Fuel Plenum Offset Liquid Conduit Thermal Strain Reduction
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Solution Overview
Problem
Known fuel nozzle assemblies for combustors face significant thermal differences between gas and liquid fuel circuits, leading to differential thermal expansion and undesirable thermal strains, which can cause temperature deviations and structural issues.
Innovation Solution
A fuel nozzle assembly design where the liquid fuel conduit is defined by an outer wall offset from the interior or outer wall of the fuel plenum, reducing structural constraints on thermal expansion and minimizing heat transfer by using an additive manufacturing process to create a conduit passage that reduces contact with hot surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the liquid fuel conduit is enclosed within the gaseous fuel plenum to save space, then the device complexity is reduced, but thermal strains increase due to differential thermal expansion between the hot gas circuit and cold liquid circuit
Solution Approach 1:
The liquid fuel conduit is nested within the gaseous fuel plenum, with the liquid fuel conduit positioned inside the plenum chamber. This nesting arrangement allows both fuel circuits to coexist in a compact configuration while maintaining thermal isolation through the plenum walls, thus reducing device complexity without causing excessive thermal strains
Solution Approach 2:
The plenum walls act as an intermediary barrier between the hot gaseous fuel circuit and the cold liquid fuel conduit. This intermediary structure provides thermal isolation, allowing the two circuits with different temperature requirements to be housed together in the same plenum without causing excessive thermal strains
2Volume of moving object
If the liquid fuel conduit is positioned close to the hot gaseous fuel circuit, then space is saved, but the liquid fuel temperature increases beyond the desired range
Solution Approach 1:
The liquid fuel conduit is nested within the gaseous fuel plenum, positioned inside the plenum chamber but thermally isolated by the plenum walls. This allows compact volume utilization while maintaining the liquid fuel temperature within the desired range through thermal barrier protection
Solution Approach 2:
The plenum walls serve as an intermediary thermal barrier between the hot gaseous fuel circuit and the liquid fuel conduit. This intermediary structure enables close positioning for space efficiency while preventing excessive heat transfer that would raise the liquid fuel temperature beyond acceptable limits
3Strength
If the liquid fuel conduit is constrained by the plenum structure, then structural integrity is improved, but thermal expansion is restricted causing thermal strains
Solution Approach 1:
The fuel nozzle assembly is segmented into distinct thermal zones: the hot gaseous fuel plenum and the cold liquid fuel conduit. This segmentation allows each component to accommodate its own thermal expansion independently, maintaining structural integrity while minimizing thermal strains through controlled separation
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 reduces thermal strains and maintains the liquid fuel within its desired temperature range by allowing axial thermal expansion without substantial structural constraint, thereby enhancing the structural integrity and operational efficiency of the fuel nozzle assembly.
Implementation Method 1
allowing axial thermal expansion without substantial structural constraint
Implementation Method 2
minimizing heat transfer by using an additive manufacturing process to create a conduit passage that reduces contact with hot surfaces
Data Source
AI summary
A fuel plenum for a fuel nozzle assembly includes a gaseous fuel conduit, a conduit passage, and a liquid fuel conduit. Said gaseous fuel conduit received at a first end of said fuel plenum. Said fuel plenum is configured to distribute gaseous fuel received from said gaseous fuel conduit. Said conduit passage extends from the first end to a second end of said fuel plenum. Said conduit passage is at least partially defined by at least one interior wall of said fuel plenum. Said liquid fuel conduit defined by an outer wall and a portion of said liquid fuel conduit extending through said conduit passage. Said liquid fuel conduit outer wall is offset from said at least one interior wall.