Turbine Vane Compliant Layer for Thermal Stress Distribution
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Solution Overview
Problem
Gas turbine engine vane assemblies face issues with localized stress due to differing thermal expansion rates between metallic and ceramic components, leading to potential damage and breakage.
Innovation Solution
The turbine vane assembly incorporates a load-distribution system comprising compliant members and rigid load pads between endwalls and flow path components, which compress to distribute pressure loads and maintain minimum distances, reducing relative movement and stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid components with different thermal expansion rates are used in the vane assembly, then the structural strength is improved, but localized stress and potential damage occur during heating and cooling
Solution Approach 1:
A compliant layer is introduced as an intermediary element between the metallic outer endwall and the ceramic flow path component. This compliant layer acts as a stress-absorbing intermediary that accommodates differential thermal expansion between the two rigid components, preventing localized stress concentrations and potential damage while maintaining the structural strength of both materials.
Solution Approach 2:
The compliant layer changes its physical parameters (compression, expansion) in response to thermal cycles and pressure loads. By allowing the compliant layer to dynamically adjust its thickness and density, the system accommodates thermal expansion differences between metallic and ceramic components without generating damaging stress concentrations.
2Stress or pressure
If a compliant layer is added to distribute pressure loads, then localized stress is reduced, but the device complexity increases
Solution Approach 1:
The compliant layer is implemented as a thin, flexible film or layer rather than a complex mechanical structure. This thin-film approach effectively distributes pressure loads and reduces localized stress while adding minimal complexity to the assembly. The compliant layer can be positioned between the metallic endwall and ceramic flow path component as a simple interlayer.
3Manufacturing precision
If the gap between mating surfaces is reduced to improve alignment, then component alignment is improved, but stress concentrations increase under pressure loads
Solution Approach 1:
The compliant layer is positioned in advance between the mating surfaces of the metallic endwall and ceramic flow path component. This pre-positioned cushioning layer absorbs and distributes pressure loads before they can concentrate at the interface, allowing for tight manufacturing tolerances and good alignment without creating stress concentration problems under operating conditions.
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 load-distribution system effectively reduces localized stress, maintains component alignment, and prevents damage by distributing pressure loads across the flow path component, ensuring operational stability and longevity.
Implementation Method 1
The outer compliant member may be configured to compress to reduce a size of the outer gap in response to pressure loads acting on the outer endwall and the flow path component
Implementation Method 2
The outer compliant member may be configured to compress to reduce a size of the outer gap in response to pressure loads acting on the outer endwall and the flow path component and to distribute the pressure loads
Implementation Method 3
The inner compliant member may be configured to compress to reduce a size of the inner gap in response to loads acting on the inner endwall and the flow path component during use of the turbine vane assembly
Data Source
AI summary
A turbine vane assembly for use in a gas turbine engine includes an endwall, a flow path component, and a load-distribution system. The endwall is arranged around a central axis of the turbine vane assembly. The flow path component is configured to direct fluid flow through the turbine vane assembly. The load-distribution system is positioned between the endwall and the flow path component to distribute loads transmitted between the endwall and the flow path component.