Industrial Fan Blade Unit With Sliding Bar Damping
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Solution Overview
Problem
Industrial fan blades experience high cyclic and impulsive loads, leading to significant fatigue stresses and reduced service life due to inadequate handling of oscillations and vibrations.
Innovation Solution
A blade unit design featuring a tubular bar with an internal sliding mechanism and bushings to dissipate kinetic energy from oscillations, combined with composite materials for enhanced flexibility and damping, effectively reducing the impact of cyclic and impulsive loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rigid blade structures are used, then structural strength is maintained, but fatigue strength is reduced due to high cyclic and impulsive loads
Solution Approach 1:
The patent applies the dynamics principle by making the bar 4 movable relative to the blade 2 through a sliding mechanism. The bar can move longitudinally within the blade's internal cavity and is constrained only at its root portion 4a. This dynamic configuration allows the bar to adapt to cyclic and impulsive loads by moving rather than remaining rigidly fixed, thereby increasing fatigue strength while maintaining reliability and service life under high-stress conditions.
2Stability of the object's composition
If rigid connection systems are used, then structural stability is maintained, but oscillations and vibrations are amplified
Solution Approach 1:
The sliding mechanism allows the bar to move dynamically in response to oscillations and vibrations, converting rigid connection into a flexible, adaptive connection. This dynamic behavior dissipates vibrational energy and reduces harmful oscillations while maintaining structural stability through the root portion constraint and frictional engagement.
Solution Approach 2:
The patent converts the harmful effect of cyclic and impulsive loads into a beneficial damping mechanism. The sliding bar experiences frictional forces during movement that dissipate vibrational energy, transforming the harmful oscillations into useful damping action that reduces overall vibrations and protects the structural integrity of the fan.
3Manufacturing precision
If fixed bar connections are used, then positioning accuracy is maintained, but kinetic energy from oscillations is not dissipated
Solution Approach 1:
The sliding mechanism provides controlled movement that maintains positioning accuracy through the root portion constraint while allowing the bar to move longitudinally to dissipate kinetic energy. The frictional engagement between the bar and blade creates damping forces that convert kinetic energy from oscillations into thermal energy, reducing vibrational amplitude while preserving accurate blade positioning.
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 significantly enhances fatigue strength, reduces blade oscillations, and minimizes stress on the fan's supporting structure, resulting in a substantial decrease in vibrations and extended service life by dissipating kinetic energy and shifting natural frequencies away from operational vibrations.
Implementation Method 1
the end or second portion 6b is able to slide with respect to the bar 4 when this undergoes deformation due to bending... the forces of friction that are set up between the bar 4 and its end or second portion 6b
Implementation Method 2
The further bar 6 mainly acts like a member for damping the high oscillations of the blade 2 deriving from the high cyclic and above all impulsive loads
Implementation Method 3
combined with composite materials for enhanced flexibility and damping
Data Source
AI summary
Described herein is a blade unit for industrial fans, which comprises: a blade; and a tubular bar, fixed on which is said blade and which has a root portion configured for being engaged by means for connecting said bar to the rotor of a fan. The unit is characterized in that it comprises a further bar mounted within said first tubular bar so as to present a first portion axially constrained to said first bar, and a second portion that is, instead, able to slide with respect to said first bar, in a condition of sliding friction, following upon a deformation due to bending of said first bar.