Transition Piece Cooling Rings for Gas Turbine Temperature Control
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Solution Overview
Problem
Current cooling methods for gas turbines, such as Thermal Barrier Coatings (TBCs) and effusion cooling, fail to effectively manage high temperatures in transition pieces without compromising engine performance or increasing emissions, and require additional maintenance.
Innovation Solution
The implementation of a transition piece design featuring a cooling ring with impingement and film holes that direct cool air through a gas channel to cool the inner transition piece, reducing pressure drop and emissions while enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If effusion cooling is used for the transition piece, then cooling performance is improved, but combustion air leaks through the transition piece reducing headend air and increasing emissions
Solution Approach 1:
The transition piece incorporates an effusion cooling structure with porous material that allows controlled leakage of combustion air through the transition piece for cooling purposes. The porous structure enables cooling air to pass through while minimizing the harmful effects of air leakage on engine performance and emissions.
Solution Approach 2:
The transition piece uses a composite structure combining different materials and cooling mechanisms (effusion cooling with porous material, flow sleeve, and TBC coating) to achieve effective cooling while managing the trade-offs between cooling performance, pressure drop, and emissions.
2Temperature
If a flow sleeve is used for cooling the transition piece, then cooling performance is improved, but combustor pressure drop increases lowering engine performance
Solution Approach 1:
The flow sleeve is designed with localized cooling features including specific hole patterns and geometries that provide cooling where most needed while minimizing interference with the main gas flow. This local quality approach reduces the overall pressure drop impact while maintaining effective cooling at critical hot spots.
Solution Approach 2:
The transition piece combines the flow sleeve structure with TBC coating and effusion cooling elements to create a composite cooling system that distributes the cooling function across multiple mechanisms, reducing the burden on any single component and minimizing overall pressure drop.
3Temperature
If TBC coating is applied to the inner surface of the transition piece, then thermal protection is improved, but shielding from hot gas is insufficient at temperatures exceeding metal melting temperature
Solution Approach 1:
The thermal protection is segmented into multiple layers and mechanisms: TBC coating on the inner surface, effusion cooling structure with porous material, and flow sleeve with cooling holes. This segmentation provides redundant protection pathways, ensuring that if one layer is insufficient, others compensate to maintain reliable thermal protection.
Solution Approach 2:
The transition piece employs a composite thermal protection system combining TBC coating material with metal matrix and porous cooling structures. This composite approach creates a multi-functional barrier that provides both thermal insulation and active cooling, ensuring reliability even at temperatures exceeding standard metal melting points.
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 provides efficient cooling of the transition piece, minimizing combustor pressure drop, reducing emissions, and improving maintenance accessibility, while maintaining high turbine inlet temperature for efficient gas turbine operation.
Implementation Method 1
a cooling ring disposed on the inner transition piece and providing a cavity; an impingement hole connecting the cavity to an outside of the inner transition piece
Implementation Method 2
a film hole connecting the cavity to the gas channel
Data Source
AI summary
A transition piece can include: an inner transition piece providing a gas channel; a plurality of cooling rings disposed on the inner transition piece; a plurality of film holes formed on the inner transition piece; and a plurality of impingement holes formed on the plurality of cooling rings, wherein the plurality of film holes are arranged to correspond to the plurality of cooling rings. Each of the plurality of cooling rings includes a cavity such that the plurality of film holes connect the cavity to the gas channel and the plurality of impingement holes connect the cavity to an outside of the inner transition piece.