatment and the first stage outer air seal (OAS) due to redesigns in casing treatments, necessitating corresponding redesigns of the OAS.
Innovation Solution
A redesigned OAS with specific geometric configurations, including forward and aft surfaces oriented along radial planes, a transitional concave surface, and a bleed air slot, which conforms to the casing's shape to enhance sealing and manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the casing treatment configuration is changed, then the sealing performance may be improved, but the OAS must be redesigned to maintain compatibility
Solution Approach 1:
The OAS is divided into multiple surfaces (first forward surface, second forward surface, and transitional surface) that can be independently configured. This segmentation allows each surface to be optimized for its specific function while maintaining overall compatibility with the casing treatment, reducing the need for complete redesigns when casing configurations change.
Solution Approach 2:
The OAS design incorporates multiple surfaces that can accommodate different casing treatment configurations. The first forward surface, second forward surface, and transitional surface work together to provide universal compatibility with various casing designs, allowing the same OAS to maintain sealing performance across different casing treatment variations.
2Reliability
If the OAS geometry is modified to improve sealing, then sealing efficiency improves, but manufacturing difficulty increases
Solution Approach 1:
The transitional surface is configured with a curved geometry that radially interposes between the first and second forward surfaces. This curvature improves sealing efficiency by conforming to the casing treatment surface while maintaining manufacturability through a single-piece construction approach that accommodates the curved geometry.
Solution Approach 2:
The OAS design modifies geometric parameters such as the recess depth of the second forward surface relative to the first forward surface, and the curvature of the transitional surface. These parameter changes optimize sealing efficiency while remaining within manufacturing capabilities for single-piece construction.
3Adaptability or versatility
If the OAS is redesigned for better compatibility with casing treatment, then adaptability improves, but device complexity increases
Solution Approach 1:
The OAS design utilizes radial and axial dimensions strategically. The second forward surface is recessed aftward from the first forward surface in the axial direction, while the transitional surface connects them in the radial direction. This multi-dimensional configuration provides adaptability to different casing treatments without significantly increasing structural complexity.
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 redesigned OAS improves sealing efficiency by directing bleed air effectively through the bleed air slot, ensuring compatibility with casing treatment changes while maintaining manufacturability.
Implementation Method 1
The transitional surface is radially interposed between the first and second forward surfaces... the second forward surface is immediately adjacent to the aft surface to form a bleed air slot
Data Source
AI summary
A compressor of a gas turbine engine is provided. The compressor includes a casing including an elongate body having an aft surface at an aft end thereof and an outer air seal (OAS) disposed aft of the casing. The OAS includes at a forward end thereof a first forward surface, a second forward surface inboard of and recessed aftward from the first forward surface and a transitional surface radially interposed between the first and second forward surfaces. The aft surface of the casing is axially interposed between the first and second forward surfaces of the OAS.