Sinusoidal Strip Seal for Gas Turbine Resonance Control
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Solution Overview
Problem
Strip seals in gas turbines face premature failure due to high stress loading from misaligned grooved recesses and resonance induced by pressure pulsations from rotating and non-rotating components, leading to leakage and fatigue issues.
Innovation Solution
A strip seal design featuring a sinusoidal curvilinear pressure face that contacts the sealing face at multiple points, preventing localized movement and resonance, with the shape configured to match the operational excitation frequency of the components, ensuring the seal remains firmly in place and resilient to fatigue failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the strip seal is made thinner to increase flexibility for accommodating groove misalignment, then the strip seal can better fit into misaligned grooved recesses, but the strip seal becomes more susceptible to resonance and fatigue failure from pressure pulsations
Solution Approach 1:
The pressure face is given a sinusoidal curvilinear shape instead of a flat surface. This curved geometry provides multiple contact points with the grooved recess surfaces, creating distributed support that reduces localized stress concentrations while maintaining overall flexibility of the thin strip seal structure.
Solution Approach 2:
The strip seal has non-uniform thickness with a thicker pressure face portion and a thinner sealing portion. The thicker pressure face provides structural rigidity to resist pressure pulsations and fatigue, while the thinner sealing portion maintains flexibility for accommodating groove misalignment and achieving proper seal contact.
2Reliability
If clamping projections are added to suppress resonance from pressure pulsations, then fatigue failure is reduced, but the small surface area of projections causes wear due to high oscillations and vibrations
Solution Approach 1:
The sinusoidal curvilinear pressure face replaces discrete clamping projections with a continuous curved surface that contacts the grooved recess at multiple points along its length. This distributes the contact area and reduces localized wear while maintaining the clamping force necessary to suppress resonance from pressure pulsations.
3Reliability
If the strip seal is made tightly fitting into grooved recesses, then sealing effectiveness is improved, but high stress loading occurs due to manufacturing tolerances and thermal expansion causing premature failure
Solution Approach 1:
The strip seal design changes the geometric parameters of the pressure face to a sinusoidal curvilinear shape with specific amplitude and wavelength. This creates multiple contact points that accommodate variations in groove positioning due to manufacturing tolerances and thermal expansion, maintaining sealing effectiveness while distributing stress to prevent premature failure.
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 sinusoidal curvilinear shape of the pressure face effectively reduces localized movement and resonance, enhancing the strip seal's durability and preventing premature fatigue failure, ensuring a reliable gas-tight seal across varying pressure conditions.
Implementation Method 1
parts of the strip seal that are not biased against faces of the grooved recess or otherwise retained can be induced into periodic resonance leading to premature fatigue failure of the strip seal
Implementation Method 2
During operation the strip seals are exposed to periodic pressure pulsations caused by various rotating components within the gas turbine
Implementation Method 3
In operation the pressure differential across the seal, due to the flexibility of the strip seal, forces the strip seal against one surface of the grooved recess so by effecting the seal
Implementation Method 4
strip seals can be made thinner than the height of the grooved recesses and flexible orthogonal to the strip seal length
Data Source
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AI summary
A strip seal (60) and method of configuration thereof for sealing portions (66 and 68) of components of a gas turbine (100) exposed to pressure pulsations. The strip seal (60) has a sealing face (70) that is configured to follow the contours of first portions (66) of the components. The strip seal (60) further has a pressure face (72) that has a sinusoidal curvilinear shape with respect to the sealing face (70). The pressure face (72) is configured to prevent localized movement of strip seal (60) by configuring pressure face (72) on its first side to contact sealing face (70) at a plurality of points, on its second side to contact second portions (68) of the components at a plurality of points.