Turbomachine Gearbox Efficiency Rating for Oil Flow Sizing
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Solution Overview
Problem
Geared turbofan engines face increased complexity due to the inclusion of a gearbox, making engine development and manufacturing more difficult, necessitating improved methods for efficiency and precision.
Innovation Solution
The introduction of a gearbox efficiency rating (GER) formula, Q(D1.56T)1.53, which aids in the development and simplification of geared turbofan engines by quantifying gearbox efficiency based on oil flow rate, fan diameter, and net thrust, allowing for optimized gearbox configuration and oil flow estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gearbox is included in a turbofan engine to allow different rotational speeds for power turbine and bypass fan, then operational efficiency and power production are improved, but device complexity increases making development and manufacturing more difficult
Solution Approach 1:
The patent introduces a gearbox efficiency rating parameter that quantifies the relationship between gearbox oil flow rate, fan diameter, and net thrust. This parameter enables systematic optimization of gearbox configurations by changing key operational parameters (oil flow rate Q, fan diameter D, net thrust T) to achieve desired efficiency levels while managing complexity through standardized rating criteria.
2Productivity
If a gearbox is included in a turbofan engine to allow different rotational speeds for power turbine and bypass fan, then operational efficiency is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent establishes manufacturing guidance based on the gearbox efficiency rating parameter, which correlates oil flow rate, fan diameter, and net thrust to predicted efficiency levels. This enables manufacturers to select from standardized gearbox configurations that meet target efficiency criteria, simplifying the manufacturing decision-making process while maintaining operational efficiency.
3Productivity
If gearbox oil flow rate is increased to improve gearbox efficiency, then operational efficiency is improved, but engine complexity and oil system requirements increase
Solution Approach 1:
The patent uses the gearbox efficiency rating parameter to systematically determine appropriate oil flow rate values based on fan diameter and net thrust requirements. Rather than arbitrarily increasing oil flow rate, the method calculates the specific flow rate needed to achieve target efficiency levels, optimizing the balance between gearbox efficiency and oil system complexity.
Data Source
AI summary
A turbomachine engine can include an unducted fan assembly, an unducted vane assembly, a core engine, a gearbox, and a gearbox efficiency rating. The unducted fan assembly can include a plurality of fan blades. The unducted vane assembly can include a plurality of vanes, and the vanes can, in some instances, be disposed aft of the fan blades. The core engine can include one or more compressor sections and one or more turbine sections. The gearbox includes an input and an output. The input is coupled to the one or more turbine sections of the core engine and comprises a first rotational speed, the output is coupled to the unducted fan assembly and has a second rotational speed, and a gear ratio of the first rotational speed to the second rotational speed is within a range of 4.1-14.0. The gearbox efficiency rating is 0.10-1.8.