Aircraft Engine Seal Assembly for Pressure Mixing and Wear Control
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Solution Overview
Problem
Existing aircraft engine seals fail to effectively manage pressure and temperature gradients between high-pressure and low-pressure sections, leading to inefficiencies in air flow and potential wear and vibrations.
Innovation Solution
A seal assembly comprising a labyrinth seal with inclined fins and a secondary seal, such as a rope or brush seal, that directs a stream of air from a higher pressure area through passages to create an intermediate pressure area for mixing with lower pressure air, reducing kinetic energy and promoting thermal exchange, while allowing axial and radial displacements between components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional seal is used to separate high-pressure and low-pressure sections, then the seal structure is simple, but it fails to effectively manage pressure and temperature gradients leading to air flow inefficiencies and increased wear
Solution Approach 1:
The seal is divided into multiple functional segments: a first seal portion (labyrinth seal with fins) for initial air flow management, passages for directing air, a chamber for mixing, and a second seal portion (brush or rope seal) for final sealing. This segmentation allows each portion to perform its specific function optimally, resolving the contradiction between reliability and complexity.
Solution Approach 2:
An intermediate pressure area is created between the high-pressure and low-pressure sections, served by a chamber that receives air from both regions and mixes them. This intermediary mechanism gradually manages pressure gradients rather than abrupt transitions, improving seal reliability while distributing the functional complexity across multiple components.
2Productivity
If air flows directly from high-pressure to low-pressure area, then the flow path is short, but kinetic energy is high causing wear and vibrations
Solution Approach 1:
The first seal portion with labyrinth fins performs preliminary action by forcing the high-pressure air to follow a tortuous path before reaching the chamber. This pre-conditioning reduces the air's kinetic energy and prepares it for mixing in the chamber, preventing direct high-speed impact that would cause wear and vibrations.
Solution Approach 2:
The high kinetic energy of the incoming air stream is converted into a beneficial mixing force within the chamber. The air's momentum drives thorough mixing with air from the low-pressure area, and the subsequent reduction in kinetic energy occurs naturally during this mixing process, eliminating wear-causing impacts.
3Temperature
If pressure gradients are not managed, then the seal structure is simple, but thermal gradients are uneven causing inefficiencies
Solution Approach 1:
The chamber acts as an intermediary mixing zone where hot high-pressure air and cooler low-pressure air are combined. This intermediate region gradually equalizes temperature differences through mixing, creating more uniform thermal gradients across the seal assembly while the passage system manages the pressure distribution required for this process.
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 enhances air flow management, reduces wear, and evenly distributes thermal gradients, minimizing vibrations and improving the operational efficiency of aircraft engine components.
Implementation Method 1
the first seal allowing a stream of air from flowing in an axial direction from the upstream end of the first seal into the spacing toward the downstream end of the first seal, the first seal at least partially defining an intermediate pressure area
Implementation Method 2
the chamber allowing for a mixing of the first portion of the stream of air with air from the second pressure area
Implementation Method 3
the second seal biasing the first portion of the stream of air toward the passages, and allowing a second portion of the stream of air from flowing through the second seal toward the second pressure area
Data Source
AI summary
A seal assembly for an aircraft engine includes a first seal having an upstream end exposed to a first pressure area, and a downstream end exposed to a second pressure area, the first seal at least partially defining an intermediate pressure area and a chamber being fluidly connected to the second pressure area and to the intermediate pressure area through passages defined in the first seal, the chamber allowing for a mixing of a first portion of a stream of air with air from the second pressure area, and a second seal connected to the first seal, the second seal biasing the first portion of the stream of air toward the passages, and allowing a second portion of the stream of air from flowing therethrough toward the second pressure area. A method of flowing air through an aircraft seal assembly is also described.