Quick Disengaging Field Joint for Gas Turbine Exhaust
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Solution Overview
Problem
The disassembly and reassembly of heat-insulating duct work in gas turbine engines pose challenges due to thermal stresses and increased maintenance time, particularly with existing hot and cold flange designs that expose components to high temperatures, leading to fatigue and safety hazards.
Innovation Solution
A quick disengaging field joint design featuring mirrored stepped ends on joint liners with high-temperature stainless steel, anchored by fasteners and retainer clips, allows for thermal growth without introducing stresses, enabling efficient disassembly and reassembly without direct exposure to hot exhaust gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hot flange design is used, then the flange can be directly exposed to hot exhaust gas, but thermal stresses cause cracks and fatigue in the flanges and bolts
Solution Approach 1:
The exhaust system is divided into separate components (liner, insulation, shell, flange) that can be independently disassembled. The liner is segmented from the shell, allowing the flange to remain on the liner while the shell is removed, enabling external disassembly without exposing the flange to thermal stress.
Solution Approach 2:
The liner acts as an intermediary between the hot exhaust gas and the flange. By allowing the liner to remain attached to the flange during shell removal, the liner protects the flange from direct thermal exposure while still enabling the necessary disassembly operations.
2Reliability
If cold flange design with internal liner system is used, then the flanges are protected from high temperature exhaust gas, but assembly and disassembly requires work both inside and outside the exhaust system housing
Solution Approach 1:
The complex internal liner system of conventional cold flange designs is extracted and replaced with a simpler approach. The liner is made removable and can be detached from the shell, allowing disassembly to be performed entirely from the external side without requiring internal work or scaffolding.
Solution Approach 2:
The system transitions from a fixed internal liner configuration to a dynamic, removable liner configuration. The liner can be detached and reattached as needed, providing flexibility in maintenance operations and eliminating the need for permanent internal structures.
3Ease of manufacture
If conventional field joints are used, then components can be connected, but cracks and distortions develop due to thermal cycling
Solution Approach 1:
The thermal parameters of the joint are changed by decoupling the flange from the hot gas path. The flange operates at lower temperatures while the liner absorbs the thermal exposure, fundamentally changing the thermal regime of the joint to prevent thermal fatigue and distortion.
Solution Approach 2:
The joint system uses composite construction with different materials optimized for different functions: the liner uses heat-resistant materials to withstand thermal exposure, while the flange uses structural materials optimized for mechanical strength at lower temperatures, creating a functionally graded composite system.
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 reduces maintenance time, minimizes thermal stress, and enhances safety by allowing external disassembly and reassembly of gas turbine engine components without exposing flanges to high temperatures, thereby extending component life and preventing gas leaks.
Implementation Method 1
allows for thermal growth without introducing stresses
Data Source
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AI summary
A quick disengaging field joint connects a first component (28a) of an exhaust system (16) of a gas turbine engine (10) to a second component (28b) of the exhaust system. The field joint includes a pair of opposed stepped liners (30,32) connected via exterior-facing connecting flanges (38,39). The field joints can be disassembled entirely from outside the exhaust housing (10) without requiring access to the interior of the exhaust housing (16).