Aircraft Engine Seal Assembly for Pressure Mixing and Thermal Gradients
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Solution Overview
Problem
Existing aircraft engine seals fail to effectively manage pressure and temperature gradients between hot/high-pressure and cold/low-pressure sections, leading to inefficiencies and potential wear and vibrations.
Innovation Solution
A seal assembly comprising a labyrinth seal with angled passages and a secondary seal, which creates an intermediate pressure area for air 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
1Temperature
If a seal assembly manages pressure and temperature gradients between hot/high-pressure and cold/low-pressure sections, then thermal exchange and mixing are improved, but device complexity increases due to multiple seals and passages
Solution Approach 1:
The seal assembly is divided into multiple functional segments: a first seal (labyrinth seal with fins) for initial air flow management, a second seal (rope or brush seal) for additional sealing, and a chamber with passages for air mixing. This segmentation allows each component to perform a specific function in managing pressure and temperature gradients, improving thermal exchange while maintaining manageable complexity through modular design.
Solution Approach 2:
An intermediate pressure area is created between the high-pressure and low-pressure sections, serving as a transition zone. This intermediary region allows gradual pressure equalization and thermal exchange, reducing thermal shock and improving overall thermal management. The chamber and passages act as mediators that facilitate controlled mixing of air from different pressure and temperature zones.
2Temperature
If air flow is directed through passages and chamber for mixing, then thermal exchange is enhanced, but pressure management becomes more complex
Solution Approach 1:
Different regions of the seal assembly are designed with locally optimized properties: the labyrinth seal portion handles high-velocity air flow from the high-pressure side, the chamber provides a controlled mixing zone with specific geometric features, and the second seal manages the transition to the low-pressure side. This local optimization allows effective thermal exchange while managing pressure gradients through region-specific design.
Solution Approach 2:
The seal assembly exploits changes in pressure and temperature parameters along the air flow path. By creating an intermediate pressure area and using passages to control flow direction and mixing, the system naturally manages pressure differentials while enhancing thermal exchange. The geometric parameters of the passages and chamber are optimized to facilitate this parameter transformation.
3Reliability
If multiple seals and passages are used for air mixing, then seal efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The seal assembly integrates multiple functions into a single component structure: the first seal serves both as a barrier and as a flow director through its fin structure, the chamber simultaneously provides mixing and pressure management, and the second seal complements the first while allowing controlled leakage for thermal exchange. This multi-functionality improves seal efficiency while reducing the need for separate components, thereby easing manufacturing.
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 mixing and thermal exchange, reducing wear and vibrations by evenly distributing thermal gradients and managing pressure differentials, thereby improving the seal's efficiency and durability.
Implementation Method 1
a 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
a 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
Implementation Method 4
the first seal is formed as a labyrinth seal having a plurality of fins, and each fin of the plurality of fins is pointing towards the second component
Data Source
Figure 1
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AI summary
A seal assembly (20) for an aircraft engine includes a first seal (22) having an upstream end (50a) exposed to a first pressure area (40a), and a downstream end (50b) exposed to a second pressure area (40b), the first seal (22) at least partially defining an intermediate pressure area (40c) and a chamber (70) being fluidly connected to the second pressure area (40b) and to the intermediate pressure area (40c) through passages (60) defined in the first seal (22), the chamber (70) allowing for a mixing of a first portion (32a) of a stream of air (32) with air (32c) from the second pressure area (40b), and a second seal (24) connected to the first seal (22), the second seal (24) biasing the first portion (32a) of the stream of air (32) toward the passages (60), and allowing a second portion (32b) of the stream of air (32) to flow therethrough toward the second pressure area (40b). A method of flowing air through an aircraft seal assembly (20) is also described.