Turbine Airfoil Trailing Edge Cooling via Segmented Diffusing Ducts
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Solution Overview
Problem
Current cooling technologies for turbine airfoils face challenges in effectively cooling the trailing edge, particularly in low cooling flow applications, where cast slots are limited by manufacturing constraints and film holes offer less uniform and less effective cooling due to restricted inclination angles and ejection positions.
Innovation Solution
An airfoil design featuring a central interior cavity with a row of triangular pedestals at the trailing edge, where diffusing ducts allow cooling flow to converge and exit through a common slot, ensuring uniform cooling and maintaining a backflow pressure margin, even in low flow applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cast slots are used for trailing edge cooling, then cooling effectiveness is improved, but the solution is restricted to large cooling flow applications due to manufacturing constraints
Solution Approach 1:
The diffusing duct is segmented into multiple sections along the flow direction, with each section having a specific expansion ratio. This segmentation allows the cooling flow to be progressively expanded and controlled, enabling effective cooling in both low and large cooling flow applications while maintaining the benefits of cast slot geometry.
2Adaptability or versatility
If film holes are used for low cooling flow applications, then the backflow pressure margin is maintained, but the cooling effectiveness and uniformity are reduced
Solution Approach 1:
The invention transitions from two-dimensional film hole geometry to a three-dimensional diffusing duct structure. The diffusing duct provides volumetric cooling flow distribution rather than surface-level film cooling, achieving both low flow adaptability and high cooling effectiveness through its expanded geometric configuration.
3Reliability
If the cooling flow is ejected closer to the trailing edge, then heat removal capability is improved, but the backflow pressure margin is reduced
Solution Approach 1:
The diffusing duct incorporates variable geometric parameters including expansion ratio, length, and cross-sectional area changes along the flow direction. By adjusting these parameters, the cooling flow can be ejected closer to the trailing edge for improved heat removal while the diffusing action maintains adequate backflow pressure margin through controlled expansion.
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 enhances cooling effectiveness by ensuring the cooling flow reaches closer to the trailing edge, providing a more uniform cooling profile and maintaining backflow margin, thus effectively managing heat removal across the airfoil span.
Implementation Method 1
diffusing ducts which allow the passage of the cooling flow from the central cavity of the airfoil towards outside the airfoil
Implementation Method 2
As the cooling flow passes through the passageways from the airfoil, heat is transferred from the turbine airfoil surfaces to the cooling fluid
Data Source
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AI summary
The present invention belongs to the technical field of turbines airfoils, and more particularly to the cooling at the trailing edge of turbines airfoils. In particular, the present invention proposes an airfoil (10) dealing with the use of a specific cooling configuration at the trailing edge (1) of the airfoil for low and large cooling flow applications.