Auxiliary Torch Igniter Premixing Cup Design
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Solution Overview
Problem
Gas turbine engines face challenges in achieving reliable ignition and flame propagation, especially under low air pressure and cold ambient conditions, due to insufficient ignition energy and stability of the torch igniter system.
Innovation Solution
The torch igniter system incorporates an auxiliary combustion chamber with a premixing cup and air swirler for enhanced fuel-air mixing and recirculation, along with cooling and dilution apertures to sustain flame stability and energy release, and a shielding device to protect the ignition source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional spark igniters are used, then device simplicity is maintained, but ignition energy is insufficient for reliable combustion under low air pressure and cold conditions
Solution Approach 1:
The igniter system is segmented into distinct functional components: a combustion chamber for fuel combustion, a premixing cup for fuel-air mixing, cooling apertures for thermal management, and an outlet for directing combustion products into the combustor. This segmentation allows each component to be optimized for its specific function, enabling high ignition energy output while maintaining manageable system complexity through modular design
Solution Approach 2:
The patent introduces a premixing cup as an intermediary component between the fuel source and combustion chamber. This cup pre-mixes fuel and air before combustion, ensuring optimal combustion conditions and maximizing ignition energy output. The intermediary structure enables controlled fuel-air mixing that directly addresses the insufficient ignition energy problem
2Reliability
If high energy combustion is achieved, then ignition reliability is improved, but temperature management becomes challenging
Solution Approach 1:
Cooling apertures are strategically positioned at specific locations on the combustion chamber to provide localized cooling where heat accumulation is most critical. This local quality approach allows targeted temperature management in high-heat zones while maintaining high combustion temperatures in the combustion chamber itself, thus preserving ignition reliability while preventing overheating
Solution Approach 2:
The system dynamically manages temperature by controlling the flow of cooling air through the cooling apertures. By adjusting cooling air flow parameters, the system can maintain optimal temperature conditions for reliable ignition while preventing excessive heat buildup that would compromise component integrity
3Stability of the object's composition
If fuel-air mixing is enhanced, then combustion stability is improved, but device complexity increases
Solution Approach 1:
The premixing cup is nested within the combustion chamber assembly, with the cup positioned concentrically inside the chamber. This nested configuration allows fuel-air mixing to occur in a compact, integrated structure rather than requiring separate external mixing equipment. The nesting principle achieves stable combustion through effective mixing while minimizing the increase in overall device complexity
Solution Approach 2:
The premixing cup structure enables self-service fuel-air mixing by utilizing the natural flow of air and fuel through its geometry. The cup's design creates turbulent mixing and recirculation zones that automatically blend fuel and air without requiring additional active mixing mechanisms, thus improving combustion stability while avoiding excessive complexity
4Duration of action of stationary object
If cooling apertures are added, then component life is extended, but ignition energy is reduced
Solution Approach 1:
Cooling air is introduced through cooling apertures in a preliminary action before the combustion products exit the chamber. This pre-cooling of the chamber walls and internal surfaces prevents excessive heat accumulation during combustion, extending component life. The timing and positioning of cooling aperture placement ensure that ignition energy is preserved while still providing thermal protection
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 ignition energy and stability across a wide range of conditions, improving cold day combustor light-off performance and providing reliable re-light capability with swirl-stabilized combustion, while extending component operational life by managing temperature and flow dynamics.
Implementation Method 1
an air swirler including a plurality of swirl openings surrounding an outlet of an auxiliary fuel injector
Implementation Method 2
An ignition source projects into the mixing chamber of the auxiliary combustion chamber
Implementation Method 3
cooling and dilution apertures to sustain flame stability and energy release
Implementation Method 4
extending component operational life by managing temperature and flow dynamics
Implementation Method 5
cooling and dilution apertures to sustain flame stability and energy release
Data Source
Figure 1
Figure 2A
Figure 2B~3
AI summary
A torch igniter (200) includes an auxiliary fuel injector (204); an ignition source (206); and an igniter body (202) carrying the auxiliary fuel injector and the ignition source. The igniter body (202) includes an auxiliary combustion chamber (210) having a side wall extending axially from a first end wall to a second end wall, the side wall defining an interior cavity between the first and second end walls. The igniter body (202) further includes a premixing cup (244) residing within the interior cavity including a cylindrical wall radially surrounding the auxiliary fuel injector and an auxiliary air inlet, the cylindrical wall of the premixing cup protruding axially outward relative to the first end wall of the auxiliary combustion chamber through a portion of the interior cavity to delineate a premixing zone radially inward of the cylindrical wall and a recirculation zone radially outward of the cylindrical wall.