Thermally Decoupled Transition Piece Heat Shield
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Solution Overview
Problem
Turbomachines face challenges in protecting transition pieces from the high thermal loads of combustion gases, leading to potential cracking and reduced operational life due to direct exposure.
Innovation Solution
A thermally decoupled transition piece design featuring a heat shield member with offset dilution passages and orifices, which creates a flow region to direct cooling airflow and shield the inner wall from combustion gases, reducing thermal exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transition piece is directly exposed to combustion gases, then the structure remains simple, but the transition piece suffers from thermal loading leading to cracking and reduced operational life
Solution Approach 1:
A heat shield member is introduced as an intermediary component between the combustion gases and the transition piece inner wall. The heat shield includes a body with a first surface facing the combustion gases and a second surface facing the flow passage, creating a thermal barrier that protects the transition piece from direct thermal exposure while maintaining the structural integrity and operational life of the component.
Solution Approach 2:
The transition piece is segmented into functional zones by introducing the heat shield member, which divides the internal space into a flow passage region and a flow region between the heat shield and the transition piece wall. This segmentation allows different parts of the structure to serve different thermal and functional purposes, with the heat shield bearing the thermal load while the transition piece maintains its structural function.
2Temperature
If cooling airflow is directed through dilution passages, then thermal exposure is reduced, but the flow dynamics become more complex due to offset passage configuration
Solution Approach 1:
The dilution passages are offset from the dilution orifices, creating a three-dimensional flow path that moves cooling airflow from one spatial dimension (through the orifice) to another dimension (through the offset passage). This dimensional transition allows the cooling air to effectively shield the heat shield member and transition piece inner wall by creating a protective flow pattern that addresses thermal exposure from multiple angles.
Solution Approach 2:
Different regions of the heat shield member are assigned different functions: the first surface receives cooling airflow to protect against combustion gases, the dilution passages are strategically offset to specific locations to maximize cooling efficiency, and the second surface directs cooled flow into the combustion flow passage. This local differentiation of functions optimizes thermal protection while managing flow dynamics.
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 effectively mitigates cracking and extends the operational life of transition pieces by thermally decoupling the inner wall from combustion gases, enhancing serviceability and maintenance while maintaining efficient energy conversion.
Implementation Method 1
The heat shield member is spaced from the at least one wall of the transition piece defining a flow region between the at least one wall and the second surface
Implementation Method 2
The cooling airflow is passed through at least one dilution orifice formed in the transition piece. The dilution orifice is fluidly connected to the flow cavity. Finally, the method includes guiding the cooling airflow through at least one dilution passage formed in the at least one heat shield member
Data Source
AI summary
A turbomachine includes a plurality of injection nozzles arranged in a can-annular array and a transition piece including at least one wall that defines a combustion flow passage. A dilution orifice is formed in the at least one wall of the transition piece. The dilution orifice guides dilution gases to the combustion flow passage. A heat shield member is mounted to the at least one wall of the transition piece in the combustion flow passage. The heat shield member includes a body having a first surface and an opposing second surface through which extends a dilution passage. The dilution passage is off-set from the dilution orifice. The heat shield member is spaced from the at least one wall of the transition piece defining a flow region between the at least one wall and the second surface.