Resonating Tubes for Combustor Acoustic Damping
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Solution Overview
Problem
Gas turbine engine combustors experience destructive acoustic pressure oscillations due to lean premixed combustion systems, leading to mechanical and thermal fatigue, and existing solutions like elevating flame temperatures or asymmetric compressor discharge pressure bleeds are either ineffective or adverse to low emissions goals.
Innovation Solution
An apparatus featuring annularly disposed resonating tubes with closed and open ends, positioned downstream of air/fuel mixers, which attenuate acoustic oscillations through dissipative losses and phase shifting, effectively reducing dynamic pressure pulses without affecting emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If lean premixed combustion systems are used to achieve low NOx emissions, then emissions are reduced, but acoustic pressure oscillations increase
Solution Approach 1:
The patent introduces resonating tubes as intermediary elements that couple the combustion chamber to the diffuser. These tubes act as mediators that extract acoustic energy from the combustion chamber and dissipate it in the diffuser region, thereby reducing pressure oscillations while maintaining the lean premixed combustion configuration for low emissions
Solution Approach 2:
The invention extracts acoustic energy from the combustion chamber by providing resonating tubes that extend into the diffuser. This extraction removes the harmful acoustic oscillations from the combustion system without affecting the combustion process itself, allowing low emissions to be maintained while reducing pressure pulses
2Object-affected harmful factors
If flame temperature is elevated to reduce pressure pulses, then acoustic oscillations are diminished, but emissions increase and liner damage occurs
Solution Approach 1:
The patent converts the harmful acoustic energy in the combustion chamber into a beneficial effect by using resonating tubes to channel this energy into the diffuser region. The acoustic oscillations that cause damage are redirected and dissipated as harmless flow disturbances in the diffuser, eliminating the need to elevate flame temperature
3Object-affected harmful factors
If asymmetric compressor discharge pressure bleed is used to counteract pressure pulses, then circumferential pulses are reduced, but axial pulses remain ineffective
Solution Approach 1:
The resonating tubes provide a universal solution that addresses both circumferential and axial pressure oscillations simultaneously. Unlike the asymmetric bleed system that only targeted circumferential modes, the resonating tubes couple to the combustion chamber in a way that dampens all acoustic modes, making the system versatile against different pulse types
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 apparatus effectively reduces dynamic pressure oscillations across the combustor, minimizing mechanical stress and hardware damage while maintaining low NOx and CO emissions, suitable for short compact combustor designs.
Implementation Method 1
which attenuate acoustic oscillations through dissipative losses and phase shifting
Implementation Method 2
at least one resonating tube with a closed end and an open end and a single cavity between the ends
Data Source
AI summary
An apparatus for attenuating acoustic oscillations of a gas flow contained in part by a combustor wall of a gas turbine engine combustor, wherein the combustor includes at least one air/fuel mixer, includes at least one resonating tube with a closed end and an open end and a single cavity between the ends. The tube is located on the combustor wall downstream of the air/fuel mixer.