Shared Sun Gear Layout for Fan and Low-Pressure Compressor Matching
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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 a gas turbine engine with a high speed spool, a low speed spool, a first epicyclic gear system, and a second epicyclic gear system, where the fan and low pressure compressor are mechanically connected to the low speed spool via these gear systems, allowing independent configuration of operating speeds to enhance efficiency.
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 divides the mechanical connection system into two separate epicyclic gear systems instead of one unified gearbox connection. The first epicyclic gear system connects the fan to the low speed spool, while the second epicyclic gear system connects the low pressure compressor to the low speed spool. This segmentation allows independent speed optimization for each component, enabling improved efficiency for the compressor while simultaneously allowing higher bypass ratios for the fan.
2Device complexity
If the low pressure compressor is directly connected to the low speed spool, then the structure is simpler, but the efficiency and power are reduced
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 devices that allow the compressor to rotate at a higher speed relative to the low speed spool, thereby improving compressor efficiency and power output without requiring a completely different direct-drive architecture.
3Power
If a large low pressure turbine is used to drive the low speed spool, then the power output is increased, but the engine size and complexity increase
Solution Approach 1:
The patent changes the speed parameter relationship between the low speed spool and the low pressure compressor through the second epicyclic gear system. By implementing a speed reduction gear system, the compressor can operate at higher speeds for improved power output while the low speed spool and turbine maintain lower speeds, avoiding the need for a larger turbine and reducing overall engine size.
Data Source
AI summary
A gas turbine engine may include a high speed spool, a low speed spool, a first epicyclic gear system, and a second epicyclic gear system. Generally, the high speed spool mechanically connects a high pressure turbine to a high pressure compressor, and the low speed spool mechanically connects a low pressure turbine to at least one of a fan and a prop via the first epicyclic gear system and to a low pressure compressor via the second epicyclic gear system, according to various embodiments. The first epicyclic gear system and the second epicyclic gear system may include a common sun gear shaft.