Leaf Seal Coupling via Thermal Unconstrained Pin
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Solution Overview
Problem
The challenge in gas turbine engines is coupling metallic leaf seals to composite materials, as they thermally expand and contract at different rates, leading to leakage and inefficiency.
Innovation Solution
A sealing assembly that includes a leaf seal, a seal holder, springs, and pins, where the pins are thermally unconstrained by the composite material walls due to passages designed to allow for thermal expansion, enabling effective sealing engagement between metallic and composite components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic leaf seals are coupled to composite gas turbine components, then sealing function is achieved, but thermal expansion mismatch causes leakage and inefficiency
Solution Approach 1:
A seal holder assembly acts as an intermediary between the metallic leaf seal and the composite stator vane. The seal holder includes a retention ring and support arms that couple the seal to the vane, with a clearance gap allowing independent thermal expansion of each component without transmitting thermal stress that would cause leakage
Solution Approach 2:
The design changes the thermal expansion parameter management by allowing differential movement through the clearance gap between the seal holder and stator vane. This enables each component to expand and contract at its own rate without compromising the sealing function, resolving the thermal compatibility issue
2Strength
If pins are rigidly coupled to composite walls, then structural support is provided, but thermal expansion constraints cause stress and potential failure
Solution Approach 1:
The pin serves as an intermediary coupling element that connects the seal holder to the stator vane through a clearance gap. This gap allows the pin to provide structural support while accommodating thermal expansion differences, preventing stress concentration and potential failure
Solution Approach 2:
The clearance gap creates a local region of freedom within the rigid structure, allowing thermal expansion only where needed between the pin and the composite wall, while maintaining structural integrity in other areas
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
This solution prevents combustion gas leakage by ensuring the metallic leaf seals remain effective despite thermal cycling, enhancing the sealing performance between composite and metallic components in gas turbine engines.
Implementation Method 1
a spring compressed between the seal holder and the leaf seal such that the leaf seal is in sealing engagement with the first gas turbine wall
Implementation Method 2
a pin extending through the passage defined by the second gas turbine wall to couple the seal holder and the leaf seal such that the pin is thermally unconstrained by the second wall during operation of the gas turbine engine
Data Source
AI summary
A sealing assembly for a gas turbine engine. The sealing assembly includes first and second gas turbine walls defining a channel therebetween. Additionally, the second gas turbine wall further defines a passage extending therethrough. Furthermore, the sealing assembly includes a leaf seal partially positioned within the channel and a seal holder coupled to the second gas turbine wall. Moreover, the sealing assembly includes a spring compressed between the seal holder and the leaf seal such that the leaf seal is in sealing engagement with the first gas turbine wall. In addition, the sealing assembly includes a pin extending through the passage defined by the second gas turbine wall to couple the seal holder and the leaf seal such that the pin is thermally unconstrained by the second wall during operation of the gas turbine engine.