Resonating Tubes for Gas Turbine Combustor Acoustic Damping
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Solution Overview
Problem
Current gas turbine combustor designs face challenges in effectively damping both high and low-frequency acoustic pressure oscillations, which can lead to hardware damage due to combustion instability and high cycle fatigue, especially in lean premixed combustion systems that aim to reduce NOx emissions.
Innovation Solution
The integration of resonating tubes with a radial dimension greater than or equal to the axial dimension between adjacent burner openings on the inner cap of the combustor, combined with additive manufacturing techniques that eliminate the need for temporary supports and optimize the geometry to reduce weight and enhance damping efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If lean premixed combustion systems are used to reduce NOx emissions, then emissions are reduced, but combustion instability increases causing high dynamic pressure oscillations
Solution Approach 1:
The patent converts the harmful dynamic pressure oscillations into beneficial acoustic damping by designing resonating tubes that are tuned to specific frequencies. The resonating tubes use the pressure oscillations themselves to drive acoustic resonance that counteracts the instability, transforming the harmful combustion dynamics into a stabilizing force while maintaining lean premixed combustion for low NOx emissions
2Reliability
If current damping devices are added to reduce pressure oscillations, then combustion stability improves, but device complexity increases
Solution Approach 1:
The patent merges the damping function directly into the inner cap structure by integrating resonating tubes that are formed as part of the cap geometry. This consolidation eliminates the need for separate damping devices and reduces overall system complexity while maintaining effective pressure oscillation control
Solution Approach 2:
The inner cap structure serves multiple functions: it provides structural support for the combustor, defines the combustion chamber geometry, and incorporates resonating tubes for acoustic damping. This multi-functionality reduces the number of separate components needed while achieving both structural and stability objectives
3Ease of manufacture
If additive manufacturing is used to create complex resonating tube geometries, then manufacturing flexibility improves, but support structure removal complexity increases
Solution Approach 1:
The patent extracts and removes the temporary support structures after the additive manufacturing process is complete, leaving only the functional resonating tube geometry. This allows the use of complex overhang structures during manufacturing that would be impossible with traditional methods, while the final product contains only the essential damping features without manufacturing artifacts
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 solution effectively dampens acoustic pressure oscillations across a range of frequencies, reducing the risk of hardware failure and operational issues while maintaining low NOx emissions, by integrating resonating tubes that are specifically designed to target both high and low-frequency modes without requiring additional manufacturing steps or support structures.
Implementation Method 1
at least one resonating tube having a resonating tube neck is integrated with and protruding from the at least one neck ring. The at least one resonating tube is disposed between adjacent burner openings, and is configured such that the radial dimension is greater than or equal to the axial dimension
Implementation Method 2
damping system for dampening acoustic pressure oscillations of a gas flow in a combustor
Data Source
AI summary
A damping system and apparatus are disclosed for dampening acoustic pressure oscillations of a gas flow in a combustor of a gas turbine engine having at least one combustor with a combustor liner. A second inner cap portion is disposed on the at least one combustor inner liner. The second inner cap portion can have a hot surface, a cold surface, at least one burner opening protruding from the cold surface, and at least one neck ring having an internal opening and protruding from the cold surface. At least one resonating tube having a resonating tube neck is integrated with and protruding from the at least one neck ring. The at least one resonating tube is disposed between adjacent burner openings, and is configured such that the radial dimension is greater than or equal to the axial dimension.