Turbine Shroud Split-Pin Assembly for Thermal Expansion Control
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Solution Overview
Problem
Turbine shroud components in gas turbine engines experience differential thermal expansion due to materials with varying coefficients of thermal expansion, leading to misalignment and stress issues when traditional fasteners are used, which can cause leakage and mechanical instability.
Innovation Solution
A turbine shroud assembly featuring a carrier and a seal segment with ceramic matrix composite materials, utilizing a split-pin fastener system that includes forward and aft pins spaced apart to accommodate independent movement, allowing for differential expansion and contraction, and retainer plugs to secure the pins in place, thereby reducing stress and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional fasteners are used to couple turbine shroud components, then the components are securely attached, but differential thermal expansion causes misalignment and stress issues
Solution Approach 1:
The fastener is divided into multiple segments (first fastener segment, second fastener segment, third fastener segment) that can independently move relative to each other along the fastener axis. This segmentation allows each segment to accommodate thermal expansion differently, maintaining attachment strength while preventing misalignment and stress issues during temperature changes.
Solution Approach 2:
The fastener transitions from a rigid, fixed structure to a dynamic system where segments can move independently. The movable segments absorb thermal expansion forces through controlled displacement, allowing the fastener to adapt to dimensional changes in the shroud components without compromising attachment integrity or alignment stability.
2Strength
If rigid fasteners are used to secure seal segments, then the seal is firmly attached, but thermal expansion differences cause leakage
Solution Approach 1:
The fastener is segmented into multiple movable sections that can independently adjust to thermal expansion. This allows the seal segment to remain firmly attached while accommodating dimensional changes, preventing gaps that would lead to leakage without sacrificing attachment firmness.
Solution Approach 2:
The fastener's physical state changes from rigid to flexible through temperature-dependent expansion. The segments can change their relative positions in response to thermal parameters, maintaining sealing integrity while adapting to thermal expansion differences between materials.
3Stability of the object's composition
If fixed fasteners are used to attach shroud components, then the structure is stable, but differential thermal expansion creates localized stress
Solution Approach 1:
The fastener is divided into multiple segments that can move independently to distribute thermal expansion forces. This segmentation prevents stress concentration at any single location, maintaining structural stability while reducing localized stress through controlled displacement of individual segments.
Solution Approach 2:
The movable segments act as built-in stress-absorbing elements that anticipate and cushion against thermal expansion forces before they can create damaging localized stress. The segments provide a compliant interface that absorbs expansion energy, protecting the overall structure from stress concentrations.
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 manages thermal expansion, reduces leakage, and decreases localized stresses by allowing independent loading of the seal segment, enhancing the durability and performance of the turbine shroud assembly.
Implementation Method 1
the components of some turbine shrouds expand at different rates when exposed to high temperatures
Data Source
AI summary
A turbine shroud assembly adapted for use with a gas turbine engine includes a carrier, a seal segment, and a mount assembly. The carrier is configured to be coupled to a turbine case. The seal segment is shaped to define a gas path boundary of the shroud assembly. The mounting assembly is configured to couple the seal segment to the carrier.