Ring Assembly for Double-Skin Combustor Liner Thermal Expansion
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Solution Overview
Problem
The challenge in double-skin combustor liners for gas turbine engines is the differing thermal growth rates of ceramic matrix composite (CMC) inner skins and metal outer skins, due to their distinct temperature exposures and material characteristics, leading to potential stress and inefficiencies in thermal expansion management.
Innovation Solution
A ring assembly with an annular end body and projecting portions is used to space and support the inner and outer skins, incorporating an expansion joint to accommodate thermal expansion differentials, allowing axial and radial movement while maintaining the annular space between the skins for cooling and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If double-skin combustor construction is used with CMC inner skin and metal outer skin, then temperature resistance and structural support are improved, but thermal expansion differential causes stress and reliability issues
Solution Approach 1:
The support structure is divided into multiple projecting portions (first and second projecting portions) that independently support the inner and outer skins. This segmentation allows each portion to accommodate the thermal expansion characteristics of its respective skin, reducing stress from differential expansion while maintaining structural support and temperature resistance.
2Strength
If rigid support structure is used to maintain annular space, then structural integrity is improved, but thermal expansion accommodation is reduced
Solution Approach 1:
The support structure incorporates dynamic elements through radially adjustable projecting portions that can move radially relative to the annular end body. This allows the structure to adapt to thermal expansion differentials while maintaining the required annular space and structural integrity through controlled radial movement rather than rigid fixation.
3Use of energy by stationary object
If annular space is maintained for cooling, then cooling efficiency is improved, but structural complexity increases
Solution Approach 1:
The projecting portions serve multiple functions: they provide structural support for both skins, maintain the annular cooling space, and accommodate thermal expansion through radial adjustment. This multi-functionality reduces the need for separate components for each function, thereby managing complexity while achieving effective cooling and structural support.
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 differentials between the CMC and metal skins, reducing stress and ensuring efficient operation by allowing for axial and radial movement, thus maintaining structural integrity and cooling efficiency within the combustor.
Implementation Method 1
an expansion joint between the ring assembly and the inner skin configured to permit motion resulting from a variation in thermal expansion between the inner skin and the ring assembly
Data Source
AI summary
A ring assembly for holding a double-skin combustor liner has an inner skin of ceramic matrix composite and an outer skin. The assembly comprises an annular end body, a first projecting portion projecting relative to the annular end body at least partially in an axial direction, the first projecting portion configured for supporting the inner skin, a second projecting portion projecting relative to the annular end body at least partially in the axial direction, the second projecting portion configured for supporting the outer skin. The first and second projecting portions are radially spaced apart to provide a radial spacing between the inner skin and the outer skin. An expansion joint is between the ring assembly and the inner skin configured to permit motion resulting from a variation in thermal expansion between the inner skin and the ring assembly.