Pre-Diffuser Assembly With Full-Hoop Interface for Thermal Stress Relief
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Solution Overview
Problem
Pre-diffusers in gas turbine engines experience reduced operational life due to local discontinuities and stress risers caused by thermal gradients and structural features for anti-rotation, axial retention, and centrality, leading to inefficiencies and reduced performance.
Innovation Solution
A pre-diffuser design incorporating a hot fairing structure with an exit guide vane ring, featuring anti-rotation interfaces, radial flanges, and a clamp ring, along with a ring-strut-ring structure that includes hollow struts and diffusion passage ducts, to manage thermal gradients and stress, ensuring alignment and thermal control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If structural features for anti-rotation, axial retention, and centrality are added to the pre-diffuser, then reliability and alignment are improved, but device complexity and stress concentration increase
Solution Approach 1:
The patent combines multiple structural features (anti-rotation tabs, axial retention elements, centrality features) into an integrated pre-diffuser assembly design where the hot fairing structure and exit guide vane ring work together as a unified system. This merging approach reduces the number of separate components and interfaces, thereby reducing stress concentration points while maintaining all necessary functional features for reliability.
2Temperature
If the pre-diffuser is exposed to large thermal gradients, then operational capability is maintained, but stress risers and reduced operational life occur
Solution Approach 1:
The patent addresses thermal gradient effects by carefully selecting materials with appropriate thermal expansion coefficients and designing the hot fairing structure with optimized wall thicknesses and cooling passage geometries. These parameter changes allow the structure to withstand large thermal gradients while minimizing thermal stress accumulation, thereby extending operational life despite continuous exposure to high temperature variations.
3Stress or pressure
If sealing means and radial flanges are added to manage thermal gradients, then thermal stress is reduced, but device complexity increases
Solution Approach 1:
The patent introduces sealing elements and radial flanges as intermediary components that facilitate controlled thermal expansion and stress distribution. These intermediaries act as buffers between the hot fairing structure and the exit guide vane ring, allowing relative movement and stress relief while maintaining structural integrity and sealing, thereby reducing thermal stress without requiring complete redesign of the primary structure.
Data Source
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AI summary
A pre-diffuser (100) for a gas turbine engine (20) includes an exit guide vane ring (104) having a multiple of exit guide vanes (108) defined around an engine longitudinal axis (A), a hot fairing structure (102) adjacent to the exit guide vane ring (10) to define a multiple of diffusion passages (120) around the engine longitudinal axis (A), an outer radial interface (190) between a radial outer surface of the hot fairing structure (102) and the exit guide vane ring (104), the outer radial interface (190) being a full hoop structure, and an anti-rotation feature (130) between the hot fairing structure (120) and the exit guide vane ring (104), the anti-rotation feature (130) inboard of the multiple of diffusion passages (120).