Geared Turbofan Electrical Conditioning Circuit
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Solution Overview
Problem
Conventional gas turbine engines face inefficiencies due to the need for extra compressor and turbine stages at high bypass ratios, leading to reduced component efficiencies and increased noise, which is exacerbated by supersonic fan tip speeds in conventional turbofans, necessitating an efficient electrical system for geared turbofans with varying shaft speeds.
Innovation Solution
A hybrid gas turbine engine with an epicyclic gear system, including a sun gear, planet gears, and a ring gear, where the gear system provides specific reduction ratios to drive a fan and a generator, with an electrical conditioning circuit using operational amplifiers to amplify the generator output signal and provide it to an electrical load, such as a motor or battery, to optimize energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single shaft connects the fan, low-pressure compressor and low-pressure turbine in a conventional turbofan, then the structure is simple, but the fan tip speed exceeds the speed of sound resulting in characteristic drone and requiring sound deadening
Solution Approach 1:
The patent segments the previously single shaft system into separate shafts for the fan and low-pressure compressor/turbine, allowing independent speed control. This enables the fan to operate at lower speeds to avoid supersonic tip speeds and noise, while the LP shaft can run at higher speeds for improved efficiency.
Solution Approach 2:
The patent introduces a planetary reduction gearbox as an intermediary mechanism between the fan and the LP shaft. This gearbox enables different rotational speeds between the two shafts, allowing the fan to run slower to reduce noise while the LP shaft runs faster to maintain compressor and turbine efficiency.
2Productivity
If the fan operates at high rotational speed in a conventional turbofan, then the bypass ratio can be increased, but the fan tip speed exceeds the speed of sound requiring sound deadening
Solution Approach 1:
By separating the fan drive from the LP compressor/turbine shaft, the system allows the fan to operate at optimized lower speeds for noise reduction, while maintaining high LP shaft speeds for efficient compression and expansion, thus achieving high bypass ratios without supersonic fan tips.
Solution Approach 2:
The planetary reduction gearbox acts as an intermediary that decouples the fan speed from the LP shaft speed, enabling the fan to rotate slower to avoid supersonic conditions and noise, while the LP shaft maintains higher speeds to support high bypass ratios and efficient operation.
3Productivity
If a planetary reduction gearbox is used between the fan and LP shaft in a geared turbofan, then the LP shaft can run at higher rotational speed enabling fewer stages, but the electrical systems must handle various shaft speeds efficiently
Solution Approach 1:
The electrical system is designed with multi-functionality to handle various shaft speeds efficiently. The generator can be coupled to different shafts (fan shaft or LP shaft) and the electrical conditioning circuit can adapt to different input speeds, providing universal electrical power and control across the entire geared turbofan system.
Solution Approach 2:
The electrical conditioning circuit acts as an intermediary between the generator and the aircraft electrical load. It conditions and regulates the electrical output regardless of which shaft drives the generator at what speed, ensuring stable and suitable electrical power delivery to the aircraft 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 solution allows for reduced fan speeds, increased efficiency, lower fuel consumption, and noise reduction by enabling fewer compressor and turbine stages, while efficiently managing electrical systems across different shaft speeds, thereby enhancing overall engine performance.
Implementation Method 1
A power circuit receives the generator output signal and provides a gain R Ring gear /R sun gear to the generator output signal and provides a gain signal indicative thereof to an electrical load
Data Source
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AI summary
A hybrid gas turbine engine (10) comprises a turbine (24), a compressor (16), and a gear system (12) that is driven by the turbine (24) where the gear system (12) includes a sun gear (29), a ring gear (32) and a plurality of planet gears (30), where the ring gear (32) has a ring gear radius of RRing gear and the sun gear (29) has a sun gear radius of RSun gear such that the gear system (12) provides a reduction ratio of RRing gear /RSun gear. A fan (26) is driven by the ring gear (32), and a generator (40) is driven by the ring gear (29) and provides a generator output signal. A power circuit (44) receives the generator output signal and provides a gain RRing gear /RSun gear to the generator output signal and provides a gain signal indicative thereof to an electrical load.