Gas Turbine Rotor Disk Scallop Shield Stress Relief

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Solution Overview

Problem

Rotor disks in gas turbine engines experience low cycle fatigue and thermal mechanical fatigue due to exposure to high temperatures and repeated acceleration/deceleration, particularly at the forward or aft edges of blade slots in the compressor and turbine sections.

Innovation Solution

A rotor disk design featuring scallops on the rim portion with a cutout portion that intersects the forward and aft faces, defining a surface intersection of elliptical, circular, or racetrack shape, which alleviates stress concentrations by positioning the radial center on the disk live circumferential arc, with a circumferential length within 30-50% and axial depth within 5-10% of the disk live circumferential length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rotor disk rim portion is exposed to high temperatures and repeated acceleration/deceleration, then the rotor disk experiences thermal mechanical fatigue and low cycle fatigue, but the durability and longevity of the rotor disk deteriorates

Engineering Contradiction:

ImprovedurabilityVSAvoidthermal mechanical fatigue

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The rotor disk rim portion is segmented by removing material to create scallop features with cutout portions. This segmentation disrupts the continuous stress distribution and creates localized regions that reduce overall stress concentrations, thereby improving durability against thermal mechanical fatigue while maintaining structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Material is extracted from the rotor disk rim portion to form scallop features with cutout portions. This extraction removes the harmful stress concentration points that would otherwise be present in the continuous rim structure, directly addressing the thermal mechanical fatigue issue while preserving the necessary structural function.

Inventive Principle:

Principle #2Taking out (Extraction)

2Strength

If scallop features with cutout portions are added to the rotor disk rim, then stress concentrations are reduced, but the structural complexity of the rotor disk increases

Engineering Contradiction:

Improvestress concentration resistanceVSAvoidstructural complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The scallop features are applied locally to specific regions of the rotor disk rim portion where stress concentrations occur. This localized modification addresses the strength issue at critical locations without requiring complex changes to the entire rotor disk structure, thereby improving stress concentration resistance while minimizing overall structural complexity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP3693541B1Gas turbine rotor disk having scallop shield feature

Publication Date: 2022.03.02 RTX CORP

Figure 1A
Figure 1B
Figure 2A~2B

AI summary

A rotor disk (200; 300) for a gas turbine engine (20) is disclosed. In various embodiments, the rotor disk (200; 300) includes a rim portion (204; 304) disposed about a central axis (A); a blade post (208; 308) disposed proximate the rim portion (204; 304), the blade post (208; 308) having a first branch (352) and a second branch (354); and a first scallop (356) disposed within the rim portion (304), between and radially inward of the first branch (352) and the second branch (354).