Gearbox Oil Gutter Layout for Windage Loss Reduction
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Solution Overview
Problem
In epicyclical gear trains used in gas turbine engines, oil lubrication leads to oil expulsion outwardly due to inertial forces, resulting in potential accumulation and increased windage loss, which existing systems fail to efficiently manage.
Innovation Solution
The implementation of a local gutter system with strategically positioned openings in the carrier and a global gutter that circumscribes the gear train, both designed to collect and efficiently remove oil expelled from bihelical planet gears, preventing accumulation and churning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil is supplied to lubricate the mesh between gears in an epicyclical gear train, then lubrication effectiveness is improved, but oil accumulation and windage loss increase due to centrifugal forces expelling oil outwardly
Solution Approach 1:
The gutter is divided into multiple segments: a plurality of first gutters positioned at different radial locations to collect oil from different gear mesh zones, and a second gutter positioned radially inward to collect oil from the first gutters. This segmented approach allows localized oil collection at the source of expulsion, preventing oil accumulation in the gear train while maintaining lubrication effectiveness.
Solution Approach 2:
The gutter system acts as an intermediary between the gear mesh zones and the oil reservoir. The gutters intercept oil expelled by centrifugal forces before it can accumulate and cause windage loss, channeling it through a controlled path back to the oil reservoir, thus mediating between the lubrication need and the energy loss problem.
2Loss of energy
If a traditional oil collection system is used, then oil removal is attempted, but oil accumulation persists and churning occurs due to inefficient collection
Solution Approach 1:
The gutters are positioned to intercept oil at the point of expulsion from gear meshes, performing preliminary collection before oil can accumulate significantly. The first gutters are strategically placed at radial locations where oil is expelled from specific gear meshes, capturing oil proactively rather than reactively.
Solution Approach 2:
The gutter system utilizes the radial dimension effectively by positioning gutters at multiple radial locations throughout the gear train. This multi-dimensional arrangement allows oil collection from various gear mesh zones simultaneously, preventing accumulation in any single zone and reducing overall oil churning loss.
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 solution effectively reduces oil accumulation and windage loss by ensuring efficient oil collection and circulation, enhancing the operational efficiency and longevity of the gearbox in aircraft and other turbine engines.
Implementation Method 1
As the gears of the epicyclical gear train rotate during operation, the oil is expelled outwardly by inertial (or centrifugal) forces.
Data Source
AI summary
A gearbox including a gear and a gutter. The gear is rotatable about a rotational axis in a rotational direction. The gear has a radial direction and an axial direction, and the gear expels oil radially outward when the gear rotates. The gutter is positioned radially outward of the gear in the radial direction of the gear to collect oil expelled by the gear when the gear rotates. The gutter includes an axial surface, a plurality of radial surfaces including a first radial surface and a second radial surface, and at least one opening to allow the oil collected in the gutter to flow therethrough. Each of the first radial surface and the second radial surface is oriented in a direction intersecting the axial surface, and the at least one opening is formed on both the axial surface and one of the first radial surface and the second radial surface.