Gas Turbine Combustor Quench Jet Pattern for NOx Reduction
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Solution Overview
Problem
Gas turbine engines face challenges in minimizing nitrogen oxide (NOx) emissions, particularly during the RQL combustion process where high flame temperatures lead to excessive NOx production, despite efforts to control combustion zones and air-fuel ratios.
Innovation Solution
The combustor design incorporates a specific pattern of outer and inner dilution passages that are clocked relative to upstream swirlers, creating a larger area for dilution passages than inner ones, with distinct pitch locations and sizes, to effectively de-swirl combustion products and reduce peak temperatures, thereby minimizing NOx formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If RQL combustion is used to minimize NOx emissions, then NOx formation is reduced, but flame temperature remains high during the quench process causing excessive NOx production
Solution Approach 1:
The combustor is divided into three distinct combustion zones: rich burn zone, quench zone, and lean burn zone. Each zone has specific air-fuel ratios and temperature controls to manage NOx formation at different stages of combustion, resolving the contradiction between minimizing NOx and controlling flame temperature.
Solution Approach 2:
The quench zone is positioned axially aft of the rich burn zone to pre-cool the combustion products before they enter the lean burn zone. This preliminary cooling action reduces the flame temperature in the quench zone, thereby minimizing NOx formation during the transition from fuel-rich to fuel-lean conditions.
2Productivity
If pressurized air is introduced radially into the quench zone to support combustion, then combustion is sustained, but peak temperature increases causing exponential NOx production
Solution Approach 1:
The quench zone introduces pressurized air radially at specific locations to locally support combustion where needed, while maintaining overall temperature control. The axial positioning and radial distribution of air injection are optimized to provide localized combustion support without creating excessive peak temperatures that would drive exponential NOx production.
3Reliability
If additional pressurized air is introduced in the lean burn zone to regulate temperature, then turbine exposure to excessive temperatures is reduced, but device complexity increases
Solution Approach 1:
The lean burn zone utilizes axial flow of combustion products to carry heat away from the turbine, leveraging the existing flow dimension rather than adding complex radial cooling structures. The annular combustion chamber geometry and axial product flow naturally provide temperature regulation, reducing the need for additional complex air passage configurations while maintaining turbine durability.
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 enhances cooling efficiency, maintains lower NOx emissions, and increases the durability of the high-pressure turbine by optimizing temperature profiles and swirl reduction, as validated by computational fluid dynamics evaluations.
Implementation Method 1
The pressurized air mixes with the combustion products to support further combustion and progressive derichment of the fuel rich combustion products
Implementation Method 2
jets of pressurized air radially enter into the quench zone. The pressurized air mixes with the combustion products to support further combustion and progressive derichment
Implementation Method 3
the fuel-air ratio of the combustion products changes from fuel rich to stoichiometric, with an attendant rise in the combustion flame temperature
Data Source
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AI summary
A combustor for a turbine engine includes an inner liner panel with a multiple of inner dilution passages. The multiple of dilution passages includes a repeating pattern of a first major inner air passage, a minor inner air passage, and a second major inner air passage. A combustor for a turbine engine includes an outer liner panel with a multiple of outer dilution passages. The multiple of outer dilution passages includes a repeating pattern of a first major outer air passage, a first minor outer air passage, a second major outer air passage, and a second minor outer air passage.