Ceramic Composite Inter-Turbine Duct Thermal Expansion
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Solution Overview
Problem
Conventional inter-turbine ducts in gas turbine engines face challenges withstanding high operating temperatures and require additional cooling, which increases weight and complexity, and are not easily retrofittable or cost-effective.
Innovation Solution
The inter-turbine duct is designed with ceramic composite materials for the annular walls and vanes, featuring slots and openings to accommodate thermal expansion, allowing for higher temperature resistance and simplified manufacturing, enabling it to be retrofitted into existing engines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional inter-turbine ducts are constructed with metal alloys and extensive cooling systems to withstand high temperatures, then thermal resistance is improved, but weight increases and device complexity increases
Solution Approach 1:
The inter-turbine duct is constructed using ceramic matrix composite (CMC) materials, specifically silicon carbide fiber-reinforced silicon carbide matrix (SiC/SiC), which provide superior high-temperature resistance compared to conventional metal alloys. This composite material enables the duct to withstand higher operating temperatures without requiring extensive cooling systems, thereby reducing both weight and complexity while maintaining thermal resistance.
Solution Approach 2:
The invention extracts and eliminates the need for extensive cooling systems and insulation blankets that are required in conventional metal alloy ducts. By using CMC materials with inherent high-temperature resistance, the cooling air flow requirements are dramatically reduced, removing the need for complex cooling channels, bypass plenum integration, and insulation layers, thus reducing weight and simplifying the overall structure.
2Strength
If conventional inter-turbine ducts are constructed as single-piece cast structures from high-temperature materials, then strength is improved, but manufacturing complexity increases and cost increases
Solution Approach 1:
The CMC inter-turbine duct is manufactured using segmented processes, specifically tape laying followed by chemical vapor infiltration (CVI). The duct is constructed by laying up preform tapes in a mold to create the basic structure, then infiltrating the porous preform with silicon carbide matrix material through chemical vapor deposition. This segmented manufacturing approach allows for easier fabrication and assembly compared to single-piece casting of metal alloys, while maintaining the required strength properties.
3Temperature
If cooling air flow from bypass plenum is used to cool the inter-turbine duct, then temperature control is improved, but device complexity increases and weight increases
Solution Approach 1:
The use of CMC materials with inherent high-temperature resistance eliminates the need for complex active cooling systems. The material's ability to withstand high temperatures without structural degradation means that minimal or no cooling air flow is required, dramatically simplifying the cooling system design and reducing weight associated with cooling channels, sensors, and control mechanisms.
4Temperature
If ceramic composite materials are used for the inter-turbine duct, then thermal resistance is improved and weight is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The manufacturing process is segmented into tape laying and CVI infiltration steps, with each step having controlled precision requirements. The tape laying process allows for flexible shaping and positioning of the preform, while the CVI process uniformly infiltrates the matrix material. This segmentation distributes the precision requirements across multiple controllable steps rather than requiring high precision in a single casting operation.
Solution Approach 2:
The manufacturing process utilizes parameter changes during CVI infiltration, controlling temperature, pressure, and chemical vapor composition to achieve uniform matrix deposition. By adjusting these parameters, the process can accommodate variations in preform geometry and achieve consistent final properties, reducing the impact of initial preform dimensional variations on the final product precision.
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 solution provides improved thermal resistance and reduced weight, eliminating the need for extensive cooling systems and simplifying manufacturing, while maintaining structural integrity and aerodynamic performance.
Implementation Method 1
featuring slots and openings to accommodate thermal expansion
Data Source
AI summary
An inter-turbine duct includes a first annular wall with a ceramic composite material and including a first plurality of layers and a second plurality of layers, the first plurality of layers including a slot extending therethrough; and a first vane with a material of a metal alloy or a ceramic material. The first vane has a first end and a flange extending through the slot with the flange extending away from the first end and being retained between the first plurality of layers and the second plurality of layers of the first annular wall.