Airfoil Trailing Edge Cooling Circuit for Lower Thermal Stress
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Solution Overview
Problem
Traditional trailing edge regions of turbomachine airfoils experience higher thermal stresses due to direct thermal conduction between the pressure and suction sides, leading to undesired thermal stresses on pins and reduced structural integrity, necessitating an improved cooling circuit that redistributes and reduces operational stresses without using pin banks.
Innovation Solution
The airfoil features a trailing edge cooling circuit with separate pressure side and suction side channels arranged in a trussed structure, where each channel is fluidly isolated and defined by shared walls, distributing stress and providing convective cooling through independent geometry customization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pin banks are used to connect pressure side and suction side walls, then structural support is provided, but thermal conduction between sides causes undesired thermal stresses
Solution Approach 1:
The cooling circuit is segmented into separate pressure side channels and suction side channels that are fluidly isolated from each other. This segmentation prevents thermal conduction between the sides while maintaining structural support, as the channels are defined by shared walls rather than discrete pins.
Solution Approach 2:
Shared walls serve as intermediary structures between the pressure side and suction side channels. These shared walls provide the necessary structural support and thermal isolation, replacing the pin bank function while preventing direct thermal conduction paths.
2Temperature
If pin banks are used for cooling, then cooling function is achieved, but pin structures are weak and experience high thermal stresses
Solution Approach 1:
The cooling function is segmented into separate pressure side channels and suction side channels, eliminating the need for pins that connect the sides. Each channel is independently defined by shared walls, distributing the thermal and structural loads more effectively throughout the trailing edge region.
Solution Approach 2:
The trailing edge region utilizes a composite channel structure where multiple channels and shared walls work together as an integrated system. This composite approach distributes stresses across the entire structure rather than concentrating them on individual pin elements.
3Temperature
If direct thermal conduction paths exist between pressure and suction sides, then heat transfer occurs, but thermal stresses concentrate on connection points
Solution Approach 1:
The cooling circuit is segmented into fluidly isolated pressure side and suction side channels, eliminating direct thermal conduction paths between the sides. Heat transfer occurs independently within each channel, preventing stress concentration at connection points.
Solution Approach 2:
Each channel is designed with local geometry optimized for its specific cooling requirements. The shared walls provide localized structural support where needed, allowing the structure to adapt to local thermal and mechanical conditions without creating stress concentrations.
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 effectively reduces thermal stresses and enhances the structural integrity of the trailing edge region by distributing thermal loads, thereby increasing the hardware life of the airfoil.
Implementation Method 1
air, typically bleed air from the compressor section, is forced through internal cooling passages within the airfoil and then discharged through cooling holes at the airfoil surface to transfer heat from the hot gas path component
Implementation Method 2
heat is conductively transferred from the pressure side to the suction side
Data Source
AI summary
An airfoil includes a leading edge, a trailing edge, and a pressure side wall and a suction side wall each extending between the leading edge and the trailing edge. The pressure side wall and the suction side wall define a main body region and a trailing edge region. The main body region extends from the leading edge to the trailing edge region and defines an upstream plenum. The trailing edge region extends from the main body region to the trailing edge. The trailing edge region defines pressure side channels and suction side channels in fluid communication with the upstream plenum and arranged in a trussed structure to reduce stress in the trailing edge region. The pressure side channels are disposed adjacent the pressure side wall, and the suction side channels are disposed adjacent the suction side wall.