Compressor Rotor Stack Assembly with Segmented Backbone
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Solution Overview
Problem
Gas turbine engines face challenges in reducing rotor stress and mass at high radius regions due to increasing operational speeds, as existing tie configurations lead to excessive compressive loads and bending of rotor backbones, necessitating thick backbone structures.
Innovation Solution
A compressor rotor assembly with a radially outer and inner backbone system, where spacers and backbone segments are integrally formed with rotor disks and axially compressed by a tie shaft, reducing the thickness and weight of the radially outer backbone and distributing compressive loads efficiently through a cylindrical inner backbone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a bore tied configuration is used to tie rotor disks together, then the rotor disks are secured against relative rotation, but a massive compressive load is put on the rotor backbone causing it to become bowed and requiring a very thick backbone structure
Solution Approach 1:
The backbone is divided into multiple discrete segments positioned at different radial locations (inner backbone segments and outer backbone segments) rather than using a single continuous thick backbone. Each segment is independently connected to rotor disks and tied together, distributing the structural function across multiple lighter components.
Solution Approach 2:
The solution transitions from a single-dimensional thick backbone to a multi-dimensional segmented backbone structure. The backbone is arranged in multiple radial dimensions (inner and outer segments) and axial dimensions (multiple segments along the rotor stack), creating a distributed three-dimensional structure that reduces the mass requirement of any single component.
2Strength
If the rotor backbone is made very thick to handle compressive loads, then the backbone can support the compressive force, but the mass in high radius regions increases which is problematic for high-speed rotation
Solution Approach 1:
The backbone is segmented into multiple discrete sections (inner backbone segments and outer backbone segments) positioned at different radial locations. This segmentation allows each segment to be optimized for its specific load conditions, reducing the overall mass compared to a single thick backbone while maintaining sufficient load capacity through the distributed structure.
Solution Approach 2:
Different backbone segments are positioned at different radial locations (inner vs outer) to provide locally optimized structural support. The inner backbone segments handle loads near the center while outer backbone segments provide support at the periphery, allowing each location to have the precise structural quality needed rather than uniformly thick construction throughout.
3Strength
If a massive thick backbone structure is used, then the compressive load can be supported, but the complexity of bolted joints and welds increases
Solution Approach 1:
The backbone is divided into discrete segments that are connected through standardized tie rods and fastening mechanisms. This segmentation creates modular connection points that simplify the joint design compared to welding a single massive backbone, as each segment connection can use standardized mechanical fasteners rather than complex weld assemblies.
Solution Approach 2:
Tie rods serve as intermediary elements that connect the inner and outer backbone segments to the rotor disks. These tie rods act as standardized mechanical mediators that simplify the connection architecture, replacing the need for direct complex welds between massive backbone components with simpler, standardized fastening mechanisms.
Data Source
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Figure 2
AI summary
A compressor rotor assembly (24) including a plurality of rotor disks (60) axially spaced from each other, each rotor disk extending radially from an inner end (78) to an outer end (76). Also included is a spacer (68) extending axially from each rotor disk to engage an adjacent spacer extending from an adjacent rotor disk, the spacer and adjacent spacer disposed proximate the outer end of the respective rotor disks, the spacers forming an outer backbone (62) of the compressor rotor assembly. Further included is an inner backbone (64) of the compressor rotor assembly, the inner backbone comprising a plurality of backbone segments (70), each of the backbone segments extending axially from each rotor disk to engage an adjacent backbone segment extending from an adjacent rotor disk, the backbone segment and the adjacent backbone segment disposed proximate the inner end of the respective rotor disks.