Swirl Mesh Lean Direct Injection Combustor
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Solution Overview
Problem
Gas turbine combustors face inefficiencies due to high pressure losses and combustion instability caused by swirlers, leading to increased NOx emissions and weight from thermal protection, despite previous attempts to control fuel distribution and emissions.
Innovation Solution
A hexagonal packing arrangement of swirlers minimizes solid mass and pressure loss, enabling direct fuel distribution through swirl mesh lean injection, with fuel injected at the center or periphery of swirlers, reducing flame temperature and residence time, and allowing for active control of combustion instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If swirlers with small passages are used to redirect air around the head end, then flame holding is improved, but pressure losses increase
Solution Approach 1:
The fuel distribution system is segmented into multiple direct injection points distributed around the combustor head end, replacing the single swirler approach. This segmentation allows fuel to be injected at multiple locations where it can be efficiently mixed with air without requiring high-pressure drops through small passages.
Solution Approach 2:
The fuel injection function is extracted from the swirler structure and implemented as separate direct injection points. This separation allows the air flow path to be optimized for minimal pressure loss while fuel is injected directly into the high-velocity air stream at strategically located points.
2Reliability
If high fuel-to-air ratio is used to hold flame against high velocity forces, then flame stabilization is improved, but NOx emissions increase
Solution Approach 1:
The fuel-to-air ratio is optimized locally at each injection point rather than using a uniform high ratio throughout. Fuel is injected directly into high-velocity air streams where immediate mixing occurs, creating localized combustion zones with optimized equivalence ratios that stabilize flames without excessive temperatures.
Solution Approach 2:
Fuel is pre-mixed with air in the high-velocity stream before combustion occurs. The direct injection into the air stream allows preliminary mixing and atomization, creating a more uniform fuel-air distribution that promotes stable combustion at lower overall fuel-to-air ratios, thereby reducing NOx formation.
3Loss of energy
If multiple swirler assemblies are used to reduce pressure drop, then area change is improved, but interaction between flames decreases
Solution Approach 1:
Multiple direct fuel injection points are merged into a unified distribution system that operates cooperatively. The injection points are positioned to create overlapping combustion zones that interact and stabilize each other, providing flame holding reliability similar to or better than multiple swirler assemblies while maintaining lower pressure drops.
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 design enhances combustion efficiency, reduces NOx emissions, and decreases combustor weight by minimizing pressure losses and thermal protection needs, while stabilizing flames against high velocities and reducing combustion instability.
Implementation Method 1
A hexagonal packing arrangement of swirlers minimizes solid mass and pressure loss
Implementation Method 2
enabling direct fuel distribution through swirl mesh lean injection, with fuel injected at the center or periphery of swirlers, reducing flame temperature and residence time
Implementation Method 3
The swirl flow causes low velocity regions for the flame to stabilize in the combustor
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A swirl mesh lean direct injection concept for distributed flame holding for low pollutant emissions and mitigation of combustion instability. The invention further relates to a new method for flame holding with least pressure drop and flame temperature, in gas turbine engine combustors, wherein the liner of the combustor is partially or fully replaced with a "swirl mesh". The invention has lean direct injection for fuel distribution over several points in gas turbine combustors along with swirl arrangement for air injection which provides low pollutant emission and low combustion instability.