Axial Non-Contact Seal Assembly for Rotor Tracking and Low Leakage

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Solution Overview

Problem

Existing non-contact seal assemblies in rotational equipment face challenges with excessive friction leading to wear and increased leakage, as they struggle to adequately track the rotor under certain conditions.

Innovation Solution

A non-contact seal assembly featuring a seal shoe and flexible ligaments that allow axial and lateral shifting, reducing friction impact by using a seal carrier and spring structures with ligaments arranged in an annular array, enabling the seal shoe to adapt to rotor movements without significant contact, thus forming a hydrostatic or knife-edge seal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If friction is used to mitigate aerodynamic instabilities in adaptive seal assemblies, then stability is improved, but the seal assembly's ability to track the rotor is limited and excessive wear occurs

Engineering Contradiction:

Improveaerodynamic stabilityVSAvoidseal tracking capability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent replaces the traditional friction-based mechanical stabilization mechanism with a magnetic field-based active control system. Magnets embedded in the seal assembly generate magnetic forces that counteract aerodynamic instabilities without requiring frictional contact, thereby maintaining stability while preserving the seal's ability to track rotor movements accurately.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical parameters of the seal assembly by incorporating magnetic fields as an additional control mechanism. By adjusting magnetic field strength and distribution, the system can dynamically respond to aerodynamic instabilities without relying on friction, enabling independent control of stability and tracking performance.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If friction is increased to mitigate aerodynamic instabilities, then stability is improved, but wear increases and leakage increases

Engineering Contradiction:

Improveaerodynamic stabilityVSAvoidwear and leakage

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent substitutes friction-based mechanical stabilization with magnetic field-based active control. This eliminates the need for frictional forces, thereby preventing wear generation and maintaining consistent seal clearances that prevent leakage, while still achieving aerodynamic stability through magnetic actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces magnetic fields as an intermediary mechanism between the seal assembly and the aerodynamic environment. This intermediary enables stability control without direct mechanical friction, thus avoiding the harmful effects of wear and leakage associated with traditional friction-based approaches.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If adaptive mechanisms are added to reduce leakage, then sealing performance is improved, but friction increases and tracking ability is limited

Engineering Contradiction:

Improvesealing performanceVSAvoidfriction

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces friction-based adaptive mechanisms with magnetic field-based active control systems. The magnets generate forces that adjust seal clearances dynamically to maintain tight sealing performance without requiring frictional contact, thereby eliminating the harmful friction effects while preserving adaptive sealing capabilities.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 significantly reduces fluid leakage and minimizes friction-related wear, ensuring the seal assembly can maintain tight clearances and adapt to transient conditions without excessive friction, enhancing engine performance and seal life.

Implementation Method 1

The flexible ligaments enable axial and/or lateral shifting of the seal shoe relative to the seal carrier

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The non-contact seal assembly may be configured as a hydrostatic seal assembly

Methodology Applied

Scientific EffectHydrostatic pressure: Pressure Gradient

Implementation Method 3

The seal element and a portion of the seal shoe with the axially extending surface form a knife-edge seal

Methodology Applied

Scientific EffectGeometric sealing: Geometry

Data Source

PatentEP4269841A1Non-contact seal with axial arrangement

Publication Date: 2023.11.01 RTX CORP

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AI summary

An assembly is provided for rotational equipment. This assembly includes a stationary structure, a rotating structure rotatable about an axial centerline, and a non-contact seal assembly. The non-contact seal assembly is configured to substantially seal a gap between the stationary structure and the rotating structure. The non-contact seal assembly includes a seal shoe configured to sealingly engage the rotating structure axially along the axial centerline.