Gas Turbine Combustor Dome Sleeve Airflow Control
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Solution Overview
Problem
Gas turbine engines face challenges in reducing NOx emissions while maintaining stable combustion flame, as lean fuel-air ratios can lead to instability and high combustion flame temperatures.
Innovation Solution
The gas turbine combustor assembly features a triple-dome annular design with adjustable dome sleeves and fuel injectors that allow for independent regulation of secondary airflow, creating a gradient fuel-air ratio and optimizing flame stabilization through swirling airflow patterns and precise fuel distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a lean fuel-air ratio is used to reduce NOx emissions, then emissions are reduced, but combustion flame stability deteriorates
Solution Approach 1:
The combustor is divided into multiple zones with different fuel-air ratios. The primary combustion zone uses a rich fuel-air ratio to ensure stable combustion, while the secondary combustion zone uses a lean fuel-air ratio to reduce NOx emissions. This spatial segmentation allows each zone to optimize for its specific function without compromising the other.
Solution Approach 2:
Different regions of the combustor are assigned different fuel-air ratios tailored to their specific requirements. The primary zone near the fuel injector operates rich to maintain flame stability, while downstream regions operate lean to minimize emissions. This local differentiation resolves the contradiction by applying the appropriate air-fuel mixture characteristics to each location.
2Power
If high combustion flame temperature is achieved for efficient combustion, then energy conversion is improved, but NOx emissions increase
Solution Approach 1:
The combustion process is segmented into two stages with different temperature characteristics. The primary combustion zone operates at higher temperatures for efficient fuel conversion, while the secondary combustion zone operates at lower temperatures to suppress NOx formation. This temporal and spatial segmentation allows the system to achieve both high power output and low emissions.
Solution Approach 2:
The combustion process alternates between high-temperature rich combustion and lower-temperature lean combustion phases. This periodic action allows the system to periodically achieve high combustion efficiency while periodically reducing temperatures to minimize NOx emissions, thereby resolving the contradiction between power output and emissions control.
3Object-generated harmful factors
If secondary airflow is increased to control fuel-air ratio, then emissions are reduced, but flame stability deteriorates
Solution Approach 1:
The airflow system is segmented into primary air passages that supply air for stable combustion near the fuel injector, and secondary air passages that introduce additional air downstream to reduce the fuel-air ratio and control emissions. This segmentation allows secondary airflow to be increased for emissions control without compromising the stability-providing primary airflow.
Solution Approach 2:
The solution moves from controlling emissions through a single-dimensional adjustment of overall air-fuel ratio to a multi-dimensional approach where primary and secondary airflows are independently controlled in different spatial dimensions. This allows secondary airflow to be optimized for emissions while primary airflow maintains flame stability.
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 design effectively reduces NOx emissions by controlling the fuel-air mixture, maintaining stable combustion, and managing thermal stress across the turbine blades, enhancing the overall efficiency and emissions control of the gas turbine engine.
Implementation Method 1
A swirler is provided in the dome stator to impart a swirling motion on the air flow
Implementation Method 2
The fuel injector support structures are designed to carry the fuel injectors and supply the fuel injectors with liquid or gaseous fuel
Implementation Method 3
Combustion of the hydrocarbon fuel in air inevitably produces harmful emissions
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A gas turbine combustor assembly (200) includes a fuel injector (204), a dome stator (220) around the fuel injector (204), and a dome sleeve (222) coupled to the dome stator. The dome sleeve (222) defines an air inlet opening (268) with the dome stator (220), and is carried to move with respect to the dome stator (220) to change a flow area of the air inlet opening (268). The dome sleeve (222) also defines a nozzle (256) sloping downstream from the air inlet opening (268) toward an outlet of the combustor assembly. The sloping nozzle (256) defines an annular pinch gap (260) adjacent an outlet of the fuel injector (204), and is coupled to move with the dome sleeve (222) to change a flow area through the pinch gap (260).