Gearbox Gutter Layout for Lubricant Scavenge and Windmilling
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Solution Overview
Problem
Existing gearbox assemblies in gas turbine engines face efficiency losses due to windage and friction, which generate heat and reduce the transfer of power from the low-pressure shaft to the fan shaft, and existing gutters for lubricant scavenging are either too large, taking up space and adding weight, or too small, failing to effectively remove lubricant and dissipate heat.
Innovation Solution
A gearbox assembly with a gutter configuration that optimally collects and removes lubricant from the gearbox, utilizing a gutter that circumscribes the ring gear and includes a scavenge port located at the bottom to facilitate lubricant removal, assisted by gravity, and a lubrication system with dual reservoirs to ensure continuous lubrication during engine operation and windmilling conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gutter volume is increased to effectively collect and remove lubricant, then lubricant removal effectiveness is improved, but the gutter takes up more space and adds weight
Solution Approach 1:
The patent applies parameter changes by optimizing the gutter volume to gearbox volume ratio (Vg/Vgb) within a specific range (0.01-0.3). This quantitative parameter optimization allows the gutter to be sufficiently large to effectively collect and remove lubricant while constraining it to be compact enough to minimize space occupation and weight addition. The ratio-based approach provides a scalable solution that adapts to different gearbox sizes.
2Temperature
If the gutter volume is increased to effectively collect and remove lubricant, then heat dissipation capability is improved, but the overall gearbox assembly size increases
Solution Approach 1:
The patent uses parameter changes by defining an optimal range for the gutter volume to gearbox volume ratio (Vg/Vgb between 0.01 and 0.3). This parameter optimization ensures the gutter is large enough to provide adequate heat dissipation through lubricant collection and removal, while simultaneously keeping the overall gearbox assembly volume constrained. The ratio-based design allows heat dissipation capability to be improved without proportionally increasing the total assembly size.
3Reliability
If a larger gutter is used to ensure continuous lubrication during windmilling, then lubrication reliability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent applies parameter changes by establishing an optimal gutter volume to gearbox volume ratio range (0.01-0.3) that ensures sufficient lubricant collection capacity during windmilling conditions. This quantitative optimization provides reliable continuous lubrication without requiring overly complex gutter configurations or excessive space. The ratio-based approach simplifies design by providing clear dimensional guidelines rather than requiring complex adaptive systems.
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
The optimized gutter and lubrication system improve gearbox efficiency by effectively removing lubricant, reducing heat generation, and maintaining lubrication even during engine shutdowns, thereby enhancing power transfer and overall engine performance.
Implementation Method 1
a scavenge port located at the bottom to facilitate lubricant removal, assisted by gravity
Data Source
AI summary
A gearbox assembly includes a gearbox having a gear assembly and a gutter for collecting a gearbox lubricant scavenge flow from the gearbox. The gutter is characterized by a lubricant extraction volume ratio between 0.01 and 0.3, inclusive of the endpoints. The lubricant extraction volume ratio is defined byVGVGB. VGis a gutter volume of the gutter and VGB is a gearbox volume. A gas turbine engine includes the gearbox assembly and a lubrication system. The lubrication system includes a sump that is a primary reservoir having a first lubricant level and a secondary reservoir in the gearbox assembly. The secondary reservoir has a second lubricant level. The lubrication system fills the secondary reservoir with a lubricant between the first lubricant level and the second lubricant level. The gear assembly collects the lubricant in the secondary reservoir to supply the lubricant to the gear assembly.