Partial Cooling Hood for Turbine Transition Piece
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Solution Overview
Problem
Gas turbine engines face efficiency reduction and increased exhaust emissions due to the pressure drop and heated air recirculation caused by impingement sleeves used for cooling transition pieces in combustors.
Innovation Solution
A partial cooling hood is employed around the transition piece, capturing compressed airflow and directing it radially outward to reduce pressure drop and mix with cooler air before entering the combustor, thereby enhancing cooling efficiency and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an impingement sleeve completely surrounds the transition piece to cool it, then the transition piece cooling effectiveness is improved, but the pressure drop increases significantly reducing engine efficiency
Solution Approach 1:
The cooling system is segmented into multiple zones: a cooling hood that partially surrounds the transition piece rather than completely enclosing it, with strategic openings positioned to direct cooling airflow to specific high-temperature areas while maintaining overall flow efficiency
Solution Approach 2:
Cooling resources are concentrated locally at the cooling hood where compressed air is directly applied to the transition piece surface, providing targeted cooling effectiveness while avoiding the need for complete surrounding enclosures that would cause excessive pressure drop
2Temperature
If an impingement sleeve directs compressed air through orifices to cool the transition piece, then the cooling effect is improved, but exhaust emissions increase due to heated air recirculation into the combustor
Solution Approach 1:
The harmful heated air is extracted and redirected away from the combustor inlet by positioning the cooling hood and its openings to channel the heated airflow in a direction that prevents recirculation, thereby reducing exhaust emissions while maintaining cooling effectiveness
Solution Approach 2:
The heated air that would normally be harmful to emissions is converted into a beneficial cooling flow by directing it through the cooling hood openings to cool the transition piece, then exhausting it away from the combustor, thus transforming a potential harm into a useful cooling mechanism
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 solution significantly reduces pressure drop and exhaust emissions by improving airflow dynamics and mixing with cooler air, leading to increased efficiency and extended transition piece life.
Implementation Method 1
The compressed airflow is captured and held against a second side of the transition piece by the cooling hood. The cooling hood then ejecting the compressed airflow in an outward radial direction away from the transition piece as it convectively cools the transition piece
Implementation Method 2
the cooling hood enables the heated airflow to mix with cooler airflow prior to entry into the combustion chamber
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An air cooling hood (82) offset from an exterior of the transition piece (58) to define an air cooling passage (87) between the air cooling hood (82) and the exterior of the transition piece (58), wherein the air cooling hood (82) comprises a plurality of air outlets (94) disposed along the exterior of the transition piece (58), and the plurality of air outlets (94) is configured to expel an airflow from the air cooling passage (87) away from the exterior of the transition piece (58).