Turbine Frame Assembly Using Heat Shield for Cost Reduction
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Solution Overview
Problem
Gas turbine engine load bearing cases, such as turbine exhaust cases, face challenges in withstanding elevated temperatures while minimizing costs without sacrificing performance, as existing designs often require expensive, high-temperature materials for both the structural frame and fairing, and there is a need to protect the frame from radiant heat exposure.
Innovation Solution
A structural case assembly comprising a frame and a fairing with a heat shield, where the frame is made from a material with a temperature limit below the engine's operating point, the fairing from a material with a higher temperature limit, and a heat shield is placed between them to inhibit radiant heat transfer, blocking all line-of-sight to prevent heat from reaching the frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If expensive high-temperature materials are used for both the frame and fairing, then the structure can withstand elevated temperatures, but the manufacturing cost increases significantly
Solution Approach 1:
The patent applies local quality by using different materials for different components based on their specific thermal requirements. The fairing, which is directly exposed to hot gases, is made from high-temperature resistant material, while the frame, which is protected by the heat shield, can use cost-effective lower-temperature materials. This localized material selection optimizes both temperature resistance and manufacturing cost.
Solution Approach 2:
The heat shield acts as an intermediary component between the fairing and the frame. It blocks radiant heat transfer from the fairing to the frame, allowing the frame to be constructed from less expensive materials that cannot withstand direct exposure to engine operating temperatures, thereby resolving the contradiction between temperature resistance and manufacturing cost.
2Ease of manufacture
If the frame is made from cost-effective materials with lower temperature limits, then manufacturing cost is reduced, but the frame cannot withstand the engine operating temperatures
Solution Approach 1:
The heat shield serves as a protective intermediary that isolates the cost-effective frame material from the high-temperature environment. By blocking radiant heat transfer, it enables the use of economical materials in the frame while maintaining the ability to withstand engine operating temperatures through the combined protection system.
Solution Approach 2:
The heat shield provides beforehand cushioning by preemptively blocking radiant heat before it can reach the frame. This protective measure is implemented in advance, allowing the frame to be made from cost-effective materials that would otherwise be unable to withstand the thermal environment, thus resolving the contradiction between manufacturing cost and temperature resistance.
3Ease of manufacture
If a heat shield is added between the frame and fairing, then radiant heat transfer is inhibited and frame material costs are reduced, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the thermal protection function into separate components: the fairing that directly faces the hot gases and the heat shield that blocks radiant heat to the frame. This segmentation allows each component to be optimized independently and enables the use of cost-effective materials in the frame, outweighing the increased structural complexity.
4Strength
If the fairing is designed with a ring-strut-ring configuration, then structural strength is improved, but the amount of material required increases
Solution Approach 1:
The fairing employs a composite structural design combining rings and struts to achieve high structural strength. This composite configuration optimizes the distribution of material, providing enhanced strength and rigidity to withstand thermal and mechanical loads while minimizing the total quantity of material required compared to solid structures.
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 allows for the use of cost-effective materials for the frame while ensuring the fairing and heat shield can withstand higher temperatures, providing thermal protection and reducing material costs, thereby achieving performance and cost savings.
Implementation Method 1
a heat shield disposed between the frame and the fairing to inhibit radiant heat transfer between the frame and the fairing
Data Source
AI summary
A structural case assembly comprises a frame, fairing and heat shield. The frame is fabricated from a material having a temperature limit below an operating point of a gas turbine engine, and comprises an outer ring, an inner ring and a plurality of struts extending therebetween to define a flow path. The fairing is fabricated from a material having a temperature limit above the operating point of the gas turbine engine, and comprises a ring-strut-ring structure that lines the flow path. The heat shield is disposed between the frame and the fairing to inhibit radiant heat transfer therebetween. The heat shield may block all line-of-sight between the fairing and the frame. The frame may be produced from CA-6NM alloy. A method for designing a turbine case structure includes selecting a frame material having a temperature limit below the operating point of an engine.