Swozzle Fuel Injector Groove Prevents Recirculation
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Solution Overview
Problem
In gas turbine combustors, cross-flow fuel injection creates a recirculation zone or bubble behind the fuel jet, leading to flame holding and hardware damage due to a flammable mixture and boundary layer disruptions, which existing designs struggle to mitigate effectively.
Innovation Solution
The swozzle assembly with an inner hub, outer shroud, and vanes includes a groove surrounding the fuel injection hole to direct airflow and prevent recirculation, using both primary and secondary fuel supply passages to control the fuel jet and air mixing, ensuring fresh air is added to the recirculation region to prevent flame holding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cross flow injection is used to introduce fuel into the combustor, then fuel injection simplicity is maintained, but a recirculation zone forms behind the fuel jet causing flame holding and hardware damage
Solution Approach 1:
The patent extracts the harmful recirculation zone by introducing a secondary air stream that targets and disrupts the recirculation bubble formation behind the fuel jet. This secondary air flow is taken from the main air stream and directed specifically to the region where recirculation occurs, removing the harmful effect while maintaining the simple cross-flow injection design.
Solution Approach 2:
The patent introduces a secondary air stream as an intermediary element between the fuel jet and the recirculation zone. This intermediary air flow acts as a barrier that prevents fuel from being entrained and recirculated, thereby mediating the interaction between the fuel injection and the harmful recirculation effects.
2Speed
If fuel jet momentum is increased to improve penetration, then fuel jet penetration is enhanced, but the recirculation bubble size increases leading to more severe flame holding
Solution Approach 1:
The patent converts the high momentum fuel jet, which normally creates a larger recirculation bubble, into a beneficial effect by using the same high momentum jet to drive a secondary air stream. This secondary air stream then acts to suppress the recirculation zone, thereby converting the harmful high-momentum effect into a beneficial one that simultaneously achieves penetration and suppresses flame holding.
3Ease of manufacture
If conventional fuel discharge hole designs are used, then manufacturing simplicity is maintained, but only a small reduction in recirculation issues can be achieved
Solution Approach 1:
The patent segments the air supply into two distinct streams: the primary air stream for combustion and the secondary air stream for recirculation suppression. This segmentation allows the system to maintain simple conventional fuel discharge holes while adding a targeted function to address recirculation issues through the separate secondary air pathway.
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 effectively reduces the size of the recirculation bubble and prevents flame holding by ensuring fresh air is introduced into the region, enhancing fuel jet penetration and air-fuel mixing while maintaining robust fuel injection performance.
Implementation Method 1
the plurality of vanes provides swirling to combustion air passing through the swozzle assembly
Implementation Method 2
a groove, formed in the inner wall, the groove surrounding the injector hole, wherein a second fluid comprising air captured in the groove is directed to the injector hole to prevent formation of a recirculation area
Implementation Method 3
a fuel jet in cross flow creates a recirculation zone or bubble located behind the fuel jet. The size of this recirculation bubble depends on many factors, including jet diameter and momentum ratio between the jet and mainstream flow
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
An injector includes a surface (132) and an injector hole (124, 508) formed in the surface (132). The injector also includes a groove (140, 516) formed in the surface (132), the groove (140, 516) surrounding the injector hole (124, 508).