Angled Cooling Divider Wall in Turbine Blade Root

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Solution Overview

Problem

Conventional blade root structures in cooled turbine rotor assemblies of gas turbine engines face challenges with structural stiffness due to high rotational speeds, leading to compressive stresses and potential buckling, which existing divider walls are insufficient to address effectively.

Innovation Solution

The proposed solution involves a rotor blade with internal cooling air passages and a blade root structure featuring side projections, platform segments, and angled divider walls within a cavity that is in fluid communication with the cooling air passages, designed to reduce torsion effects and enhance structural stiffness by directing cooling airflow effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional divider walls or ribs are used in the blade root cavity, then the structural stiffness is partially maintained, but the centrifugal load at high rotational speeds causes compressive stresses, buckling, and shear effects that initiate cracks

Engineering Contradiction:

Improvestructural stiffnessVSAvoidcrack initiation resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The divider wall is configured at an angle relative to the rotational axis rather than being radially symmetric. This asymmetric angular orientation allows the divider wall to resist torsional and shear stresses more effectively under centrifugal loading, preventing crack initiation while maintaining structural stiffness.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The divider wall extends at an angular dimension within the cavity rather than simply radially outward. This angular configuration adds a dimensional component that enhances resistance to multi-directional stresses including compressive, shear, and torsional loads generated during high-speed rotation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Power

If the rotor assembly rotates at high speed, then the engine produces sufficient power, but large compressive stresses and buckling effects are generated in the blade attachment structure

Engineering Contradiction:

Improveengine power outputVSAvoidcompressive stress in blade attachment

Core Design Contradiction:

PowerVSStress or pressure

Solution Approach 1:

The angled divider wall configuration creates an asymmetric stress distribution pattern that better withstands the large compressive stresses generated during high-speed rotation, allowing the rotor to operate at higher speeds without structural failure.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The angular parameter of the divider wall is optimized to change the stress distribution characteristics within the cavity, transforming the stress state from one prone to buckling and compression into a more stable configuration that can handle high rotational loads.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional radial divider walls are used, then the cooling air passage is simply divided, but the torsion effect on the blade root from rotational speed is not sufficiently reduced

Engineering Contradiction:

Improvecooling air passage divisionVSAvoidtorsion effect on blade root

Core Design Contradiction:

Device complexityVSForce

Solution Approach 1:

The divider wall's angular orientation relative to the rotational axis creates an asymmetric configuration that actively counteracts torsional effects. This angular arrangement transforms the simple radial division into a structured configuration that reduces torsion on the blade root while maintaining cooling air passage division.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The angular configuration of the divider wall converts the harmful torsional and shear effects into beneficial stress distribution patterns. The angled structure utilizes the centrifugal and torsional loads to enhance its own structural integrity while reducing the net torsion effect on the blade root attachment.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 design improves the structural stiffness of the blade root by reducing torsion effects and managing compressive stresses, thereby enhancing the durability and performance of the turbine rotor assembly.

Implementation Method 1

the blade root defines a cavity therein with an opening thereof in a bottom of the blade root. The cavity is in fluid communication with the cooling air passages through the airfoil section

Methodology Applied

Scientific EffectFluid flow through passages:

Implementation Method 2

a centrifugal load which is born by the blade attachment, is generated as the blade rotates around the main engine axis

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 3

means defined within the cavity for reducing a torsion effect on the blade root resulting from a rotational speed of the turbine rotor assembly

Methodology Applied

Scientific EffectTorsion: Torsion Spring

Data Source

PatentUS7357623B2Angled cooling divider wall in blade attachment

Publication Date: 2008.04.15 PRATT & WHITNEY CANADA CORP

AI summary

A rotor blade of a gas turbine engine includes a blade root defining a cooling airflow entry cavity therein, in fluid communication with internal cooling air passages through the blade. The cavity includes opposed side walls and at least one divider wall extending therebetween. At least one end portion of the divider walls adjoins one of the side walls in an angled direction relative to a perpendicular direction of the side walls.