Multi-Resonator Damper for Broadband Combustion Damping
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Solution Overview
Problem
Traditional Helmholtz dampers are ineffective in addressing pressure oscillations with frequency shifts and multiple frequency modes in gas turbines, leading to incomplete damping and instability in combustion chambers due to their narrow frequency bandwidth and limited installation locations.
Innovation Solution
A damper arrangement with interconnected volumes and necks connected at multiple points to the combustion chamber, allowing for simultaneous damping of multiple frequencies across a broader bandwidth without the need for extensive fine-tuning, using various configurations such as parallel and series connections, and adjustable acoustic coupling with materials like absorption materials and pistons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single Helmholtz damper is used with a fixed resonance frequency, then it can effectively damp pressure oscillations at that specific frequency, but it becomes ineffective when the pressure oscillation frequency shifts even slightly
Solution Approach 1:
The damper is divided into multiple independent Helmholtz resonators, each tuned to a different frequency. This segmentation allows the system to target multiple frequency ranges simultaneously, resolving the contradiction between precise damping at a specific frequency and adaptability to frequency shifts.
Solution Approach 2:
The damper arrangement is designed to perform multiple functions by incorporating resonators with different resonance frequencies. This multi-functional design enables the single damper structure to effectively damp pressure oscillations across a broad frequency spectrum, making it universally applicable regardless of frequency variations.
2Adaptability or versatility
If multiple Helmholtz dampers are connected in series to address different frequencies, then the damping bandwidth increases, but the arrangement becomes complex and requires precise positioning at multiple locations
Solution Approach 1:
Multiple Helmholtz resonators that would traditionally require separate damper units are merged into a single integrated damper structure. This combining approach maintains the broad frequency damping capability while reducing the number of separate components and simplifying the installation process to a single location.
Solution Approach 2:
The single damper structure is designed to perform the function of multiple dampers by incorporating multiple resonators with different frequency tuning capabilities. This universal design eliminates the need for multiple installation locations while maintaining the ability to damp a wide frequency range.
3Adaptability or versatility
If multiple Helmholtz dampers are installed at different locations to damp different frequency modes, then broadband damping is achieved, but the limited installation locations in a combustion chamber make this impractical
Solution Approach 1:
The solution merges multiple frequency-targeting resonators into a single damper unit that can be installed at one location. This consolidation maintains the ability to address multiple frequency modes while making the installation practical given the limited available locations in the combustion chamber.
Solution Approach 2:
Instead of distributing multiple dampers across different spatial locations (one-dimensional approach), the invention stacks multiple resonators within a single damper structure (three-dimensional approach). This dimensional transformation allows broadband damping capability while concentrating all functionality at a single installation point.
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 dampens pressure oscillations across a wide frequency range, stabilizing the combustion chamber by positioning the damper contact points near anti-nodes of dominant frequencies, reducing amplitude and preventing mode shifts, thus enhancing the operational stability of gas turbines.
Implementation Method 1
The resonance frequency (i.e. the damped frequency) of the Helmholtz damper depends on the geometrical features of the damping volume 2 and entrance portion 3 (neck) and must correspond to the frequency of the pressure oscillations generated in the combustion chamber 5
Implementation Method 2
adjustable acoustic coupling with materials like absorption materials and pistons
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The damper arrangement (20) comprises a plurality of interconnected volumes (V1 and V2) and a plurality of necks (N1 and N2) for connecting the damper (20) to a combustion chamber (5) at a plurality of contact points. The plurality of necks being connected to the plurality of volumes.