Gas Turbine Fan Hub Center of Gravity Shift
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Solution Overview
Problem
Conventional fan hub designs in gas turbine engines face challenges in minimizing airfoil stresses and optimizing the center of gravity, leading edge stresses, and weight, while maintaining efficient tooling access and machining capabilities.
Innovation Solution
The design features a fan blade hub with a rim section integrally connected to a central neck section through a web section with an inward concavature, shifting the center of gravity rearward and incorporating an annular channel at the leading edge to reduce airfoil stresses, specifically tuned to the 2M3ND mode of vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the web section extends aft of the center of gravity of the fan blades, then the center of gravity of the hub is shifted rearwards to reduce airfoil stresses, but the structural complexity increases
Solution Approach 1:
The web section extends in the axial dimension (aft of the center of gravity) rather than only radially, creating a three-dimensional configuration that shifts the hub's center of gravity rearwards. This dimensional extension reduces airfoil stresses by optimizing the mass distribution along the axial direction while maintaining structural integrity through the integrated design.
2Stress or pressure
If the rim section has an inwardly projecting annular channel at the leading edge, then airfoil stresses in the leading edge are reduced, but the manufacturing complexity increases
Solution Approach 1:
The annular channel modifies the geometric parameters of the leading edge by creating an inwardly projecting feature with specific dimensions tuned to the 2M3ND mode. This geometric parameter change reduces stress concentration at the leading edge while the channel's integrated formation during manufacturing minimizes the impact on manufacturing complexity.
3Strength
If the web section has an inward concavature, then the center of gravity is optimized and airfoil stresses are reduced, but the machining difficulty increases
Solution Approach 1:
The inward concavature in the web section introduces a curved, non-linear geometric feature that optimizes the mass distribution to shift the center of gravity. This curved geometry reduces airfoil stresses by creating a more favorable stress path, while the concavature's smooth contours facilitate machining compared to sharp angles or complex discontinuities.
4Strength
If the rim section merges uninterrupted into the web section, then the structural integrity is improved, but the weight increases
Solution Approach 1:
The rim section merges uninterrupted into the web section, creating a continuous integrated structure that eliminates stress concentration at joints and improves overall structural integrity. This merging ensures load paths are smooth and continuous, enhancing the hub's ability to withstand operational loads while the optimized geometry minimizes material usage.
Data Source
AI summary
A fan rotor has a fan web and a plurality of circumferentially spaced-apart fan blades extending radially outwardly from an outer rim of the fan web. The outer rim is integrally connected to an inner rim through an axially facing web section. The web section has an inward concavature and extends aft of the center of gravity of the fan blades to shift the center of gravity of the hub rearwards while maintaining airfoil stress below critical levels. The rim section may have an inwardly projecting annular channel formed in a leading edge thereof and tuned to the 2M3ND mode of the fan hub.