Dual-Spool Power Extraction Gearbox for Balanced Turbofan Loads
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Solution Overview
Problem
Turbine engine performance is limited by increasing loads on a single spool, which can degrade engine efficiency and power extraction capabilities, necessitating improved power distribution and extraction methods.
Innovation Solution
A turbofan engine design incorporating a dual spool configuration with a superposition gear system within an accessory gearbox, utilizing electric motors to input power into both spools and distribute power through a sun gear and ring gear system, allowing for efficient power extraction and reduced load on individual spools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If increasing loads are applied to a single spool to extract more power, then power extraction capability is improved, but engine efficiency and performance are degraded
Solution Approach 1:
The invention divides the power extraction function into two separate spools (first spool with first turbine, second spool with second turbine), allowing power to be extracted from both spools independently. This segmentation enables balanced load distribution across multiple spools rather than overloading a single spool, thereby maintaining engine efficiency while achieving the required power extraction capability.
2Device complexity
If a single tower shaft is used to extract power from one spool, then the structure is simple, but power distribution capability is limited
Solution Approach 1:
The invention merges two tower shafts (first tower shaft engaged to first spool, second tower shaft engaged to second spool) with a superposition gear system that combines their outputs. This allows power from both spools to be distributed to multiple accessory components simultaneously, enhancing power distribution capability while maintaining reasonable structural complexity through the integrated gear system.
3Adaptability or versatility
If a dual spool configuration with superposition gear system is implemented, then power distribution capability is improved, but device complexity increases
Solution Approach 1:
The superposition gear system acts as an intermediary mechanism that efficiently combines the outputs of two tower shafts. By using a standardized epicyclic gear train design with sun gear, ring gear, and planet gears, the system achieves sophisticated power distribution capability while managing complexity through proven mechanical designs and modular component integration.
4Power
If electric motors are added to input power into both spools, then engine performance is enhanced, but device complexity increases
Solution Approach 1:
The electric motors are integrated into the existing dual spool architecture, allowing them to serve multiple functions: providing auxiliary power input to either or both spools, enabling the engine to operate in electric-only mode, or assisting during startup. This multi-functionality enhances engine performance while managing complexity by leveraging the existing dual spool and gear system infrastructure.
Data Source
AI summary
A turbofan engine includes a first spool including a first turbine and a second spool including a second turbine. A superposition gear system includes a plurality of intermediate gears engaged to a sun gear and supported in a carrier and a ring gear circumscribing the intermediate gears. A second tower shaft is engaged to drive the sun gear. A starter is selectively coupled to the sun gear through a starter clutch. A first electric motor and a second electric motor are coupled to the superposition gear system and are operable to input power into a corresponding one of the first and second spools.