Composite Fan Blade Geometry for Larger Geared Turbine Fans
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Solution Overview
Problem
Conventional gas turbine engines face limitations in fan blade size due to the mechanical properties of metal materials, which restrict efficiency and thrust output, and the transition to composite materials is hindered by high manufacturing costs and complexity.
Innovation Solution
Designing gas turbine engines with fan blades made of composite materials, utilizing a reduction gearbox to reduce rotational speed and incorporating specific relationships between leading and trailing edge radii and hub radii to optimize aeronautical efficiency, thereby allowing for larger fan blades with reduced solidity and blade count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If metal fan blades are used, then structural strength is maintained, but fan blade size is limited and weight is higher
Solution Approach 1:
The patent applies composite materials (specifically carbon fiber reinforced polymers) to manufacture fan blades, replacing traditional metal materials. This enables the creation of larger fan blades with reduced weight, directly resolving the contradiction between increasing fan blade size and reducing weight. The composite structure provides sufficient structural strength while allowing for larger dimensions and weight reduction.
2Weight of moving object
If composite materials are used for fan blades, then weight is reduced and fan size is increased, but manufacturing cost and complexity increase
Solution Approach 1:
The patent employs preliminary action by pre-impregnating carbon fiber bundles with resin to create prepreg tapes before final assembly. This preliminary preparation of materials simplifies the manufacturing process, reduces complexity, and enables more efficient production of composite fan blades, thereby addressing the manufacturing cost and complexity issue.
Solution Approach 2:
The manufacturing process is segmented into distinct stages: carbon fiber bundle preparation, resin impregnation to create prepreg tapes, layering of prepreg tapes according to design specifications, and final curing. This segmentation of the manufacturing process makes the complex composite fabrication more manageable, controllable, and cost-effective.
3Productivity
If fan blade size is increased, then thrust output and efficiency are improved, but aerodynamic penalties and drag increase
Solution Approach 1:
The patent utilizes parameter changes by optimizing the composite material composition, fiber orientation angles, layer sequences, and resin content to achieve the desired balance between aerodynamic performance and structural requirements. By carefully controlling these parameters, the design maximizes thrust output and efficiency while minimizing aerodynamic penalties and drag on the enlarged fan blades.
Data Source
AI summary
A gas turbine engine includes: a turbomachine comprising a drive turbine and defining a working gas flowpath and an inlet to the working gas flowpath; a fan having a fan blade formed of a composite material, the fan blade defining a leading edge fan radius RFan_LE and a trailing edge fan radius RFan_TE, and the fan defining a leading edge hub radius RHub_LE and a trailing edge hub radius RHub_TE, the gas turbine engine defining a bypass ratio during operation of the gas turbine engine in a cruise operating mode; and a reduction gearbox mechanically coupling the drive turbine of the turbomachine to the fan; wherein the gas turbine engine 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.