Torch Igniter Cooling System for Gas Turbine Combustors
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Solution Overview
Problem
Torch igniters in gas turbine engines face durability issues due to high temperatures exceeding 3000-4000° F, which exceed the thermal limits of materials used in their construction, leading to potential thermal stress and reduced longevity.
Innovation Solution
A cooling system that utilizes high-pressure air from the gas turbine engine to cool the torch igniter, specifically channeling air through cooling channels and passages around the glow plug housing and igniter wall, preventing thermal stress and allowing the use of high-temperature metallic components fabricated via additive manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If torch igniters are used in combustors of gas turbine engines, then a larger target for fuel injectors is provided allowing greater range of fuel injector designs, but the igniters experience temperatures exceeding 3000-4000° F. which exceed thermal limits of materials and negatively impact durability
Solution Approach 1:
The igniter assembly is divided into distinct functional components: a structural wall forming the housing, an igniter wall defining the combustion chamber, and a glow plug housing extending through both walls. This segmentation allows each component to be optimized for its specific function while managing thermal loads independently.
Solution Approach 2:
A cooling system acts as an intermediary between the hot combustion environment and the igniter components. The cooling system includes cooling channels formed in the structural wall and air passages in the igniter wall, which channel compressed air to cool the glow plug housing and igniter components, protecting them from excessive thermal stress.
2Temperature
If high-temperature materials are used in torch igniter construction to withstand 3000-4000° F. temperatures, then thermal limits are met, but manufacturing complexity and cost increase
Solution Approach 1:
The cooling system utilizes pneumatic principles by channeling compressed air from the gas turbine engine's compressor section through cooling channels and air passages. This pneumatic cooling system provides efficient heat removal without requiring complex active cooling mechanisms, simplifying manufacturing while maintaining thermal resistance.
Solution Approach 2:
The cooling system changes the thermal parameters of the igniter components by introducing cool compressed air into the hot environment. The cooling channels and air passages create controlled thermal zones, reducing the temperature experienced by the glow plug housing and igniter walls, thereby allowing the use of more manufacturable materials.
3Duration of action of stationary object
If cooling channels are added to protect glow plug housing from thermal stress, then component longevity is improved, but device complexity increases
Solution Approach 1:
The cooling system serves multiple functions: it cools the glow plug housing, protects the igniter wall, and utilizes compressed air already present in the gas turbine engine system. The same compressed air source that powers the engine also provides the cooling medium, eliminating the need for separate cooling systems and reducing overall complexity.
Solution Approach 2:
The cooling channels are integrated into the structural wall, and air passages are formed in the igniter wall, merging the cooling function with the structural and combustion chamber functions. This integration reduces the number of separate components and simplifies manufacturing while providing comprehensive 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
The cooling system effectively reduces temperature tolerance requirements for the torch igniter components, enabling their construction from durable metallic materials and preventing heat transfer to electrical connections, thus enhancing the longevity and operational efficiency of the torch igniter.
Implementation Method 1
a cooling channel forming a flow path extending from the air inlet and through the structural wall at the glow plug housing... configured to flow air taken in at the air inlet around the glow plug housing to cool the glow plug housing
Implementation Method 2
an air passage extending through the igniter wall transverse to the axis... The air passage fluidly connects the cooling channel to the combustion chamber
Data Source
AI summary
An embodiment of a torch igniter for a combustor of a gas turbine engine includes a combustion chamber oriented about an axis, a cap defining an axially upstream end of the combustion chamber, a tip defining the axially downstream end of the combustion chamber, an 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, an outlet passage defined by the igniter wall within the tip, a glow plug housing configured to receive a glow plug and allow an innermost end of the glow plug to extend into the combustion chamber, and a cooling system. The cooling system includes an air inlet formed within an exterior of the structural wall, a cooling channel forming a flow path through the structural wall at the glow plug housing, and an air passage.