Distributed Mass Vibration Device for Rotorcraft Lift Rotors
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Solution Overview
Problem
Current devices for reducing vibrations in rotorcraft lift rotors are ineffective in counteracting forces along all three orthonormal axes of the 'rotor head torsor', particularly the axis perpendicular to the rotor's plane, and are difficult to adjust for variable frequencies.
Innovation Solution
A distributed-mass device with at least two main swinging masses connected to a support via deformable means, allowing movement in a horizontal plane to filter forces along the first and second axes, and secondary masses suspended inside the main masses to filter forces along the third axis, enabling easy adjustment by moving the secondary masses vertically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a concentrated mass device with constant beating mass is used, then vibrations at a specific frequency are effectively reduced, but the device cannot adapt to variable frequencies
Solution Approach 1:
The device incorporates adjustable secondary swinging masses that can be moved vertically along the third resultant axis to change the mass distribution and tuning characteristics. This dynamic adjustability allows the device to adapt to variable operating frequencies and different vibration conditions, transforming a static system into a dynamically可调 system.
Solution Approach 2:
The invention enables parameter changes by allowing adjustment of the secondary swinging masses' positions and potentially their masses. By changing these parameters, the device can be retuned to effectively counter vibrations at different frequencies, making it versatile for variable frequency applications.
2Object-affected harmful factors
If distributed masses are arranged between blades with complex adjustment mechanisms, then vibrations along three axes can be countered, but the device becomes difficult to adjust
Solution Approach 1:
The invention uses a nested structure where secondary swinging masses are suspended inside the main swinging masses. This nested arrangement consolidates multiple vibration counteraction functions into a compact, integrated structure that is easier to adjust and maintain compared to distributed masses arranged between blades with complex adjustment mechanisms.
Solution Approach 2:
The main swinging masses serve multiple functions: they counter vibrations along the first and second resultant axes through their horizontal swinging motion, and simultaneously provide structural support and housing for the secondary swinging masses that counter vibrations along the third axis. This multi-functionality simplifies the overall adjustment mechanism.
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
Effectively counters vibrations along all three orthonormal axes of the 'rotor head torsor' by allowing horizontal movement of main masses and vertical movement of secondary masses, providing adjustable and balanced vibration reduction.
Implementation Method 1
each main swinging mass being connected to the support by a deformable means
Implementation Method 2
each secondary swinging mass being suspended inside the recess of the associated main swinging mass by an elastic means so as to be able to move according to a direction perpendicular to said horizontal plane
Implementation Method 3
The operation of a lift rotor of a rotorcraft generates parasitic forces at the head of this lift rotor. These parasitic forces then induce vibrations which propagate in the fuselage
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a distributed mass device (1) for reducing vibrations generated by a rotor, comprising a support (10) adapted to be rotationally fixed about an axis of rotation (AX) of said support rotor. Furthermore, the distributed mass device (1) comprises at least two main flapping masses (21, 22, 23), each having a longitudinal through-hole (21', 22', 23'), and each being connected to the support (10) by a deformable means (30), the main flapping masses (21, 22, 23) being constrained to move only in a horizontal plane (P) by said deformable means (30). The said distributed mass device (1) is provided with a secondary striking mass (41, 42, 43) per main striking mass (21, 22, 23), each secondary striking mass (41, 42, 43) being suspended inside the recess (21', 22', 23') of the associated main striking mass (21, 22, 23) by an elastic means (50).