Air-Activated Piston Seals for Turbine Shroud Expansion
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Solution Overview
Problem
Sealing between turbine shroud components with different thermal expansion coefficients is challenging due to differential expansion, leading to potential gas leakage and reduced effectiveness.
Innovation Solution
A turbine shroud assembly with a carrier segment, blade track segment, and a seal system featuring a buffer air seal assembly that uses pressure-activated seals and bias members to maintain engagement with the blade track segment, utilizing buffer air to urge seals radially inward for effective sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If components are made from materials with different coefficients of thermal expansion to withstand high temperatures, then temperature resistance is improved, but sealing effectiveness deteriorates due to differential expansion
Solution Approach 1:
The seal member is designed to move dynamically between a retracted position (at low temperature) and an engaged position (at high temperature). The biasing member provides continuous force to maintain the seal in the engaged position during thermal expansion, allowing the sealing system to adapt to temperature changes while maintaining effectiveness.
Solution Approach 2:
The system utilizes parameter changes in the form of thermal expansion. The seal member's position changes from retracted to engaged as temperature increases, and the biasing member's force changes to compensate for differential expansion between components made from materials with different coefficients of thermal expansion.
2Reliability
If a seal system is added to block gas flow between carrier and blade track segments, then gas leakage is reduced, but device complexity increases
Solution Approach 1:
Buffer air is introduced into the buffer cavity to apply pressure on the seal member, enhancing its engagement with the blade track segment. This pneumatic assistance simplifies the mechanical design by reducing the force requirements for the biasing member while improving sealing effectiveness against high-temperature gases.
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 provides robust sealing against high-temperature gases, reducing leakage and enhancing the durability and effectiveness of the turbine shroud assembly.
Implementation Method 1
The biasing member may be a spring arranged radially between the carrier segment and the seal to apply the bias force to the seal
Implementation Method 2
The at least one buffer air passageway may be configured to discharge buffer air radially inward away from the carrier segment into the buffer cavity to urge the seal radially inward into engagement with the blade track segment
Data Source
AI summary
A turbine shroud assembly for use with a gas turbine engine includes a carrier segment, a blade track segment, and a seal system. The carrier segment arranged circumferentially at least partway around an axis. The blade track segment is coupled to the carrier segment and defines a portion of a gas path of the gas turbine engine. The seal system is arranged radially between the carrier segment and the blade track segment to block gases from flowing between the carrier segment and the blade track segment.