Pilot Swirler Combustor for Acoustic Stability
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Solution Overview
Problem
Existing combustion systems, such as gas turbine engines, face combustion instabilities and high emissions of pollutants like NOx and CO due to flame temperature issues, which affect operability and component lifespan.
Innovation Solution
A combustor design featuring a pilot swirler with a hollow centerbody and annular splitter, operating with 0-8% of the total airflow, injects a portion of the fuel flow through apertures to create a non-premixed pilot flame, stabilizing the main swirler flame and reducing combustion instabilities while maintaining low emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If lean fuel-air mixtures and pre-mixed combustion are used to lower flame temperature, then emissions of pollutants (NOx, CO, UHC) are reduced, but combustion acoustics and combustion instabilities increase
Solution Approach 1:
The combustor is segmented into multiple zones with different combustion characteristics: a pre-mixed combustion zone for low emissions and a non-premixed combustion zone for stability. The pilot swirler creates a separate non-premixed combustion region that stabilizes the overall combustion process while the main combustor operates in lean pre-mixed mode for emission control.
Solution Approach 2:
A pilot flame is introduced as an intermediary element to stabilize the main combustion process. The pilot swirler generates a stable non-premixed flame that acts as a continuous ignition source and stabilizes the lean pre-mixed combustion in the main combustor, preventing combustion instabilities without compromising emission levels.
2Object-generated harmful factors
If lean fuel-air mixtures are used to reduce emissions, then NOx and CO emissions are limited, but combustion instabilities increase to levels that may cause damage
Solution Approach 1:
The combustor combines two combustion modes in separate zones: lean pre-mixed combustion for emission control and non-premixed combustion for stability. This segmentation allows each zone to optimize for its specific function while working together to ensure both low emissions and high reliability.
Solution Approach 2:
The invention changes the combustion parameters by introducing a pilot flame with different fuel-air mixing characteristics. The pilot swirler creates a non-premixed combustion zone with higher local fuel concentration that provides thermal stability and prevents combustion instabilities, allowing the main combustor to maintain lean pre-mixed operation for emission control.
3Object-generated harmful factors
If pre-mixed combustion is used to lower flame temperature, then pollutant formation is suppressed, but combustion acoustics limit operability and performance
Solution Approach 1:
The combustor is divided into functional segments: a pilot section for stability and a main combustion section for emission control. The pilot swirler with its hollow centerbody and annular splitter creates a stable non-premixed flame that broadens the operable range, allowing the main combustor to operate in lean pre-mixed mode for pollutant suppression.
Solution Approach 2:
The pilot flame serves as an intermediary that mediates between the conflicting requirements of emission control and operability. It provides continuous ignition and thermal stability, enabling the main combustor to operate efficiently in lean pre-mixed mode across a wider range of operating conditions without combustion instabilities limiting performance.
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 suppresses combustion instabilities and limits NOx and CO emissions, enhancing the operational stability and lifespan of combustor components while maintaining low pollutant levels.
Implementation Method 1
injecting a portion of the fuel flow supplied to the burner through a plurality of apertures defined in a hollow pilot centerbody coupled within the pilot swirler... such that the portion of fuel is pre-mixed with a portion of the total airflow
Implementation Method 2
The pilot swirler is operable with only between about 0% and about 8% of the total airflow entering the combustor... effectively suppresses combustion instabilities and limits NOx and CO emissions
Implementation Method 3
channeling the remaining airflow discharged from the compressor towards the main swirler, and injecting the remaining fuel flow supplied to the burner through at least one main swirler vane coupled within the main swirler
Data Source
AI summary
A method for operating a gas turbine engine including a compressor and a combustor is provided. The method comprises channeling between about 0% to about 8% of the total airflow discharged from a compressor towards a pilot swirler coupled within the burner, wherein the burner includes a main swirler and an annular centerbody extending between the pilot and main swirlers, injecting a portion of the total fuel flow supplied to the burner through a plurality of apertures defined in a hollow pilot centerbody coupled within the pilot swirler, channeling the remaining airflow discharged from the compressor towards the main swirler, and injecting the remaining fuel flow supplied to the burner through at least one main swirler vane coupled within the main swirler, such that the portion of fuel is pre-mixed with a portion of the total airflow.