Turbine Diffuser Stress Reduction via Curved Spinning and Segmentation
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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 diffuser section is improved by manufacturing a desired curvature using a spinning process, incorporating a circumferential groove in the inner barrel, a circumferential lap joint, and discrete brackets to reduce stress and enhance mechanical integrity, including the use of poles to couple the aft and forward plates and support the diffuser section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional diffuser sections are used with straight or simple curved walls, then the structure is simple and easy to manufacture, but high hoop stresses occur due to thermal expansion and gas pressure
Solution Approach 1:
The patent applies curved wall sections with continuous curvature in the diffuser design. The curved geometry allows the structure to better accommodate thermal expansion and reduce stress concentrations compared to straight walls, while maintaining manufacturing feasibility through controlled curvature radii
Solution Approach 2:
The diffuser is divided into multiple wall sections (first wall section, second wall section, third wall section) with different curvature characteristics. This segmentation allows each section to be optimized for specific stress conditions while simplifying manufacturing of individual segments that can be assembled together
2Strength
If the diffuser walls are made rigid to withstand high temperatures and pressures, then structural strength is improved, but thermal expansion is constrained leading to increased hoop stresses
Solution Approach 1:
The diffuser structure incorporates dynamic characteristics through curved walls that can flex and accommodate thermal expansion. The continuous curvature allows the structure to adapt to thermal loading conditions while maintaining structural integrity, transforming the rigid structure into a more compliant system
Solution Approach 2:
The patent changes geometric parameters of the diffuser walls, specifically implementing continuous curvature with controlled radii. This parameter modification allows the structure to better handle thermal expansion and pressure loads, reducing hoop stresses while maintaining strength
3Strength
If axial segments with continuous curvature are used to reduce stresses, then mechanical integrity is improved, but manufacturing complexity increases
Solution Approach 1:
The diffuser is constructed from multiple axial wall segments that can be manufactured separately and assembled. Each segment contains continuous curvature designed to reduce stresses, while the segmentation allows for simpler manufacturing of individual pieces compared to creating one large complex curved structure
Solution Approach 2:
Each axial wall segment incorporates continuous curvature with specific radius constraints. This curvature design reduces stress concentrations while maintaining manufacturability through controlled geometric parameters that can be achieved with standard fabrication processes
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 mechanical improvements significantly reduce hoop stresses and improve the mechanical integrity of the diffuser section, enhancing its reliability and reducing wear by allowing for axial movement and thermal expansion, thereby extending its lifespan.
Implementation Method 1
manufacturing a desired curvature of the diffuser section through utilization of a spinning process
Implementation Method 2
allowing for axial movement and thermal expansion, thereby extending its lifespan
Data Source
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AI summary
A system includes a diffuser configured to receive exhaust gas from a turbine. The diffuser includes an outer barrel (50), an inner barrel (48), a seal interface, an outer aft plate (62), an inner aft plate, and poles. An upstream end of the outer barrel (50) includes an upstream lip interfacing with a downstream lip of an outer wall (106) of the turbine outlet, forming a lap joint. The outer barrel (50) includes a plurality of axial segments disposed between the upstream end of the outer barrel (50) and the outer aft plate (62), and the axial segments. The inner barrel (48) includes a plurality of axial segments disposed between an upstream end (102) of the inner barrel (48) and the seal interface. The seal interface includes a groove configured to receive the inner aft plate. The poles are spaced about the turbine axis (76) and couple an end of the outer aft plate (62) to an end of the inner aft plate (63).