Axially Offset Rotor Disk With Bladed Ring For Gas Turbine Fatigue
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Solution Overview
Problem
Gas turbine engine rotor assemblies in the high-pressure compressor section face low fatigue life due to large strain ranges caused by extreme temperature differences, and existing cooling methods compromise compressor efficiency.
Innovation Solution
The implementation of axially offset rotor disks with integrated bladed rings that are formed as a single continuous piece, decoupling rotor airfoils from rotor disks to minimize strain and enhance part life without relying on airflow cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If primary flowpath air is extracted to cool the inner diameters of the compressor rotor assembly, then component fatigue life is improved, but compressor efficiency is compromised
Solution Approach 1:
The rotor assembly is segmented into functionally distinct components: rotor airfoils for compression and a separate bladed ring for structural support and strain distribution. This segmentation allows each component to be optimized independently, eliminating the need for airflow extraction while maintaining fatigue resistance.
Solution Approach 2:
The bladed ring acts as an intermediary structure between the rotor airfoils and the rotor disk. It decouples the rotor airfoils from direct attachment to the rotor disk, distributing strains more evenly and reducing stress concentrations without requiring active cooling from primary flowpath air.
2Strength
If rotor airfoils are directly attached to rotor disks, then structural integrity is maintained, but strain range increases reducing fatigue life
Solution Approach 1:
The direct attachment between rotor airfoils and rotor disks is segmented by introducing a bladed ring intermediate structure. This allows the rotor airfoils to be supported while distributing the mechanical strains across the bladed ring structure, reducing peak stresses and improving fatigue life.
Solution Approach 2:
The bladed ring structure provides dynamic strain distribution capabilities, allowing the rotor assembly to better accommodate thermal and mechanical loading variations during operation. This dynamic response reduces strain ranges compared to rigid direct attachment.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A rotor assembly (26) for a gas turbine engine includes a rotor airfoil (28) and a first rotor disk (36). The rotor airfoil (28) extends along a radial axis (R). The first rotor disk (36) includes an outer rim (38), a bore (40) and a web (42) extending between the outer rim (38) and the bore (40). The first rotor disk (36) is axially offset from the radial axis (R) of the rotor airfoil (28).