Radially Oriented Torch Igniter Internal Mounting
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Solution Overview
Problem
Torch igniters in gas turbine engines face damage from high temperatures and require thick structural walls to withstand external pressure differentials when mounted externally, leading to increased stress and risk of rupture when mounted internally.
Innovation Solution
Mounting the torch igniter partially within the high pressure case of the gas turbine engine, where the combustion chamber is located inside the case, reduces the pressure differential and allows for thinner structural walls, containing potential ruptures within the case while preventing damage from high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the torch igniter is mounted externally to the high pressure case, then the structural walls can be thinner, but the igniter is exposed to extremely high temperatures that can damage temperature-sensitive elements
Solution Approach 1:
The patent introduces a cooling fluid as an intermediary substance that flows through channels in the structural wall between the combustion chamber and the external environment. This cooling fluid acts as a thermal barrier, absorbing heat from the high-temperature combustion chamber and preventing extreme temperatures from reaching temperature-sensitive elements of the igniter, thus resolving the contradiction between thermal protection and structural thinness
2Temperature
If the torch igniter is mounted internally within the high pressure case, then the igniter is protected from high temperatures, but the structural walls must be thicker to withstand the high pressure differential
Solution Approach 1:
The patent applies local quality by making the structural wall thickness non-uniform: the wall is thickest at the combustion chamber where high temperatures occur, providing thermal protection, and gradually thinners toward the external environment where pressure differential is less critical. This localized variation in thickness optimizes both thermal protection and pressure resistance, resolving the contradiction between these two requirements
3Strength
If the structural walls are made thicker to withstand pressure differentials, then pressure resistance improves, but the overall bulk and weight of the torch igniter increase
Solution Approach 1:
The patent employs thin-walled structural designs with optimized cross-sectional geometries that provide sufficient pressure differential resistance while minimizing material usage. The structural walls are designed with efficient load-bearing configurations that achieve the required strength with minimal thickness, thereby reducing the overall bulk and weight of the torch igniter while maintaining pressure resistance
Data Source
AI summary
An embodiment of a combustor for a gas turbine engine includes a combustor case, a combustor liner disposed within the combustor case, a fuel nozzle, and a torch igniter within the combustor case. The torch igniter includes a combustion chamber, a cap defining the upstream end of the combustion chamber and configured to receive a fuel injector and a surface igniter, a tip defining the downstream end of the combustion chamber, an annular igniter wall extending from the cap to the tip and defining a radial extent of the combustion chamber, a structural wall coaxial with and surrounding the igniter wall, and an outlet passage within the tip that fluidly connects the combustion chamber to the combustor. The torch igniter is situated such that the tip is mounted through the combustor liner, the combustion chamber is within the combustor case, and the cap extends through the combustor case.