Transition Duct Assembly Floating Seal Thermal Expansion
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Solution Overview
Problem
The connection and sealing of off-axis transition ducts in turbomachines are prone to thermal expansion issues, leading to stresses and potential failure due to undesirable shifts, which existing technologies have not adequately addressed.
Innovation Solution
The implementation of a turbomachine design featuring a plurality of transition ducts in an annular array with offset outlets, a support ring assembly, mechanical fasteners, and seals to accommodate thermal growth and ensure secure connection and sealing, eliminating the need for first stage nozzles and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If off-axis transition ducts are used to eliminate first stage nozzles, then efficiency and power output are improved, but thermal expansion causes undesirable shifts and stresses leading to potential failure
Solution Approach 1:
The transition duct assembly incorporates a floating seal mechanism that allows dynamic adjustment and movement to accommodate thermal expansion. The seal can move axially and radially within the transition duct, maintaining sealing contact while adapting to dimensional changes caused by thermal effects, thus preventing stress concentration and connection failure.
Solution Approach 2:
The patent employs materials with different thermal expansion coefficients in the transition duct assembly. The seal and support structures are designed with parameters that change in response to temperature variations, allowing the assembly to expand and contract uniformly without generating excessive stresses or undesirable shifts during operation.
2Productivity
If off-axis transition ducts are used to eliminate first stage nozzles, then efficiency is improved, but connection and sealing becomes more complex
Solution Approach 1:
The transition duct assembly is divided into modular components including the transition duct, support ring assembly, and floating seal as separate but interconnected elements. This segmentation allows for simplified manufacturing, assembly, and maintenance of the sealing system while maintaining the off-axis configuration that eliminates the need for first stage nozzles.
Solution Approach 2:
The floating seal acts as an intermediary element between the transition duct and the turbine section. It provides the sealing function while accommodating relative movements and thermal expansions, simplifying the overall connection design by decoupling the sealing requirement from the structural support requirements.
3Device complexity
If transition ducts are shifted off-axis, then first stage nozzles can be eliminated, but thermal expansion causes stresses and strains within the ducts
Solution Approach 1:
The transition duct assembly is explicitly designed to accommodate thermal expansion through its floating seal mechanism and support ring structure. The design allows the duct to expand and contract along the axial and radial directions without generating excessive stresses or strains that would compromise structural integrity during turbine operation.
Solution Approach 2:
The floating seal and support ring assembly are designed with built-in compliance features that cushion against thermal stresses before they can cause damage. The seal's ability to move and deform elastically provides a cushioning effect that protects the rigid duct structure from stress concentration and potential failure.
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 design effectively manages thermal expansion and stress issues, ensuring reliable operation and increased efficiency by allowing for the elimination of first stage nozzles, thus improving the overall performance and longevity of turbomachines.
Implementation Method 1
thermal expansion of the ducts can cause undesirable shifts in the ducts along or about various axes. These shifts can cause stresses and strains within the ducts, and may cause the ducts to fail
Data Source
Figure 1~2
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AI summary
A turbomachine (10) includes a plurality of transition ducts (50) disposed in a generally annular array and including a first transition duct (130) and a second transition duct (132). Each of the plurality of transition ducts (50) includes an inlet (52), an outlet (54), and a passage (56) extending between the inlet (52, 162) and the outlet (54, 164) and defining a longitudinal axis (90), a radial axis (94), and a tangential axis (92), the outlet (54) of each of the plurality of transition ducts (50) offset from the inlet (52) along the longitudinal axis (90) and the tangential axis (92). The turbomachine further includes a support ring assembly downstream of the plurality of transition ducts (50) along a hot gas path (104), and a plurality of mechanical fasteners (200) connecting at least one transition duct (50) of the plurality of transition ducts (50) to the support ring assembly.