Labyrinth Seal Axial Element Stator Abradable
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Solution Overview
Problem
Current sealing solutions in gas turbine engines, such as labyrinth seals and baffle seals, fail to achieve sufficient fluidtightness due to air recirculation and thermal expansion issues, leading to reduced lifespan of turbine components.
Innovation Solution
The implementation of an elongate axial element on the turbine rotor and abradable material elements on the stator to form a labyrinth seal, positioned close to the air flow duct, with spurs designed to engage and vent overpressure, and optionally supported by a ring for optimal positioning and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If abradable elements are positioned at the outer portion of the annular annulus to form a labyrinth seal, then sealing effectiveness is improved, but thermal inertia increases and thermal expansion of stator vanes is reduced, leading to mechanical stresses and cracks
Solution Approach 1:
The invention repositions the abradable elements from the outer radial portion to the inner radial portion of the annular annulus, changing the spatial dimension of seal formation. This dimensional shift allows the seal to form closer to the rotor without extending the thermal mass of the stator structure, thereby maintaining sealing effectiveness while preserving stator vane thermal expansion characteristics and mechanical strength.
Solution Approach 2:
The invention applies abradable elements locally at the inner portion of the annular annulus where they are most effective for sealing, rather than extending them radially outward where they would add unnecessary thermal inertia. This localized application optimizes the sealing function while minimizing the negative thermal effects on stator vanes.
2Reliability
If sealing baffles are used upstream and downstream between stator and rotor, then some sealing is achieved, but fluidtightness is insufficient due to air recirculation vortices entering the cavities
Solution Approach 1:
The invention introduces abradable elements as an intermediary sealing mechanism that works in conjunction with the sealing baffles. These elements form a labyrinth seal that disrupts air recirculation vortices and prevents them from entering the cavities, thereby enhancing the overall sealing capability beyond what the baffles alone can achieve.
Solution Approach 2:
The sealing system combines multiple sealing mechanisms: sealing baffles made from structural materials and abradable elements made from softer, conformable materials. This composite sealing approach leverages the geometric blocking capability of the baffles and the conformal sealing capability of the abradable elements to achieve superior fluidtightness.
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
This configuration enhances fluidtightness and extends the lifespan of turbine components by creating a more effective axial seal near the air flow duct, reducing mechanical stresses and air recirculation.
Implementation Method 1
the lips of the labyrinth seal are driven in rotation while maintaining as little clearance as possible with respect to the abradable elements which remain stationary
Implementation Method 2
designed to engage with outer annular lamellar elements, known as lips, of an element of the rotor, arranged radially so as to form a labyrinth seal
Implementation Method 3
an upstream spur and a downstream spur, each defining a sealing baffle in, respectively, the upstream cavity and the downstream cavity delimited by the wall and the annular annulus
Implementation Method 4
their thermal inertia is considerable. This, in combination with the lower temperature to which they are exposed, acts counter to the thermal expansion of the stator vanes which are then subjected to substantial mechanical stresses
Data Source
AI summary
A turbine for a gas turbine engine comprising at least one turbine stator and one turbine rotor, said turbine stator comprising at least one inner annular platform, said inner platform comprising a radial wall delimiting at least one cavity between the turbine stator and the turbine rotor, wherein the turbine rotor comprises at least one elongate element positioned substantially axially and defining a sealing baffle in said cavity, and in that the turbine stator comprises at least one element made of abradable material designed to engage with said elongate element of the turbine rotor so as to form a labyrinth seal.