Convolution Seal for Turbine Transition Duct Thermal Expansion
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Solution Overview
Problem
Turbine systems with offset combustor ducts experience thermal expansion issues, leading to undesirable shifts and gaps between adjacent ducts, causing leakage and mixing of cooling air and hot gas, which interferes with the performance of airfoil surfaces formed by these ducts.
Innovation Solution
The implementation of convolution seals at the interfaces between transition ducts, which accommodate thermal growth by allowing movement along multiple axes, preventing gaps and maintaining a seal between adjacent ducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If offset ducts are used to shift hot gas flow and eliminate first stage nozzles, then efficiency and power output are improved, but thermal expansion causes gaps between adjacent ducts leading to leakage
Solution Approach 1:
The convolution seal is designed with a flexible, convoluted structure that can dynamically adapt to thermal expansion and contraction of the ducts. The seal accommodates movement along multiple axes (longitudinal, radial, tangential) while maintaining contact between adjacent ducts, preventing gaps and leakage during thermal cycles.
Solution Approach 2:
The seal design accounts for changes in dimensional parameters caused by thermal expansion. The convolution structure allows the seal to expand and contract with the ducts while maintaining sealing contact, effectively compensating for thermal growth variations without compromising seal integrity.
2Device complexity
If ducts are offset to create airfoil surfaces for flow shifting, then first stage nozzles are eliminated, but gaps between ducts allow leakage and mixing of cooling air and hot gas
Solution Approach 1:
The convolution seal acts as an intermediary element between adjacent offset ducts. It fills the potential gaps created by the offset configuration and maintains continuous sealing contact, preventing harmful leakage and mixing while allowing the ducts to maintain their offset airfoil geometry for flow shifting.
Solution Approach 2:
The seal utilizes a flexible, convoluted structure that can conform to the relative positions of adjacent ducts. The flexible convolution design allows the seal to maintain contact and prevent leakage despite the offset configuration and thermal expansion, effectively mediating between the ducts without rigid constraints.
3Reliability
If convolution seals are added to accommodate thermal growth, then seal integrity is maintained, but device complexity increases
Solution Approach 1:
While the seal structure itself is complex, its dynamic convolution design allows it to accommodate thermal growth without requiring additional active control mechanisms. The seal's ability to flex and adapt to thermal cycles reduces the need for supplementary systems, balancing structural complexity with functional effectiveness.
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 convolution seals effectively prevent leakage and mixing by accommodating thermal expansion, ensuring a secure seal between transition ducts, thus enhancing the performance and efficiency of the turbine system by maintaining the integrity of airfoil surfaces.
Implementation Method 1
thermal expansion of the ducts can cause undesirable shifts in the ducts along or about various axes
Data Source
AI summary
A turbine system is disclosed. In one embodiment, the turbine system includes a transition duct. The transition duct includes an inlet, an outlet, and a passage extending between the inlet and the outlet and defining a longitudinal axis, a radial axis, and a tangential axis. The outlet of the transition duct is offset from the inlet along the longitudinal axis and the tangential axis. The transition duct further includes an interface feature for interfacing with an adjacent transition duct. The turbine system further includes a convolution seal contacting the interface feature to provide a seal between the interface feature and the adjacent transition duct.