Adjustable Helmholtz Damper for Gas Turbine Pressure Oscillations
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Solution Overview
Problem
Traditional Helmholtz dampers have a narrow damping frequency bandwidth, making them ineffective for frequency shifts in pressure oscillations within gas turbines, and existing solutions for tuning are complex and space-intensive.
Innovation Solution
A Helmholtz damper design featuring a slidingly connected pipe within the neck, adjustable via an actuator, allowing for fine tuning of resonance frequency through threaded drive mechanisms and automatic regulation by sensors, enhancing damping efficiency and bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional Helmholtz dampers are used with fixed resonance frequency, then the structure is simple and compact, but the damping frequency bandwidth is very narrow and cannot adapt to frequency shifts
Solution Approach 1:
The patent applies the dynamics principle by making the pipe length adjustable through a sliding connection mechanism. The pipe can be extended or retracted along the neck, allowing the resonance frequency to be dynamically adjusted to match varying pressure oscillation frequencies in the combustion chamber, thereby resolving the contradiction between frequency adaptability and structural simplicity.
Solution Approach 2:
The patent implements parameter changes by varying the effective length of the pipe, which is a key geometric parameter determining the resonance frequency. By changing the pipe length parameter through the sliding mechanism, the damper can adapt to different operating conditions and frequency shifts without requiring a completely different device design.
2Adaptability or versatility
If adjustable volume solutions are used to tune resonance frequency, then the resonance frequency can be adjusted, but the device becomes complex and space-intensive
Solution Approach 1:
The patent applies segmentation by dividing the neck into two functional parts: a fixed portion and a movable pipe portion. This segmentation allows the pipe to be slidably connected to the neck, enabling independent adjustment of the pipe length without affecting the overall damper structure. This resolves the contradiction by providing frequency tuning capability while maintaining structural simplicity and compactness.
3Adaptability or versatility
If the neck length is adjusted by overlapping plates, then the resonance frequency can be tuned, but the structure becomes complex and fine tuning capability is limited
Solution Approach 1:
The patent replaces the static plate-overlapping method with a dynamic sliding connection mechanism. The pipe can be continuously adjusted along the neck through the sliding connection, enabling fine-tuning of the resonance frequency. This dynamic approach resolves the contradiction by providing both ease of adjustment and fine-tuning capability while avoiding the structural complexity of multiple plates.
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
Enables precise resonance frequency adjustment and increased damping efficiency with a compact, simple structure, effectively coping with frequency shifts in gas turbines, and providing continuous regulation during operation.
Implementation Method 1
The resonance frequency (i.e. the damped frequency) of the Helmholtz damper depends on the geometrical features of the resonator volume and neck and must correspond to the frequency of the pressure oscillations generated in the combustion chamber.
Implementation Method 2
combustion chambers are equipped with damping devices, such as quarter wave tubes, Helmholtz dampers or acoustic screens, to damp these pressure oscillations
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The Helmholtz damper (1) comprises an enclosure (2) from which a neck (3) extends. A pipe (5) is inserted into and fits the neck (3).