Transition Piece In-Wall Flow Path Segmentation for Gas Turbine Cooling
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Solution Overview
Problem
The existing transition pieces in gas turbine engines face challenges with temperature gradients and stresses due to long in-wall flow paths, leading to reduced cooling effectiveness and potential material failure, especially where shape changes are significant.
Innovation Solution
The transition piece is designed with multiple in-wall flow path groups that partially overlap in the flow direction, with larger overlap areas corresponding to larger shape changes, to reduce temperature gradients and stress concentrations, and includes dilution holes to enhance cooling and combustion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the length of in-wall flow paths is increased to improve cooling coverage, then the cooling area is expanded, but the temperature gradient in the plate material increases and cooling effectiveness decreases
Solution Approach 1:
The transition piece is divided into multiple sections along the flow direction, with each section containing independent in-wall flow paths. This segmentation allows the total cooling area to be distributed across multiple shorter flow path segments rather than relying on a single long flow path, thereby reducing temperature gradients while maintaining comprehensive cooling coverage.
2Duration of action of stationary object
If the length of in-wall flow paths is increased to extend cooling reach, then more areas are cooled, but the cooling effectiveness lowers due to air heating
Solution Approach 1:
The cooling system is segmented into multiple shorter in-wall flow paths arranged in series along the flow direction. Each segment provides effective cooling with compressed air that has not been excessively heated, ensuring reliable cooling performance throughout the entire transition piece length without the effectiveness degradation that would result from a single long flow path.
3Stability of the object's composition
If multiple in-wall flow path groups are added to reduce temperature gradients, then cooling uniformity improves, but device complexity increases
Solution Approach 1:
The transition piece is segmented into multiple sections with in-wall flow paths in each section, creating a modular structure that improves temperature distribution uniformity. This segmented approach achieves better thermal stability while keeping each individual flow path simple and manageable, balancing uniformity improvement with structural complexity.
4Productivity
If the transition piece shape changes significantly from circular inlet to square outlet, then flow distribution improves, but stress concentration increases
Solution Approach 1:
Different sections of the transition piece are given different local characteristics. The inlet section maintains a circular shape optimized for compressor flow, while the outlet section transitions to a square shape optimized for turbine flow distribution. This local quality differentiation allows each section to be optimized for its specific function while managing stress concentrations through gradual transition 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 design extends the lifetime of the transition piece by effectively managing temperature gradients and stresses, improving cooling efficiency, and maintaining combustion stability even under varying operational conditions.
Implementation Method 1
Part of compressed air for combustion flows into the in-wall flow paths, and after cooling a transition piece, spouts out to an inner combustion gas flow path of the transition piece
Data Source
AI summary
Provided is a transition piece including a first flow path group formed by arraying a plurality of in-wall flow paths that extend inside a plate material forming the transition piece and a second flow path group that is positioned on a side closer to a combustor liner than the first flow path group is. Each in-wall flow path in the first flow path group and the second flow path group has an inlet that is located at one end section in a flow direction of a combustion gas and that faces a compressed air main flow path, and an outlet that is located at the other end section in the flow direction of the combustion gas and that faces a combustion gas flow path. An installation area of the first flow path group and an installation area of the second flow path group partially overlap in the flow direction of the combustion gas by a predetermined overlap amount, and the overlap amount is set large for a portion where a shape change of the transition piece is relatively large, as compared with a portion where the shape change of the transition piece is relatively small.