Fuel Nozzle Reduces Residence Time in Gas Turbine Combustor
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Solution Overview
Problem
Gas turbine engines face issues with auto ignition, high emissions, and elevated combustion dynamics due to prolonged residence time of the fuel and air mixture at elevated temperatures and pressures in the combustor.
Innovation Solution
The solution involves re-positioning the fuel nozzle closer to the combustion chamber and increasing the swirler angle to reduce the residence time of the fuel and air mixture while maintaining mixedness, thereby minimizing auto ignition. This is achieved by creating a passageway between a centerbody and an outer shroud with swirlers, which allows for efficient mixing and reduces the axial distance and associated time before entering the combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the fuel nozzle is positioned farther from the combustion chamber to allow adequate mixing time, then the mixedness of fuel and air is improved, but the residence time increases leading to auto ignition
Solution Approach 1:
The fuel nozzle is repositioned to the exit plane of the combustion liner end cap, performing the mixing action earlier in the flow path. This preliminary positioning reduces the residence time in the premixing chamber while still achieving adequate mixedness by the time the mixture reaches the combustion chamber
Solution Approach 2:
The swirler angle of the fuel nozzle is increased to compensate for the reduced residence time. By changing this geometric parameter, the mixing intensity is enhanced, maintaining the mixedness of fuel and air despite the shorter time available for mixing
2Reliability
If the residence time is reduced by repositioning the fuel nozzle, then auto ignition is minimized, but the mixedness of fuel and air may be adversely impacted
Solution Approach 1:
The swirler angle parameter is increased to enhance mixing intensity. This parameter change compensates for the reduced residence time, ensuring that the mixedness of fuel and air is maintained despite the fuel nozzle being repositioned closer to the combustion chamber
Solution Approach 2:
The fuel nozzle is positioned at the exit plane of the combustion liner end cap to perform mixing action as early as possible in the flow path. This preliminary action ensures adequate mixing is achieved within the shortened residence time, preventing auto ignition while maintaining combustion 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 approach effectively reduces the residence time by approximately 15% compared to traditional designs, allowing operation at higher temperatures and pressures without significant changes in emissions or flame temperature, thus enhancing combustor durability and performance.
Implementation Method 1
a plurality of swirlers extending from the centerbody
Implementation Method 2
Air is drawn into the passageway and mixes with fuel from the centerbody as the air and fuel exit the fuel nozzle
Data Source
AI summary
Embodiments for an apparatus and associated method for reducing the residence time in a gas turbine combustor are disclosed. The embodiments of the present invention comprise a fuel nozzle that extends to a downstream plane of an end cap for a combustion liner where the axial distance of the premixer is reduced, however the swirl for mixing the fuel and air, is increased. As a result, the mixing of the fuel and air is essentially unchanged, thereby allowing higher air pressures and operating temperatures within the premixer without inducing auto-ignition.