Combustor Liner Weld Protection via Heat Shield
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Solution Overview
Problem
Current thermal barrier coatings (TBCs) cannot be applied over welds in combustor liner sections of gas turbine engines, limiting the operational lifetime of the welded joints due to high temperatures and thermal stresses.
Innovation Solution
A heat shield is introduced along the weld line between combustor liner sections, spaced apart to form a passage for cooling fluid, protecting the weld area from high temperatures and thermal stresses, and can be integrally formed or separately fitted using various mechanical fixing methods, including welding, spring connectors, or castellated structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If combustor liner sections are welded together to form a continuous structure, then the structural integrity and sealing of the combustion chamber is improved, but the operational lifetime is limited because thermal barrier coatings cannot be applied over welds, exposing the welded joints to high temperatures and thermal stresses
Solution Approach 1:
The combustor liner is divided into multiple liner sections that are joined together, allowing the heat shield to be positioned at the join line between sections. This segmentation enables the protective heat shield to be installed specifically at the vulnerable welded joint without requiring re-welding or coating the entire liner.
Solution Approach 2:
A heat shield is introduced as an intermediary component between the hot combustion gases and the welded joint. The heat shield, positioned within 5mm of the join line, acts as a thermal barrier that protects the weld from direct exposure to high temperatures, thereby extending the operational lifetime of the joined liner sections.
2Temperature
If the heat shield is positioned close to the join line to maximize protection, then the thermal protection effectiveness is improved, but the risk of hot gases entering the passage between the heat shield and liner sections increases
Solution Approach 1:
The passage cross-sectional area is varied along the length of the heat shield to optimize local flow characteristics. The passage has a maximum cross-sectional area at a specific location, creating controlled turbulence that prevents hot gases from penetrating into the cooling passage while maintaining effective thermal protection at the join line.
Solution Approach 2:
The geometry of the passage is modified by varying the cross-sectional area along the heat shield length. This parameter change creates optimal flow conditions that balance thermal protection effectiveness with prevention of hot gas intrusion, using fluid dynamics principles rather than simply increasing distance from the join line.
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 heat shield extends the operational lifetime of the combustor liner by reducing thermal stresses and temperatures at the weld line, allowing the gas turbine engine to operate at higher temperatures while maintaining structural integrity.
Implementation Method 1
the heat shield extending along the join line but spaced apart therefrom to define a passage between the heat shield and the first and second liner sections for the introduction of a cooling fluid
Implementation Method 2
Further protection is afforded by the introduction of a cooling fluid such as air, for example, through the passage to reduce the temperature of the liner sections in the region of the join line
Data Source
AI summary
A combustor liner for use in a gas turbine engine includes a first liner section and a second liner section. They are joined together by welding or a mechanical fixing along a common join line or weld. A heat shield extends along the join line to protect it from the high temperatures and thermal stresses that are experienced by the combustor liner during the operation of the gas turbine engine. The heat shield is spaced apart from the joint line to define a passage between the heat shield and the first and second liner sections for the introduction of a cooling fluid such as air. The heat shield and the exposed surfaces of the liner sections are coated with a thermal barrier coating.