Thimble Cooling Passage for Combustor Pressure Loss Reduction

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Solution Overview

Problem

Existing gas turbine engine cooling systems experience pressure loss and inefficient cooling due to opposing flow orientations in cooling passages, leading to reduced axial momentum and heat transfer effectiveness.

Innovation Solution

The use of thimbles with converging and recovery portions in cooling passages to channel cooling air, minimizing pressure loss and optimizing airflow by maintaining a Taylor-Gortler type of flow, which enhances heat transfer and reduces dynamics in the combustor assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cooling air is directed into cooling passages at an angle perpendicular to the existing flow, then the cooling air is effectively channeled into the passages, but axial momentum is lost and pressure loss increases

Engineering Contradiction:

Improvecooling effectivenessVSAvoidpressure loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Instead of directing cooling air perpendicular to the flow (which causes momentum loss), the thimble is designed with a flow channel that aligns with the axial flow direction, inverting the traditional perpendicular injection approach to maintain momentum and reduce pressure loss

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The thimble geometry parameters (flow channel angle, converging portion dimensions, recovery portion length) are optimized to transition the flow from perpendicular injection to axial alignment, changing the flow parameters to minimize pressure loss while maintaining cooling effectiveness

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If cooling air flow orientation is changed to perpendicular injection, then cooling air enters the passages, but axial momentum is reduced

Engineering Contradiction:

Improvecooling air flowVSAvoidaxial momentum

Core Design Contradiction:

Quantity of substanceVSSpeed

Solution Approach 1:

The thimble inverts the conventional perpendicular injection method by designing the flow channel to maintain axial flow orientation, thereby preserving axial momentum while still effectively introducing cooling air into the passage

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The thimble acts as an intermediary device between the plenum and cooling passage, mediating the flow transition to maintain axial momentum while enabling effective cooling air introduction through its specially designed flow channel geometry

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If thimbles with perpendicular flow orientation are used, then cooling air is directed into passages, but a barrier to momentum is created

Engineering Contradiction:

Improvecooling air distributionVSAvoidflow momentum

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The invention inverts the traditional perpendicular thimble design by creating a flow channel that maintains axial flow direction, eliminating the momentum barrier effect while still achieving effective cooling air distribution in the passage

Inventive Principle:

Principle #13The other way round (Inversion)

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 reduces pressure loss and improves cooling efficiency, ensuring even temperature distribution and prolonged mechanical life of combustor components by optimizing airflow patterns and minimizing wasted pressure loss.

Implementation Method 1

The flow channel has a converging portion and a recovery portion that is downstream from the converging portion

Methodology Applied

Scientific EffectConverging flow: Venturi Effect

Implementation Method 2

the recovery portion has a substantially constant diameter therethrough

Methodology Applied

Scientific EffectMomentum conservation: Conservation of Momentum

Implementation Method 3

optimizing airflow by maintaining a Taylor-Gortler type of flow, which enhances heat transfer

Methodology Applied

Scientific EffectTaylor-Gortler flow: Turbulence

Implementation Method 4

Cooling air flowing through the transition passage is discharged into the liner passage. The cooling air, which is heated by the metal surface of the transition piece and/or the combustor liner

Methodology Applied

Scientific EffectConvection heat transfer: Convection

Data Source

PatentUS8281600B2Thimble, sleeve, and method for cooling a combustor assembly

Publication Date: 2012.10.09 GE INFRASTRUCTURE TECH LLC

AI summary

A method for cooling a combustor assembly having a cooling passage. The method includes providing at least one thimble including an inner surface that defines a first opening, a second opening that is downstream from the first opening, and a flow channel that extends between the first opening and the second opening. The flow channel has a converging portion and a recovery portion that is downstream from the converging portion. The method also includes inserting the at least one thimble into at least one inlet that is defined in at least one sleeve such that cooling air is discharged from the flow channel into the cooling passage.