Axial Staged Combustor Main Injector with Central Plug
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Solution Overview
Problem
The existing axially staged combustors in gas turbine engines have a main injector with a circular port, resulting in a longer flame that complicates combustor design and increases sensitivity to flame distance, leading to longer combustor lengths and instability.
Innovation Solution
The main injector is redesigned with a central plug within the flow path, either concentric or non-concentric, to restrict flow and induce swirl in the fuel-air mixture, enhancing mixing and anchoring the flame, and can extend at an angle to improve flame expansion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a circular port main injector is used, then the fuel-air mixture can be injected into the combustion chamber, but the flame becomes longer resulting in increased combustor length and sensitivity to flame distance
Solution Approach 1:
The main injector is segmented into multiple flow paths by introducing a central plug within the flow path. This divides the single circular port into multiple restricted flow channels, creating multiple smaller flames that burn more efficiently and reduce the overall flame length in the combustion chamber.
Solution Approach 2:
The central plug creates localized flow restrictions at specific positions within the injector, generating swirl and enhancing mixing in localized regions. This local modification of flow quality improves combustion efficiency and reduces flame length without requiring complete redesign of the entire injector system.
2Device complexity
If the main injector uses a circular port design, then fuel injection is simple, but the flame distance sensitivity increases leading to instability
Solution Approach 1:
By segmenting the flow path with a central plug, the injector creates multiple stable flame zones instead of a single long flame. This segmentation reduces sensitivity to flame distance variations and improves overall flame stability while maintaining reasonable structural complexity.
Solution Approach 2:
The central plug acts as an intermediary element that modifies the flow characteristics between the fuel-air mixture injection and the combustion process. It introduces swirl and enhances mixing, serving as a mediator that stabilizes the flame while the injector structure remains relatively simple.
3Reliability
If a central plug is added to the main injector flow path, then flame anchoring and stability improve, but the injector structure becomes more complex
Solution Approach 1:
The central plug is nested within the existing injector flow path, utilizing the available internal space efficiently. This nested configuration provides flame stabilization benefits without requiring additional external components or significant structural additions to the injector assembly.
Solution Approach 2:
The central plug modifies flow parameters (velocity distribution, swirl, mixing characteristics) rather than requiring complex mechanical structures. By changing the physical parameters of the fuel-air mixture flow, flame stability is improved with minimal increase in structural complexity.
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 results in a shorter combustor with improved temperature profiles and reduced sensitivity to disturbances, providing better flame anchoring and stability, while allowing for higher swirl numbers without flashback.
Implementation Method 1
The main injector is redesigned with a central plug within the flow path, either concentric or non-concentric, to restrict flow and induce swirl in the fuel-air mixture, enhancing mixing
Implementation Method 2
The air is mixed with fuel through injectors and a number of different scenarios may be utilized. In one scenario, an axially staged combustor includes a front end or pilot injector which injects fuel into air within a combustion chamber
Data Source
Figure 1
Figure 2~3D
Figure 4A~4B
AI summary
A combustor for a gas turbine engine comprises a combustion chamber having a pilot injector at one end and at least one main injector spaced radially from the pilot injector. The main injector includes a fluid flow path with a plug that restricts flow at least at an interior portion of the flow path. A gas turbine engine is also disclosed.