Turbine Flap Seal Gap Leakage Reduction
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Solution Overview
Problem
Gas turbines experience inefficiency due to leakage caused by misalignment and thermal expansion, which conventional flap seals fail to adequately address, especially at lower pressures and when mechanical springs are insufficient to close crescent-shaped gaps.
Innovation Solution
A sealing apparatus with a primary sealing plate and two connector portions, where the connector portions have a width less than the sealing portion, reducing stiffness and mass, and are designed to accommodate thermal expansion, ensuring complete sealing by engaging with structural components on either side of the gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single primary plate seal is used, then the structure is simple, but gaps must be left between plates to allow for movement and thermal expansion, resulting in significant leakage
Solution Approach 1:
The seal is divided into multiple primary sealing components (first and second primary sealing components) that work together with a sealing plate. Each component can move independently to accommodate thermal expansion while the sealing plate bridges the gap between them, eliminating the need for large gaps and reducing leakage.
Solution Approach 2:
The sealing plate acts as an intermediary element between the first and second primary sealing components. It fills the gap that would otherwise be necessary for thermal expansion accommodation, thereby preventing gas leakage while allowing the primary components to move freely.
2Loss of energy
If overlap plates are used to cover gaps between primary plates, then leakage is reduced, but the structure becomes more complex and requires additional springs to load the primary plate against adjacent components
Solution Approach 1:
The sealing plate is integrated with the primary sealing components to form a unified sealing system. The connector portions of the sealing plate connect to both primary sealing components, merging their functions into a single coordinated assembly that reduces leakage without requiring separate spring loading mechanisms.
Solution Approach 2:
The sealing plate performs multiple functions: it seals the gap between primary components, accommodates thermal expansion through its connector portions, and eliminates the need for separate spring loading systems. This multi-functionality reduces overall structural complexity while maintaining effective sealing.
3Device complexity
If the connector portions have the same width as the sealing portion, then the structure is simpler, but stress concentrations increase and the seal cannot accommodate movement as effectively
Solution Approach 1:
The sealing plate has varying width along its length: the connector portions are narrower than the sealing portion. This local variation in geometry concentrates material where sealing is most critical while reducing material in regions where flexibility and stress distribution are more important, optimizing both strength and adaptability.
Solution Approach 2:
The gradient in width creates a tapered or curved transition from the connector portions to the sealing portion. This gradual change in geometry reduces stress concentrations by avoiding sharp transitions, allowing the seal to accommodate movement more effectively while maintaining structural integrity.
4Loss of energy
If mechanical springs are used to close crescent-shaped gaps, then sealing is improved at high pressure, but the force required is insufficient at lower pressures and the structure becomes more complex
Solution Approach 1:
The sealing plate with its gradient width structure is designed to be self-actuating. The differential width creates inherent mechanical advantage that allows the seal to automatically adjust and maintain contact across a wide pressure range without requiring external spring loading or complex actuation systems.
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 seals gaps between structural components in gas turbines, particularly at lower pressures, reducing the force required for sealing and improving performance by accommodating movement and thermal expansion, while minimizing stress concentrations and leakage.
Implementation Method 1
a first of said connector portions has a first connector which is fixed to one of said structural components and a second of said connector portions has a second connector which is slidably engaged with one of said structural components
Data Source
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AI summary
A sealing plate (100) for sealing a gap (3) between two primary sealing plates (1) is provided. The sealing plate has a sealing portion (102) and a connector portion (104, 106), wherein the sealing portion has a width (w1) which is greater than a width (w2) of the connector portion. An apparatus for sealing a gap between two structural components (2, 4) of a turbine (10), the apparatus including a plurality of primary sealing components (1), and at least one sealing plate (100) is also provided, as is a turbine having a plurality of structural components (2, 4) with a gap between said structural components, wherein the gap is sealed by a plurality of sealing components, the sealing components comprising a plurality of primary sealing components (1) and at least one sealing plate (100).