Concentric Fuel Manifold Insulation for Gas Turbine Stagnation
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Solution Overview
Problem
Gas turbine engine combustion chambers face issues with fuel stagnation and heat conduction in main fuel manifolds and pipework, leading to potential fuel breakdown, carbon formation, and blockages due to thermal and mechanical stresses in curved fuel pigtails, especially at low power conditions.
Innovation Solution
A fuel manifold and injector arrangement featuring concentric pipes with a thermally insulating medium between them, where the main fuel flow path is surrounded by a pilot fuel flow path, reducing heat transfer and stagnation, and incorporating a thermally insulating coating to prevent fuel breakdown and blockages, with the pipes made from durable alloys like steel or nickel alloys using advanced manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If curved fuel pigtails are used to supply fuel from the fuel manifold to the fuel nozzle, then fuel delivery is achieved, but thermal and mechanical stresses lead to potential fuel breakdown, carbon formation, and blockages
Solution Approach 1:
The patent employs a nested pipe structure where an inner fuel-carrying pipe is positioned within an outer pipe. This nested arrangement allows the inner pipe to be thermally insulated by the outer pipe while maintaining fuel flow, thereby reducing thermal stresses and preventing fuel breakdown and carbon formation.
Solution Approach 2:
The outer pipe acts as an intermediary element between the fuel manifold and the fuel nozzle, providing thermal insulation and mechanical protection to the inner fuel-carrying pipe. This intermediary structure reduces harmful thermal and mechanical stresses on the fuel.
2Use of energy by moving object
If the main fuel nozzles are not supplied with fuel at low power conditions, then fuel consumption is reduced, but heat conduction leads to fuel stagnation, breakdown, and blockage
Solution Approach 1:
The nested pipe structure with the inner fuel-carrying pipe within the outer insulating pipe prevents heat conduction to stagnant fuel in the main fuel nozzles during low power conditions, thereby preventing fuel breakdown and blockage while allowing reduced fuel consumption.
Solution Approach 2:
The patent converts the harmful effect of heat conduction to stagnant fuel into a beneficial insulation effect. The outer pipe, which would normally conduct heat, is configured to insulate the inner pipe, thereby protecting stagnant fuel from thermal degradation during low power operation.
3Ease of manufacture
If conventional single-layer fuel pipes are used, then manufacturing is simple, but thermal insulation is insufficient leading to fuel stagnation and blockage
Solution Approach 1:
The nested dual-layer pipe structure provides effective thermal insulation to prevent fuel stagnation and blockage. While the structure is more complex than single-layer pipes, the patent describes manufacturing methods that make the dual-layer construction feasible.
Solution Approach 2:
The patent employs a composite pipe structure with an inner pipe for fuel delivery and an outer pipe for thermal insulation. This composite arrangement combines the functionality of fuel transport with thermal protection, improving fuel flow reliability.
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
This design minimizes fuel stagnation and heat transfer, reducing the risk of fuel breakdown and blockages, while maintaining structural integrity and flexibility to accommodate thermal expansion, thus enhancing the reliability and efficiency of fuel delivery in gas turbine engines.
Implementation Method 1
a vacuum or a thermally insulating medium being provided in a chamber defined between the outer pipe and the intermediate pipe
Implementation Method 2
Heat may be conducted from the surroundings through the main fuel manifold and main fuel pipework and into the main fuel
Data Source
AI summary
A fuel manifold and fuel injector arrangement has a fuel manifold and at least one fuel injector. The fuel injector has main and pilot fuel nozzles. The fuel manifold has at least one fuel pipe segment and each fuel pipe segment has an outer pipe, an intermediate pipe arranged within the outer pipe and an inner pipe arranged within the intermediate pipe. A thermally insulating medium is provided in a chamber defined between the outer pipe and the intermediate pipe. The chamber between the intermediate pipe and the inner pipe is fluidly connected to a first fuel supply and the chamber within the inner pipe is fluidly connected to a second fuel supply. The at least one pilot fuel nozzle is fluidly connected to the chamber between the intermediate pipe and the inner pipe and the main fuel nozzle is fluidly connected to the chamber within the inner pipe.