Variable Stiffness Diaphragm Seal for Gas Turbine Leakage
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Solution Overview
Problem
Conventional finger seals in gas turbine engines experience reduced effectiveness due to increased pressure differentials and centrifugal growth, leading to relative shifts in finger gaps and potential leakage across the seal, which can compromise engine performance and efficiency.
Innovation Solution
A sealing apparatus featuring diaphragm members with varying stiffnesses, where the sealing element includes at least two diaphragm members with different stiffnesses, positioned to prevent leakage by maintaining continuous overlapping contact and equalizing pressure loads across the seal, thereby reducing wear and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional finger seals are used with uniform diaphragm stiffness, then the seal structure is simple and easy to manufacture, but the pressure loads are not equalized across layers causing finger gap shifts and leakage
Solution Approach 1:
The patent applies local quality by varying the stiffness of individual diaphragm members within the sealing assembly. Specifically, inner diaphragm members have different stiffness characteristics than outer diaphragm members, allowing each layer to be optimized for its specific pressure loading conditions. This non-uniform stiffness distribution equalizes the pressure loads across all diaphragm layers, preventing finger gap shifts and maintaining sealing effectiveness without requiring a completely complex redesign of the entire seal structure.
Solution Approach 2:
The patent implements parameter changes by modifying the physical properties of the diaphragm members, specifically their stiffness characteristics. By changing the stiffness parameter of different diaphragm members (through variations in material properties, thickness, or geometric configuration), the system achieves equalized pressure loading across all layers. This parameter optimization allows the seal to maintain effectiveness under high pressure differentials while managing the complexity through targeted modifications rather than comprehensive redesign.
2Productivity
If engine speed is increased to improve efficiency, then engine performance improves, but pressure differential across the seal increases causing greater finger deflection and leakage
Solution Approach 1:
The patent addresses the high-speed operation challenge by applying local quality through non-uniform diaphragm stiffness distribution. Inner diaphragm members are designed with stiffness characteristics optimized for handling the higher pressure differentials that occur at elevated engine speeds, while outer members have different stiffness properties. This localized optimization allows the seal to maintain effectiveness under the increased pressure loads generated during high-efficiency engine operation, preventing finger gap shifts and leakage even when centrifugal and thermal growth effects are magnified.
Solution Approach 2:
The patent incorporates dynamics by designing the diaphragm members to dynamically respond to varying pressure differentials that occur during engine operation. The varying stiffness characteristics allow the diaphragm assembly to adapt its deformation behavior under different operating conditions, particularly under the high pressure differentials generated during high-speed operation. This dynamic response capability enables the seal to maintain effectiveness across a range of engine speeds and efficiency levels.
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 maintains a tight seal by equalizing pressure loads and reducing wear on diaphragm members, enhancing the sealing apparatus' performance and extending its usable life, while being simple and cost-effective for retrofitting into existing engines.
Implementation Method 1
the fingers restore themselves radially towards the rotating surface as it changes its size
Implementation Method 2
centrifugal and thermal growth of the rotating surface
Implementation Method 3
centrifugal and thermal growth of the rotating surface
Data Source
AI summary
Sealing apparatus and engine are provided. A sealing apparatus includes a first cover plate, a second cover plate spaced apart from the first cover plate, and a sealing element disposed between the first cover plate and the second cover plate and including at least two diaphragm members, wherein a first diaphragm member has a first stiffness and a second diaphragm member has a second stiffness that is different than the first stiffness. The sealing apparatus may be disposed in an engine.