Heat Shield Retention via Anti-Rotation Flange
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Solution Overview
Problem
In high-pressure turbines of gas turbine engines, existing heat shields for tangential on-board injectors face challenges with thermal mechanical fatigue and require mechanical fasteners that add weight and do not scale well with reduced engine core sizes, leading to inefficiencies in cooling airflow and potential mixing of hot combustion gases with cooling air.
Innovation Solution
A heat shield design that is retained by abutment with the stator and tangential on-board injector, utilizing an anti-rotation flange for circumferential constraint, eliminating the need for mechanical fasteners and allowing for reduced weight and space usage, while maintaining effective thermal protection and airflow separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical fasteners are used to secure the heat shield, then the heat shield is reliably retained, but the weight and device complexity increase
Solution Approach 1:
The patent replaces mechanical fasteners (screws, bolts, rivets) with a mechanical interference fit system. The heat shield includes an anti-rotation flange that engages with a corresponding feature on the tangential on-board injector, creating a fastenerless retention system that eliminates additional fastener components while maintaining secure attachment
Solution Approach 2:
The patent extracts and eliminates the mechanical fasteners from the heat shield assembly, retaining only the essential heat shield component with integrated anti-rotation features. This removal of unnecessary components reduces weight and simplifies the overall device while maintaining functional retention through the anti-rotation flange design
2Reliability
If mechanical fasteners are used to secure the heat shield, then the heat shield is reliably retained, but the device complexity and space requirements increase
Solution Approach 1:
The patent substitutes complex mechanical fastening systems with a simplified anti-rotation flange design. The flange integrates directly into the heat shield structure and engages with a corresponding feature on the tangential on-board injector, eliminating the need for separate fasteners and reducing assembly complexity
Solution Approach 2:
The patent merges the retention function into the heat shield structure itself through the anti-rotation flange. The flange is an integral part of the heat shield that provides both thermal protection and mechanical retention, combining multiple functions into a single component rather than requiring separate fasteners
3Weight of moving object
If the heat shield design uses abutment retention without fasteners, then weight and complexity are reduced, but thermal mechanical fatigue resistance may be compromised
Solution Approach 1:
The patent employs abutment retention where the heat shield abuts against the stator and tangential on-board injector, creating a composite structural system that distributes thermal and mechanical loads across multiple contact surfaces. This abutment system provides reliable retention without mechanical fasteners by utilizing the structural integrity of the surrounding components
Solution Approach 2:
The patent applies local quality through the anti-rotation flange design, which concentrates the anti-rotation function at a specific location while maintaining overall weight reduction. The flange provides localized structural reinforcement exactly where rotational forces are applied, rather than requiring fasteners throughout the entire heat shield assembly
4Weight of moving object
If the heat shield is retained by abutment with stator and injector, then weight is reduced, but the circumferential constraint must be achieved differently
Solution Approach 1:
The patent employs asymmetry in the anti-rotation flange design, where the flange features an asymmetric profile that engages with a corresponding asymmetric feature on the tangential on-board injector. This asymmetric engagement provides effective circumferential constraint against rotational forces while maintaining a simple, fastenerless structure that does not require symmetric fastener patterns
Data Source
Figure 1
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Figure 4~5
AI summary
A high pressure turbine (20') includes a stator (38'), a rotor (60), a tangential on-board injector (36'), and a heat shield (58). The rotor (60) is located downstream of the stator (38') and the tangential on-board injector (36') directs cooling air to the rotor. The heat shield (58) is retained by abutment with the stator and the tangential on-board injector.