Annular Spring with Serpentine Ligaments for Compact Gas Turbine Bearings
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Solution Overview
Problem
Conventional bearing systems in gas turbine engines require significant axial space due to the need for spring and damper components to meet rotor dynamic stiffness and vibrational force transfer requirements, which complicates engine design and increases weight.
Innovation Solution
An annular spring with serpentine-shaped ligaments, supported by an inner and outer ring, is used in conjunction with an oil film damper to provide the necessary stiffness and damping, allowing for a compact bearing compartment design that reduces axial length and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spring and damper components are used to meet rotor dynamic stiffness and vibrational force transfer requirements, then the bearing system provides necessary rotor dynamic support, but the axial space required increases significantly
Solution Approach 1:
The bearing system is segmented into distinct functional zones: the annular spring provides stiffness support in the radial direction through its ligament structure, while the oil film damper handles vibrational damping. This segmentation allows each component to be optimized for its specific function, reducing the overall axial space requirement compared to conventional stacked spring-damper assemblies.
Solution Approach 2:
The oil film damper is positioned within the annular spring structure, with the damper nested between the inner and outer races of the spring assembly. This nested configuration allows both components to occupy overlapping axial spaces, significantly reducing the total axial length required while maintaining both stiffness and damping functions.
2Reliability
If conventional spring and damper components are used to meet rotor dynamic stiffness and vibrational force transfer requirements, then the bearing system provides necessary rotor dynamic support, but the weight increases
Solution Approach 1:
The annular spring and oil film damper are merged into a single integrated bearing assembly where the damper is positioned within the spring structure. This merging eliminates redundant structural elements and allows the two components to share load paths, reducing the total material required and thus the weight, while maintaining both stiffness and damping functions.
3Length of moving object
If the bearing compartment axial length is reduced to meet engine arrangement and clearance requirements, then engine compactness improves, but the rotor dynamic stiffness and damping performance may be compromised
Solution Approach 1:
The annular spring utilizes a ligament structure that acts as a flexible element, providing radial stiffness while occupying minimal axial space. The serpentine-shaped ligaments are designed with specific geometric parameters to achieve the required stiffness characteristics in a compact form, allowing the bearing compartment to maintain rotor dynamic performance with reduced axial length.
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 annular spring and oil film damper combination effectively absorbs rotor motion and vibrational forces while minimizing axial space, enabling a more compact and lightweight bearing compartment that supports engine shafts efficiently.
Implementation Method 1
An annular spring for a bearing assembly of gas turbine engine includes an inner support, an outer support and a multiple of ligaments between the inner support and the outer support. Each of the multiple of ligaments are serpentine shaped.
Implementation Method 2
An oil film damper is radially between the bearing assembly and the bearing support static structure. The damper minimizes the transfer of vibrational forces from and into static structure.
Data Source
AI summary
An annular spring for a bearing assembly of gas turbine engine is provided. The annular spring includes a multiple of ligaments between an inner support and an outer support.