Diffuser Seal Shoe Structure for Stable Non-Contact Sealing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing non-contact seals for rotational equipment have room for improvement in terms of sealing efficiency and reducing seal shoe flutter, particularly in gas turbine engines.

Innovation Solution

A seal device with a plurality of seal shoes, a seal base, and spring elements, featuring a diffuser structure and a ramp structure that enhances sealing by reducing flutter and improving pressure distribution, while maintaining a stable seal between rotating and stationary structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional non-contact seals are used, then the seal structure is simple, but seal shoe flutter occurs and sealing efficiency is insufficient

Engineering Contradiction:

Improvesealing efficiencyVSAvoidseal structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The seal shoe is divided into multiple functional surfaces including a diffuser surface with increasing radius, a ramp surface, and a seal surface. This segmentation allows each surface to perform a specific function: the diffuser surface reduces pressure gradients, the ramp surface controls flow direction, and the seal surface maintains the sealing gap, collectively reducing flutter while improving sealing efficiency

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The diffuser surface is designed with a radius that increases in the axial direction, introducing a dimensional gradient to the seal shoe geometry. This axial variation in radius creates a progressive pressure distribution that stabilizes the seal shoe position and reduces flutter, while the three-dimensional geometry enhances sealing performance

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If seal shoes are positioned close to rotating structures, then sealing efficiency improves, but seal shoe flutter increases

Engineering Contradiction:

Improvesealing efficiencyVSAvoidseal shoe stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The diffuser surface design converts the harmful pressure gradient that causes flutter into a beneficial progressive pressure distribution. By increasing the radius in the axial direction, the diffuser surface gradually equalizes pressure differences, transforming the unstable pressure forces into a stabilizing effect that maintains close positioning without flutter

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The seal shoe geometry parameters are optimized with specific surface angles and radius gradients. The diffuser surface incorporates a controlled radial increase in the axial direction, and the ramp surface uses specific angular orientations to control fluid flow and pressure distribution, thereby stabilizing the seal shoe at optimal positioning

Inventive Principle:

Principle #35Parameter changes

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 effectively reduces seal shoe flutter and enhances sealing efficiency by improving pressure distribution, ensuring a stable seal and reducing fluid leakage, thereby improving the operational performance of rotational equipment.

Implementation Method 1

a plurality of spring elements, each configured to apply a resilient force to a respective seal shoe

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

A diffuser radius measured from the axis to the diffuser surface increases as the diffuser surface extends axially along the axis from the interface location to an axial distal side of the first seal shoe

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS12503950B2Non-contact seal shoe with diffuser structure

Publication Date: 2025.12.23 RTX CORP

AI summary

An apparatus is provided for rotational equipment which includes a seal device. The seal device includes a plurality of seal shoes, a seal base and a plurality of spring elements. The seal shoes are arranged circumferentially around an axis in an annular array. A first of the seal shoes includes a seal surface and a diffuser surface. The seal surface extends axially along the axis to an axial interface location where the seal surface axially meets the diffuser surface. A minimum radius of the first seal shoe measured from the axis to the seal surface is defined at least at the axial interface location. A diffuser radius measured from the axis to the diffuser surface increases as the diffuser surface extends axially along the axis from the interface location to an axial distal side of the first seal shoe. The spring elements connect the seal shoes and the seal base.