Variable Pitch Fan Parameters for Geared Turbofan Complexity
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Solution Overview
Problem
Existing turbofan engines with gearboxes and variable pitch fans face increased complexity, making development and manufacturing more difficult.
Innovation Solution
The introduction of turbomachinery engines with a variable pitch fan (VPF) and a gearbox, characterized by specific fan parameters such as hub-to-tip radius ratio and bearing spanwise force, to simplify and improve the development and manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a gearbox and variable pitch fan are included in a turbofan engine, then propulsive efficiency and power production are improved, but device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent segments the variable pitch control system into individual blade pitch actuators, each independently controlling the pitch of a single fan blade. This segmentation allows the complex variable pitch functionality to be broken down into manageable, modular components that can be developed and manufactured separately, then assembled into the complete engine system.
Solution Approach 2:
The pitch actuator design incorporates multiple functions within a single component: it provides pitch control capability, structural support for the blade, and integration with the gearbox system. This multi-functionality reduces the overall number of separate components needed, thereby managing complexity while maintaining the adaptability benefits of variable pitch control.
2Adaptability or versatility
If a gearbox and variable pitch fan are included in a turbofan engine, then operational flexibility across different flight conditions is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring the blade pitch actuators with integrated mounting structures and connection interfaces during the design phase. This allows the complex assembly to be prepared in advance with standardized interfaces, reducing manufacturing difficulty and assembly complexity when the complete engine is being produced.
Solution Approach 2:
The invention utilizes parameter changes by allowing the fan blade pitch angle to vary continuously across a defined range, enabling the engine to adapt to different operational conditions. The actuator mechanism is designed to accommodate this parameter variation through controlled mechanical displacement, transforming the static blade configuration into a dynamic, adjustable system that maintains manufacturing feasibility.
3Use of energy by moving object
If variable pitch control mechanisms are added to fan blades, then propulsive efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges the pitch control mechanism directly with the fan blade structure itself, integrating the actuator, linkage, and control interface into a unified assembly. This merging eliminates the need for separate, bulky external control systems and reduces overall device complexity while maintaining the energy efficiency benefits of variable pitch control.
Solution Approach 2:
The invention applies dynamics by enabling the fan blade pitch angle to change dynamically in response to operational conditions. The pitch actuator mechanism is designed to provide smooth, controlled movement of the blade pitch, allowing the system to adapt efficiently to varying flight conditions and optimize propulsive efficiency through dynamic adjustment rather than static configuration.
Data Source
AI summary
A turbomachinery engine can include a fan assembly with a plurality of variable pitch fan blades. The fan blades are configured such that they define a first 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. In certain examples, the turbomachinery engine further includes a pitch change mechanism, a vane assembly, a core engine, and a gearbox.