Tunable mass damper assembly for a rotor blade
A tunable mass damper assembly is attachable to a rotor blade. The tunable mass damper assembly comprises a base configured to be attached to the rotor blade and a pendulum mass structure 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 being configured to be contained within and enclosed by the rotor blade.
1 . A tunable mass damper assembly attachable to a rotor blade comprising a leading edge and a trailing edge, the tunable mass damper assembly comprising:
a base configured to be attached to the rotor blade, the base comprising two base extensions configured to extend from an outer surface of the rotor blade, the two base extensions defining two end stops and an inner area therebetween, the two base extensions supporting a portion of the base that defines a pivot axis; and
a pendulum mass structure comprising:
a pendulum mass; and
a pendulum arm having a first end coupled to the pendulum mass and a second end pivotably coupled to the base about the pivot axis, the pendulum mass structure configured to pivot about the pivot axis depending on a rotational speed of the rotor blade about a rotor axis, the pendulum mass structure being configured to reduce vibratory forces of the rotor blade induced by rotation of the rotor blade about the rotor axis, wherein the pendulum arm comprises a pendulum arm extension configured to contact the two end stops to limit the rotation of the pendulum arm.
2 . The tunable mass damper assembly of claim 1 , wherein the pendulum mass includes a first mass end configured to be positioned closer to the leading edge of the rotor blade and a second mass end configured to be positioned closer to the trailing edge of the rotor blade, wherein the first mass end and the second mass end of the pendulum mass are shaped differently to form a contoured shape.
3 . The tunable mass damper assembly of claim 1 , wherein the pendulum mass structure is configured to be positioned along and move substantially perpendicular to a feathering axis of the rotor blade.
4 . The tunable mass damper assembly of claim 1 , wherein the pendulum mass structure is configured to be positioned on a top portion of the rotor blade.
5 . The tunable mass damper assembly of claim 1 , wherein the pendulum mass structure is configured to be positioned along one of the leading edge and the trailing edge of the rotor blade.
6 . The tunable mass damper assembly of claim 1 , wherein the rotor blade comprises a rotor blade body with the leading edge and the trailing edge and a blade neck configured to attach to a rotor hub, wherein the tunable mass damper assembly is configured to be positioned along and secured to the rotor blade body.
7 . The tunable mass damper assembly of claim 1 , further comprising a second pendulum mass structure positioned along the trailing edge of the rotor blade, wherein the pendulum mass structure is a first pendulum mass structure that is positioned along the leading edge of the rotor blade.
8 . The tunable mass damper assembly of claim 7 , further comprising a connector, wherein the first pendulum mass structure and the second pendulum mass structure are statically connected together by the connector such that the first pendulum mass structure and the second pendulum mass structure move together.
9 . The tunable mass damper assembly of claim 8 , wherein the connector extends along a top portion or a bottom portion of the rotor blade.
10 . The tunable mass damper assembly of claim 7 , wherein the first pendulum mass structure and the second pendulum mass structure are independently movable relative to each other.
11 . The tunable mass damper assembly of claim 1 , wherein the tunable mass damper assembly is configured to be positioned on a rotor blade that is part of at least one of a coaxial rotor system or a rigid rotor system.
12 . The tunable mass damper assembly of claim 1 , wherein the pendulum mass is lacrimiform in shape.
13 . The tunable mass damper assembly of claim 12 , wherein the pendulum mass includes a leading end forming a point at a first angle and a trailing end forming a point at a second angle smaller than the first angle.
14 . The tunable mass damper assembly of claim 1 , wherein the pivot axis is transverse to a feathering axis of the rotor blade.
15 . The tunable mass damper assembly of claim 1 , wherein the pendulum mass structure is configured to rotate freely and without restricted motion between the two end stops.
16 . The tunable mass damper assembly of claim 1 , wherein the inner area is hollow so as to allow airflow therethrough in the direction between the leading edge and the trailing edge of the rotor blade.
17 . The tunable mass damper assembly of claim 1 , wherein the base comprises a mounting bracket configured to extend along the outer surface of the rotor blade from a position adjacent the leading edge of the rotor blade to a position adjacent the trailing edge of the rotor blade.
18 . The tunable mass damper assembly of claim 1 , wherein the pendulum arm extends partially into the pendulum mass, the tunable mass damper assembly comprising a fastener coupling the pendulum mass to the pendulum arm.
19 . The tunable mass damper assembly of claim 1 , wherein the base is configured to be coupled to a top portion of the rotor blade such that the base extensions extend upward from the surface of the rotor blade.