Tunable Combustor Acoustic Damper for Shifting Instability Frequencies
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Solution Overview
Problem
Existing acoustic dampers in turbine engine combustors are often mistuned due to initial frequency assumptions during design, leading to ineffective suppression of combustion instability as environmental conditions shift.
Innovation Solution
The acoustic damper is designed to be tunable in frequency through mechanical and thermodynamic adjustments, including movable pistons, bellows, adjustable neck holes, and varying gas mixtures to align with actual combustion frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed-frequency acoustic damper is designed based on initial frequency assumptions, then the manufacturing and installation process is simplified, but the damper becomes mistuned when environmental conditions shift, leading to ineffective suppression of combustion instability
Solution Approach 1:
The acoustic damper incorporates movable components (pistons, bellows) that allow the cavity volume to be dynamically adjusted. This enables the resonant frequency of the damper to be tuned to match the actual combustion instability frequency, resolving the contradiction between fixed design simplicity and adaptive performance reliability.
Solution Approach 2:
The damper design allows changing physical parameters (cavity volume, neck area) to adjust the resonant frequency. By modifying these parameters, the damper can be tuned to different frequencies, maintaining effectiveness across varying environmental conditions while preserving the basic fixed-structure advantage.
2Reliability
If the acoustic damper cavity volume is increased to improve damping effectiveness, then the suppression capability is enhanced, but the device complexity and space requirements increase
Solution Approach 1:
Instead of using a large fixed cavity volume, the invention employs a smaller cavity with movable pistons or bellows that can dynamically adjust the effective volume. This maintains high damping effectiveness when needed while keeping the physical structure compact and less complex.
Solution Approach 2:
The use of pneumatic elements (bellows, movable pistons) allows for dynamic volume adjustment without requiring large structural changes. These elements provide efficient volume modulation with relatively simple mechanical structures, enhancing damping capability without proportionally increasing device complexity.
3Adaptability or versatility
If the acoustic damper is made tunable with movable components, then the adaptability to different combustion frequencies is improved, but the device complexity and potential failure points increase
Solution Approach 1:
The invention achieves tunability by allowing adjustment of physical parameters (cavity volume, neck area) through movable components. This provides adaptability to different combustion frequencies while maintaining a relatively straightforward mechanical adjustment mechanism rather than complex active control systems.
Solution Approach 2:
The movable components (pistons, bellows) are localized within the damper structure, allowing frequency tuning without requiring complex changes throughout the entire system. This concentrates the adaptability function in specific adjustable regions, minimizing overall device complexity.
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 adaptability ensures optimal damping of acoustic vibrations, effectively suppressing combustion instability across varying environmental conditions.
Implementation Method 1
the acoustic damper can have its performance optimized in real time by enabling the acoustic damper to be thermodynamically adaptively tunable... The measured frequency of the acoustic instability of the combustor can also shift over the operational space and the frequency of maximum damping attenuation for the acoustic damper can also shift
Data Source
AI summary
A combustor for a turbine engine includes a wall defining a combustion chamber, and an acoustic damper. The acoustic damper includes a housing in fluid communication with the combustion chamber through an opening provided in the wall, the housing defining a cavity and having one or more neck holes in fluid communication with the combustion chamber, and a mechanism configured to vary a damping acoustic frequency of the acoustic damper so as to vary the damping acoustic frequency of the acoustic damper to align with an acoustic frequency of acoustic vibrations generated in the combustion chamber to attenuate an acoustic instability within the combustion chamber.