Thermally Isolated Pre-Diffuser Fairing for Gas Turbine Thermal Stress
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Solution Overview
Problem
Gas turbine engines face thermal expansion issues due to temperature differences between hot, compressed air and cooler components in the pre-diffuser section, leading to unequal thermal expansion and potential stress on components.
Innovation Solution
The design incorporates a pre-diffuser fairing with a first and second portion forming a pre-diffuser passageway, featuring radially inward and outward plates that engage with the compressor section, and an offset distance to create an insulating region between the hot air and cooler components, reducing thermal stresses by providing a thermal barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pre-diffuser section is positioned just downstream of the compressor to guide and condition the compressed air, then the velocity of compressed air is reduced and pressure is increased, but the temperature difference between the hot compressed air and cooler surrounding air causes unequal thermal expansion of the components
Solution Approach 1:
A thermal barrier is introduced as an intermediary component between the hot compressed air and the cooler pre-diffuser section components. This thermal barrier mediates the thermal interaction, allowing the pre-diffuser to perform its air conditioning function while protecting the structural components from excessive thermal stress and unequal thermal expansion.
2Productivity
If the pre-diffuser section is exposed to hot compressed air to perform its function, then the air velocity is reduced and pressure is increased, but the components experience unequal thermal expansion due to temperature differences
Solution Approach 1:
The thermal barrier serves as a protective intermediary that allows the pre-diffuser section to maintain exposure to hot compressed air for effective diffuser function, while simultaneously protecting the structural components from excessive thermal stress that would compromise their strength.
3Manufacturing precision
If the pre-diffuser section components are in direct contact with hot compressed air, then the air conditioning is effective, but the temperature difference causes unequal thermal expansion
Solution Approach 1:
The thermal barrier acts as a mediating layer that permits the pre-diffuser to maintain precise flow conditioning by being positioned in the hot compressed air flow, while the barrier itself protects the downstream components from thermal exposure, thereby maintaining their dimensional stability.
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 configuration reduces thermal stresses on struts and the inner wall by acting as a thermal barrier, maintaining desired flow characteristics and accommodating variable strut lengths, thereby enhancing the durability and efficiency of the gas turbine engine.
Implementation Method 1
The design incorporates a pre-diffuser fairing with a first and second portion forming a pre-diffuser passageway, featuring radially inward and outward plates that engage with the compressor section, and an offset distance to create an insulating region between the hot air and cooler components, reducing thermal stresses by providing a thermal barrier.
Data Source
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AI summary
The present invention relates to a pre-diffuser fairing (400; 500; 600) for a gas turbine engine (20) , the pre-diffuser fairing (400; 500; 600) including a first side wall (410; 510), said first wall comprising a first radially inward portion (412) and a first radially outward portion (414). The pre-diffuser further comprises a second side wall (416; 516), having a second radially inward portion (418) and a second radially outward portion (420). The first side wall (410; 510) and the second side wall (416; 516) are spaced apart to form a cavity (407) configured to receive a strut The first and second side walls may further comprise an aft end stop (422, 424) for abutting against an inner diffuser case (328). This pre-diffuser fairing allows to accommodate differential thermal dilatation of the inner diffuser case.