Variable Volume Acoustic Damper for Gas Turbine Fan Flutter
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Solution Overview
Problem
Gas turbine engines face issues with fan flutter and other acoustic phenomena, leading to reduced efficiency, shortened blade life, and increased noise, particularly during high-load conditions like take-off and landing.
Innovation Solution
A variable volume acoustic damper with a movably coupled diaphragm and an expandable bladder, controlled by a feedback loop system, adjusts its acoustic volume in response to ambient pressure and detected operating conditions to dampen fan flutter and other acoustic energies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed volume acoustic damper is used, then the structure is simple, but the acoustic damping effectiveness varies under different operating conditions
Solution Approach 1:
The patent applies the dynamics principle by making the acoustic damper volume variable rather than fixed. A diaphragm is introduced that can move between different positions to change the volume of the acoustic damping chamber based on operating conditions. The diaphragm is actuated by an actuator (such as a motor or pneumatic device) that adjusts the diaphragm position in response to detected acoustic conditions, thereby dynamically adapting the damper volume to optimize acoustic damping effectiveness across different operating scenarios.
2Object-affected harmful factors
If the acoustic volume is increased, then the acoustic energy damping capability is improved, but the device size increases
Solution Approach 1:
The patent implements a variable volume acoustic damper where the acoustic volume can be dynamically adjusted based on operating conditions. A diaphragm is positioned within the acoustic damping chamber and can move between different positions, changing the effective acoustic volume. The diaphragm is actuated by an actuator that responds to detected acoustic conditions, allowing the system to increase the acoustic volume when high damping is needed and decrease it when less damping is required, thereby optimizing the balance between damping capability and device size.
3Volume of stationary object
If the acoustic volume is decreased, then the device size is reduced, but the acoustic energy damping capability is reduced
Solution Approach 1:
The patent implements a variable volume acoustic damper where the acoustic volume can be dynamically adjusted based on operating conditions. A diaphragm is positioned within the acoustic damping chamber and can move between different positions, changing the effective acoustic volume. The diaphragm is actuated by an actuator that responds to detected acoustic conditions, allowing the system to increase the acoustic volume when high damping is needed and decrease it when less damping is required, thereby optimizing the balance between damping capability and device size.
4Adaptability or versatility
If a variable volume acoustic damper is used, then the acoustic damping effectiveness is improved, but the device complexity increases
Solution Approach 1:
The patent applies the dynamics principle by making the acoustic damper volume variable rather than fixed. A diaphragm is introduced that can move between different positions to change the volume of the acoustic damping chamber based on operating conditions. The diaphragm is actuated by an actuator (such as a motor or pneumatic device) that adjusts the diaphragm position in response to detected acoustic conditions, thereby dynamically adapting the damper volume to optimize acoustic damping effectiveness across different operating scenarios.
Solution Approach 2:
The patent implements a feedback control system where acoustic conditions are detected by sensors (such as microphones or acoustic transducers) and this information is fed back to a controller. The controller processes the acoustic condition data and generates control signals to the actuator, which adjusts the diaphragm position accordingly. This closed-loop feedback mechanism enables the system to automatically adapt to changing acoustic conditions and optimize damping effectiveness without manual intervention.
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 solution effectively reduces fan flutter and acoustic noise, enhancing the operational efficiency and lifespan of gas turbine engine fan blades while minimizing community noise impacts.
Implementation Method 1
The expandable bladder is configured to expand in response to a decrease in ambient pressure, thereby moving the position of the diaphragm to decrease the acoustic volume. The expandable bladder may also be configured to retract in response to an increase in ambient pressure
Implementation Method 2
an acoustic volume is defined by a position of the diaphragm relative to the case and the acoustic volume corresponds to and is configured to damp the acoustic energy
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A gas turbine engine (20) includes at least one of a fan inlet case and a bypass duct case. Additionally, the gas turbine engine (20) includes a variable volume acoustic damper (210) coupled to the at least one of the fan inlet case (220) and the bypass duct case, wherein the variable volume acoustic damper (210) is configured to damp acoustic energy. The variable volume acoustic damper (210) includes a case (212; 312) and a diaphragm (214; 314) movably coupled within the case (212; 312). An acoustic volume is defined by a position of the diaphragm (214; 314) relative to the case (212; 312) and the acoustic volume corresponds to and may be configured to damp acoustic energy of the gas turbine engine (20).