Gas Turbine Seal Assembly with Backside Cavity for Pressure Load Reduction
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Solution Overview
Problem
Gas turbine engine components face challenges in efficiently reducing gas flow escape around turbine blades due to existing seal technologies, which often rely on metallic materials that may not effectively manage high-temperature and pressure conditions.
Innovation Solution
A seal assembly using ceramic matrix composite materials with a radially facing component of the total surface area divided by the second region equal to or less than 0.2, featuring a backside cavity and undulations between rails, and a cooling cavity coupled to a pressurized fluid source to manage pressure differentials and reduce radial loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metallic seal materials are used in turbine blades, then the seal structure can be simple and easy to manufacture, but the seal effectiveness is reduced under high-temperature and pressure conditions
Solution Approach 1:
The patent applies composite materials by combining metallic carrier segments with ceramic tile segments to create a seal assembly that maintains structural integrity while providing effective sealing under high-temperature and pressure conditions. The ceramic material provides thermal insulation and sealing effectiveness, while the metallic carrier provides structural support and ease of manufacture.
2Strength
If the backside surface area of the seal arc segment is increased, then the structural strength is improved, but the radial pressure load on the seal increases
Solution Approach 1:
The patent applies local quality by creating a backside cavity that removes material from specific regions of the seal arc segment. This reduces the radial pressure load on the seal while maintaining structural strength in critical areas through the retained metallic carrier structure and strategic placement of ceramic tiles.
3Reliability
If ceramic matrix composite materials are used for seal arc segments, then the seal effectiveness and thermal resistance are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies segmentation by dividing the seal assembly into discrete metallic carrier segments and ceramic tile segments. This modular approach allows for simplified manufacturing of individual components that can be assembled together, reducing overall device complexity while maintaining the benefits of ceramic materials for seal effectiveness and thermal resistance.
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 reduces gas flow escape and manages thermal stresses, enhancing the durability and efficiency of the seal assembly by distributing loads and maintaining a reduced pressure load arrangement.
Implementation Method 1
a cooling scheme operable to cool the seal arc segment. The assembly includes a feeding passage arranged to convey a pressurized cooling flow from a cooling source
Implementation Method 2
The seal arc segment is arranged such that a fluid pressure established in the cooling cavity is greater than a fluid pressure across a leading edge section and/or a trailing edge section of the seal arc segment
Data Source
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AI summary
A seal assembly (60) for a gas turbine engine (20) includes, a seal arc segment (66), a sealing portion (72), a first rail (74R-1) and a second rail (74R-2) opposed to the first rail. The sealing portion extends in a circumferential direction between opposed mate faces in an axial direction between a leading edge (72LE) and a trailing edge (72TE). Each of the first and second rails extend outwardly in a radial direction from the sealing portion (72) to respective first and second edge faces (74RF-1, 74RF-2), and the sealing portion (72) has a sealing face (72A) dimensioned to bound a gas path (GP) and includes a backside face (72C) opposed to the sealing face. Each of the first and second rails includes at least one interface bore (74B) dimensioned to receive a retention pin (84).