Split-Ring Heatshield for Gas Turbine Diffuser Case Thermal Protection
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Solution Overview
Problem
Gas turbine engine diffuser cases experience thermal gradients that lead to stress, degradation, and misalignment of components due to high thermal loads, reducing operational life and efficiency.
Innovation Solution
A split-ring heatshield made from sheet metal or nickel alloy with locking elements and a mid-body portion that contacts the diffuser case, providing thermal protection and minimizing heat conduction through an air gap, is installed between the diffuser and turbine case flanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the diffuser case is directly coupled to the combustor, then the engine structure is simple, but thermal gradients cause stress, deformation, and degradation of the diffuser case
Solution Approach 1:
A heatshield is introduced as an intermediary component between the combustor and the diffuser case. The heatshield absorbs and blocks thermal radiation, preventing direct heat transfer to the diffuser case. This mediator protects the diffuser case from thermal gradients while maintaining the overall structural configuration.
Solution Approach 2:
The heatshield is designed as a replaceable, relatively simple component that can be easily installed and removed. Instead of designing a complex cooling system for the diffuser case, a simpler, sacrificial heatshield is used that protects the expensive diffuser case and can be replaced when degraded.
2Strength
If the diffuser case is designed with thick walls to withstand thermal loads, then structural strength is improved, but thermal gradients still cause stress and degradation over time
Solution Approach 1:
The heatshield serves as a protective intermediary that absorbs the thermal burden, allowing the diffuser case to be designed with optimized wall thickness rather than excessive thickness. This reduces thermal mass and thermal gradients while maintaining structural integrity.
3Loss of energy
If thermal protection is provided by insulating materials, then heat conduction is reduced, but the protection is insufficient against high thermal loads from the combustor
Solution Approach 1:
The heatshield utilizes oxidation of aluminum to form aluminum oxide, a phase transition that creates a dense, heat-resistant barrier. This chemical transformation provides superior thermal protection compared to simple physical insulation, blocking high thermal loads effectively.
Solution Approach 2:
The heatshield is made from aluminum alloy that forms aluminum oxide through oxidation. This creates a composite structure with the base metal providing structural integrity and the oxide layer providing thermal protection, combining the benefits of metal strength and ceramic insulation.
4Object-affected harmful factors
If a complete ring heatshield is used, then thermal protection is maximized, but installation and inspection become difficult
Solution Approach 1:
The heatshield is designed as a segmented C-shaped cross-section rather than a complete ring. This segmentation allows the heatshield to be installed by positioning it within the diffuser case and securing it with retainers, making installation and inspection straightforward while still providing effective thermal protection around the perimeter.
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 heatshield reduces thermal stresses and extends the operational life of gas turbine engine components by protecting them from excessive temperatures and preventing material degradation, while allowing for easy installation and inspection.
Implementation Method 1
configured to minimize heat conduction to the diffuser case
Implementation Method 2
A combustor of the combustor section is typically coupled to an engine case of the gas turbine engine. The engine case may include a diffuser case, which circumscribes the compressor section. The diffuser case and associated fittings may be subjected to relatively high temperatures due to heat convectively transferred from the combustor to the diffuser case.
Data Source
Figure 1
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AI summary
Heatshields (322; 400; 522) for installation within gas turbine engines are described. The heatshields include a metal body having a first end (402), a second end (404), a first side (410), and a second side (412), wherein the first side and the second side define parallel sides extending from the first end to the second end, an engagement portion (326; 414) formed along the first side and arranged to engage with a portion of a case, a shielding portion (330; 418) formed along the second side, and a mid-body portion (328; 416) extending between the engagement portion and the shielding portion and has an arcuate shape in cross-section. The metal body is configured to form a hoop, split-ring structure with the first end attached to the second end.