Gas Turbine Seal Arc Segments with Distributed Cooling
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Solution Overview
Problem
Gas turbine engine components, particularly the blade outer air seal assemblies, face challenges in efficiently managing thermal gradients and reducing thermal stress due to non-uniform temperature distributions across the sealing face, which can lead to durability issues and potential delamination in ceramic matrix composite materials.
Innovation Solution
A distributed cooling scheme is implemented using a ceramic material for the seal arc segments, with a feeding passage and cooling passages arranged to directly impinge cooling flow on specific regions, establishing a pressure differential to uniformly cool the leading, intermediate, and trailing edge portions, thereby reducing thermal gradients and stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blade outer air seal assembly is positioned in close radial proximity to turbine blade tips to reduce gas flow escape, then sealing effectiveness is improved, but thermal stress and thermal gradients increase due to exposure to high temperature combustion gases
Solution Approach 1:
The seal assembly is divided into multiple arc segments that are circumferentially arranged, allowing each segment to be independently cooled and managed for thermal stress, while collectively providing continuous sealing around the turbine blade tips
Solution Approach 2:
Cooling schemes are applied locally to the seal assembly, with cooling passages and feed passages positioned to deliver cooling flow to specific regions experiencing highest thermal stress, creating non-uniform temperature distribution that reduces thermal gradients
2Stress or pressure
If cooling schemes are applied to the seal assembly to manage thermal stress, then thermal stress is reduced, but device complexity increases due to additional cooling passages and fluid delivery systems
Solution Approach 1:
The cooling passages are integrated within the seal assembly structure itself, combining the sealing function and cooling function into a single integrated component rather than separate systems, reducing overall device complexity
Solution Approach 2:
The seal assembly performs multiple functions simultaneously: it provides mechanical sealing to prevent gas flow escape, serves as a structural support component, and acts as a heat management system through integrated cooling passages and feed passages
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 distributed cooling scheme effectively reduces thermal stress and improves durability by uniformly cooling the seal arc segments, maintaining consistent temperatures across the sealing face and minimizing the risk of delamination.
Implementation Method 1
establishing a pressure differential to uniformly cool the leading, intermediate, and trailing edge portions
Implementation Method 2
a distributed cooling scheme is implemented using a ceramic material for the seal arc segments, with a feeding passage and cooling passages arranged to directly impinge cooling flow on specific regions
Implementation Method 3
A distributed cooling scheme is implemented using a ceramic material for the seal arc segments
Data Source
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AI summary
An assembly for a gas turbine engine according to an example of the present disclosure includes, among other things, a seal arc segment (66; 166; 266; 366) that has a sealing portion (72; 372) and a pair of opposed rails extending outwardly from the sealing portion (72; 372). The sealing portion (72; 372) includes a sealing face (72A) dimensioned to bound a core flow path (C) and has a backside face (72C; 172C) opposed to the sealing face (72A). The backside face (72C; 172C) includes a first localized region (LR1), a second localized region (LR2) between the pair of rails, and a third localized region (LR3). A support (68; 168; 268; 368) includes a mounting portion (76) and a first interface portion (78; 178; 374). At least one retention pin (84; 284; 384) is dimensioned to engage the first interface portion (78; 178; 374) of the support (68; 168; 268; 368) and at least one of the pair of rails such that the seal arc segment (66; 166; 266; 366) is carried by the at least one retention pin (84; 284; 384). A support plate (86; 186; 286; 386) is arranged relative to the support (68; 168; 268; 368) such that the at least one retention pin (84; 284; 384) is trapped between the support plate (86; 186; 286; 386) and the support (68; 168; 268; 368). A cooling cavity (96; 196; 296; 396) is established between the support (68; 168; 268; 368), the support plate (86; 186; 286; 386), and the second localized region (LR2). A method of sealing is also disclosed.