Annular Cavity Rotor Structure for Lightweight Centrifugal Strength

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Solution Overview

Problem

Gas turbine engine rotors face challenges in minimizing weight while maintaining structural integrity under high centrifugal forces, with existing designs limited by material constraints and production considerations.

Innovation Solution

The design incorporates structural plates with a higher thermal expansion coefficient than the rotor body, featuring splayed legs and a central portion that increases compression stress and opposes centrifugal forces, allowing for weight reduction and enhanced structural stability through interference fitting and strategic placement within an annular cavity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If material is removed to reduce rotor weight, then weight decreases, but structural strength deteriorates

Engineering Contradiction:
Improverotor weightVSAvoidstructural strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The invention creates a localized hollow cavity within the rotor body rather than uniformly reducing material throughout. This allows weight reduction in specific regions while maintaining material density and structural strength in critical load-bearing areas. The cavity is strategically positioned to remove non-critical mass while preserving the integrity of the rotor's load path.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention employs a composite structure combining solid rotor material with a hollow cavity, creating a composite cross-section that optimizes the strength-to-weight ratio. The remaining solid material forms a optimized profile that provides necessary structural strength while the hollow portion reduces overall mass.

Inventive Principle:
Principle #40Composite materials

2Weight of moving object

If rotor weight is reduced, then weight decreases, but resistance to centrifugal forces deteriorates

Engineering Contradiction:
Improverotor weightVSAvoidcentrifugal force resistance
Core Design Contradiction:
Weight of moving objectVSForce

Solution Approach 1:

The hollow cavity is strategically positioned and shaped to remove mass from regions experiencing lower centrifugal stresses while preserving material in high-stress regions. The cavity geometry is optimized to maintain the rotor's moment of inertia and centrifugal force resistance characteristics.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The cavity employs curved and optimized contours rather than simple geometric shapes, allowing the remaining material to be distributed in a manner that maximizes resistance to centrifugal forces. The curved profiles help maintain structural integrity under rotational loading.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Strength

If complex rotor shapes are designed to optimize strength, then structural strength improves, but manufacturing complexity increases

Engineering Contradiction:
Improvestructural strengthVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The complex rotor geometry is created by combining simpler components: a base rotor body with a defined cavity. This segmentation allows each component to be manufactured using standard processes, then combined to achieve the final optimized shape, reducing overall manufacturing complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cavity dimensions, shape, and position are optimized as design parameters to achieve the desired strength-to-weight ratio. By systematically varying these parameters, the design achieves optimal structural performance while remaining manufacturable with standard industrial processes.

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

This configuration effectively reduces weight while maintaining structural integrity by countering centrifugal forces and enabling thermal expansion, allowing for boroscopy inspection and improved manufacturing flexibility.

Implementation Method 1

the structural plates have a greater thermal expansion coefficient than the solid-of-revolution-shaped portion of the rotor body such that a compression stress of the interference-fit increases to force a frontward wall portion away from a rearward wall portion when the body is subjected to a temperature rise

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The rotor has a plurality of structural components, in the form of structural plates (40), which are interference-fitted, in compression, between the two wall portions (33, 35)

Methodology Applied
Scientific EffectInterference fit:

Data Source

PatentEP2985414B1Gas turbine engine rotor with annular cavity
Publication Date: 2022.01.19 PRATT & WHITNEY CANADA CORP
  • EP2985414B1 patent drawingFigure 1
  • EP2985414B1 patent drawingFigure 2A~2B
  • EP2985414B1 patent drawingFigure 3

AI summary

The gas turbine engine rotor (20) includes a body (22) having a solid-of-revolutionshaped portion centered around a rotation axis (24), the body (22) defining an annular cavity (30) centered around the rotation axis (24). The annular cavity (30) penetrates into the body (22) from an annular opening (31), which extends between two opposite annular wall portions (33, 35) each leading to a corresponding edge of the opening (21). At least one structural plate (40) is mounted to and extending between the two opposite annular wall portions (33, 35) and forming an interference fit therewith.