Turbomachine Blade Pitch Control via Variable Axial Displacement
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Solution Overview
Problem
Turbomachine fan blades experience premature mechanical wear and undesirable coupling between upstream and downstream rotor blades due to non-homogeneous aerodynamic flows and gyroscopic effects, leading to mechanical and noise amplifications.
Innovation Solution
A pitch control device with a radial shaft linked to the blade by a pivot and connecting rods, featuring a mobile first part and a second part that can tilt and translate, allowing each connecting rod to follow a variable axial displacement, thereby adjusting the blade pitch during rotation to mitigate aerodynamic disturbances and reduce coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a uniform pitch control device is used for all blades, then the structure is simple, but the blades are subjected to high loads and premature wear due to non-homogeneous aerodynamic flow
Solution Approach 1:
The patent applies dynamics by making the pitch control device adjustable during operation. The connecting rods can be repositioned along the radial shaft to change the pitch angle of blades dynamically, allowing adaptation to non-homogeneous aerodynamic flows and reducing loads on individual blades, thereby improving reliability without excessive structural complexity
Solution Approach 2:
The patent changes the pitch parameter of blades by allowing connecting rods to be positioned at different locations on the radial shaft. This enables variation of the pitch angle to match local aerodynamic conditions along the blade span, reducing premature wear while maintaining a relatively simple overall device structure
2Device complexity
If the pitch of all blades is adjusted uniformly, then the control mechanism is simple, but mechanical vibrations and noise are amplified due to coupling between upstream and downstream rotor blades
Solution Approach 1:
The patent applies local quality by allowing different pitch angles for different blades or different sections of blades. The connecting rods can be independently positioned on the radial shaft, enabling local pitch adjustment to break the synchronous coupling between upstream and downstream rotor blades, thereby reducing mechanical vibrations and noise amplification
Solution Approach 2:
The patent enables dynamic pitch adjustment where connecting rods can be repositioned during operation to optimize blade pitch angles. This dynamic capability allows the system to break harmful couplings between rotors by introducing pitch variations, reducing vibrations and noise while keeping the control mechanism relatively simple
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
The solution enhances the robustness of the fan, reduces mechanical and noise amplifications, and allows for a degraded operating mode that avoids immediate engine shutdown in case of failure, while maintaining blade pitch adjustments to counteract aerodynamic flow disturbances.
Implementation Method 1
a radial shaft linked to the blade by a pivot and a connecting rod for which axial displacement controls rotation of the radial shaft
Implementation Method 2
at least three cylinders capable of moving said second part in axial translation and varying its tilt
Implementation Method 3
varying its tilt, translation and tilt of the second part leading to a corresponding translation and tilt of the first part
Implementation Method 4
each connecting rod follows an axial displacement with a variable amplitude that depends on the tilt of the first part, in order to vary the pitch of the blade during its revolution
Data Source
AI summary
The invention concerns a device (1) for controlling the pitch of the blades of a fan (4) rotor (3), comprising a radial shaft (6) linked to the blade, a connection rod (8) of which the axial movement controls the rotation of the radial shaft (6), characterized in that it comprises:—a first part (10) that is mobile in rotation with the rotor (3) about the axis (11) of the fan (4), and on which one end of each connection rod (8) is secured,—a second part (12) linked to the first part (10), and—at least three cylinders (14) capable of moving said second part (12) in axial translation, and of varying the tilt of said second part, the translation and tilt of the second part (12) driving a corresponding translation and tilt of the first part (10), such that, when the first part (10) rotates, each connection rod (8) is subject to axial displacement of which the amplitude is variable and is a function of the tilt of the first part (10), making it possible to vary the pitch of the blade during the rotation of same. The invention also concerns a fan, and a method for controlling the pitch of blades.