Staged Fuel-Air Mixer With Prefilming Shrouds for Uniform Atomization
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Solution Overview
Problem
Existing fuel injectors for gas turbine engines face challenges in achieving uniform and consistent fuel mixing, while avoiding coking and improving combustor dynamics, particularly in staged combustion processes.
Innovation Solution
A fuel-air mixer with multiple nested mixer elements, including radial swirlers and prefilming surfaces, is designed to facilitate staged fuel injection, featuring a floating connection between mixer elements to maintain consistent prefilming and dispersion, ensuring uniform fuel atomization and mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single mixer element is used, then the device complexity is low, but the fuel atomization and dispersion uniformity is insufficient
Solution Approach 1:
The mixer is divided into multiple nested mixer elements (first mixer element, second mixer element, third mixer element) with different functions. The first mixer element handles primary fuel atomization, the second handles secondary fuel dispersion, and the third handles tertiary fuel mixing. This segmentation allows each element to specialize in a specific mixing stage, achieving superior overall fuel atomization uniformity while maintaining manageable complexity through modular design.
Solution Approach 2:
The mixer elements are arranged in a nested configuration where the second mixer element is positioned within the flow path of the first, and the third mixer element is positioned within the flow path of the second. This nested arrangement allows multiple stages of fuel mixing to occur in a compact space, with each subsequent mixer element receiving fuel that has been partially atomized by the previous element, thereby achieving progressive refinement of fuel dispersion uniformity.
2Adaptability or versatility
If fixed connection between mixer elements is used, then the structural stability is high, but the adaptability to varying engine states is reduced
Solution Approach 1:
The connection between mixer elements is designed to be dynamically adjustable rather than fixed. The second mixer element can move relative to the first mixer element, and the third mixer element can move relative to the second mixer element, allowing the system to adapt to varying engine operating conditions. This dynamic capability enables the mixer to optimize fuel atomization and dispersion for different engine states while maintaining structural integrity through controlled movement ranges.
3Productivity
If multiple stages of fuel injection are implemented, then the combustion efficiency is improved, but the device complexity increases
Solution Approach 1:
The fuel injection system is segmented into multiple stages with distinct functions: primary fuel injection through the first mixer element for initial atomization, secondary fuel injection through the second mixer element for dispersion, and tertiary fuel injection through the third mixer element for final mixing. This segmentation allows each stage to optimize for its specific function, improving overall combustion efficiency while managing complexity through functional specialization.
Solution Approach 2:
The mixer elements are positioned and configured to perform preliminary fuel atomization and dispersion actions before the fuel reaches the combustion zone. The first mixer element performs preliminary atomization, the second performs preliminary dispersion, and the third performs preliminary mixing, ensuring that fuel is properly prepared in advance of combustion, thereby improving combustion efficiency without requiring complex in-combustion injection systems.
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 enhances fuel atomization and dispersion, improving combustor dynamics and ensuring consistent mixing across varying engine states, thereby optimizing combustion efficiency.
Implementation Method 1
Each of the first, second, and third mixers includes a radial swirler
Implementation Method 2
Each of the first, second, and third mixers includes a prefilming surface disposed downstream of its radial swirler
Data Source
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AI summary
A gas turbine engine combustor includes a combustor liner dome, a fuel nozzle assembly (204) with a distal nozzle, and a fuel-air mixer situated between the distal nozzle and the dome. The fuel nozzle assembly (204) includes a generally axially-oriented primary fuel outlet (326), and stages of additional fuel outlets (328, 330) circumferentially distributed about the distal nozzle. The fuel air mixer includes a first mixer element (302), a second mixer element (310), and a floating connection between the first and second mixer elements (302, 310). The first and second mixers each include radial swirlers (304, 312) and, downstream of those radial swirlers (304, 312), prefilming surfaces (306, 314) situated in output paths of a respective stage additional fuel outlets (328, 330). The floating connection permits radial but not axial deflection of the first mixer element (302) relative to the second mixer element (310).