Floating Collar Igniter Cooling for Gas Turbine Combustors
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Solution Overview
Problem
In gas turbine engines, the existing combustor designs face issues with igniter stability and altitude re-ignition due to the interaction between the fuel nozzle spray and spark, and the exposure of the igniter tip to hot gases, which can lead to damage from hot gas ingestion into the cavity between the igniter and the cavity wall.
Innovation Solution
A floating collar mounting system is used on the combustor liner assembly with annular surfaces and purge openings to create cooling airflow passages, directing pressurized air from the plenum into the cavity surrounding the igniter tip, thereby protecting it from hot gases and maintaining mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the igniter tip is exposed close to the fuel spray for effective ignition, then the ignition stability and altitude re-ignition capability are improved, but the igniter tip becomes vulnerable to hot gas ingestion and thermal damage
Solution Approach 1:
A floating collar is introduced as an intermediary component between the igniter tip and the hot combustion gases. The collar includes cooling passages that allow cooling air to flow through, creating a thermal barrier that protects the igniter tip while maintaining its proximity to the fuel spray for effective ignition.
Solution Approach 2:
The invention utilizes pneumatic cooling by directing cooling air through passages in the floating collar. This airflow creates a protective cooling effect around the igniter tip, allowing it to remain exposed for reliable ignition without suffering thermal damage from hot gas ingestion.
2Reliability
If a gap is provided between the igniter and cavity wall to prevent mechanical interference, then the igniter reliability during flight envelope operations is improved, but hot gas can ingress into the cavity and burn the igniter
Solution Approach 1:
The floating collar acts as an intermediary barrier between the igniter cavity and the hot combustion gases. It seals the cavity while allowing relative movement, preventing hot gas ingress that would otherwise occur through the gap between the igniter and cavity wall.
Solution Approach 2:
The cooling air flowing through the floating collar creates an inert or cooler atmosphere around the igniter tip, replacing the hot combustion gases in the immediate vicinity of the igniter and protecting it from thermal damage.
3Object-affected harmful factors
If the igniter is buried in a cavity with minimal exposure, then protection from hot gases is improved, but the interaction between fuel spray and spark is reduced affecting combustion stability
Solution Approach 1:
The floating collar is designed to slide axially relative to the mounting bracket, allowing dynamic adjustment of the igniter tip position. This enables the system to optimize the balance between exposing the tip for effective spark-fuel interaction and protecting it through the cooling collar structure.
Solution Approach 2:
The pneumatic cooling system through the floating collar provides thermal protection, enabling the igniter to maintain better exposure to the fuel spray than traditional buried designs while still being protected from hot gas damage through active 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 effectively minimizes damage to the igniter tip by providing a cooling airflow that prevents hot gas ingestion, ensuring stable combustion and re-ignition capabilities while maintaining the igniter's mechanical integrity throughout the flight envelope.
Implementation Method 1
a plurality of cooling passages defined in the floating collar, the cooling passages communicating from an outer surface of the floating collar to an inner surface of the floating collar
Implementation Method 2
the igniter having an axis concentric with said axis of the collar opening and sealingly engaging the annular surface
Data Source
AI summary
A gas turbine engine comprising a combustor having a combustor liner assembly and a mounting bracket provided on the combustor liner assembly, a floating collar being slidingly received on the mounting bracket for relative sliding movement in a plane normal to an axis of an igniter opening in the liner assembly. The floating collar includes an annular surface defining a collar opening, and an igniter having an axis concentric with the axis of the collar opening is sealingly engages the annular surface. A plurality of purge openings defined in at least one of the igniter and the floating collar form cooling airflow passages communicating from the plenum to the cavity.