Transition Duct Aft End Cooling Channels
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Solution Overview
Problem
Existing gas turbine transition ducts without an integral or attached aft frame pose challenges in cooling the aft end, as conventional cooling techniques rely on the aft frame for cooling geometry, which is not applicable in such configurations.
Innovation Solution
The implementation of cooling channels on the exterior surface of the aft end of the transition duct, covered by a closure band with a seal, to form passageways for forced convection and potential impingement cooling, allowing direct cooling of the duct.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling techniques using aft frame with controlled seal leakage and small cooling holes are used, then cooling is effective for ducts with aft frame, but cooling cannot be achieved for ducts without aft frame
Solution Approach 1:
The cooling system is segmented into multiple independent cooling channels formed on the exterior surface of the tubular body at the aft end. These channels divide the cooling function into discrete pathways, allowing cooling air to be distributed effectively across the aft end surface without requiring an aft frame structure.
Solution Approach 2:
The cooling approach transitions from the traditional internal aft frame structure to an external surface-based cooling system. Cooling channels are formed on the exterior surface of the tubular body, representing a dimensional shift from internal to external cooling geometry, enabling cooling of ducts without aft frame.
2Temperature
If cooling channels are formed on the exterior surface of the tubular body, then direct cooling of the aft end is achieved, but the cooling channels need to be covered and sealed
Solution Approach 1:
The closure band and seal are merged into a single integrated component. The closure band surrounds the aft end and incorporates a seal that engages with the cooling channel openings, combining the functions of channel coverage and sealing in one element, thereby reducing overall structural complexity.
Solution Approach 2:
A seal (potentially a flexible sealing element) is incorporated into the closure band to engage with the cooling channel openings. This flexible sealing mechanism provides effective sealing without requiring complex rigid sealing structures, simplifying the overall design.
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 effectively cools the aft end of transition ducts without an aft frame by creating a network of cooling channels and passageways that utilize compressor discharge air or separate cooling air sources, enhancing heat transfer and preventing leakage.
Implementation Method 1
forced convection and potentially impingement cooling are used as a means to directly cool a transition duct
Implementation Method 2
forced convection and potentially impingement cooling are used as a means to directly cool a transition duct
Data Source
AI summary
A transition duct for a gas turbine includes a tubular body having a forward end and an aft end; a plurality of cooling channels formed on an exterior surface of the tubular body at the aft end; a closure band surrounding the aft end, covering at least a portion of the cooling channels; and a seal attached to the closure band, surrounding the aft end of the tubular body.