Restricted Outer Race Damper for Compact Bearing Compartments
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Solution Overview
Problem
Bearing compartments in gas turbine engines face challenges with space constraints, making it difficult to incorporate essential components and meet rotor dynamic requirements, particularly in reducing axial length while maintaining effective damping and fatigue life.
Innovation Solution
The implementation of radially separated damping cavities that combine to provide an effective damper length, allowing for a longer damper to be packaged in an axially compressed space by subdividing the damper into radially separated segments, which are then 'stacked' to achieve the desired axial damper length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the damper axial length is increased to meet rotor dynamic requirements, then the damping effectiveness is improved, but the bearing compartment axial space requirement increases
Solution Approach 1:
The patent transitions from a conventional axial damper configuration to a radial damper configuration. By orienting the damper segments radially rather than axially, the effective damper length is achieved in the radial dimension while minimizing axial space consumption. The radially extending damper segments create squeeze film damping effects that meet rotor dynamic requirements without increasing the bearing compartment axial length.
Solution Approach 2:
The damper is divided into multiple radially spaced damper segments that are axially offset from each other. These segments collectively provide the required effective damper length through their radial extension, while their axial offset arrangement allows them to be packaged within a compressed axial space. The segmented structure enables the stacking of damper functionality in the radial direction rather than requiring continuous axial length.
2Length of moving object
If the bearing compartment size is reduced to save space, then the axial length is decreased, but it becomes difficult to incorporate essential components and perform maintenance tasks
Solution Approach 1:
By reorienting the damper configuration from axial to radial, the patent reduces the axial length requirement of the bearing compartment. This dimensional change allows the compartment to be more compact in the axial direction while maintaining adequate space for components and maintenance activities in the radial and circumferential dimensions, where access can be facilitated through the bearing housing structure.
3Length of moving object
If the damper is packaged in axially compressed space, then the axial length is reduced, but the bending stresses on the centering spring increase
Solution Approach 1:
The radial damper configuration changes the load distribution geometry compared to an axial damper arrangement. By extending the damper segments radially and offsetting them axially, the centering spring experiences more favorable stress distribution with reduced bending moments. The radial orientation allows the spring to primarily experience axial loads rather than combined axial and bending loads, thereby reducing bending stresses even in a compact axial package.
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
This approach efficiently packages a longer damper, enhancing rotor dynamic damping and meeting dynamic behavior requirements while reducing bending stresses and increasing fatigue life of the centering spring.
Implementation Method 1
the outer race is shaped to form an annular cavity between the outer race and the bearing support, which forms a squeeze film damper (SFD) when filled with a damping fluid. With this configuration, radial displacement of the outer race relative to the bearing support is restrained by squeeze film pressure.
Data Source
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AI summary
A bearing assembly comprises a housing (104) that includes a first housing surface (105) and a second housing surface (106). The first and second housing surfaces (105, 106) are substantially axially parallel with respect to a rotor centerline (12). The bearing assembly also comprises a damped outer race (108) that includes a first outer race surface (110) radially adjacent to and opposing the first housing surface (105) which is located radially interior to the first outer race surface (110). A second outer race surface (116) is radially adjacent to and opposing the second housing surface (106) which is located radially exterior to the second outer race surface (116). The housing comprises an oil passage (122) that is configured to provide oil from an outlet to a first space (124) between the first outer race surface (110) and the first housing surface (105), and configured to provide oil to a second space (126) radially between the second outer race surface (116) and the second housing surface (106).