Bluff Body Fuel Mixer for Gas Turbine NOx Reduction
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Solution Overview
Problem
Gas turbine engines face challenges in reducing nitrogen oxide (NOx) emissions, which are subject to regulatory standards, due to the inefficiencies in fuel combustion within the combustor.
Innovation Solution
The implementation of a combustor with an axial and radial fuel injection system, featuring a bluff body mixer with a v-shaped gutter and a turbulator, which mixes fuel and air to create a stable burn pattern, reducing NOx emissions by ensuring a consistent flow and complete fuel burn.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional fuel injection systems are used, then the device complexity is low, but NOx emissions increase due to incomplete fuel burn and inconsistent combustion
Solution Approach 1:
The fuel injection system is segmented into multiple independent injectors arranged in a circular pattern, each injecting fuel at different locations. The bluff body is segmented with multiple gutters (V-shaped, U-shaped, or rectangular) that create separate flow paths. This segmentation allows each injector and gutter to contribute to consistent mixing, ensuring complete fuel burn and reducing NOx emissions while maintaining manageable complexity through modular design
Solution Approach 2:
The bluff body acts as an intermediary element between the fuel injectors and the combustion chamber. It receives fuel from multiple injectors, mixes it with air through its gutter structures and turbulence promoters, and delivers a consistent fuel-air mixture to the combustion chamber. This intermediary function ensures complete combustion and reduces harmful emissions without requiring direct complex control systems
2Object-generated harmful factors
If fuel injection parameters are not optimized, then the ease of operation is high, but combustion efficiency decreases leading to increased NOx emissions
Solution Approach 1:
The system utilizes parameter changes in the bluff body design, including varying gutter shapes (V-shaped, U-shaped, rectangular), different turbulence promoter configurations, and adjustable injector positions. These parameter variations optimize fuel-air mixing and combustion efficiency to reduce NOx emissions. The parameters are designed to work together automatically, maintaining ease of operation while achieving emission reductions through optimized combustion
3Stability of the object's composition
If a simple mixing structure is used, then the device complexity is low, but the fuel/air mixture consistency is poor resulting in unstable burn patterns
Solution Approach 1:
The bluff body incorporates curved surfaces and rounded edges in its design, including circular or annular gutter cross-sections and curved turbulence promoters. These curved geometries promote smooth airflow patterns and consistent fuel-air mixing, creating stable burn patterns. The spherical or cylindrical overall shape of the bluff body enhances flow uniformity without requiring excessively complex internal structures
Solution Approach 2:
Turbulence promoters are incorporated into the bluff body design to create controlled mechanical disturbances in the fuel-air mixture. These promoters may include ridges, fins, or textured surfaces that generate turbulence as fuel and air pass through the gutters. The induced turbulence enhances mixing efficiency and consistency, ensuring stable combustion while maintaining a relatively simple overall mixer structure
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 effectively reduces NOx emissions by promoting a consistent fuel/air mixture burn pattern, enhancing combustion efficiency and compliance with regulatory standards.
Implementation Method 1
A fuel and air mixer comprises an outer housing with an exit port and a bluff body. The bluff body extends across the exit port of the outer housing.
Implementation Method 2
The bluff body may include a v-shaped gutter.
Implementation Method 3
A turbulator is disposed in the outer housing.
Implementation Method 4
a fuel injector disposed within the mixer
Data Source
AI summary
A fuel injection system may comprise a mixer and a fuel injector disposed within the mixer. The mixer may comprise an outer housing with an exit port and a bluff body extending across the exit port of the outer housing. A flared surface of the mixer may match a contour of the bluff body.