Combustor Acoustic Damper for Gas Turbine Pressure Oscillation Control
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Solution Overview
Problem
Gas turbine engine combustion sections experience increased pressure oscillations, particularly at lean conditions, which can lead to structural degradation and engine failure, necessitating effective attenuation methods to reduce emissions and maintain structural life.
Innovation Solution
The combustor assembly incorporates an acoustic damper with a first and second walled enclosure defining cavities and orifices, configured to attenuate pressure oscillations by enabling fluid communication between the combustion chamber and diffuser cavity, using specific tube lengths and diameters to target various frequencies, and is coupled to the bulkhead and dome assembly to suppress acoustic modal shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the combustion section operates at lean conditions to reduce emissions, then emissions are reduced, but pressure oscillations increase causing structural degradation
Solution Approach 1:
An acoustic damper is introduced as an intermediary component between the combustion chamber and diffuser cavity. The damper includes a walled enclosure with cavities and orifices that mediates the pressure oscillations, allowing controlled fluid communication while attenuating harmful acoustic modal shapes and pressure fluctuations, thus reducing structural degradation while maintaining lean combustion operation
Solution Approach 2:
The acoustic damper converts the harmful pressure oscillations into beneficial attenuation. By designing cavities with specific volumes and orifices with specific dimensions, the system transforms the harmful acoustic energy into reduced pressure fluctuations, where the oscillations are channeled through the damper structure to achieve damping效果, turning the harmful lean-combustion-induced oscillations into a controlled attenuation process
2Duration of action of stationary object
If pressure oscillations are attenuated to protect structural integrity, then structural life is maintained, but combustion efficiency may be compromised
Solution Approach 1:
The acoustic damper applies local quality by creating specific cavity volumes and orifice dimensions at targeted locations within the combustion section. The first and second cavities have different volumes, and the orifices have different diameters, each configured to attenuate pressure oscillations at specific frequencies. This localized tuning allows selective damping of harmful acoustic modal shapes without interfering with the overall combustion process and efficiency
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 broad range of frequencies, reducing the risk of structural degradation, maintaining engine stability, and enabling reduced emissions while improving combustion efficiency.
Implementation Method 1
an acoustic damper with a first and second walled enclosure defining cavities and orifices, configured to attenuate pressure oscillations by enabling fluid communication between the combustion chamber and diffuser cavity, using specific tube lengths and diameters to target various frequencies
Implementation Method 2
The first walled enclosure defines a first cavity and a hot side orifice. The second walled enclosure defines a second cavity and a second opening. a length of the first cold side walled tube versus a diameter of the cold side orifice, each configured to attenuate pressure oscillations at one or more frequencies
Data Source
AI summary
The present disclosure is directed to a combustor assembly for a gas turbine engine. The combustor assembly includes an annular bulkhead adjacent to a diffuser cavity; a deflector downstream of the bulkhead and adjacent to a combustion chamber; a bulkhead support coupled to an upstream side of the deflector; a first walled enclosure coupled to the bulkhead support; and a second walled enclosure coupled to the first walled enclosure. The deflector and the bulkhead support together define a bulkhead conduit therethrough to the combustion chamber. The first walled enclosure defines a first cavity and a hot side orifice. The hot side orifice is adjacent to and in fluid communication with the bulkhead conduit. The second walled enclosure defines a second cavity and a second opening adjacent to a diffuser cavity.