Gas Turbine CMC Combustor Sealing for Liner and Dome Gaps
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Solution Overview
Problem
Gas turbine engines experience airflow leakage through gaps in connections between CMC liners, inner and outer liners, and metallic cowl structures, reducing the available air for combustion and cooling.
Innovation Solution
Implementing seal members within seal cavities at the connections between CMC components, located downstream of the connection features, to control airflow leakage and enhance air availability for combustion and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If seal members are installed at connection gaps between CMC liners and cowl structure, then airflow leakage is reduced, but device complexity increases
Solution Approach 1:
The seal member is nested within a seal cavity that is integrated into the connection structure between the CMC liner and cowl assembly. The seal cavity is formed by the interaction of the liner flange and cowl flange surfaces, creating a contained space where the seal member operates. This nesting approach allows the sealing function to be embedded within the existing structural connection without requiring entirely separate sealing components.
Solution Approach 2:
The seal member acts as an intermediary element between the CMC liner and the metallic cowl structure. It is positioned within the seal cavity to bridge the gap between these two components, preventing airflow leakage while accommodating the thermal expansion differences between the ceramic matrix composite liner and the metallic cowl assembly through its flexible sealing action.
2Loss of energy
If seal cavities are positioned downstream of connection features, then airflow leakage is controlled, but manufacturing precision requirements increase
Solution Approach 1:
The seal cavity is formed in advance during the assembly process by the interaction of pre-formed flange surfaces on the CMC liner and cowl assembly. The flange surfaces are prepared beforehand with appropriate geometries that define the seal cavity space, ensuring that when components are assembled, the seal cavity is automatically positioned downstream of the connection features without requiring additional precision machining or adjustment steps.
Data Source
AI summary
A combustor for a gas turbine engine includes a ceramic matrix composite (CMC) dome structure, a CMC outer liner, a CMC inner liner, and a cowl structure, that are connected together via at least one outer connection and at least one inner connection. An outer seal member is arranged to seal an outer gap between an outer liner connecting flange and an outer dome connecting flange, and an inner seal member is arranged to seal an inner gap between an inner liner connecting flange and an inner dome connecting flange.