Turbine Blade Tip Shroud Cooling via Segmented Impingement

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Solution Overview

Problem

Turbine blade tip shrouds face high mechanical stresses and temperature challenges, making it difficult to design an effective cooling method that maintains engine performance over the blade's useful life without reducing tip shroud coverage or performance.

Innovation Solution

Localized directional impingement cooling is applied to the tip shroud, particularly at the fillets between the airfoil and the shroud, using exit holes to direct cooling fluid towards targeted impingement zones within shroud cooling chambers, enhancing heat transfer and reducing metal temperature in stressed regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If integral tip shrouds are used to cover the entire outer surface of the blade, then engine performance is improved, but the shroud experiences high mechanical stresses and high temperatures that reduce its reliability

Engineering Contradiction:

Improveengine performanceVSAvoidshroud reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The shroud cooling system is segmented into multiple independent cooling chambers (first cooling chamber, second cooling chamber, third cooling chamber) that can be designed and operated independently. This segmentation allows targeted cooling of different stress regions without requiring uniform cooling across the entire shroud, thereby maintaining reliability while preserving performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the shroud are provided with different cooling characteristics through multiple cooling chambers with varying numbers of cooling holes. The first cooling chamber has a different number of cooling holes than the second and third chambers, allowing localized adaptation to specific thermal and stress conditions in different shroud regions.

Inventive Principle:

Principle #3Local quality

2Reliability

If the tip shroud coverage is reduced to decrease stress, then shroud reliability is improved, but engine performance deteriorates

Engineering Contradiction:

Improveshroud reliabilityVSAvoidengine performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Cooling air is introduced into the shroud cooling chambers before the hot gas reaches the shroud, pre-cooling the shroud structure in advance. This preliminary cooling action allows the shroud to withstand high temperatures and stresses without requiring reduced coverage, thereby maintaining both reliability and engine performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Cooling air acts as an intermediary substance that is introduced into the shroud cooling chambers to transfer heat away from the shroud structure. This intermediary cooling medium allows the shroud to maintain structural integrity under high stress and temperature conditions without reducing coverage.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If cooling air is discharged at the blade tip to provide film cooling, then shroud temperature is reduced, but the cooling effectiveness in highly stressed regions is insufficient

Engineering Contradiction:

Improveshroud temperatureVSAvoidcooling effectiveness in stressed regions

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The cooling system is divided into multiple cooling chambers (first, second, and third cooling chambers) with different numbers and arrangements of cooling holes. This segmentation enables targeted cooling of specific high-stress regions such as the fillet areas, providing enhanced cooling effectiveness where it is most needed rather than uniform cooling across the entire shroud.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different cooling chambers are designed with different numbers of cooling holes to provide localized cooling intensity matched to the specific thermal and stress conditions of different shroud regions. The first cooling chamber has a different number of cooling holes than the second and third chambers, optimizing cooling effectiveness in highly stressed regions.

Inventive Principle:

Principle #3Local quality

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 method effectively reduces metal temperature in highly stressed areas, increasing the useful life of the blade tip shroud and allowing it to operate in hotter environments without detracting from engine performance.

Implementation Method 1

exit hole being directed towards a target wall surface of said cooling chamber, whereby said exit hole defines an impingement hole for impingement cooling said target wall surface

Methodology Applied

Scientific EffectImpingement cooling: Forced Convection