Aircraft Engine Squeeze Film Damper With Adaptive Fluid Regimes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft engine squeeze film dampers vary in behavior with operating conditions, affecting their ability to effectively dampen vibrations, and there is a need for a system that can adaptively adjust damping characteristics to manage vibrations of varying amplitudes.
Innovation Solution
A controller system that operates the squeeze film damper in two regimes based on vibration amplitude, adjusting the speed of the damping fluid by modifying the pressure of the oil and air relative volume within the damper, allowing the damper to switch between a stiff and compliant state to optimize vibration damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the squeeze film damper operates in a first regime with subsonic fluid speed, then the damping characteristics are stable and predictable, but the damping coefficient is insufficient for high amplitude vibrations
Solution Approach 1:
The system dynamically transitions between two operating regimes based on vibration amplitude. The controller monitors vibration levels and switches the damper from a first regime (with first damping coefficient) to a second regime (with second damping coefficient) when vibration amplitude exceeds a threshold, enabling adaptive optimization of damping performance
Solution Approach 2:
The invention changes physical parameters of the damping fluid by injecting gas into the oil, transforming it from a single-phase liquid to a two-phase mixture. This parameter change reduces the speed of sound in the fluid and increases compressibility, thereby increasing the damping coefficient in response to high amplitude vibrations
2Productivity
If the squeeze film damper operates in a second regime with supersonic fluid speed, then the damping coefficient increases for high amplitude vibrations, but the damping characteristics become less stable
Solution Approach 1:
The controller continuously monitors vibration amplitude and uses this feedback to determine when to switch between operating regimes. When vibration amplitude exceeds a threshold, the controller activates the second regime with higher damping coefficient; when vibrations decrease, it returns to the first regime, maintaining optimal stability and performance
Solution Approach 2:
The system dynamically adjusts its operating state based on real-time vibration conditions, transitioning between two distinct regimes. This dynamic adaptation allows the damper to provide high damping coefficients when needed while maintaining stability during normal operation
3Productivity
If gas is injected into the damping fluid to increase damping coefficient, then the speed of sound in the fluid decreases and damping performance improves, but the system complexity increases
Solution Approach 1:
The invention uses pneumatic injection of gas into the oil-based damping fluid to create a two-phase mixture. This pneumatic approach modifies the fluid's physical properties (reducing speed of sound, increasing compressibility) to enhance damping coefficients without requiring mechanical redesign of the damper structure
Solution Approach 2:
The system changes the physical and chemical parameters of the damping fluid by introducing gas bubbles into the oil. This transforms the fluid from incompressible to compressible, fundamentally altering its damping characteristics and enabling higher damping coefficients in response to vibration amplitude
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 system effectively adapts to manage vibrations of varying amplitudes by adjusting the damping characteristics, enhancing the ability to absorb and dampen vibrations, thereby improving the overall performance of the aircraft engine.
Implementation Method 1
the damping fluid in the annular space between the bearing outer race and the bearing housing. The controller is configured to operate the squeeze film damper in a first regime in which a speed of the damping fluid in the annular space is less than a speed of sound in the damping fluid; determine that the shaft is subjected to vibrations having an amplitude greater than an amplitude threshold; and upon determining that the amplitude of the vibrations is greater than the amplitude threshold, operate the squeeze film damper in a second regime in which the speed of the damping fluid in the annular space is greater than the speed of sound in the damping fluid
Implementation Method 2
operate the squeeze film damper in a second regime in which the speed of the damping fluid in the annular space is greater than the speed of sound in the damping fluid
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An aircraft engine (10) is described which has: a shaft (16, 18); a bearing housing (25) extending around the shaft (16, 18) and defining a bearing cavity; a bearing (21) within the bearing cavity and supporting the shaft (16, 18); a squeeze film damper (26) having an annulus (27) receiving a damping fluid; and a controller (40). The controller (40) is configured to: operate the squeeze film damper (26) in a first regime in which a speed of the damping fluid in the annulus (27) is less than a speed of sound in the damping fluid; determine that the shaft (16, 18) is subjected to vibrations having an amplitude greater than an amplitude threshold; and upon determining that the amplitude of the vibrations is greater than the amplitude threshold, operate the squeeze film damper (26) in a second regime in which the speed of the damping fluid in the annulus (27) is greater than the speed of sound in the damping fluid.