Lever-arm vibration damper for a rotor of a gas turbine engine

Abstract

A vibration damper for a rotor blade of a gas turbine engine, includes a plate for placing between an inner bearing surface and an outer bearing surface of the rotor, the bearing surfaces extending in directions that are substantially axial and being radially spaced apart from each other, the plate being folded so as to form two plate portions that are inclined relative to each other, the mass of the plate being distributed in such a manner that its center of gravity is situated on the side of one of these plate portions, the free end of the other plate portion being designed to bear radially against the inner bearing surface, and the junction zone between the two plate portions being designed to bear radially against the outer bearing surface under the effect of centrifugal force when the rotor is rotating so as to provide axial sealing against gas.

1 . A vibration damper for a rotor blade of a gas turbine engine, the damper comprising a plate for placing between an inner bearing surface and an outer bearing surface of the rotor, the bearing surfaces extending in directions that are substantially axial and being radially spaced apart from each other, the plate being folded so as to form two plate portions that are inclined relative to each other, the mass of the plate being distributed in such a manner that its center of gravity is situated on the side of one of these plate portions, the free end of the other plate portion being designed to bear radially against the inner bearing surface, and the junction zone between the two plate portions being designed to bear radially against the outer bearing surface under the effect of centrifugal force when the rotor is rotating, thereby providing axial sealing against gas. 
     
     
         2 . A damper according to  claim 1 , further including a holder configured to hold the plate between the two bearing surfaces of the rotor when the rotor is stopped. 
     
     
         3 . A damper according to  claim 2 , wherein the plate includes at least one holder tab that extends in a direction that is substantially inclined relative to the radial direction and that is designed to pass through the outer bearing surface. 
     
     
         4 . A rotor element of a gas turbine engine, the element comprising:
 first and second mutually adjacent blades, the first blade having, at a radially free end, a portion constituting a spoiler outer platform without a portion constituting a wiper outer platform, and the second blade having, at a radially free end, a portion constituting a wiper outer platform without a portion constituting a spoiler outer platform; and   a vibration damper according to  claim 1 , with the plate thereof being arranged between the spoiler outer platform of the first blade forming an inner bearing surface and the wiper outer platform of the second blade forming an outer bearing surface.   
     
     
         5 . A rotor element of a gas turbine engine, the element comprising:
 a pair of mutually adjacent blades, each comprising an airfoil presenting two faces, each connecting a leading edge to a trailing edge of the blade, each blade having a single portion extending from each of the faces of its airfoil, one of these portions forming a spoiler outer platform and the other portion forming a wiper outer platform; and   a vibration damper according to  claim 1 , with the plate thereof being arranged between the spoiler outer platform of one of the blades forming an inner bearing surface and the wiper outer platform of the other blade forming an outer bearing surface.   
     
     
         6 . An element according to  claim 4 , wherein the mass of the damper plate lies in the range 1% to 10% of the mass of a blade. 
     
     
         7 . An element according to  claim 4 , wherein the mass of the damper plate lies in the range 4% to 6% of the mass of a blade. 
     
     
         8 . An element according to  claim 4 , wherein the damper plate is positioned between the bearing surfaces in such a manner that the portion having its free end bearing radially against the inner bearing surface is located on the upstream side. 
     
     
         9 . A rotor element of a gas turbine engine, the element comprising:
 a blade having an airfoil, a root for mounting in a disk of the rotor, and an inner platform situated between the root and the airfoil; and   a vibration damper according to  claim 1 , with the plate thereof designed to be arranged between an outside surface of the disk forming an inner bearing surface and an inside surface of the platform of the blade forming an outer bearing surface.   
     
     
         10 . An element according to  claim 4 , wherein the blades are made of composite material. 
     
     
         11 . A rotor of a gas turbine engine including a plurality of elements according to  claim 4 . 
     
     
         12 . A gas turbine engine including at least one rotor according to  claim 11 .