Airblast Fuel Injector Segmented Circuits NOx Reduction
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Solution Overview
Problem
Conventional airblast injectors for gas turbine engines face challenges in reducing NOx emissions due to larger nozzle sizes, which increase recirculation volumes and fuel flow, leading to higher pollutant production.
Innovation Solution
The design incorporates a fuel distributor with multiple fluid circuits and heat shields to manage fuel and air flow efficiently, using radially adjacent and axially aligned fluid outlets, and helically threaded passages within conical surfaces to enhance fuel distribution and thermal isolation, along with a core air swirler for airblast injection, allowing for the injection of multiple fuels with reduced pollutant emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If larger nozzle diameter is used to increase fuel flow, then fuel delivery capacity is improved, but recirculation volume increases leading to higher NOx emissions
Solution Approach 1:
The fuel distributor is segmented into multiple radially adjacent fluid circuits (first fluid circuit, second fluid circuit) with separate outlets. This segmentation allows the total fuel flow to be divided into multiple smaller streams, each with reduced recirculation volume, thereby maintaining fuel delivery capacity while reducing NOx emissions proportional to the cube of the diameter reduction.
Solution Approach 2:
The fluid outlets are arranged radially adjacent and substantially aligned axially relative to the spray axis, transitioning from a single-point injection to a distributed radial arrangement. This dimensional change in outlet configuration enables multiple small-diameter injection points that collectively deliver the required fuel flow while minimizing individual recirculation zones.
2Object-generated harmful factors
If multiple fuel circuits are added to reduce emissions, then NOx production is reduced, but device complexity increases
Solution Approach 1:
Multiple fuel circuits (first fluid circuit, second fluid circuit) are merged into a single integrated fuel distributor body with radially adjacent outlets. This merging approach consolidates what could be separate complex injection systems into one unified component, reducing overall device complexity while maintaining the emission-reduction benefits of multiple circuits.
Solution Approach 2:
The fuel distributor is designed as a universal component that handles multiple fuel types through its multi-circuit configuration. The same distributor structure can deliver different fuels (e.g., liquid and gaseous) through its radially arranged circuits, eliminating the need for fuel-specific injection hardware and reducing overall system complexity.
3Temperature
If heat shields are added to protect fuel from hot air, then thermal isolation is improved, but weight and cost increase
Solution Approach 1:
Heat shields are applied selectively only in regions where thermal isolation is critically needed, rather than providing uniform protection throughout the entire injector. This local quality approach places heat shielding materials precisely at the fuel distributor and critical fuel flow paths exposed to hot compressor discharge air, reducing overall weight while maintaining adequate thermal protection.
Solution Approach 2:
Heat shields serve as intermediary protective elements positioned between the hot compressor discharge air and the fuel distributor. These shields act as thermal mediators that protect the fuel system from excessive heating without requiring complete enclosure or excessive material, thereby minimizing weight and cost while providing sufficient thermal isolation.
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 enables improved fuel distribution and thermal management, resulting in lower NOx emissions and enhanced mixing of fuels, while maintaining a compact and lightweight design with reduced heat shielding weight and cost.
Implementation Method 1
The outer distributor ring includes an internal conical surface with a helically threaded fluid passage defined therein... and wherein the inner distributor ring includes an outer surface with a helically threaded fluid passage defined therein
Implementation Method 2
A braze and/or weld joint can mount the intermediate and inner distributor rings together
Implementation Method 3
A braze and/or weld joint can mount the intermediate and inner distributor rings together
Implementation Method 4
An inner heat shield can be mounted inboard of the inner distributor ring for thermal isolation of fuel in the distributor from compressor discharge air inboard of the inner heat shield
Implementation Method 5
A core air swirler can be mounted inboard of the inner heat shield for swirling compressor discharge air inboard of the fuel distributor for airblast injection of fuel issued from the fuel distributor
Implementation Method 6
core air swirler can be mounted inboard of the inner heat shield for swirling compressor discharge air inboard of the fuel distributor for airblast injection of fuel issued from the fuel distributor
Data Source
Figure 1
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AI summary
An injector includes a fuel distributor (101) with a first fluid inlet (103) and a first fluid outlet (105), with a first fluid circuit (120) for fluid communication between the first fluid inlet (103) and the first fluid outlet (105). The fuel distributor (101) includes a second fluid inlet (107) and a second fluid outlet (109), with a second fluid circuit (121) for fluid communication between the second fluid inlet (107) and outlet (109). The fuel distributor (101) defines a spray axis. The first and second fluid outlets can be radially adjacent and/or can be substantially aligned axially relative to the spray axis, e.g., for issuing multiple different fuels from substantially the same outlet.