U-Shaped Beam Support Damper for Off-Center Rotor Vibration
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Solution Overview
Problem
Squeeze film dampers in gas turbine engines can become stiff and inadequate for absorbing vibration when the rotor becomes off-center, leading to increased rotor unbalance response and vibration, particularly at specific engine operating speeds, and they may not effectively limit rotor radial excursion or accommodate thrust loads.
Innovation Solution
A support damper comprising an inner ring, an outer ring, and U-shaped beams that couple them, providing axial extension around the bearing assembly and radial extension outwardly, which helps maintain a controlled clearance and accommodates off-center rotor positions, while allowing fluid flow to enhance damping capabilities and structural stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a squeeze film damper is used to damp rotor vibration, then vibration reduction is achieved in some cases, but the damper becomes stiff when the rotor becomes off-center, reducing its ability to absorb vibration
Solution Approach 1:
The support damper is segmented into multiple U-shaped beams (typically three) that are distributed around the bearing assembly. Each beam independently provides damping support, allowing the system to adapt to off-center rotor positions while maintaining overall vibration damping effectiveness. The segmentation enables the damper to flexibly accommodate rotor movement in different directions.
Solution Approach 2:
The U-shaped beams are designed with controlled flexibility to dynamically adapt to rotor position changes. The beams can deflect and deform elastically as the rotor moves off-center, maintaining contact and damping effectiveness throughout the rotor's orbital motion. This dynamic behavior allows the damper to remain effective across varying operating conditions.
2Strength
If the support housing stiffness is increased to provide structural support, then structural stability is improved, but the rotor group vibrates with certain modes at particular engine operating speeds
Solution Approach 1:
The U-shaped beams function as flexible structural elements that provide both support and vibration isolation. These beams act as elastic films that can deflect under rotor loads while maintaining structural integrity, thereby reducing transmitted vibrations to the support housing and preventing resonant vibrations at critical speeds.
Solution Approach 2:
The stiffness of the U-shaped beams is carefully controlled through parameter optimization (cross-sectional dimensions, material properties, beam length) to achieve the desired balance between structural support and vibration damping. By adjusting these parameters, the damper provides adequate support while minimizing vibration transmission to the rigid support housing.
3Volume of moving object
If a compact design is implemented to fit existing engine spaces, then space utilization is improved, but manufacturing and assembly complexity may increase
Solution Approach 1:
The support damper is designed as a nested structure where the U-shaped beams are positioned within the clearance space between the bearing assembly and support housing. The inner ring fits around the bearing assembly, and the U-shaped beams extend radially outward to connect with the outer ring, utilizing existing engine spaces efficiently without requiring additional external volume.
Solution Approach 2:
The support damper combines multiple functions into a single integrated structure: the U-shaped beams simultaneously provide mechanical support, vibration damping, and rotor position accommodation. This merging of functions reduces the need for separate components, simplifying the overall assembly and reducing the volume required in the engine.
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 support damper improves damping effectiveness, minimizes rotor unbalance response, limits radial excursion, and accommodates thrust loads, with a compact design suitable for retrofitting into existing engines, effectively addressing the limitations of traditional squeeze film dampers.
Implementation Method 1
The U-shaped beam couples the inner ring to the outer ring
Implementation Method 2
A squeeze film damper operates by supplying fluid (usually oil) through dedicated oil delivery passages into a squeeze film cavity formed via a clearance between the support housing and the bearing assemblies
Data Source
AI summary
A support damper is provided for a bearing assembly to improve the damping capabilities of an uncentered squeeze film damper and to provide a support structure stiffness to minimize rotor to structure unbalance response. In one embodiment, and by way of example only, the support damper includes an inner ring, an outer ring, and U-shaped beams. The inner ring is configured to be disposed around the bearing assembly and to extend axially along a portion thereof. The outer ring is spaced apart from the inner ring and extends radially outwardly relative thereto. The U-shaped beams couple the inner ring to the outer ring. Methods of manufacturing the support damper are also provided.