Dual-Staged Fuel Nozzle for Gas Turbine Emissions Control
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Solution Overview
Problem
Gas turbine engine fuel nozzles require greater operational flexibility and control to meet stricter requirements for noise, emissions, and efficiency, particularly in staged combustors where the main injection structure needs improved performance.
Innovation Solution
A fuel nozzle design featuring two axially-separated rings of main fuel orifices with a suspension structure that allows for controlled deflection, along with a fuel system capable of independently controlling fuel flow to each stage, enabling variable fuel flowrates and tailored fuel-air mixing profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single main injection ring with uniform fuel orifices is used, then the structure is simple, but operational flexibility and control are insufficient
Solution Approach 1:
The main injection ring is segmented into two axially-separated rings of fuel orifices (forward main fuel orifices and aft main fuel orifices), each with independent fuel galleries and flow control. This segmentation allows independent adjustment of fuel flow rates in different axial zones, providing operational flexibility while maintaining a relatively simple annular structure.
Solution Approach 2:
The fuel nozzle incorporates variable fuel flow capability within each stage, allowing the fuel flow rate to be dynamically adjusted. The suspension structure permits controlled deflection of the main injection ring, enabling dynamic adaptation to different operating conditions while maintaining proper fuel-air mixing.
2Object-generated harmful factors
If fuel flow control is simplified, then the system is easier to operate, but emissions management and noise control become insufficient
Solution Approach 1:
The fuel injection system is divided into discrete controllable stages (pilot stage and main stage) with independent fuel flow paths. The main stage is further divided into forward and aft orifice rings with separate fuel galleries, enabling zone-specific fuel control for optimized combustion and reduced emissions.
Solution Approach 2:
Different regions of the injection ring have different fuel orifice configurations and flow characteristics. The forward and aft main fuel orifices can have different flow rates and spray patterns, allowing localized optimization of fuel-air mixing in different axial zones to control emissions and noise.
3Adaptability or versatility
If the main injection ring is rigidly fixed, then positioning is precise, but thermal expansion and operational adjustments are restricted
Solution Approach 1:
The suspension structure provides a hybrid solution with defined degrees of freedom: it rigidly constrains the main injection ring in axial and lateral directions for stable positioning, while permitting controlled deflection in the radial direction to accommodate thermal expansion and enable operational adjustments.
Solution Approach 2:
The suspension structure provides different types of constraints at different locations and directions: rigid constraints in axial and lateral directions for stability, and flexible constraints in radial directions for adaptation. This directional differentiation resolves the contradiction between stability and adaptability.
Data Source
AI summary
A fuel nozzle apparatus for a gas turbine engine includes: an annular outer body extending parallel to a centerline axis and having an exterior surface, and having a ring of forward openings passing through the exterior surface, and a ring of aft openings passing through the exterior surface, the aft openings positioned axially aft of the forward openings; an annular main injection ring disposed inside the outer body and including: a forward main fuel gallery extending in a circumferential direction; an aft main fuel gallery extending in a circumferential direction; a ring of forward main fuel orifices communicating with the forward main fuel gallery and each aligned with one of the forward openings; a ring of aft main fuel orifices, communicating with the aft main fuel gallery and each aligned with one of the aft openings; and a pilot fuel injector disposed along the centerline axis.