Rotor Element Irregularity Layout to Inhibit Flutter
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Solution Overview
Problem
High-speed rotor blades in turbomachines are prone to aeroelastic instability known as flutter, which causes excessive stresses and necessitates rotational speed restrictions, limiting performance and increasing fuel consumption.
Innovation Solution
A rotor element with irregularities in its circumferential direction is designed to separate mechanical natural frequencies, achieved by varying mass and/or rigidity in different sectors, which disrupts the interaction between natural frequencies without affecting the internal relationship as conventional dampers do.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dampers are added to the rotor, then the magnitude of natural frequency vibrations is damped, but the internal relationship between natural frequencies remains unaffected and flutter is not effectively inhibited
Solution Approach 1:
The patent applies local quality by creating sector-specific variations in mass and rigidity properties within the rotor structure. Different sectors have deliberately different characteristics (some sectors have higher mass, others have different rigidity) to disrupt the uniformity of natural frequency distribution. This localized differentiation in structural properties effectively separates the mechanical natural frequencies, preventing the resonant interactions that cause flutter, while avoiding the complexity of adding separate damper components.
2Reliability
If rotational speed is restricted to prevent excessive stresses from flutter, then rotor safety is maintained, but performance and fuel efficiency are reduced
Solution Approach 1:
The patent implements preliminary anti-action by pre-modifying the rotor's mass and rigidity distribution before operation to prevent flutter from occurring in the first place. By deliberately creating sector variations that separate natural frequencies ahead of time, the rotor becomes inherently resistant to flutter across its operational range. This allows the rotor to operate at higher speeds without the need for restrictive speed limits, maintaining both safety and performance simultaneously.
Data Source
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AI summary
The invention relates to a rotor element (101) characterized in that it comprises at least one irregularity (119) with regard to rotational properties in its circumferential direction and that the irregularity is positioned so as to separate the mechanical natural frequencies of the rotor element.