Trapped Vortex Fuel Injector Additive Manufacturing
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Solution Overview
Problem
Existing fuel injector systems for gas turbines face challenges in achieving adequate radial penetration of liquid fuel into the combustion gas flow field due to momentum inhibition, leading to local evaporation and potential high temperature zones, which affects thermodynamic efficiency and emissions performance.
Innovation Solution
A trapped vortex fuel injector system is introduced, featuring a main body with an annular and semi-annular portion, defining a combustion air flow passage and a trapped vortex pre-mix zone, with fuel injection ports for improved mixing and stability, and fabricated using additive manufacturing for enhanced accuracy and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid fuel is injected into the combustion gas flow field using existing LLI or axial fuel staging systems, then the firing temperature of the combustor may be increased without producing a corresponding increase in residence time, but the momentum of the combustion gases inhibits adequate radial penetration of the liquid fuel, leading to local evaporation and high temperature zones
Solution Approach 1:
The fuel injection system is segmented into multiple injection points arranged circumferentially around the combustor axis. Each injection point introduces fuel at a different angular position, creating multiple discrete fuel streams that collectively achieve better radial penetration and more uniform distribution throughout the combustion gas flow field, preventing localized evaporation issues
Solution Approach 2:
The fuel injection approach transitions from axial injection (single dimension) to radial injection circumferentially distributed around the combustor (adding angular dimension). This dimensional change allows fuel to penetrate radially outward from the center, overcoming the axial momentum inhibition and achieving better spatial distribution in the combustion flow field
2Reliability
If the fuel injector is extended radially inward through the liner and into the combustion gas flow field to improve fuel penetration, then fuel distribution may be improved, but the fuel injector is exposed to hot combustion gases which may impact mechanical life and lead to fuel coke buildup
Solution Approach 1:
Compressed working fluid acts as an intermediary medium that carries the fuel from the injection ports into the combustion gas flow field. The fuel is injected into this intermediate fluid stream rather than directly into the hot combustion gases, providing thermal protection during the injection and initial mixing process while still achieving effective fuel distribution
3Productivity
If multiple fuel injectors are arranged around the liner for Late Lean Injection to balance emissions performance and thermodynamic efficiency, then the overall thermodynamic efficiency may be increased without sacrificing emissions performance, but the system complexity and manufacturing difficulty increase
Solution Approach 1:
The fuel injector design integrates multiple functions into a single component: it provides fuel injection, compressed working fluid mixing, and structural support for circumferential distribution. This multi-functional approach achieves the performance benefits of multiple separate injectors while reducing overall system complexity and the number of discrete components required
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 trapped vortex fuel injector enhances fuel penetration and mixing, reducing NOx emissions and increasing thermodynamic efficiency while extending the mechanical life of the component by utilizing additive manufacturing for intricate designs and cooling channels.
Implementation Method 1
successively forming each layer of the main body by fusing a metallic powder using laser energy
Implementation Method 2
The semi-annular portion defines a trapped vortex pre-mix zone that is downstream from the combustion air flow passage
Data Source
AI summary
A method for fabricating a main body of a trapped vortex fuel injector having a main body defining a fuel circuit. The method includes determining three-dimensional information of the main body including the fuel circuit where the fuel circuit is fully circumscribed within the main body and extends between an annular portion and a semi-annular portion of the main body and where the three-dimensional information of the main body further includes a plurality of fuel injection ports which provide for fluid communication between the fuel circuit and a trapped vortex pre-mix zone. The method further includes converting the three-dimensional information into a plurality of slices that define a cross-sectional layer of the main body and successively forming each layer of the main body by fusing a metallic powder using laser energy or electron beam energy.