Continuous-Flow Fuel Manifold Circulation for Shutdown Coking Control
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Solution Overview
Problem
Coking in the fuel system of gas turbine engines occurs due to heat soak-back after shutdown, leading to compromised fuel nozzle performance and increased maintenance needs.
Innovation Solution
A fuel system with a manifold assembly and a fuel circulator pump that circulates fuel through the fuel injectors and manifolds after shutdown, preventing fuel injection into the combustor and cooling the system to mitigate coking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel flow is halted at shutdown, then fuel injection into combustor stops, but heat soak-back causes coking in fuel system
Solution Approach 1:
The patent converts the harmful heat soak-back effect into a beneficial cooling mechanism by circulating fuel through the fuel system after shutdown. The fuel, instead of being wasted or causing coking, absorbs heat from the combustor and fuel lines, actively cooling the system and preventing coke formation. This transforms the problematic thermal energy into a protective cooling action.
Solution Approach 2:
The patent extends the useful cooling action of fuel circulation beyond normal operation into the shutdown phase. By activating the fuel circulator pump after shutdown, the system maintains continuous fuel flow through the fuel injectors and lines, ensuring the cooling function persists even when combustion has stopped. This continuous action prevents the temperature rise that leads to coking.
2Temperature
If fuel circulator pump is activated after shutdown, then cooling of fuel system improves, but device complexity increases
Solution Approach 1:
The fuel circulator pump serves multiple functions: it operates during normal operation to maintain fuel circulation and pressure, and activates after shutdown to provide cooling. This multi-functionality eliminates the need for a separate cooling pump, reducing overall system complexity despite the added control logic. The same hardware component handles both operational and post-shutdown requirements.
Solution Approach 2:
The fuel system uses its own fuel supply to cool itself after shutdown. The circulated fuel absorbs heat from the fuel lines and injectors, and the cooled fuel returns to the system continuously. This self-cooling mechanism eliminates the need for external cooling systems or additional active cooling components, allowing the system to service its own thermal management needs.
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 likelihood of coke formation, maintaining fuel injector performance and reducing maintenance time and costs by keeping the fuel system clear and functional.
Implementation Method 1
heat from the combustor and case structure soaks into the fuel system
Implementation Method 2
fuel circulator pump is activated to flow fuel into at least one fuel manifold and a plurality of fuel injectors
Data Source
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AI summary
A fuel system (66) for a gas turbine engine (20) includes a manifold assembly (74) with an assembly inlet (94), an assembly outlet (96), and a plurality of fuel injectors (68; 148). The manifold assembly (74) also includes at least one fuel manifold (98) fluidically connecting each fuel injector (68; 148) of the plurality of fuel injectors (68; 148) to the assembly inlet (94) and to the assembly outlet (96). A fuel return line (78) is fluidically connected to the assembly outlet (96). A fuel circulator pump (72) includes a pump outlet (88) fluidically connected to the assembly inlet (94).