Labyrinth Seal With Variable Cell Density for Corrugated Wiper Tightness
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Solution Overview
Problem
Labyrinth seals in turbomachines experience degraded tightness due to the corrugation and non-zero axial extent of the wiper's radial end, leading to reduced sealing effectiveness across various flight phases.
Innovation Solution
A labyrinth seal design featuring a rotor element with an annular wiper having a corrugated outer radial end and an abradable element with varying cell densities in distinct annular areas, each optimized to face the wiper during different flight phases, enhancing the seal's tightness and abradability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the wiper's radial end has corrugation and non-zero axial extent, then the wiper can accommodate thermal expansion and mechanical flexibility, but the sealing tightness is degraded
Solution Approach 1:
The abradable element is designed with variable cell density: higher density in the first annular area facing the wiper's radial end to improve tightness, and lower density in the second annular area to maintain abradability. This local differentiation allows the seal to simultaneously achieve both tightness and adaptability to thermal expansion.
Solution Approach 2:
The cell density parameter of the abradable element is varied across different radial positions. The first annular area has a higher cell density (first density) while the second annular area has a lower cell density (second density), allowing optimization of both sealing tightness and material removal characteristics in different zones.
2Reliability
If the abradable element has high cell density, then the sealing tightness is improved, but the abradability is reduced
Solution Approach 1:
The abradable element is designed with variable cell density: higher density in the first annular area facing the wiper's radial end to improve tightness, and lower density in the second annular area to maintain abradability. This local differentiation allows the seal to simultaneously achieve both tightness and adaptability to thermal expansion.
Solution Approach 2:
The abradable element is segmented into at least two distinct annular areas with different cell densities. The first annular area (higher density) handles the sealing function, while the second annular area (lower density) maintains abradability, allowing both functions to coexist without compromising either.
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 design maintains improved sealing performance across varying flight phases by adjusting cell density and distribution to counteract the corrugation, balancing tightness and abradability.
Implementation Method 1
The presence of the cells 20 contributes to creating turbulence in the gas flow. This creates turbulence in the gas flow which generates pressure drops and thus improves the tightness of the seal.
Implementation Method 2
The abradable elements 7 aim at protecting the wipers 5 from the risk of wear by contact with the stator element 3 which surrounds them.
Data Source
AI summary
The present invention relates to a labyrinth seal for a turbine engine, in particular of an aircraft, comprising a rotor element and a stator element extending around the rotor element, the rotor element being suitable for rotating relative to the stator element about an axis of rotation having an axial direction (DA), the rotor element comprising an annular lip having an outer radial end extending towards an abradable element (57) carried by the stator element, the outer radial end of the annular lip having a corrugation in the axial direction (DA) and a non-zero axial expanse (E5) associated with the corrugation, the abradable element (57) comprising a plurality of cells (50a, 50b) arranged adjacent to one another along the axial direction (DA) and an ortho-radial direction (O), the cells (50a, 50b) comprising walls which extend in an essentially radial direction, the cells being distributed with a first cell density in a first densified annular zone (Z51) of the abradable element, said densified annular zone (Z51) being located opposite the radial end of the lip, said densified annular zone having an axial expanse less than or equal to the axial expanse of the outer radial end of the lip, the cells being distributed according to a reference density of cells outside said first zone, the first density being greater than the reference density.