CMC Blade Track Retention System for Gas Turbine Engines
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Solution Overview
Problem
Traditional fasteners and retention systems are challenging to incorporate into assemblies of metallic and Ceramic Matrix Composite (CMC) components in gas turbine engines, limiting the maximum operating temperature and efficiency of metallic components compared to CMC materials.
Innovation Solution
A retention system comprising a metallic carrier with apertures and ceramic matrix composite blade track segments or liner tiles, using threaded stud receivers and nuts to securely attach studs and tabs, preventing movement and release, and allowing for limited movement to accommodate thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional fasteners and retention systems are used to attach CMC components to metallic carriers, then the assembly can be manufactured with conventional methods, but the maximum operating temperature is limited due to the lower temperature tolerance of metallic fasteners compared to CMC materials
Solution Approach 1:
The patent applies composite materials by integrating the fastener (stud) directly into the CMC component (blade track segment) as a one-piece monolithic structure. This eliminates the need for separate metallic fasteners that would limit operating temperature, allowing the entire assembly to withstand higher temperatures while maintaining ease of manufacture through single-piece fabrication.
Solution Approach 2:
The patent merges the fastener and the CMC component into a single integrated structure. The stud is formed as an integral part of the blade track segment, eliminating the interface between separate fastener and component parts. This merging resolves the contradiction by allowing the use of CMC material throughout the assembly, enabling higher operating temperatures without complicating the manufacturing process.
2Strength
If metallic fasteners are used to attach CMC components, then the assembly structure is simple and easy to manufacture, but the structural integrity at high temperatures is compromised due to the lower temperature tolerance of metallic materials
Solution Approach 1:
The patent uses CMC material for both the blade track segment and the integrated stud, creating a monolithic CMC structure that maintains structural integrity at high temperatures. This eliminates the need for temperature-limiting metallic fasteners while the one-piece design keeps the device complexity low.
Solution Approach 2:
The CMC blade track segment serves dual functions: it provides the structural component and simultaneously provides its own fastening mechanism through the integrated stud. This self-service approach eliminates the need for separate metallic fasteners, maintaining structural integrity at high temperatures without increasing device complexity.
3Reliability
If CMC blade track segments are securely attached to metallic carriers, then the retention system prevents movement and release, but the thermal expansion differences between CMC and metallic materials create stress and potential failure
Solution Approach 1:
The patent addresses thermal expansion by making the blade track segment and stud a one-piece CMC structure, eliminating the interface between CMC and metallic materials. This removes the source of differential thermal expansion stress, allowing the assembly to expand uniformly at high temperatures while maintaining secure attachment and reliability.
Solution Approach 2:
By using CMC material for both the blade track segment and the integrated stud, the patent creates a homogeneous composite structure that experiences uniform thermal expansion. This eliminates the stress concentration that would occur at the interface between CMC and metallic materials with different thermal expansion coefficients, improving reliability at high temperatures.
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
Enhances the secure attachment of CMC components to metallic carriers, enabling higher operating temperatures and improved efficiency by maintaining the structural integrity and thermal compatibility of both materials.
Implementation Method 1
The retention system may include a pair of threaded stud receivers that capture a portion of the stud arranged outside of the aperture to block movement of the stud out of the aperture, and a nut that engages the threaded stud receivers to block release of the stud from the stud receivers.
Implementation Method 2
The stud and the second stud may be sized relative to their respective apertures to allow the stud and the second stud to move within their respective apertures so that the blade track segment is movable relative to the carrier.
Data Source
AI summary
A combustor of a gas turbine engine and a turbine shroud for a turbine of a gas turbine engine are disclosed. The combustor is configured to ignite a mixture of compressed air and fuel in a combustion chamber included therein. The turbine shroud is configured to direct products of the combustion reaction toward a plurality of rotatable turbine blades of the turbine to cause the plurality of turbine blades to rotate.