Variable Pitch Fan Design for Geared Turbomachinery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The development of turbofan engines with gearboxes and variable pitch fans is complicated, making engine development and manufacturing more challenging, and there is a need for improved turbomachinery engines with simplified complexity and efficient manufacturing processes.
Innovation Solution
The use of specific fan parameters such as the hub-to-tip radius ratio divided by the fan pressure ratio and bearing spanwise force divided by fan area to design and develop variable pitch fans and geared turbomachinery engines, which simplifies the design and manufacturing process by defining a reduced number of practical embodiments that meet structural requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a gearbox and variable pitch fan are included in a turbofan engine, then propulsive efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by defining specific dimensional relationships (hub-to-tip radius ratio divided by fan pressure ratio within 0.05-0.45, and bearing spanwise force divided by fan area within 1-30 lbf/in²) to optimize the variable pitch fan's performance. These parameter specifications enable the fan to achieve improved propulsive efficiency across different operating conditions while managing the complexity through quantifiable design criteria.
2Use of energy by moving object
If a gearbox and variable pitch fan are included in a turbofan engine, then propulsive efficiency is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent establishes specific manufacturable parameter ranges including hub-to-tip radius ratio divided by fan pressure ratio of 0.05-0.45 and bearing spanwise force divided by fan area of 1-30 lbf/in². These quantified parameters provide clear manufacturing targets and acceptance criteria, making the production of variable pitch fans with gearboxes more manageable despite the increased manufacturing difficulty.
3Device complexity
If specific fan parameters are used to design variable pitch fans, then device complexity is reduced, but design precision requirements increase
Solution Approach 1:
The patent reduces design complexity by focusing on two key parameter relationships rather than optimizing all fan dimensions independently. The specified ranges (hub-to-tip radius ratio divided by fan pressure ratio: 0.05-0.45; bearing spanwise force divided by fan area: 1-30 lbf/in²) provide sufficient design guidance while maintaining manufacturing precision through clear quantitative boundaries.
Solution Approach 2:
The patent applies local quality by identifying specific critical parameters (hub-to-tip radius ratio and bearing spanwise force) that have disproportionate impact on overall fan performance. By concentrating design and manufacturing precision on these localized parameter relationships rather than all fan components uniformly, the patent achieves effective complexity reduction while maintaining necessary precision where it matters most.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A turbomachinery engine (100) includes a fan assembly (104) with a plurality of variable pitch fan blades (108). The fan blades are configured such that they define a first Variable Pitch Fan (VPF) parameter and a second VPF parameter. The first VPF parameter is within a range of 0.10 to 0.40 and is defined as the hub-to-tip radius ratio divided by the fan pressure ratio. The second VPF parameter is within a range of 1-30 lbf/in2 and is defined as the bearing spanwise force divided by the fan area. The turbomachinery engine further includes a vane assembly, a core engine, and a gearbox.