Electric Compressor Cooling for Fuel Nozzle Coking Prevention
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Solution Overview
Problem
Coking in fuel systems of gas turbine engines occurs during shutdown due to heat soak from the combustor and case structure, compromising fuel nozzle performance and requiring maintenance.
Innovation Solution
An electrically powered compressor is integrated within the gas turbine engine to direct air from the bypass flow path to cool the turbine and combustion sections during and after shutdown, preventing fuel from overheating and forming coke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel flow is halted at shutdown, then fuel system operation stops, but heat from combustor and case structure soaks into fuel system causing coking
Solution Approach 1:
The system applies preliminary cooling action to the fuel system before shutdown occurs. By detecting engine shutdown conditions and activating cooling flow to fuel nozzles and lines before heat soak can cause coking, the system prevents the harmful effect before it manifests. This anticipatory approach addresses the technical contradiction by preparing the fuel system against heat soak damage in advance.
Solution Approach 2:
The patent introduces cooling air as an intermediary substance between the heat source (combustor and case structure) and the fuel system components. This cooling air acts as a thermal barrier that absorbs heat from the combustor and case structure, preventing direct heat transfer to the fuel nozzles and lines. The intermediary cooling flow protects the fuel system from heat soak without requiring changes to the fuel itself.
2Reliability
If cooling air is directed to fuel system, then coking is prevented, but additional system complexity is required
Solution Approach 1:
The cooling air system serves multiple functions simultaneously: it cools the turbine section during operation, cools the combustor and case structure, and provides protective cooling to the fuel system during shutdown. By using a single cooling air source and distribution network to accomplish multiple cooling objectives, the system avoids the complexity that would arise from separate dedicated cooling systems for each function.
Solution Approach 2:
The system uses engine operating parameters and existing temperature gradients to automatically control cooling air distribution. The cooling air flow is directed based on inherent system conditions rather than requiring complex external control systems. This self-regulating approach reduces control system complexity while maintaining effective cooling of both the turbine and fuel system components.
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
Maintains fuel injector performance by preventing coke formation, enhancing reliability and reducing maintenance needs.
Implementation Method 1
pumping air from the compressor section to the at least one cooling passage in the turbine section by the electric compressor
Implementation Method 2
pumping air from the bypass flow path to the combustion section by the electric compressor to cool the combustion section
Data Source
AI summary
A gas turbine engine includes an engine core with a compressor section, a combustion section downstream of the compressor section relative to a core flow path, and a turbine section downstream of the combustion section relative to the core flow path. A core casing extends around the compressor section, the combustion section, and the turbine section. A second casing extends around the core casing and a core compartment is between the core casing and the second casing. An electric compressor is in the core compartment. A first port is formed in the second casing and fluidically is connected to the electric compressor. A second port is formed in the core casing in the combustion section and is fluidically connected to the electric compressor.