Combustor Suction Cooling During Shutdown to Prevent Fuel Nozzle Coking

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Solution Overview

Problem

During gas turbine engine shutdown, residual heat causes temperature increases leading to carbon deposits (coking) in fuel nozzles and other components, resulting in costly issues like engine start problems and inefficient combustion.

Innovation Solution

A suction enabled post shutdown combustor cooling and ventilation system that draws cooling air from the core flow path and combustor cavity, using valves and pumps to promote airflow from aft to forward, dumping hot air to the fan bypass stream and venting the core compartment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the engine is shutdown, then the cooling systems stop operating, but residual heat causes temperature increases leading to carbon deposits in fuel nozzles and components

Engineering Contradiction:

Improveprevention of carbon depositsVSAvoidresidual heat in components

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The system performs cooling action before the engine fully shuts down by detecting shutdown conditions and activating the suction system in advance. The controller monitors engine parameters and initiates cooling airflow through the combustor before residual heat can cause coking, thereby preventing carbon deposits while the engine is still in a controlled state.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The cooling system maintains continuous operation during the shutdown transition period. The suction system continues to draw cooling air through the combustor and discharge it through the fan bypass duct throughout the shutdown sequence, ensuring uninterrupted cooling action that prevents temperature rise and carbon deposit formation while transitioning from operational to shutdown state.

Inventive Principle:

Principle #20Continuity of useful action

2Temperature

If cooling systems operate during shutdown, then residual heat can be managed, but the system complexity increases with additional valves and pumps

Engineering Contradiction:

Improvecontrol of residual heatVSAvoidadditional valves and pumps

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The suction system and pump are designed to serve multiple functions: during normal operation, the pump maintains suction line pressure and the system prepares cooling air; during shutdown, the same system activates post-shutdown cooling by drawing air through the combustor. This multi-functionality reduces the need for separate dedicated shutdown cooling components, thereby managing residual heat without proportionally increasing system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the engine's own core flow path and existing fan bypass duct to provide cooling during shutdown. The suction system draws cooling air from the core flow path and discharges it through the fan bypass duct, utilizing already-present infrastructure rather than requiring entirely new cooling pathways. This self-service approach manages residual heat while minimizing additional component requirements.

Inventive Principle:

Principle #25Self-service

3Reliability

If suction system draws cooling air from core flow path, then combustion air supply is reduced, but this prevents coking in fuel nozzles

Engineering Contradiction:

Improveprevention of cokingVSAvoidcombustion air supply

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The system dynamically adjusts the suction valve opening based on engine operating conditions. During normal operation, the suction valve remains closed to maintain full combustion air supply. Upon detecting shutdown conditions, the controller opens the suction valve to activate cooling airflow. This dynamic control ensures that combustion air supply is maintained during operation while enabling coking prevention during shutdown, resolving the contradiction between air supply quantity and coking prevention.

Inventive Principle:

Principle #15Dynamics

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

Reduces the risk of coking in fuel nozzles and other components, preventing costly failures and ensuring efficient engine operation post-shutdown.

Implementation Method 1

Methodology Applied

Scientific EffectSuction: Suction

Implementation Method 2

dumping hot air to the fan bypass stream and venting the core compartment

Methodology Applied

Scientific EffectHeat transfer: Convection

Data Source

PatentUS20260063072A1Suction enabled post shutdown combustor cooling and ventilation

Publication Date: 2026.03.05 RTX CORP

AI summary

A post shutdown combustor cooling system including a pump with a suction line coupled with bleed ports; a bleed port line coupled with the suction line; a pump suction valve positioned in the suction line upstream of the pump; a bleed valve positioned in the bleed port line; a pump discharge line coupled with the pump, a core compartment supply line coupled with a turbine cooling air port, a core compartment inlet located within a core compartment coupled with the core compartment, the core compartment supply line having a core compartment supply valve; a turbine cooling air supply line coupled to the core compartment supply line and the high pressure turbine cooling air port, the turbine cooling air supply line comprising a turbine cooling air valve; and an engine core flow path coupled with the bleed ports and turbine cooling air port.