Axially Compact Pressurized Seal for Turbine Engines
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Solution Overview
Problem
Existing seal technologies in gas turbine engines, such as carbon seals and labyrinth seals, face inefficiencies due to excessive clearance gaps leading to air and lubricant leakage, as well as contamination ingress, which increase weight, mechanical complexity, and reduce performance.
Innovation Solution
A dual labyrinth seal assembly with overlapping outer and inner seals and an intermediate plenum pressurized with compressed gas, optimized with minimal clearance gaps and durable materials like metal fins and heat-tolerant plastic runners, ensures effective sealing and contamination prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon seals are used for sealing between stationary bearing housings and rotating shafts, then sealing performance is improved, but weight and mechanical complexity increase
Solution Approach 1:
The patent replaces carbon seals with a labyrinth seal system that uses compressed air pressure and geometric structure instead of mechanical contact. The labyrinth seal uses alternating stationary and rotating elements to create a tortuous path for gas flow, eliminating the need for carbon sealing materials while reducing weight and complexity.
Solution Approach 2:
The patent employs compressed air pressure within the bearing housing to achieve sealing functionality. By maintaining positive pressure in the bearing housing relative to the atmosphere, the system prevents contaminant ingress and lubricant egress without requiring heavy carbon seals, thus improving the weight-to-sealing-performance ratio.
2Reliability
If multiple carbon seals are arranged axially along the shaft surface to improve seal performance, then sealing effectiveness is enhanced, but axial length increases elongating the engine
Solution Approach 1:
The patent combines multiple sealing functions into a single integrated labyrinth seal assembly. The bearing housing incorporates both the seal structure and the pressurized air supply system, eliminating the need for multiple separate carbon seal components arranged axially. This consolidation maintains sealing effectiveness while reducing overall axial length.
Solution Approach 2:
The patent transitions from axial arrangement of multiple seals to a radial labyrinth structure with alternating stationary and rotating elements. The sealing action occurs in the radial direction through the tortuous path created by the labyrinth teeth, rather than requiring multiple axial layers, thus compressing the axial dimension while maintaining sealing performance.
3Ease of manufacture
If excessive clearance gaps are provided between stationary and rotating components in the seal area to enable assembly, then ease of assembly is improved, but leakage of compressed air and lubricants increases
Solution Approach 1:
The patent divides the clearance space into multiple narrow passages using alternating stationary and rotating labyrinth elements. Instead of a single large clearance gap, the segmentation creates multiple tortuous paths that significantly increase flow resistance. This allows maintaining adequate assembly clearance while minimizing leakage through the combined effect of multiple narrow restrictions.
Solution Approach 2:
The patent employs a dynamic seal configuration where rotating elements move with the shaft while maintaining sealing engagement. The relative motion between stationary and rotating labyrinth teeth creates a dynamic sealing action that adapts to operational conditions, preventing excessive leakage while allowing necessary assembly clearances. The compressed air pressure also dynamically balances the seal elements against the shaft surface.
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 dual labyrinth seal assembly reduces axial length, minimizes leakage, and prevents contamination, enhancing the durability and efficiency of gas turbine engines by maintaining a pressurized environment within the seal area.
Implementation Method 1
an intermediate plenum, defined between the outer fins, the inner fins, the housing and the shaft, the intermediate plenum in communication with a source of compressed gas having a supply pressure greater than an ambient pressure external to the housing and greater than an internal pressure within the housing
Data Source
AI summary
A seal assembly for a turbine engine having a shaft with a rotary axis and a housing surrounding the shaft; the seal assembly being disposed between the shaft and the housing, the seal assembly comprising: an outer labyrinth seal having multiple outer fins in opposing sealing engagement with a concentric outer seal runner, one of: the outer labyrinth seal fins; and the outer seal runner, engaging the housing, and the shaft engaging an opposing one of: the outer seal runner; and the outer labyrinth seal fins; an inner labyrinth seal, disposed radially inwardly concentric to and axially overlapping the outer labyrinth seal and the outer seal runner, the inner labyrinth seal having multiple inner fins in opposing sealing engagement with a concentric inner seal runner, one of: the inner labyrinth seal fins; and the inner seal runner, engaging the housing, and the shaft engaging an opposing one of: the inner seal runner; and the inner labyrinth seal fins; and an intermediate plenum, defined between the outer fins, the inner fins, the housing and the shaft, the intermediate plenum in communication with a source of compressed gas having a supply pressure greater than an ambient pressure external to the housing and greater than an internal pressure within the housing.