Gas Turbine Blade Cooling Cavity Indentations

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Solution Overview

Problem

Conventional cooling systems for 'long and thin' turbomachine gas turbine blades with high aspect ratio cooling cavities face challenges in air flow disturbance and mechanical strength due to the fineness of the cavities, making it difficult to achieve effective cooling without obstructing air flow or reducing mechanical integrity.

Innovation Solution

The implementation of a cooling cavity with indentations on the walls, rather than traditional spike or bridge flow disturbers, to disturb the air flow and enhance heat exchange without obstructing it, allowing for effective cooling with lower head losses and improved mechanical strength, and simplified fabrication through casting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional spike or bridge flow disturbers are used in high aspect ratio cooling cavities, then air flow disturbance and heat exchange are improved, but air flow obstruction and mechanical strength reduction occur

Engineering Contradiction:

Improvecooling efficiencyVSAvoidmechanical strength

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The cooling cavity wall is segmented into multiple indentations rather than using a single continuous spike or bridge structure. These segmented recesses disturb the air flow effectively while maintaining structural integrity and avoiding excessive stress concentrations that would compromise mechanical strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of adding protruding spike or bridge structures into the cooling cavity, the invention uses recesses or indentations that are removed from the wall material. This inverted approach achieves flow disturbance through material removal rather than addition, preserving mechanical strength while enhancing heat exchange.

Inventive Principle:

Principle #13The other way round (Inversion)

2Speed

If cooling cavity width is reduced to increase aspect ratio, then internal air flow speed increases, but fabrication complexity and stress concentrations increase

Engineering Contradiction:

Improveinternal air flow speedVSAvoidfabrication ease

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The indentations are strategically placed at specific locations along the cooling cavity walls where flow disturbance is most needed, rather than uniformly distributing features throughout. This localized approach achieves effective flow disturbance while maintaining easier fabrication compared to comprehensive structural modifications.

Inventive Principle:

Principle #3Local quality

3Temperature

If conventional flow disturbers are added to cooling cavities, then heat exchange coefficients increase, but device complexity and fabrication difficulty increase

Engineering Contradiction:

Improveheat exchange coefficientVSAvoidcooling circuit complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The flow disturbance function is merged directly into the cooling cavity wall structure itself through integrally formed indentations, rather than adding separate spike or bridge components. This integration simplifies the overall device complexity while achieving the desired heat exchange enhancement.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cooling cavity wall serves multiple functions: it provides structural support, defines the cooling passage geometry, and incorporates flow-disturbing indentations. This multi-functionality eliminates the need for separate flow disturber components, reducing device complexity while maintaining effective heat exchange.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enables effective cooling of 'long and thin' blades with improved mechanical strength and reduced stress concentrations, while maintaining air flow and simplifying the fabrication process, ensuring uniform cooling without air emission through the blade faces.

Implementation Method 1

at least one of the walls of the cooling cavity is provided with a plurality of indentations so as to disturb the flow of cooling air in said cavity and increase heat exchange

Methodology Applied

Scientific EffectHeat exchange: Convection

Data Source

PatentUS7513737B2Gas turbine blade cooling circuit having a cavity with a high aspect ratio

Publication Date: 2009.04.07 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A blade for a turbomachine gas turbine, the blade having a cooling circuit comprising at least one cooling cavity with a high aspect ratio extending radially between a root and a tip of the blade, and at least one air admission opening at a radially inner end of the cavity to feed it with cooling air, at least one of the walls of the cooling cavity being provided with a plurality of indentations so as to disturb the flow of cooling air in said cavity and increase heat exchange.