Ceramic Runner Seal Assembly With Compliant Holder for Thermal Stress Relief

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Solution Overview

Problem

Existing runner mount designs in gas turbine engines lead to excessive stresses in seal rings, runners, and mounts, necessitating improvements to prevent damage and ensure effective sealing.

Innovation Solution

A seal assembly featuring a ceramic runner supported by a compliant holder with cantilevered fingers that elastically deform to accommodate radial growth, reducing stress concentrations and allowing for thermal expansion mismatch between components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a runner mount contacts both radially inner and radially outer surfaces of the runner, then the runner is securely held in place, but excessive stresses are generated in the seal ring, runner, and runner mount

Engineering Contradiction:

Improverunner positioning stabilityVSAvoidstress in seal ring and runner

Core Design Contradiction:

Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The runner mount is divided into two separate holders (first holder and second holder) that contact only the radially inner and radially outer surfaces respectively, eliminating the concentrated stress of dual-surface contact from a single mount while maintaining secure positioning through distributed contact points

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each holder is designed with specific local properties - the first holder contacts the radially inner surface while the second holder contacts the radially outer surface, allowing each component to be optimized for its specific contact location and stress distribution requirements

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If a runner mount engages the outer diameter of the seal ring, then the seal ring is secured, but excessive stresses are generated in the seal ring, runner, and runner mount

Engineering Contradiction:

Improveseal ring positioning stabilityVSAvoidstress in seal ring

Core Design Contradiction:

Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The function of securing the seal ring is extracted from the runner mount and transferred to the seal ring itself through its engagement with the housing assembly, allowing the runner mount to focus solely on securing the runner without the additional stress of dual engagement functions

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The securing function is segmented between two separate engagement systems: the seal ring engages the housing assembly for radial positioning, while the runner mount engages the runner for axial positioning, eliminating concentrated stress at any single interface

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If rigid holder design is used, then manufacturing precision is easier to achieve, but thermal expansion mismatch causes excessive stresses during engine operation

Engineering Contradiction:

Improveholder manufacturing simplicityVSAvoidstress from thermal expansion mismatch

Core Design Contradiction:

Ease of manufactureVSStress or pressure

Solution Approach 1:

The holder design incorporates elastic compliance that allows dynamic adjustment during thermal cycles - the holders remain rigid during assembly and operation for manufacturing precision but become compliant under thermal stress to accommodate expansion mismatch, effectively transitioning between rigid and flexible states based on operating conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The mechanical properties of the holder are changed from purely rigid to elastically compliant, allowing the material to deform within elastic limits to accommodate thermal expansion differences while maintaining structural integrity and positioning accuracy

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 compliant holder design reduces stress on the ceramic runner and holder, maintaining radial position and preventing oil leakage by minimizing edge loading and wear, while ensuring effective sealing and thermal expansion compensation.

Implementation Method 1

The plurality of first fingers and the plurality of second fingers engage an inner diameter of the ceramic runner and are configured to elastically deform during use of the gas turbine engine to allow for radial growth between the compliant holder and the ceramic runner

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11466584B1Ceramic runner seal assembly with compliant holder

Publication Date: 2022.10.11 ROLLS ROYCE CORP

AI summary

A seal assembly adapted for use with a gas turbine engine includes a runner, a seal, and a compliant holder. The runner extends circumferentially about an axis and the compliant holder. The compliant holder engages the runner and is configured to support the runner radially relative to the axis. The seal extends circumferentially around the runner to block fluid flow through the seal assembly.