Variable Pitch Fan Rotor With Ball-Jointed Blade Attachment
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Solution Overview
Problem
Existing turbofan engines face challenges with blade pitch modification systems that are bulky, complex, and inefficient, leading to instability and potential engine malfunction during taxiing, particularly in high bypass rate turbojets, where current solutions like variable-nozzle and variable-pitch systems result in increased mass, drag, and aerodynamic issues.
Innovation Solution
A fan rotor design featuring two discs with a swivel connection and ball-and-socket attachment for blades, allowing tangential and axial movement, which simplifies the pitch modification process without the need for additional components like bevel gears or flexible supports, maintaining compactness and aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bevel gears are used to rotate the blade around its main axis, then the blade pitch can be modified, but the hub becomes bulky and the fan diameter increases, leading to increased mass and drag
Solution Approach 1:
The patent combines the functions of blade retention, rotation guidance, and pitch control into a single integrated attachment means that connects the blade to both discs. This eliminates the need for separate bevel gear mechanisms and hub structures, significantly reducing the overall mass while maintaining all necessary functionalities.
Solution Approach 2:
The invention extracts and eliminates the bulky hub structure and separate bevel gear components from the system. By using a direct attachment means that connects blades to two discs, the design removes unnecessary intermediate components that contributed to increased mass and drag.
2Adaptability or versatility
If bevel gears are used to rotate the blade around its main axis, then the blade pitch can be modified, but the mechanical architecture becomes complex to ensure feathering of the fan
Solution Approach 1:
The patent merges multiple functions (blade retention, rotation guidance, and pitch control) into a single integrated attachment means. This attachment connects the blade to two discs that can rotate relative to each other, providing all necessary functionalities without complex separate mechanisms for feathering or pitch adjustment.
Solution Approach 2:
Instead of using a fixed hub with rotating blades controlled by bevel gears, the invention inverts the approach by using two rotatable discs with attachment means that move tangentially and axially. This reverses the traditional mechanical architecture, simplifying the system while maintaining the ability to control blade pitch and ensure feathering.
3Adaptability or versatility
If flexible blade foot supports or pivots mounted on bearings are used, then the blade rotation and pitch change can be accommodated, but the structure becomes difficult to reconcile with the high forces required to hold the blades
Solution Approach 1:
The attachment means is designed with a ball-and-socket connection that preliminarily establishes the correct geometric relationship between the blade and the two discs. This pre-configured connection ensures that the blade can rotate and adjust pitch while maintaining proper alignment and withstanding high forces without requiring flexible supports or additional bearings.
4Reliability
If variable-pitch fan blades are used to improve surge margin, then the pumping margin increases, but the device mass and complexity increase
Solution Approach 1:
The patent combines blade retention, rotation guidance, and pitch control functions into a single attachment means connecting the blade to two discs. This integrated approach achieves variable-pitch capability to improve pumping margin while minimizing mass increase compared to traditional separate mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables efficient blade pitch adjustment with reduced mass and drag, maintaining performance and simplicity, while ensuring reliable operation and easy maintenance, as it concentrates the functions of blade retention, rotation guidance, and pitch control in a single, mechanically robust connection.
Implementation Method 1
said connection being a swivel connection, mobile tangentially and axially
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a compressor rotor for a turbomachine comprising a shaft (12) and at least two disks (10a, 10b) mounted on said shaft in order to hold a single set of vanes (2) that are rotatably mobile about the rotational axis of said shaft, at least one first disk (10a) being mounted in a mobile manner on said shaft in such a way as to be able to generate an angular gap in relation to said second disk (10b) and to trigger a rotation of the vanes (2) about the radial axis of same, at least one of the two disks being shaped in such a way as to receive at least one means for attaching the vanes (11), the connection between said disk and said means enabling a rotation of said means about a radial axis, characterised in that said connection is a ball-jointed connection that is tangentially and axially mobile.