Variable Squeeze Film Damper for Gas Turbine Engine Damping Control
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Solution Overview
Problem
Existing squeeze film damper systems in gas turbine engines provide consistent damping levels, which are inadequate during engine start conditions and excessive during cruising, leading to inefficiencies in engine performance.
Innovation Solution
A variable squeeze film damper system with independently controllable fluid supplies and annuli volumes, allowing for adjustable damping levels based on engine operational modes, where multiple fluid supplies are engaged during high damping needs and reduced or eliminated during low damping requirements, utilizing a movable piston to control annulus volume in alternative configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If consistent damping is provided during all engine operating conditions, then damping is sufficient during engine start conditions, but engine efficiency decreases during cruising conditions due to excess damping
Solution Approach 1:
The patent applies dynamics by making the damping characteristic variable rather than fixed. The squeeze film damper is configured to provide different damping levels at different engine operating conditions through variable oil film thickness or viscosity control mechanisms, allowing high damping during start conditions and low damping during cruising conditions.
Solution Approach 2:
The patent changes physical parameters of the damping system, specifically the oil film thickness or oil viscosity in the squeeze film damper. By varying these parameters based on engine operating conditions, the system achieves high damping when needed (during start) and low damping when efficiency is priority (during cruising).
2Loss of time
If higher damping is provided during engine start conditions, then air motoring time is reduced, but engine efficiency decreases during high speed operation
Solution Approach 1:
The variable damping characteristic allows the system to be dynamically adjusted: high damping is activated during start conditions to reduce air motoring time, and then switched to low damping during high-speed operation to maximize horsepower and efficiency.
Solution Approach 2:
The damping level is periodically adjusted based on engine operating phase. The system transitions from high damping during start-up phase to low damping during normal operation phase, matching the periodic nature of engine operation cycles.
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 enables optimized damping levels that enhance engine performance by shortening air motoring times during starts and increasing horsepower at high speeds, improving overall engine efficiency by dynamically adjusting damping according to operational conditions.
Implementation Method 1
Vibratory and/or radial motion of the shaft and its bearing generate hydrodynamic forces in the damper oil within the annular film space for damping purposes
Implementation Method 2
An annular film space is defined between an outer surface of the outer race and an opposite inner surface of the bearing housing such that damper oil can be introduced therein. Vibratory and/or radial motion of the shaft and its bearing generate hydrodynamic forces in the damper oil within the annular film space for damping purposes
Data Source
AI summary
A damper assembly includes a bearing assembly including a radially outer surface. A housing surrounds the bearing assembly and includes a radially inner surface facing the radially outer surface. The radially outer and inner surfaces define a plurality of annuli therebetween. The damper assembly further includes a plurality of fluid supplies coupled in flow communication with the plurality of annuli and configured to deliver a fluid to each annulus of the plurality of annuli. Each fluid supply of the plurality of fluid supplies independently controls the fluid within the respective annulus.