CMC Airfoil Cooling via Embedded Environmental Barrier Tubes
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Solution Overview
Problem
Design and manufacture of gas turbine engine airfoils with composite components pose challenges due to high-temperature resistance requirements and the need for effective cooling, as existing materials and cooling methods are inadequate in preventing recession and maintaining structural integrity.
Innovation Solution
An airfoil comprising a ceramic matrix composite body with embedded hollow tubes made from environmental barrier material, providing a cooling passageway for fluid communication between the inner cooling cavity and the gas path, while avoiding fiber fracturing and using a different material for the tubes to prevent ceramic matrix infiltration and enhance thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials and cooling methods are used in airfoils, then manufacturing is simpler, but high-temperature resistance and structural integrity deteriorate under combustion conditions
Solution Approach 1:
The airfoil employs a ceramic matrix composite (CMC) structure combining ceramic reinforcement fibers with a ceramic matrix material, providing superior high-temperature resistance and structural integrity. Environmental barrier coating tubes are integrated within the CMC structure to protect against chemical degradation from combustion products, enabling the airfoil to withstand extreme temperatures while maintaining manufacturability through a structured multi-material composite approach.
Solution Approach 2:
Environmental barrier coating tubes are embedded within the ceramic matrix composite airfoil structure, creating a nested configuration where the tubes are positioned inside the CMC material. This nesting allows the tubes to provide internal protection against chemical degradation while the outer CMC structure provides mechanical strength and thermal resistance, solving both durability and manufacturing challenges.
2Reliability
If cooling passages are added to airfoils to maintain structural integrity, then high-temperature resistance improves, but device complexity increases
Solution Approach 1:
The environmental barrier coating tubes serve multiple functions simultaneously: they provide chemical protection against combustion products, define cooling passage geometry, and enable fluid communication between the cooling cavity and gas path. This multi-functionality reduces overall system complexity by combining what would otherwise be separate components into a single integrated element.
Solution Approach 2:
The environmental barrier coating tubes act as intermediaries that facilitate cooling fluid flow from the cooling cavity through the airfoil to the gas path. By serving as the structural boundary and flow conduit simultaneously, the tubes simplify the cooling system architecture while maintaining effective thermal management and structural integrity.
3Reliability
If environmental barrier material tubes are embedded in ceramic fibers, then recession prevention improves, but fiber fracturing may occur during insertion
Solution Approach 1:
The environmental barrier coating tubes are inserted into the ceramic reinforcement fiber preform before the ceramic matrix infiltration process. This preliminary action allows the tubes to be positioned correctly while the fibers are still flexible and can be parted around the tubes, preventing fiber fracturing. After infiltration, the fibers harden in their parted configuration, maintaining both fiber integrity and tube positioning.
Solution Approach 2:
The ceramic reinforcement fibers are parted locally around the environmental barrier coating tubes during insertion, creating a localized adjustment in fiber arrangement. This local quality change allows the fibers to accommodate the tubes without fracturing, while maintaining their load-bearing capacity in other regions of the airfoil structure.
4Temperature
If cooling fluid is directed through the airfoil to cool the gas path, then temperature control improves, but heat transfer efficiency may be reduced by poor thermal conductivity
Solution Approach 1:
The environmental barrier coating tubes are made from material with high thermal conductivity to enhance heat transfer from the hot gas path through the tube walls to the cooling fluid inside. This parameter change in material selection optimizes the thermal performance of the cooling system, improving cooling effectiveness while minimizing energy loss through the airfoil structure.
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 effectively cools the airfoil by directing cooling fluid from the cavity to the gas path, preventing recession and maintaining structural integrity, with optimized cooling passage designs and materials that enhance heat transfer and reduce interaction losses.
Implementation Method 1
The hollow tube is made from an environmental barrier material and extends through the body between the inner surface and the outer surface to provide fluid communication between the cooling cavity and a gas path environment surrounding the outside surface
Implementation Method 2
The solution effectively cools the airfoil by directing cooling fluid from the cavity to the gas path, preventing recession and maintaining structural integrity, with optimized cooling passage designs and materials that enhance heat transfer
Implementation Method 3
The tube is made from an environmental barrier material... using a different material for the tubes to prevent ceramic matrix infiltration and enhance thermal conductivity
Data Source
AI summary
An airfoil for a gas turbine engine is made from ceramic matrix composite materials. The airfoil has an inner surface that defines a cooling cavity in the body and an outer surface that defines a leading edge, a trailing edge, a pressure side, and a suction side of the body. The airfoil is formed with a hollow tube that extends through the body to define a cooling passage that extends from the cooling cavity through the airfoil to provide fluid communication between the cooling cavity and a gas path environment surrounding the airfoil.