Thickened Root Fan Blade for Gas Turbine Stress
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Solution Overview
Problem
New gas turbine engine and aircraft designs increase boundary layer distortion, leading to reduced engine efficiency due to ingested low-energy air, causing high cycle fatigue and resonant stresses, which existing fan blades fail to mitigate effectively.
Innovation Solution
The fan blades feature a thicker root, approximately 25% of the radial height, with an aerodynamically smooth transition zone from the tip to the root, and an optional fillet shape between the blade and platform to distribute stress and reduce air drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If new aircraft and engine designs are implemented to reduce noise, emissions, and fuel burn, then environmental performance is improved, but boundary layer distortion increases causing reduced engine efficiency
Solution Approach 1:
The fan blade root is designed with increased thickness specifically at the root region (approximately 25% of radial height) while maintaining thinner sections elsewhere. This localized structural enhancement addresses boundary layer distortion effects specifically where they impact the blade most severely, without compromising overall aerodynamic efficiency or increasing unnecessary weight throughout the entire blade structure.
Solution Approach 2:
An aerodynamically smooth transition zone is implemented between the thickened root and the thinner blade sections. This curved transition eliminates abrupt geometric changes that would create additional distortion and flow separation, allowing the blade to maintain aerodynamic efficiency while benefiting from the structural reinforcement at the root.
2Strength
If fan blade root thickness is increased to mitigate stress from boundary layer distortion, then structural strength is improved, but device complexity increases
Solution Approach 1:
The design applies the thickness increase only to the root region where structural reinforcement is most needed to withstand boundary layer distortion stresses. The rest of the blade maintains its original optimized geometry, minimizing the impact on manufacturing complexity while providing targeted structural enhancement where it is most effective.
Solution Approach 2:
The smooth transition zone uses curved geometry to connect the thickened root to the thinner blade sections. This curved transition is simpler to manufacture than abrupt angular transitions and eliminates stress concentration points, reducing the need for additional reinforcement features and simplifying the overall manufacturing process.
Data Source
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AI summary
In accordance with one aspect of the disclosure, an airfoil is disclosed. The airfoil may include a platform and a blade extending from the platform. The blade may have a root proximate the platform and a tip radially outward from the platform. The root may have a greater thickness than a cross-section at about a quarter-span of the blade or greater.