Gas Turbine Combustor Sliding Joint for Thermal Growth
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Solution Overview
Problem
Current gas turbine engine combustors face issues with thermal growth mismatch between the combustor and turbine vane assembly, leading to increased wear and reduced lifespan due to fretting caused by thermal expansion, which is exacerbated by the thicker sheet metal required for effusion holes and the resulting stiffness changes.
Innovation Solution
A sliding joint is introduced between the combustor's large exit duct and the turbine vane assembly, featuring an elongated flexible arm and spacer that allows axial displacement during thermal expansion, reducing loads on support structures and preventing combustion gas leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If effusion holes are implemented for cooling, then cooling performance is improved, but sheet metal thickness must increase
Solution Approach 1:
The patent employs effusion cooling holes drilled through the combustor liner, creating a porous structure that allows cooling air to pass through and form a protective film on the outer surface. This porous material approach enables effective cooling while managing the thickness requirements of the sheet metal
2Temperature
If sheet metal thickness is increased for effusion holes, then cooling capability is improved, but combustor stiffness decreases
Solution Approach 1:
The patent applies effusion holes only in specific regions of the combustor liner where cooling is most needed, rather than uniformly throughout. This local quality approach allows cooling capability to be improved in critical areas while maintaining overall combustor stiffness by avoiding unnecessary thickness increases in non-critical regions
3Temperature
If axial length increases due to thermal growth, then thermal expansion is accommodated, but support structure wear increases
Solution Approach 1:
The patent introduces a sliding joint mechanism between the combustor and turbine vane assembly that allows dynamic movement to accommodate thermal expansion. This dynamic joint absorbs the axial length changes due to thermal growth without transferring excessive loads to the support structures, thereby preventing increased wear and maintaining reliability
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 sliding joint effectively absorbs thermal growth mismatch, reducing fretting and wear on support structures, thereby extending the combustor's operational life and maintaining structural integrity.
Implementation Method 1
as the axial length of the combustor with respect to its surrounding parts increases due to thermal growth
Implementation Method 2
an elongated flexible arm extending between a first end joined to the outer surface of the distal flange and an opposed free second end disposed radially inward of the distal flange
Data Source
AI summary
A sliding joint in a gas turbine engine between a large exit duct of a combustor and a turbine vane assembly having a leading edge lug. The sliding joint has an elongated flexible arm extending between a first end joined to the outer surface of the large entry duct, and an opposed free second end disposed radially inward of the outer surface of the large entry duct. A spacer is joined to the second end of the arm and projects radially away therefrom toward the outer surface of the large entry duct. The spacer is spaced apart from the outer surface and defines a gap therebetween. The spacer, the arm, and the sliding joint axially displace with respect to the lug upon thermal expansion of the large entry duct.