Offset Seal Base Reduces Radial Height in Hydrostatic Seals

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Solution Overview

Problem

Hydrostatic non-contact seals in rotational equipment, such as gas turbine engines, face challenges with radial height and weight due to the full ring portion that connects beams and shoes, which can be space-constrained and require redesign or thinning of parts.

Innovation Solution

A non-contact seal assembly with axially offset seal shoes and spring elements connecting to a seal base, reducing radial height and weight by allowing for a more compact design, and incorporating materials like nickel alloy or cobalt alloy for enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a full ring portion is used to connect beams and shoes in a hydrostatic non-contact seal, then the seal assembly can function properly as a full seal ring, but the radial height and weight of the seal assembly increase

Engineering Contradiction:

Improvesealing functionVSAvoidseal assembly weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The full ring portion is segmented into multiple discrete seal shoes that are independently mounted on the stator structure. Each seal shoe functions as an independent sealing element, eliminating the need for a continuous full ring structure. This segmentation reduces the overall weight and radial height of the seal assembly while maintaining the sealing function through the collective action of multiple shoes arranged in an annular array.

Inventive Principle:

Principle #1Segmentation

2Reliability

Engineering Contradiction:

Improvesealing functionVSAvoidradial height

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The seal shoes are arranged in an annular array around the rotor-stator interface, distributing the sealing function across the circumferential dimension rather than relying on a single full ring structure in the radial dimension. This dimensional redistribution allows each shoe to be thinner while collectively providing full circumferential sealing, thereby reducing the radial height of the overall assembly.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Length of stationary object

If parts are thinned or reconfigured to reduce radial height and weight, then the seal assembly fits better in space-constrained designs, but the structural integrity and sealing performance may be compromised

Engineering Contradiction:

Improveradial heightVSAvoidstructural integrity

Core Design Contradiction:

Length of stationary objectVSStrength

Solution Approach 1:

The seal shoes are constructed from composite materials including nickel alloy or cobalt alloy, which provide high strength-to-weight ratios. These materials enable the seal shoes to be thinner and lighter while maintaining sufficient structural integrity and sealing performance. The use of advanced materials allows the design to achieve reduced radial height without compromising the strength required for reliable operation in space-constrained environments.

Inventive Principle:

Principle #40Composite materials

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 the radial height and weight of the seal assembly, improving packaging and functionality within the design space while maintaining sealing efficiency between stator and rotor structures.

Implementation Method 1

a plurality of spring elements, each of the spring elements radially distal from and connecting to a respective one of the seal shoes

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

Hydrostatic non-contact seal includes a full ring portion that connects beams and shoes together

Methodology Applied

Scientific EffectHydrostatic pressure: Pressure Increase

Data Source

PatentUS10731761B2Hydrostatic non-contact seal with offset outer ring

Publication Date: 2020.08.04 RTX CORP

AI summary

A non-contact seal assembly includes a plurality of seal shoes arranged about a centerline in an annular array, the seal shoes including a first seal shoe extending axially along the centerline between a first shoe end and a second shoe end. The non-contact seal assembly may comprise a seal base circumscribing axially offset from the annular array of the seal shoes. The non-contact seal assembly may further comprise a plurality of spring elements, each of the spring elements radially distal from and connecting to a respective one of the seal shoes, and each of the plurality of spring elements is axially adjacent to the seal base.