Turbine Airfoil Cooling Hole Geometry to Prevent Flow Separation
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Solution Overview
Problem
Existing turbine airfoils face challenges in implementing effective film cooling due to inefficiencies in cooling hole designs, which affect their ability to withstand high-temperature combustion gases in gas turbines.
Innovation Solution
The turbine airfoil features a cooling hole design with an inner surface that includes a first inner surface defining an inner hole region, a second inner surface defining multiple spaced outer hole regions, and a third inner surface forming a connection hole region, with specific angles and configurations to enhance film cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple cooling hole design is used, then the structure is simple and easy to manufacture, but the film cooling effect is insufficient
Solution Approach 1:
The cooling hole is divided into multiple functional regions: an inner hole region for receiving cooling fluid, an outer hole region for discharging cooling fluid, and a connection hole region for transitioning between them. This segmentation allows each region to be optimized for its specific function, improving overall cooling effectiveness while maintaining manufacturing feasibility.
Solution Approach 2:
Different sections of the cooling hole are designed with different geometric characteristics. The inner hole region has a first cross-sectional area, the connection hole region has a second cross-sectional area that is larger, and the outer hole region has a third cross-sectional area. This local variation in geometry optimizes fluid flow characteristics at each location, enhancing film cooling performance.
2Reliability
If the cooling hole cross-sectional area is increased to improve cooling fluid distribution, then the cooling effect is enhanced, but the velocity loss increases and flow separation occurs
Solution Approach 1:
The connection hole region is designed with a curved inner surface that smoothly transitions between the inner hole region and the outer hole region. This curved geometry reduces flow separation and minimizes velocity loss by eliminating sharp corners and abrupt changes in flow direction, while still providing adequate cross-sectional area for effective cooling fluid distribution.
3Reliability
If multiple outer hole regions are spaced apart, then the film cooling coverage is improved, but the partition sections between them increase structural complexity
Solution Approach 1:
The outer hole region is divided into multiple spaced-apart openings, each contributing to different portions of the film cooling coverage. The partition sections between these openings are designed as integral parts of the airfoil structure, providing both structural support and flow management functions. This segmentation approach enhances cooling coverage while keeping the overall structure manufacturable.
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 designed cooling holes effectively distribute cooling fluid, maintaining momentum and preventing flow separation, thereby enhancing the film cooling effect and reducing velocity loss, thus improving the airfoil's resistance to high temperatures.
Implementation Method 1
a film cooling method is applied to cool the turbine nozzles, the turbine blades, or the like used for the gas turbine. The film cooling method refers to a method of forming a hole in a surface of the turbine blade or the like and then spraying compressed air through the hole to protect the surface of the turbine blade or the like exposed to a high-temperature combustion gas
Data Source
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AI summary
Disclosed is a turbine airfoil including an airfoil body including an outer wall configured to define an internal space, in which a cooling hole is formed in the outer wall and allows the internal space S and an external space of the airfoil body to communicate with each other. The inner surface of the outer wall, which defines the cooling hole, includes a first inner surface, and a second inner surface configured to define an outer hole region of the cooling hole H that communicates with the external space, in which the outer hole region is provided as a plurality of outer hole regions spaced apart from one another, and in which the outer wall includes a partition section provided between the two adjacent outer hole regions.