Gas Turbine Diffuser Poles Reduce Hoop Stress
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Solution Overview
Problem
Traditional diffuser sections in gas turbine engines experience high stresses due to high temperatures and exhaust gases, leading to increased wear and reduced mechanical integrity.
Innovation Solution
The implementation of a diffuser section design featuring a curved shape formed by a spinning process, with a plurality of poles, a circumferential groove, and discrete brackets to reduce stress and improve mechanical integrity, including a circumferential lap joint and discrete brackets to facilitate movement and support, thereby alleviating stress and enhancing structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional diffuser section is used, then the structure is simple, but high stresses occur due to high temperatures and exhaust gases
Solution Approach 1:
The diffuser section is divided into multiple segments including an outer barrel, an inner barrel, an outer aft plate, an inner aft plate, and multiple poles. This segmentation allows each component to independently handle thermal expansion and stress, preventing catastrophic failure and improving overall mechanical integrity under high temperature conditions.
2Strength
If the diffuser section is made more robust to withstand high stresses, then strength improves, but weight and complexity increase
Solution Approach 1:
The diffuser section employs thin-walled barrel structures with integrated circumferential grooves that provide flexibility to accommodate thermal expansion. The outer and inner barrels are designed with optimized wall thicknesses that maintain structural strength while minimizing weight, allowing the diffuser to withstand high stresses without excessive mass.
3Stability of the object's composition
If the diffuser section is rigid to maintain structural stability, then strength improves, but thermal expansion causes stress
Solution Approach 1:
The diffuser section incorporates dynamic features including circumferential grooves in the barrels and a lap joint between the outer and inner aft plates. These features enable controlled movement and flexibility, allowing the structure to adapt to thermal expansion while maintaining overall stability. The poles provide support while permitting the necessary degrees of freedom for thermal deformation.
Solution Approach 2:
The design explicitly accounts for thermal expansion by incorporating circumferential grooves that allow the barrels to expand radially, and a lap joint that permits relative movement between the outer and inner aft plates. This dedicated accommodation of thermal expansion reduces hoop stress while maintaining structural integrity under high temperature operation.
4Reliability
If traditional diffuser design is used, then manufacturing is simple, but wear increases due to high stresses
Solution Approach 1:
The segmented design with separate outer and inner barrels, aft plates, and poles allows each component to be manufactured independently using standard fabrication processes. This modularity improves reliability by enabling easier replacement of worn components without replacing the entire diffuser assembly, while keeping manufacturing complexity manageable through the use of conventional manufacturing techniques for each segment.
Data Source
AI summary
A system includes a diffuser section comprising an outer barrel, an outer aft plate, an inner barrel, an inner aft plate, and a plurality of poles, where the outer aft plate is disposed at a downstream end of the outer barrel, the inner aft plate is disposed at a downstream end of the inner barrel, the outer barrel and the inner barrel are disposed about a turbine axis, the diffuser section receives an exhaust gas from a gas turbine, the plurality of poles is circumferentially spaced about the turbine axis, and each pole of the plurality of poles couples a downstream end of the outer aft plate to a downstream end of the inner aft plate.