Gas Turbine Igniter Seal Arrangement Reducing Wake Effect
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Solution Overview
Problem
The conventional igniter tower in gas turbine engines creates a wake in the air flow, disrupting the cooling air supply to the combustion chamber downstream, requiring additional cooling and necessitating a separate, welded component that avoids cooling features in the heat-affected zone.
Innovation Solution
A novel igniter seal arrangement featuring a boss with a platform and L-shape rails, a sealing member with a tear-drop shaped aperture, and frusto-conical guide members, which reduces the wake effect and integrates seamlessly with the combustion chamber wall, minimizing the need for additional cooling and eliminating the heat-affected zone issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tubular igniter tower is used to extend across the outer annular flow, then the igniter can be secured to the combustion chamber wall, but it produces a wake in the air flow that disrupts cooling air supply downstream
Solution Approach 1:
The igniter support structure is divided into multiple functional segments: a boss portion integrated into the wall, a platform portion for mounting, and a seal portion with rails. This segmentation allows each part to perform its specific function while minimizing overall interference with airflow.
Solution Approach 2:
The boss, platform, and seal portions are merged into a single integrally formed component manufactured by additive manufacturing. This integration eliminates the need for separate welded parts and allows the structure to be optimized as a unified aerodynamic element that minimizes wake while providing support and sealing functions.
2Reliability
If a separate igniter tower component is welded onto the combustion chamber wall, then the igniter can be secured, but cooling features cannot be placed in the heat affected zone of the weld
Solution Approach 1:
The igniter support structure is merged with the combustion chamber wall as an integrally formed component. The boss portion is directly formed as part of the wall structure, eliminating the need for separate welding operations and allowing cooling features to be seamlessly integrated without heat-affected zone constraints.
Solution Approach 2:
The manufacturing method is changed from conventional welding to additive manufacturing. This parameter change enables the creation of complex integral structures with internal cooling passages that would be difficult or impossible to achieve with traditional welding and assembly methods.
3Temperature
If additional cooling air is supplied to compensate for the wake effect, then the combustion chamber downstream can be cooled, but the overall cooling air requirement increases
Solution Approach 1:
The cooling system is segmented into regions: primary cooling air flows through the combustor liner, while secondary cooling air is directed through the annular space between the igniter support structure and the liner. This segmentation allows efficient cooling distribution without requiring excessive total cooling air.
Solution Approach 2:
Cooling air is supplied from multiple spatial dimensions: through the liner wall and through the annular space surrounding the igniter support structure. This multi-dimensional cooling approach improves cooling efficiency and reduces the total quantity of cooling air required compared to single-direction cooling.
4Reliability
If a conventional igniter tower is used, then the igniter can be supported, but the structure interferes with the outer annular flow and requires additional cooling air
Solution Approach 1:
The igniter support structure is segmented into functional portions (boss, platform, seal) that can be independently optimized. The seal portion with rails and stop members provides a simplified mounting system for the igniter, reducing overall structural complexity while maintaining support reliability.
Solution Approach 2:
The integrally formed igniter support structure performs multiple functions simultaneously: structural support for the igniter, sealing between the igniter and combustion chamber wall, and aerodynamic flow management. This multi-functionality reduces the number of separate components needed and simplifies the overall system.
Data Source
Figure 1~2
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Figure 5
AI summary
An igniter seal arrangement (112) for a combustion chamber (16). The combustion chamber (16) comprises a wall (72, 74) having a first surface (114) and a second surface (116). A boss (118) projects from the first surface (114) of the wall (72, 74). The boss (118) has a platform (12) on a remote end of the boss (118). The platform (120) has an inner surface (122) spaced from the first surface (114) of the wall (72, 74) to define a chamber (124) between the first surface (114) of the wall (72, 74) and the inner surface (122) of the platform (120). The platform (120) has an outer surface (126) facing away from the first surface (114) of the wall (72, 74) and an aperture (110) extends through the wall (72, 74) from the outer surface (126) of the platform (120) of the boss (118) to the second surface (116). First and second L-shape rails (128, 130) extend from the platform (120) and a sealing member (132) has a first edge and a second edge (134, 136) locatable between the outer surface (126) of the platform (120) and the first and second L-shape rails (128, 130) and the sealing member (132) has an aperture (138) to receive an igniter (108).