Gas Turbine Blade Platform Cooling via Segmented Channels

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Solution Overview

Problem

Concave platforms of industrial gas turbine blades experience high metal temperature and thermal strain, leading to thermo mechanical fatigue cracking, platform separation, and thermal barrier coating spallation due to uneven cooling and mass differences between the platform web and the rest of the component.

Innovation Solution

A gas turbine blade assembly with a neck defining a neck cavity and a platform having inner and film cooling channels to actively cool the platform, reducing thermal strain and oxidation, featuring a core channel to direct cooling air and film cooling channels to cool the platform exterior to the airfoil, along with grain control to manage strain levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the platform is left uncooled, then the structure is simpler, but the metal temperature and thermal strain increase causing cracking and oxidation

Engineering Contradiction:

Improvecooling system complexityVSAvoidmetal temperature

Core Design Contradiction:

Device complexityVSTemperature

Solution Approach 1:

The cooling system is segmented into multiple independent channels: inner cooling passages within the platform web, core channels in the neck, and film cooling channels through the platform. This segmentation allows targeted cooling of different regions experiencing thermal stress, effectively reducing metal temperature without requiring a monolithic complex cooling system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses pneumatic cooling by directing compressed cooling air through the inner cooling passages, core channels, and film cooling channels. This hydraulic/pneumatic system efficiently removes heat from the platform structure, preventing excessive metal temperature and thermal strain while maintaining structural integrity.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Reliability

If the platform is actively cooled with multiple channels, then the metal temperature and thermal strain are reduced, but the device complexity increases

Engineering Contradiction:

Improvecrack preventionVSAvoidcooling channel structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple cooling functions are merged into an integrated cooling system where inner cooling passages, core channels, and film cooling channels work together as a unified network. The cooling air flow is merged through these channels to simultaneously cool the platform web, neck, and exterior surfaces, achieving comprehensive thermal protection through a coordinated system rather than separate independent systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cooling system performs multiple functions simultaneously: inner cooling passages cool the platform web, core channels cool the neck structure, and film cooling channels protect the platform exterior. This multi-functional cooling network addresses various thermal stress points throughout the blade assembly, enhancing reliability across the entire structure with a single integrated system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If cooling air is directed through core channels and film cooling channels, then oxidation and thermal strain are prevented, but the manufacturing complexity increases

Engineering Contradiction:

Improveoxidation and thermal strainVSAvoidblade manufacturing

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The invention changes the thermal parameters of the platform by introducing cooling air at controlled flow rates and temperatures through the inner cooling passages and film cooling channels. This parameter change maintains the platform metal temperature below critical thresholds during operation, preventing oxidation and thermal strain while allowing standard manufacturing processes to be used.

Inventive Principle:

Principle #35Parameter changes

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 active cooling system reduces metal temperature and thermal strain, prevents cracking and oxidation, extends the life of industrial gas turbine blades by an additional overhaul cycle, and can be applied to both new and re-engineered blades.

Implementation Method 1

The active cooling system reduces metal temperature and thermal strain

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

cooling air to flow through the inner cooling passage into the neck cavity and through a portion of the platform exterior to the airfoil

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS7708525B2Industrial gas turbine blade assembly

Publication Date: 2010.05.04 RTX CORP

AI summary

A gas turbine blade assembly includes a neck defining a neck cavity, and has a first end and a second end at an opposite side relative to the first end. A platform has first and second sides. The first side is disposed on and faces the second end of the neck. An airfoil is supported on the second side of the platform. The neck, platform and airfoil define an inner cooling passage extending through the neck, platform and into the airfoil. The neck defines at least one core channel extending between the cooling passage and the neck cavity. The platform defines at least one film cooling channel extending from the first side facing the neck cavity to the second side disposed exterior to the airfoil to permit cooling air to flow through the inner cooling passage into the neck cavity and through the platform exterior to the airfoil.