Gas Turbine Spacer Disk Rim Grooves Stress Relief

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Solution Overview

Problem

Gas turbine spacer disks experience alternating stress due to elastic expansion and contraction, leading to potential cracking and reduced operational lifetime, particularly under high temperatures and centrifugal forces.

Innovation Solution

The design incorporates a rim portion with circumferential grooves and fillets, where the grooves alternate in diameter and depth, and a diaphragm with radially inward teeth to create a tortuous path, allowing the rim to elastically deform and contact adjacent disks, forming seals and reducing stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the rim portion is made thicker to increase strength, then the spacer disk can better resist centrifugal forces, but the elastic expansion and contraction create more severe alternating stress and cracking

Engineering Contradiction:

Improveresistance to centrifugal forceVSAvoidoperational lifetime

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The rim portion is segmented into multiple grooves that alternate in diameter and depth, creating a segmented structure that distributes stress more evenly across the rim. This segmentation prevents stress concentration at any single location, thereby reducing cracking while maintaining the ability to resist centrifugal forces.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The grooves are strategically positioned at specific locations on the rim portion, creating local variations in geometry. The alternating diameter and depth of the grooves create localized stress distribution patterns that prevent crack initiation and propagation, while the fillets provide localized stress relief at transition zones.

Inventive Principle:

Principle #3Local quality

2Reliability

If the grooves are made deeper to reduce stress concentration, then cracking is prevented, but the rim portion requires more material removal reducing structural integrity

Engineering Contradiction:

Improveprevention of crackingVSAvoidstructural integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The groove structure is designed to be dynamic in nature, where the alternating depth creates a flexible stress distribution system. The grooves allow the rim to flex and deform elastically in a controlled manner, absorbing stress energy without requiring excessive material removal, thus maintaining structural integrity while preventing cracking.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The groove parameters (depth, diameter, spacing) are optimized to achieve the desired stress distribution. By carefully controlling these parameters, the design achieves crack prevention without excessive material removal. The fillet radius and groove depth are balanced to provide stress relief while maintaining sufficient rim thickness for structural integrity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the fillet radius is increased to reduce stress concentration, then cracking is reduced, but the manufacturing complexity increases

Engineering Contradiction:

Improveresistance to stress concentrationVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of using excessively large fillet radii throughout the entire rim structure, the design applies fillets selectively at critical stress concentration points. This partial application of filleting provides sufficient stress relief while avoiding the manufacturing complexity and material waste associated with excessive filleting across the entire component.

Inventive Principle:

Principle #16Partial or excessive action

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 configuration enhances the operational lifetime of spacer disks by reducing stress and maintaining effective seals, thereby preventing cracking and improving the engine's performance under centrifugal forces.

Implementation Method 1

the rim portion is configured to elastically deform under centrifugal force such that the rim portion contacts the first and second stage disks to close the first and second gaps respectively

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

the rim portion is configured to elastically deform under centrifugal force

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11326462B2Gas turbine and spacer disk for gas turbine

Publication Date: 2022.05.10 MECHANICAL DYNAMICS & ANALYSIS LLC

AI summary

A gas turbine spacer disk includes a disk portion, a rim portion, a first fillet, and a second fillet. The disk portion is disposed about a rotational axis. The rim portion is disposed about the disk portion. An outer face of the rim portion defines a plurality grooves extending circumferentially about the rotational axis. The first fillet transitions from the rim portion to a first side of the disk portion. The second fillet transitions from the rim portion to a second side of the disk portion. The plurality of grooves includes a pair of first grooves having a first diameter and a pair of second grooves having a second diameter that is less than the first diameter. A first one of the first grooves overlaps in an axial direction with the first fillet. A second one of the first grooves overlaps in the axial direction with the second fillet.