Geared Fan and Low Pressure Compressor Speed Split for Higher Bypass
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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 via a gearbox, which often requires a large low pressure turbine.
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 can be optimized, but the bypass ratio is limited and a large low pressure turbine is required
Solution Approach 1:
The patent segments the drive system into two independent geared paths: a first epicyclic gear system connecting the fan to the low speed spool, and a second epicyclic gear system connecting the low pressure compressor to the low speed spool. This segmentation allows each component (fan and low pressure compressor) to be independently optimized for efficiency while enabling flexible configuration of the bypass ratio without requiring a large low pressure turbine.
2Use of energy by moving object
If the low pressure compressor is mechanically connected to the low speed spool via a gearbox, then the efficiency can be optimized, but the size of the low pressure turbine increases
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 mediators that enable efficient power transmission and independent speed optimization without requiring a large low pressure turbine, thereby reducing the turbine size while maintaining optimized efficiency.
3Device complexity
If the fan and low pressure compressor are directly driven by the low speed spool, then the structure is simple, but the operating speeds cannot be independently optimized
Solution Approach 1:
The patent implements dynamic speed optimization by introducing epicyclic gear systems that enable the fan and low pressure compressor to rotate at independently optimized speeds relative to the low speed spool. This dynamic configuration allows each component to operate at its optimal speed for maximum efficiency, transforming the system from a fixed direct-drive architecture to a flexible geared architecture with independent speed control.
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.