Impingement Cooled Igniter Seals for Dual Walled Combustors
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Solution Overview
Problem
Conventional combustors for gas turbine engines face challenges in efficiently cooling igniters without disrupting combustion processes, particularly in dual walled combustors where relative movements of components complicate cooling air delivery, leading to inefficiencies and potential thermal stress issues.
Innovation Solution
A dual walled combustor design with an igniter support assembly featuring floating seals and cooling holes that direct impingement air to the igniter tip, accommodating radial and axial movements to ensure effective cooling while minimizing interference with combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional igniters use longitudinal slots to channel cooling air to the tip portion, then the igniter can be cooled, but a large amount of cooling air is required which adversely impacts combustion conditions and creates perturbative effects
Solution Approach 1:
The igniter cooling system is segmented into multiple cooling air passages distributed along the igniter length, with cooling holes positioned at specific locations to deliver cooling air directly to the tip portion. This segmentation allows targeted cooling with reduced total cooling air quantity compared to conventional longitudinal slot designs.
Solution Approach 2:
Cooling air is delivered locally to the tip portion of the igniter through strategically positioned cooling holes, concentrating the cooling effect where it is most needed. The floating seal assembly with cooling holes provides localized impingement cooling rather than distributed cooling along the entire igniter length.
2Temperature
If a large amount of cooling air is used to cool the igniter tip, then the igniter is sufficiently cooled, but excess cooling air disrupts the liner cooling film and creates local hot spots in the combustor liner
Solution Approach 1:
The cooling air delivery system uses localized cooling holes positioned to provide impingement cooling directly at the igniter tip, concentrating cooling where needed while avoiding excessive cooling air that would disrupt the liner cooling film. The floating seal assembly with strategically positioned cooling holes ensures precise cooling delivery.
Solution Approach 2:
The system uses a controlled partial amount of cooling air delivered through multiple cooling holes, providing sufficient cooling to the igniter tip without the excessive cooling that would disrupt the liner cooling film and create hot spots. The floating seal assembly optimizes the quantity and distribution of cooling air.
3Temperature
If dual walled combustors are used, then component movement and sealing challenges are introduced, but the design provides better thermal management and reduced thermal stresses
Solution Approach 1:
The floating seal assembly is designed to accommodate radial and axial relative movements between the inner and outer liners during operation. The floating seals maintain sealing contact dynamically as the dual-walled combustor components move relative to each other, providing both sealing and cooling functions while adapting to thermal expansion and mechanical deformation.
Solution Approach 2:
The floating seal assembly with cooling holes serves multiple functions simultaneously: it provides sealing between the inner and outer liners, delivers cooling air to the igniter tip, and accommodates relative movements of the dual-walled structure. This multi-functionality reduces overall system complexity despite the dual-walled configuration.
4Temperature
If cooling air is channeled through the outer passageway to cool the outer liner and igniters, then the igniters are cooled, but thermal stresses exceed material strength leading to low cycle fatigue failure
Solution Approach 1:
Cooling air is delivered locally to the igniter tip through the floating seal assembly with cooling holes, providing targeted cooling that reduces thermal stresses in the igniter. This localized cooling approach prevents excessive thermal gradients that would cause low cycle fatigue failure, thereby extending igniter lifespan while maintaining effective cooling.
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 solution provides efficient impingement cooling, reducing the amount of cooling air needed and minimizing thermal stresses, thereby enhancing igniter performance and extending its lifespan while maintaining combustion efficiency.
Implementation Method 1
The igniter support assembly defines a plurality of holes configured to direct cooling air toward the tip portion of the fuel igniter
Implementation Method 2
direct cooling air to the vicinity of the tip portion of the igniter
Data Source
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AI summary
A combustor for a gas turbine engine includes an inner liner and an outer liner circumscribing the inner liner and forming a combustion chamber therewith. The outer liner is a dual walled liner with a first wall and a second wall. A fuel igniter includes a tip portion configured to ignite an air and fuel mixture in the combustion chamber. An igniter support assembly positions the fuel igniter relative to the combustion chamber. The igniter support assembly defines a plurality of holes configured to direct cooling air toward the tip portion of the fuel igniter. The igniter support assembly includes first and second floating seals that are configured to accommodate radial and axial relative movements.