Gas Turbine Vane Ring Thermal Expansion Management
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Solution Overview
Problem
Gas turbine engine static vane rings face challenges due to differing coefficients of thermal expansion among components, leading to issues with expansion and contraction during operation, which traditional coupling methods fail to address effectively.
Innovation Solution
A vane ring design incorporating metal spars with airfoil-shaped web sections, ceramic-matrix outer and inner end walls, and end caps that allow for relative movement and secure positioning, using locator holes and connectors to manage thermal expansion and contraction, and ceramic web skins for protection from high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional coupling methods are used to join components with different coefficients of thermal expansion, then the structure appears simple and easy to manufacture, but the components cannot accommodate differential expansion and contraction during operation, leading to structural failure
Solution Approach 1:
The coupling mechanism transitions from a rigid fixed connection to a dynamic system that allows controlled movement. The deformable spacer element can elastically deform to accommodate differential thermal expansion between metal spars and ceramic end walls, while the sliding engagement between the spacer and positioning feature allows the components to move relative to each other during thermal cycling, maintaining structural integrity without excessive complexity
Solution Approach 2:
The system changes the physical state and properties of the coupling mechanism to adapt to thermal conditions. The deformable spacer element changes its dimensional parameters through elastic deformation in response to temperature changes, allowing the coupling to accommodate expansion and contraction while maintaining a relatively simple overall structure
2Reliability
If rigid coupling methods are used to secure components, then manufacturing precision can be maintained, but the components cannot accommodate thermal expansion differences, causing stress and potential failure
Solution Approach 1:
The coupling mechanism transitions from a rigid fixed connection to a dynamic system that allows controlled movement. The deformable spacer element can elastically deform to accommodate differential thermal expansion between metal spars and ceramic end walls, while the sliding engagement between the spacer and positioning feature allows the components to move relative to each other during thermal cycling, maintaining structural integrity without excessive complexity
Solution Approach 2:
The deformable spacer element acts as a pre-designed cushioning element that anticipates thermal expansion differences. By incorporating this compliant element before thermal cycling occurs, the design prevents stress buildup and potential failure that would result from rigid constraints, while the locator holes and positioning features ensure precise initial positioning during assembly
3Reliability
If components are designed to accommodate thermal expansion through movable connections, then reliability under thermal cycling improves, but the assembly complexity and manufacturing difficulty increase
Solution Approach 1:
The coupling mechanism transitions from a rigid fixed connection to a dynamic system that allows controlled movement. The deformable spacer element can elastically deform to accommodate differential thermal expansion between metal spars and ceramic end walls, while the sliding engagement between the spacer and positioning feature allows the components to move relative to each other during thermal cycling, maintaining structural integrity without excessive complexity
Solution Approach 2:
Rather than making the entire coupling system complex and movable, only specific localized elements are designed with special properties. The deformable spacer element and the sliding engagement feature are localized compliance mechanisms embedded within an otherwise relatively simple structure. This allows thermal expansion accommodation while keeping the majority of the assembly straightforward to manufacture
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 design enables efficient guidance of hot gases and accommodates thermal expansion differences, enhancing the durability and performance of gas turbine engines by maintaining structural integrity and efficiency across varying operational conditions.
Implementation Method 1
The outer end wall may comprise ceramic-matrix materials
Implementation Method 2
the components of some vane rings expand at different rates when exposed to combustion products
Data Source
AI summary
A vane ring for a gas turbine engine includes an outer end wall and a plurality of spars coupled to the outer end wall. The vane ring further includes an inner end wall positioned radially inward of the outer end wall and coupled to the spars. The outer and inner end walls cooperate to form a flowpath.