Combustor Cowl Damper Using Helmholtz Resonance for Noise Control
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Solution Overview
Problem
Combustors in turbomachine engines face challenges in meeting increased performance demands for higher cycle overall pressure ratio and fuel efficiency while managing acoustic noise, emissions, and extending component life cycles.
Innovation Solution
A cowl damper configured as a Helmholtz resonator is integrated into the combustor to reduce combustion dynamics by targeting specific frequencies of hydrodynamic and acoustic instability, using a hollow cavity with adjustable volume, neck length, and neck area to dampen noise and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher cycle overall pressure ratio is pursued to increase engine performance, then fuel efficiency is improved, but acoustic noise and emissions increase
Solution Approach 1:
The harmful acoustic noise and combustion dynamics are extracted and isolated into a separate damping cavity within the cowl, allowing the main combustor to operate at high pressure ratio while the cavity absorbs and dampens the unwanted acoustic energy through Helmholtz resonance mechanisms
Solution Approach 2:
A Helmholtz resonator cavity is introduced as an intermediary element between the high-pressure combustor and the external environment, serving as a mediator that absorbs acoustic energy and reduces combustion dynamics without affecting the core combustion process or engine performance
2Productivity
If higher cycle overall pressure ratio is pursued to increase engine performance, then fuel efficiency is improved, but component life cycle decreases
Solution Approach 1:
The damping cavity provides beforehand cushioning by absorbing and dampening combustion dynamics and acoustic energy before they can cause damage to combustor components, thereby extending component life cycle while allowing the engine to operate at higher pressure ratios for improved performance
3Object-affected harmful factors
If acoustic damping measures are added to reduce noise, then acoustic noise is reduced, but device complexity increases
Solution Approach 1:
The acoustic damping function is merged with the existing cowl structure by incorporating a damping cavity within the cowl itself, rather than adding separate external damping devices. This integration reduces overall device complexity while achieving effective acoustic noise reduction through Helmholtz resonance
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 cowl damper effectively reduces engine noise and improves combustor durability by suppressing combustion dynamics, enhancing mechanical stability, and allowing for easier retrofitting and cost-effective implementation.
Implementation Method 1
A cowl damper configured as a Helmholtz resonator is integrated into the combustor to reduce combustion dynamics by targeting specific frequencies of hydrodynamic and acoustic instability
Data Source
AI summary
A combustor for a turbomachine engine. The combustor includes a combustion chamber, and a cowl having an annular shape that is symmetric around a centerline axis of the turbomachine engine. The cowl includes a hollow cavity that is in fluid communication with the combustion chamber. The hollow cavity is a damper that reduces combustion dynamics of the combustor.