Concentric Shaft-Stator Support for Supercritical Vibration Damping
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Solution Overview
Problem
Power transmission systems in gas turbine engines face issues with high vibration and whirl instability at supercritical speeds, leading to excessive wear and premature failure, which current solutions like stiffer shafts or external dampers cannot effectively address due to material costs and space constraints.
Innovation Solution
A power transmission system comprising a shaft with a stator and supporting elements, such as oil squeeze film dampers or oil journal bearings, positioned between the stator and shaft to reduce vibration and allow rotation, thereby mitigating the effects of supercritical speeds without requiring expensive materials or additional space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a stiffer shaft is used to reduce vibration at supercritical speeds, then shaft strength is improved, but weight and manufacturing cost increase
Solution Approach 1:
The stator is nested inside the shaft, creating a concentric structure where the stator serves as an internal support element. This nested configuration allows the shaft to maintain its original lightweight design while the internal stator provides the necessary stiffness and vibration resistance, eliminating the need to increase shaft weight or use expensive materials.
2Object-affected harmful factors
If external dampers are added to reduce vibration, then vibration control is improved, but device complexity and space requirements increase
Solution Approach 1:
The damping function is merged with the shaft structure itself by installing the stator and supporting elements directly within the shaft. This integration combines the shaft's rotational function with the stator's vibration-damping function into a single unified structure, eliminating the need for separate external damper components and reducing overall system complexity.
Solution Approach 2:
The stator and supporting elements are nested within the shaft's internal space, utilizing the existing structural volume rather than adding external components. This nested arrangement provides vibration control functionality without increasing the overall device footprint or requiring additional installation space.
3Strength
If a stiffer shaft is used to reduce vibration, then shaft strength is improved, but manufacturing cost increases
Solution Approach 1:
The stator is nested inside the shaft as a separate, manufacturable component rather than requiring the shaft itself to be made from expensive specialized materials. This allows the shaft to be manufactured from standard materials at lower cost, while the internal stator provides the necessary structural reinforcement and vibration resistance.
Solution Approach 2:
The vibration control function is segmented from the shaft structure and implemented as a separate stator component. This segmentation allows each component to be optimized and manufactured independently using cost-effective processes, rather than requiring the entire shaft to be made from expensive specialized materials.
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
The solution significantly reduces shaft vibration and flexion, extending bearing life and reducing operational stresses, achieving up to 90%-99% reduction in shaft center motion at specific frequencies, while avoiding the need for costly materials or external dampers.
Implementation Method 1
at least one supporting element positioned between the stator and the shaft and configured to support the shaft on the stator to reduce a vibration of the shaft
Implementation Method 2
supporting elements, such as oil squeeze film dampers or oil journal bearings
Data Source
AI summary
A power transmission system includes a shaft, a stator disposed within the shaft and substantially concentric with the shaft; and at least one supporting element positioned between the stator and the shaft and configured to support the shaft on the stator to reduce a vibration of the shaft and allow the shaft to rotate relative to the stator. A gas turbine engine including the power transmission system is also described.