Asymmetric Annular Centering Spring for Bearing Vibration Damping
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Solution Overview
Problem
Conventional centering spring designs in gas turbine engines, such as the squirrel cage design, are prone to amplifying vibrations and do not effectively reduce cyclic fatigue, leading to excessive structural loads and potential damage.
Innovation Solution
The use of asymmetric annular springs in the bearing compartment, which can be adjusted in material, thickness, turns per unit area, length, or shape, to reduce vibration amplification and provide improved damping, including a combination of first and second annular springs with angular or material asymmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional symmetric centering spring designs (squirrel cage) are used, then the structure is simple and easy to manufacture, but vibration amplification occurs and cyclic fatigue is not reduced
Solution Approach 1:
The patent applies asymmetry by designing the annular spring with non-uniform thickness, material distribution, or geometric parameters around the circumference. This asymmetric configuration creates unequal stiffness characteristics that prevent resonance and vibration amplification, thereby reducing cyclic fatigue in the bearing compartment while accepting increased design complexity.
2Object-affected harmful factors
If asymmetric annular springs are implemented, then vibration amplification is reduced and damping is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements local quality by varying the thickness, material composition, or geometric parameters of the annular spring at different circumferential locations. This allows specific regions of the spring to have different stiffness characteristics, effectively reducing vibration amplification while maintaining manufacturability through localized modifications rather than complete redesign.
3Strength
If symmetric spring designs are used, then manufacturing is easier, but excessive structural loads occur due to vibration
Solution Approach 1:
The patent uses asymmetric spring configuration to eliminate resonant conditions that cause excessive structural loads. By creating non-uniform stiffness distribution around the annular spring, the design prevents vibration amplification that would otherwise transmit harmful loads to the bearing compartment and surrounding structures.
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 asymmetric annular springs effectively reduce vibration amplification and enhance damping, leading to reduced structural loads and improved durability of gas turbine engine components.
Implementation Method 1
During operation, the rotating shafts and other rotating turbomachinery can vibrate about the engine centerline. If not dampened, these vibrations may cause excessive structural loads and result in damage.
Implementation Method 2
Dampers are used adjacent to the bearing assemblies to reduce the amplitudes of vibrations in the rotating shaft that are transmitted to the rest of the gas turbine engine.
Implementation Method 3
One commonly used viscous damper is the squeeze film damper, which utilizes a small, fluid-filled annular gap between the bearing and a nonrotating housing. Radial motion of the rotating shaft causes relative motion between the bearing and the nonrotating housing, which changes the gap to squeeze a damping fluid within the annulus, dampening the motion of the rotating shaft.
Data Source
AI summary
An assembly for use in a bearing compartment having an axis includes a bearing outer race configured to be located in the bearing compartment. The assembly further includes at least one annular spring positioned in the bearing outer race and being asymmetric in at least one of the axial direction or the circumferential direction relative to the axis to reduce the likelihood of amplification of vibration experienced by the at least one annular spring.