Rotor Blade Tunable Mass Damper for Vibration Without Drag
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Solution Overview
Problem
Asymmetric lift of helicopter blades in forward flight creates significant vibrations, detrimental to aircraft components and crew, and existing dampers increase aerodynamic drag, reducing performance.
Innovation Solution
A tunable mass damper assembly is attached to the rotor blade, with a base and pendulum mass structure that moves relative to the base, reducing vibratory forces and enclosed within the rotor blade to minimize drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple weighted pendulum mechanism is attached to the external surface of helicopter main rotor blades, then vibration attenuation is achieved, but aerodynamic drag increases and aerodynamic performance decreases
Solution Approach 1:
The damper assembly is positioned within the rotor blade structure itself, nesting the vibration damping function inside the existing blade geometry. This eliminates the need for external attachments while maintaining the pendulum mass mechanism's ability to counteract vibrations, thereby avoiding additional aerodynamic drag.
Solution Approach 2:
The damper assembly is integrated with the rotor blade structure, merging the vibration damping function with the blade's structural components. The base is rigidly secured to or movably secured within the rotor blade, combining structural support and damping functionality into a unified system that does not protrude externally.
2Loss of energy
If a damper assembly is integrated within the rotor blade, then aerodynamic performance is maintained, but the base and pendulum mass structure require precise positioning and movement mechanisms
Solution Approach 1:
The base is configured to be movably secured to the rotor blade, allowing the base and pendulum mass structure to move independently from the blade's rotational and pitch motions. This dynamic configuration enables the damper to maintain its damping function while accommodating the blade's operational movements without requiring complex rigid mounting mechanisms.
Solution Approach 2:
The damper assembly is divided into distinct functional components: a base for mounting to the rotor blade, a pendulum mass structure for vibration counteraction, and connection mechanisms allowing relative movement. This segmentation enables each component to be optimized independently and simplifies the overall integration by allowing modular assembly within the blade structure.
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 effectively reduces vibrations, extends aircraft life, improves ride characteristics, and maintains aerodynamic performance by eliminating drag penalties.
Implementation Method 1
a pendulum mass structure (60) movably attached to the base and configured to move relative to the base in accordance with a rotational speed of the rotor blade about a rotor axis
Implementation Method 2
The pendulum mass structure is configured to reduce vibratory forces of the rotor blade induced by a rotation of the rotor blade about the rotor axis
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A tunable mass damper assembly is attachable to a rotor blade (30). The tunable mass damper assembly comprises a base (52) configured to be attached to the rotor blade and a pendulum mass structure (60, 70) movably attached to the base and configured to move relative to the base in accordance with a rotational speed of the rotor blade about a rotor axis. The pendulum mass structure is configured to reduce vibratory forces of the rotor blade induced by a rotation of the rotor blade about the rotor axis. An entirety of the pendulum mass structure is configured to be contained within and enclosed by the rotor blade. Alternatively, the tunable mass damper assembly has a contoured shape in a direction between a leading edge and a trailing edge of the rotor blade. The mass structure may alternatively be positioned on a top portion of the blade, or along the leading or trailing edge of the blade.