Geared Fan and Low Pressure Compressor for Higher Bypass Ratio
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Solution Overview
Problem
Conventional two-spool gas turbine engines face limitations in optimizing efficiency and bypass ratio due to the mechanical connection of the low pressure compressor to the low speed spool, which often requires a large low pressure turbine and restricts the bypass ratio.
Innovation Solution
The implementation of two epicyclic gear systems driven off the low speed spool to independently configure and optimize the operating speeds of the fan and low pressure compressor, allowing for improved efficiency by mechanically coupling both to the low speed spool via a common sun gear shaft and a common static support structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the low pressure compressor is mechanically connected to the low speed spool via a gearbox, then the efficiency is optimized, but the bypass ratio is limited
Solution Approach 1:
The patent segments the drive system by introducing two separate epicyclic gear systems: one dedicated to driving the fan and another for driving the low pressure compressor. Both gear systems are driven by the low speed spool but operate independently, allowing the bypass ratio to be optimized without compromising the efficiency benefits of geared compression.
2Power
If the low pressure compressor is mechanically connected to the low speed spool, then the power is maximized, but a large low pressure turbine is required
Solution Approach 1:
The patent introduces epicyclic gear systems as intermediary mechanisms between the low speed spool and the low pressure compressor. These gear systems act as speed reduction and torque multiplication devices, enabling the low pressure compressor to receive adequate power from a smaller low pressure turbine, thereby reducing the turbine size while maintaining power output.
3Use of energy by moving object
If the fan and low pressure compressor are independently configured, then the operational efficiency is enhanced, but the device complexity increases
Solution Approach 1:
The patent merges two epicyclic gear systems into a compact integrated arrangement where both the fan drive gear system and the low pressure compressor drive gear system share common elements such as the low speed spool and are mounted on a common static support structure. This integration reduces overall complexity compared to having completely separate drive systems while still enabling independent configuration of the fan and low pressure compressor operating speeds.
Data Source
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AI summary
A gas turbine engine (100) may include a high speed spool (132), a low speed spool (130), a first epicyclic gear system (110), and a second epicyclic gear system (120). Generally, the high speed spool (132) mechanically connects a high pressure turbine (154) to a high pressure compressor (152), and the low speed spool (130) mechanically connects a low pressure turbine to at least one of a fan (142) and a prop via the first epicyclic gear system (110) and to a low pressure compressor (144) via the second epicyclic gear system (120), according to various embodiments. The first epicyclic gear system (110) and the second epicyclic gear system (120) may include a common sun gear shaft (135).