Turbofan Composite Fan Blades for Larger Fans and Lower Solidity
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Solution Overview
Problem
Conventional gas turbine engines face limitations in fan blade size due to mechanical properties of metal materials, leading to inefficiencies in thrust output and fan pressure ratio, with the use of composite materials posing manufacturing challenges.
Innovation Solution
Designing fan blades out of composite materials, which allows for increased size and reduced solidity, coupled with a reduction gearbox to optimize fan efficiency and thrust output, utilizing relationships between leading and trailing edge radii and hub radii to achieve desired aeronautical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal fan blades are used, then manufacturing is easier, but fan blade size is limited due to mechanical properties
Solution Approach 1:
The patent applies composite materials for fan blade construction to overcome the mechanical property limitations of metal materials. Composite materials enable larger fan blade sizes while maintaining structural integrity, resolving the contradiction between ease of manufacture and fan blade size by providing a material solution that scales better than traditional metals.
2Length of moving object
If composite materials are used for fan blades, then fan blade size can be increased, but manufacturing becomes more challenging
Solution Approach 1:
The patent embraces composite materials despite manufacturing challenges, as they enable significantly larger fan blade sizes. The design accepts the manufacturing complexity as a trade-off for achieving the desired increase in fan blade dimensions and improving overall engine efficiency.
3Power
If fan blade size is increased, then thrust output improves, but solidity increases which reduces efficiency
Solution Approach 1:
The patent utilizes parameter changes in the fan blade design, specifically optimizing the relationship between blade size, solidity, and hub radius. By carefully controlling these parameters and using the formula relating leading edge radius, trailing edge radius, and hub radius, the design achieves larger thrust output while maintaining acceptable solidity levels for efficient operation.
Data Source
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AI summary
A turbofan engine (10) includes: a turbomachine (16) comprising a drive turbine and defining a working gas flowpath (37) and an inlet (20) to the working gas flowpath (37); a fan (38) having a fan blade (40) formed of a composite material, the fan blade (40) defining a leading edge fan radius RFan_LE and a trailing edge fan radius RFan_TE, and the fan (38) defining a leading edge hub radius RHub_LE and a trailing edge hub radius RHub_TE, the turbofan engine (10) defining a bypass ratio during operation of the turbofan engine (10) in a cruise operating mode; and a reduction gearbox (46) mechanically coupling the drive turbine of the turbomachine (16) to the fan (38); wherein the turbofan engine (10) defines a Fan Leading Edge to Trailing Edge Compression Factor (FLTCF) greater than or equal to 1.05 and less than or equal to 1.8.