Hydrostatic Seal Secondary Seal Protection Against Pressure Reversal

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Solution Overview

Problem

Traditional hydrostatic seal assemblies in gas turbine engines lack substantial structural protection for secondary seals, which can be damaged by pressure surges or reversals, leading to permanent bending and potential liberation, resulting in debris and loss of functionality.

Innovation Solution

A hydrostatic seal assembly with a structural component, such as a secondary seal cover or spacer, extending radially inward to cover at least 90% of the secondary seal's radial distance, providing additional exposed surface area and structural support to prevent damage from pressure differentials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional hydrostatic seal assemblies are used without additional structural protection, then the device complexity is low, but the secondary seal is vulnerable to pressure surge damage and reliability deteriorates

Engineering Contradiction:

Improvesecondary seal functionalityVSAvoidseal assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The structural component (cover or spacer) is positioned in advance to protect the secondary seal before pressure surges occur. This protective structure acts as a cushioning barrier that prevents direct exposure of the thin secondary seal to damaging pressure reversals, thereby maintaining reliability without requiring complex active protection systems.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The structural component serves as an intermediary element between the high-pressure fluid environment and the secondary seal. This mediator protects the vulnerable secondary seal from direct exposure to harmful pressure differentials while still allowing the seal to function properly in its intended application.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the secondary seal is made thinner to reduce friction and improve sealing, then sealing performance improves, but the seal becomes more susceptible to pressure reversal damage

Engineering Contradiction:

Improvesealing performanceVSAvoidpressure resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The structural component provides pre-positioned protection for the thin secondary seal against pressure reversals. By having this protective structure in place beforehand, the thin seal can maintain its low-friction, high-performance characteristics without needing to be thicker for protection, as the structural component absorbs the protective function.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the structural component covers more of the secondary seal radially, then protection from pressure surges improves, but the exposed surface area for high pressure fluid exposure decreases

Engineering Contradiction:

Improveprotection from pressure reversalVSAvoidexposed seal surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The structural component is designed to provide protection at specific critical locations (axially forward end) while leaving other areas (radial edges) exposed to maintain necessary fluid communication. This localized protection approach ensures the seal receives protection where most needed while preserving functional exposure areas.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The structural component covers at least 90% of the radial distance but not necessarily 100%, providing sufficient protection (partial action) to prevent damage from pressure reversals while leaving enough exposed surface area to maintain proper seal functionality and fluid exposure.

Inventive Principle:

Principle #16Partial or excessive action

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 structural component effectively protects the secondary seal from pressure-induced damage, maintaining its functionality and preventing bending, thus ensuring reliable operation even under conditions of pressure reversal.

Implementation Method 1

when a pressure differential is developed across the seal

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

aerodynamic forces developed between the seal shoe and a rotor surface during operation

Methodology Applied

Scientific EffectAerodynamic forces:

Implementation Method 3

Proper functioning and positioning of the secondary seal(s) is dependent upon a positive pressure differential

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP3722560B1Hydrostatic seal with secondary seal structural protection

Publication Date: 2023.08.09 RTX CORP

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AI summary

A hydrostatic seal assembly (100) configured to be disposed between relatively rotatable components includes a base (107). The seal also includes a shoe (108) operatively coupled to the base (107). The seal further includes a secondary seal (122) disposed proximate an axially forward end of the shoe (108), the secondary seal (122) extending radially from a radially inner end (124) to a radially outer end (126) to define a radial distance of the secondary seal (122), the secondary seal (122) having an axially forward face. The seal yet further includes a structural component (120, 130, 132) located adjacent to the axially forward face of the secondary seal (122) and extending radially inwardly to cover at least half of the radial distance of the secondary seal (122).