Staggered Quench Jet Arrangement for RQL Combustor NOx Reduction
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Solution Overview
Problem
The design of the quench zone in RQL combustors for gas turbine engines is a challenge in achieving low NOx emissions, as it affects the mixing of fuel-rich gases with excess air, leading to high-temperature excursions and NOx formation.
Innovation Solution
A combustor design with a staggered 2-2-4-2 configuration of air admission holes in the outer and inner liners, where the first row holes are larger and circumferentially offset, and the second row holes are smaller and aligned, to optimize the mixing of dilution air with combustion products, reducing NOx formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the quench zone geometry is designed to mix fuel-rich gases with excess air, then the combustion process can be controlled, but high-temperature excursions occur leading to increased NOx emissions
Solution Approach 1:
The air admission holes are divided into two distinct rows with different sizes and positions. The first row holes are larger and positioned upstream, while the second row holes are smaller and positioned downstream. This segmentation allows different portions of the quench zone to receive different amounts of dilution air, enabling precise control over the mixing process and temperature profile to reduce NOx formation.
Solution Approach 2:
Different regions of the quench zone are provided with different air admission hole characteristics. The first row holes provide stronger, more focused jets in specific angular sectors, while the second row holes provide weaker, more distributed jets in other sectors. This local differentiation optimizes the mixing characteristics in different parts of the quench zone, reducing peak temperatures and NOx emissions.
2Temperature
If dilution air is introduced to cool the combustion products, then the temperature can be controlled, but the mixing efficiency affects NOx formation
Solution Approach 1:
The air admission holes are configured with different diameter parameters across two rows. The first row holes have larger diameters creating higher velocity jets, while the second row holes have smaller diameters creating lower velocity jets. This parameter variation allows optimization of the dilution air injection to control temperature rise during mixing, reducing NOx formation by preventing excessive temperature excursions.
3Device complexity
If the air admission holes are arranged in aligned rows, then the structure is simple, but the mixing of dilution air with combustion products is suboptimal
Solution Approach 1:
The air admission holes are arranged in an asymmetric staggered configuration rather than aligned rows. The first row holes are positioned at different angular locations than the second row holes, creating a staggered pattern. This asymmetric arrangement optimizes the flow interaction between dilution air jets and combustion products, enhancing mixing efficiency and reducing NOx formation while maintaining reasonable structural complexity.
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 configuration effectively reduces NOx emissions by more than 20% through improved mixing and temperature control, minimizing recirculation and optimizing the penetration depth of dilution air, thereby reducing NOx formation in the quench zone.
Implementation Method 1
the mixing of dilution air with combustion products
Implementation Method 2
the penetration depth of dilution air
Implementation Method 3
a combustor for burning a hydrocarbon fuel in the presence of the pressurized air
Implementation Method 4
burning a hydrocarbon fuel in the presence of the pressurized air
Data Source
AI summary
A combustor includes an outer liner having a first row and a second row of circumferentially distributed air admission holes penetrating therethrough. The combustor further includes an inner liner circumscribed by the outer liner and having a first row and a second row of circumferentially distributed air admission holes penetrating therethrough. The combustor further includes a plurality of fuel injectors extending into the combustion chamber and configured to deliver an air-fuel mixture to the combustion chamber. Each of the plurality of fuel injectors are associated with two air admission holes in the first row of the outer liner, two air admission holes in the first row of the inner liner, four air admission holes in the second row of the outer liner, and two air admission holes of the second row of the inner liner.