Oil Cooled Runner Thermal Management for Gas Turbine Seals

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Solution Overview

Problem

In gas turbine engines, the thermal expansion and contraction of metal runners due to frictional heat generation pose a challenge in maintaining a controlled radial clearance gap between the runner and the carbon seal, leading to potential oil leakage and reduced sealing effectiveness.

Innovation Solution

An oil cooled runner with an annular runner ring and an oil distributor that maintains a desired temperature by directing a flow of liquid lubricant against its surface, controlling the radial clearance gap through thermal management, using a conical oil layer to absorb heat uniformly and maintain optimal geometry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the runner-to-seal gap is minimized to reduce leakage, then sealing effectiveness is improved, but frictional resistance increases generating excessive heat

Engineering Contradiction:

Improvesealing effectivenessVSAvoidrunner temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent converts the harmful frictional heat generated by the minimized runner-to-seal gap into a beneficial cooling mechanism. Oil jets are directed at the runner surface to absorb and remove the heat, transforming the thermal problem caused by tight sealing into a manageable cooling challenge that maintains both low leakage and acceptable temperature levels.

Inventive Principle:

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

Solution Approach 2:

The patent introduces oil jets as an intermediary cooling medium between the friction-generated heat source (runner-seal interface) and the runner component. This intermediary fluid absorbs thermal energy and transports it away, preventing excessive temperature rise while allowing the runner-to-seal gap to remain minimized for optimal sealing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If the runner temperature is controlled to maintain radial clearance gap, then sealing performance is improved, but device complexity increases due to cooling system requirements

Engineering Contradiction:

Improveradial clearance gap controlVSAvoidcooling system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a self-service cooling approach where the lubrication oil already present in the system is repurposed for cooling the runner. The same oil that lubricates the bearing housing is directed through jets onto the runner surface, eliminating the need for separate cooling systems and reducing overall device complexity while maintaining precise radial clearance gap control.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent makes the lubrication oil multi-functional by using it for both lubrication and cooling purposes. The oil serves dual functions: reducing friction at the runner-seal interface and removing heat from the runner surface, thereby simplifying the system architecture while achieving precise temperature and clearance gap control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Temperature

If conventional oil jets are used to cool the runner, then temperature control is achieved, but uniform heat distribution and cooling efficiency are reduced

Engineering Contradiction:

Improverunner temperature controlVSAvoidcooling efficiency

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The patent employs periodic action through rotating oil jets that sweep across the runner surface. The jets are directed at the runner at specific angles and positions, creating a periodic cooling pattern that ensures uniform heat distribution across the entire runner surface, thereby improving cooling efficiency and reducing energy loss.

Inventive Principle:

Principle #19Periodic 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

This solution effectively maintains a consistent radial clearance gap over the operating temperature range, preventing excessive movement and leakage, ensuring efficient sealing and lubrication within the bearing housing.

Implementation Method 1

maintaining the desired temperature of the runner by directing a flow of liquid lubricant against a surface of the runner

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

Cooled lubricant flows into the bearing housing from a heat exchanger and is distributed through various channels and ejected through jets toward sources of heat to cool and lubricate moving parts

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

Since the runner is made of metal, the temperature of the runner during operation results in thermally induced expansion and contraction

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

Friction generates heat which is dissipated by bathing the runner in a flow of liquid lubricant

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8678741B2Oil cooled runner

Publication Date: 2014.03.25 PRATT & WHITNEY CANADA CORP

AI summary

An oil cooled runner, for a rotary seal between an engine case and a shaft rotationally mounted to the case, includes an annular runner ring having a platform with a radially outer seal engagement surface and a radially inner surface, and an oil distributor having a radially inner portion in communication with a source of liquid lubricant and an outer lubricant casting cone with a rim disposed radially inwardly from the inner surface of the platform.