Arcuate Heat Pipe System for Engine Rotor Cooling

Solution Overview

Problem

Gas turbine engines face a 'bowed rotor' condition due to thermal expansion after shutdown, which can delay engine starting and cause premature starter system wear, and existing mitigation methods either delay engine restart or require additional energy sources.

Innovation Solution

A heat pipe system with arcuate segments shaped to conform to the engine rotor's inner wall, utilizing a heat pipe fluid that transitions from an evaporated to a partially liquid state in response to temperature non-uniformity, establishing a thermal communication path to reduce temperature differences and prevent bowing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a starter system is used to drive rotation for extended period to cool down the rotor, then the bowed rotor condition is mitigated, but engine starting is delayed and starter system wear increases

Engineering Contradiction:

Improvebowed rotor condition mitigationVSAvoidengine starting delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The heat pipe system is pre-installed on the rotor surface to provide passive cooling during shutdown. The heat pipe fluid is pre-positioned to automatically activate when temperature differentials occur, eliminating the need for delayed starter activation and enabling immediate engine restart capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The heat pipe system operates autonomously using the rotor's own thermal energy. During shutdown, heat naturally flows from hot upper portions to cooler lower portions through the heat pipe segments, requiring no external power source or control system, thus avoiding starter system wear and time delays.

Inventive Principle:

Principle #25Self-service

2Reliability

If a starter system is used to drive rotation for extended period to cool down the rotor, then the bowed rotor condition is mitigated, but starter system wear increases

Engineering Contradiction:

Improvebowed rotor condition mitigationVSAvoidstarter system wear

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The heat pipe system operates autonomously using the rotor's own thermal energy. During shutdown, heat naturally flows from hot upper portions to cooler lower portions through the heat pipe segments, requiring no external power source or control system, thus avoiding starter system wear and time delays.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The passive thermal conduction system replaces the active mechanical starter system for rotor cooling. Instead of using mechanical rotation to achieve cooling, the invention uses thermal conduction through heat pipe segments to equalize temperatures, eliminating mechanical wear entirely.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If existing approaches to engine rotation are used to alleviate bowed rotor condition, then the condition is mitigated, but additional energy sources are required

Engineering Contradiction:

Improvebowed rotor condition mitigationVSAvoidenergy source requirement

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The heat pipe system operates autonomously using the rotor's own thermal energy. During shutdown, heat naturally flows from hot upper portions to cooler lower portions through the heat pipe segments, requiring no external power source or control system, thus avoiding starter system wear and time delays.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention extracts and utilizes the thermal energy already present in the rotor system itself, rather than requiring external energy sources. The heat pipe segments capture and redirect the rotor's own heat to cool critical areas, making the system self-sufficient.

Inventive Principle:

Principle #2Taking out (Extraction)

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 heat pipe system effectively reduces or prevents the bowed rotor condition by enhancing temperature uniformity across the engine, thereby facilitating quicker engine restarts and reducing starter system wear.

Implementation Method 1

a heat pipe fluid within the one or more arcuate heat pipe segments establishes a thermal communication path from an upper portion of the high pressure spool through the low pressure spool to a lower portion of the high pressure spool

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

The heat pipe fluid can be in an evaporated state during engine operation and transitions to at least a partially liquid state in response to temperature non-uniformity after engine shutdown

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

The heat pipe system effectively reduces or prevents the bowed rotor condition by enhancing temperature uniformity across the engine

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10443388B2Heat pipe system for engine rotor cooling

Publication Date: 2019.10.15 HAMILTON SUNDSTRAND CORP

AI summary

A heat pipe system includes one or more arcuate heat pipe segments shaped conforming to an inner wall of an engine rotor. The heat pipe system also includes a heat pipe fluid within the one or more arcuate heat pipe segments.