Turbine Blade Tip Sealing via Segmented Pockets and Cooling
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Solution Overview
Problem
High-temperature operating environments in gas turbines lead to differential thermal growth, making efficient sealing between turbine blade tips and stationary components challenging, resulting in efficiency losses due to fluid leakage.
Innovation Solution
The design incorporates a tip portion with a perimeter wall and trench structures that create pressure-side and suction-side pockets, enhanced by split cooling holes to direct cooling air and reduce operating temperatures, thereby improving sealing efficiency and reducing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional tip seal arrangements are used in high-temperature gas turbine environments, then the sealing structure is simple, but differential thermal growth causes sealing inefficiency and fluid leakage
Solution Approach 1:
The tip seal is divided into multiple functional segments: a perimeter wall defining a sealing chamber, trench structures creating pressure-side and suction-side pockets, and multiple cooling holes distributed throughout the tip portion. This segmentation allows each region to address specific thermal and sealing challenges independently, improving overall sealing efficiency while managing thermal growth differentials.
Solution Approach 2:
Cooling air acts as an intermediary substance that enters through cooling holes, flows through the sealing chamber and pockets, and exits through the leading and trailing edges. This cooling air mediates between the hot high-pressure fluid and the seal structures, reducing thermal growth differentials and maintaining sealing effectiveness without requiring complex active control systems.
2Temperature
If cooling structures are added to reduce thermal growth, then sealing efficiency improves, but device complexity increases
Solution Approach 1:
The cooling function is merged with the sealing structure itself. Cooling holes are integrated into the perimeter wall and trench structures, allowing cooling air to flow through the same pathways that define the sealing chambers and pockets. This merging eliminates separate cooling systems while achieving effective temperature control of the seal arrangement.
Solution Approach 2:
The tip seal structure is self-cooling through the integrated cooling holes that allow cooling air to pass through the perimeter wall and trench structures. The structure uses its own geometry to channel cooling air where it is most needed to counteract thermal growth, without requiring external cooling systems or complex active control mechanisms.
3Loss of substance
If tip seal structures are made more complex to prevent leakage, then sealing performance improves, but manufacturing difficulty increases
Solution Approach 1:
The sealing structure incorporates local variations in geometry: the perimeter wall extends at specific locations to form pockets, trenches are positioned at particular angles and depths, and cooling holes are distributed non-uniformly. These localized structural modifications create effective sealing zones without requiring complex manufacturing processes throughout the entire blade, as each feature can be addressed independently during fabrication.
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 reduces fluid leakage across the turbine blade tips by creating vortices that enhance sealing and directs cooling air to critical areas, improving the overall efficiency and reducing the risk of damage from high temperatures.
Implementation Method 1
The solution effectively reduces fluid leakage across the turbine blade tips by creating vortices that enhance sealing
Implementation Method 2
enhanced by split cooling holes to direct cooling air and reduce operating temperatures
Data Source
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AI summary
A turbine blade (200) includes a root (202) arranged to attach the turbine blade (200) to a rotor (122) and a vane extending in a radial direction from the root (202) to a tip surface (302). The vane includes a leading edge (208), a trailing edge (210), a pressure-side surface (212), and a suction-side surface (214) that cooperate to define a vane perimeter (216). A perimeter wall (304) extends radially from the tip surface (302) and surrounds a portion of the vane perimeter (216). A first trench wall (306) extends across the tip surface (302) and cooperates with the perimeter wall (304) to substantially enclose a pressure-side pocket (316) and a second trench wall (308) extends across the tip surface (302) and cooperates with the perimeter wall (304) to substantially enclose a suction-side pocket (314).