Angled Flange Ladder Seal for Gas Turbine Leakage
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Solution Overview
Problem
Gas turbine engines experience fluid leakage through gaps between adjacent airfoil platforms, leading to undesirable pressure loss due to the inefficiency of existing ladder seal systems.
Innovation Solution
A ladder seal system with angled flanges and flexible design to accommodate tolerance variations and alignment issues between airfoil platforms, featuring asymmetric upstream and downstream flanges and barbell-shaped openings for airfoil roots, providing a sealing mechanism that adapts to the shape of the airfoil platforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rigid ladder seal systems are used, then manufacturing and installation are simpler, but sealing effectiveness deteriorates due to inability to accommodate tolerance variations and alignment issues
Solution Approach 1:
The ladder seal system employs flexible seal segments that can dynamically adjust their position and shape to accommodate manufacturing tolerances and alignment variations between airfoil platforms. The segments are designed to flex and conform to the actual geometry of the platforms, transforming a rigid static sealing approach into a dynamic adaptive one that maintains reliable sealing despite dimensional variations.
Solution Approach 2:
The seal system utilizes changes in the physical state and geometry of the seal segments through flexing and deformation. The segments can change their shape parameters to match the actual platform geometry, allowing the sealing interface to adapt to manufacturing variations without requiring precise dimensional control during assembly.
2Reliability
If angled flanges with flexible design are implemented, then sealing efficiency improves by accommodating tolerance variations, but manufacturing precision requirements worsen due to asymmetric upstream and downstream flanges
Solution Approach 1:
The ladder seal segments feature asymmetric upstream and downstream flanges with different angles optimized for their respective flow directions. This asymmetric design allows each flange to be specifically tailored to its local sealing requirements, improving overall sealing efficiency while the flexibility of the segments compensates for variations in manufacturing precision.
Solution Approach 2:
The seal segments are constructed as flexible structures that can bend and conform to the actual platform geometry. This flexibility compensates for manufacturing tolerances and alignment issues, allowing the asymmetric flange design to achieve high sealing efficiency without requiring extremely tight manufacturing precision.
3Loss of energy
If ladder seals are positioned between rotor disks and blade platforms, then fluid leakage is reduced, but pressure loss worsens due to gaps between adjacent blade platforms
Solution Approach 1:
The sealing system divides the sealing function into multiple discrete ladder seal segments positioned at different locations between the rotor disk and blade platforms. Each segment addresses leakage at its specific location, and the collective arrangement of segments provides comprehensive sealing coverage, reducing overall fluid leakage and associated pressure losses more effectively than a single continuous seal.
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 seal system effectively reduces fluid leakage by flexing to fit the airfoil platforms, enhancing sealing efficiency and accommodating manufacturing and operational variations, thereby minimizing pressure loss in gas turbine engines.
Implementation Method 1
The seal system effectively reduces fluid leakage by flexing to fit the airfoil platforms
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A sealing system for a gas turbine engine (10) includes an arcuate first ladder seal segment (60) having a central portion (60-1), an upstream flange (60-2) adjoining the central portion, a downstream flange (60-3) adjoining the central portion opposite the upstream flange, and a plurality of openings (60-4). The upstream flange is arranged at an angle θυ greater than 0° and less than 90° relative to a given tangential plane, and the downstream flange is arranged at an angle θο greater than 0° and less than 90° relative to the given tangential plane.