Offset Damper Reduces Vibratory Stress in Gas Turbine Blades
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Solution Overview
Problem
Conventional gas turbine engines face challenges in reducing vibratory stresses without increasing weight, as traditional dampers are centered on the blade-to-blade centerline and do not effectively optimize load distribution between adjacent blades.
Innovation Solution
The damper is positioned at an offset position within the gap between adjacent turbine blades, allowing for an unequal load split and reduced mass distribution, which optimizes damping performance by shifting the center of mass off the blade-to-blade centerline, thereby reducing vibratory stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the damper is centered on the blade-to-blade centerline, then the damper provides balanced support between adjacent blades, but the vibratory stress reduction performance is insufficient
Solution Approach 1:
The patent applies asymmetry by positioning the damper at an offset location within the gap between adjacent turbine blade platforms, rather than at the traditional centered position on the blade-to-blade centerline. This asymmetric positioning creates an unequal load split between the adjacent blades (approximately 60% to one blade and 40% to the other), which optimizes the damping effect and reduces vibratory stress more effectively than symmetric positioning.
2Reliability
If the damper mass is increased to improve damping performance, then the vibratory stress reduction improves, but the overall weight of the turbine engine increases
Solution Approach 1:
The patent changes the positional parameter of the damper within the gap between adjacent blades, specifically offsetting the damper from the centerline position. This parameter change optimizes the load distribution and damping effectiveness, allowing for reduced damper mass while maintaining or improving vibration reduction performance, thereby avoiding increased engine weight.
3Reliability
If the damper is positioned at an offset position, then the load split between adjacent blades is optimized for reduced vibrations, but the manufacturing and installation precision requirements increase
Solution Approach 1:
The patent applies local quality by creating a specific asymmetric load distribution (60%/40% split) at the local position of the damper within the gap between adjacent blades. This localized optimization of load distribution at the damper position achieves superior vibration reduction while the offset position can be designed to accommodate reasonable manufacturing and installation tolerances.
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 configuration achieves reduced vibratory stress while maintaining high stiffness and minimizing weight, improving damper performance without increasing the overall mass of the turbine engine.
Implementation Method 1
a damper is typically installed between adjacent turbine blades to dissipate potentially damaging vibrations
Data Source
AI summary
A gas turbine engine rotor assembly includes a plurality of blades spaced apart from each other for rotation about an axis. Each of the blades includes a platform having an inner surface and an outer surface. Adjacent platforms are separated from each other by a gap. A damper is positioned at an offset position within the gap to contact the inner surfaces of the adjacent platforms.