Dual-Spool Power Extraction Gearbox for Balanced Turbofan Load
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Solution Overview
Problem
The increasing loads on a single spool in gas turbine engines limit their performance capabilities and efficiency, as excessive power extraction from a single spool can degrade overall engine performance and efficiency.
Innovation Solution
A dual spool power extraction gearbox system that utilizes a superposition gear system with concentric and angled tower shafts, coupled with electric motors and mechanical clutches, to distribute and extract power from both low and high-speed spools, reducing the load on each spool and improving power transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If increasing power extraction from a single spool, then power output increases, but engine performance and efficiency deteriorate
Solution Approach 1:
The power extraction system is segmented into two independent spools (first spool and second spool), each capable of independently extracting power from the turbine engine. This segmentation allows the total power demand to be distributed across multiple sources, preventing excessive load on any single spool and maintaining engine performance while achieving the required power output.
2Power
If increasing power extraction from a single spool, then power output increases, but efficiency decreases
Solution Approach 1:
The dual spool configuration segments the power extraction function, allowing each spool to operate within optimal efficiency ranges. By distributing the power extraction load, the system avoids the efficiency penalties associated with excessive single-spool extraction, thereby maintaining better overall energy efficiency while delivering the required power output.
Solution Approach 2:
The system dynamically allocates power extraction between the two spools based on operating conditions. The control system can adjust the power distribution to optimize efficiency across different flight regimes, ensuring that the engine operates at peak efficiency points while still meeting power demands.
3Reliability
If using a dual spool power extraction gearbox, then load distribution improves, but device complexity increases
Solution Approach 1:
The patent merges the power extraction functions of two spools into a single integrated gearbox assembly. The first and second tower shafts, along with their respective gear systems (first gear system driven by first tower shaft, second gear system driven by second tower shaft), are combined within one gearbox housing, sharing common structural elements and mounting interfaces with the engine accessory gearbox. This merging approach distributes load effectively while minimizing the increase in overall device complexity compared to separate extraction systems.
Solution Approach 2:
The dual spool gearbox is designed as a universal power extraction system that can serve multiple functions: extracting power for accessory drives, providing starting capability, and enabling flexible power distribution across different operating conditions. The first and second electric motors are selectively coupleable to either spool, providing multi-functional capability that justifies the increased complexity through enhanced versatility and load distribution.
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 configuration allows for efficient power distribution and extraction from both spools, enhancing engine performance and reducing the load on individual spools, thereby improving thermal, transfer, and propulsive efficiencies.
Implementation Method 1
an electric power supply provides power to the first electric motor and the second electric motor
Implementation Method 2
the starter clutch, first motor clutch, second motor clutch, first ring gear clutch and the second ring gear clutch comprise one-way mechanical clutches
Data Source
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AI summary
A turbofan engine (20) includes a first spool (30) including a first turbine (46) and a second spool (32) including a second turbine (54). A superposition gear system (66) includes a plurality of intermediate gears (104) engaged to a sun gear (102) and supported in a carrier (106) and a ring gear (108) circumscribing the intermediate gears (104). A second tower shaft (78) is engaged to drive the sun gear (102). A starter (70) is selectively coupled to the sun gear (102) through a starter clutch (75). A first electric motor (130) and a second electric motor (132) are coupled to the superposition gear system (66) and are operable to input power into a corresponding one of the first and second spools (30, 32).