Compressor blade root for engine blades of aircraft engines

Abstract

On a compressor blade ( 1 ) for gas turbine engines which is made of a fiber-composite core ( 4 ) with metallic enclosure ( 5 ) and which comprises a blade root ( 3 ) connected to an airfoil ( 2 ) and held in a recess ( 9 ) of a compressor disk ( 10 ), the fiber-composite core is made of transversely compressed fibers with subsequent matrix infiltration and is intimately connected via a surface enlargement by a micro-structure ( 7 ) to inner surfaces of the enclosure ( 5 ). Thus, the forces are introduced into the blade root ( 3 ) directly via the fiber material. Opposite side faces of the longitudinally straight blade root ( 3 ) each feature circularly arched bearing faces ( 8 ) with different centers (M 1 , M 2 ) which mate with similarly arched bearing areas ( 11 ) provided in the recess ( 9 ) to provide for a limited, dampened pendular movement for the absorption of the bending forces acting upon the fiber-composite core.

1 . A compressor blade root connection for a gas turbine engine which comprises: a recess of a compressor disk and a blade having a blade root and comprising a fiber-composite core and a metallic enclosure for engagement with the recess of the compressor disk, wherein fibers of the fiber-composite core are packed sufficiently densely in the enclosure that compressive loads on the blade act directly upon the fibers, the enclosure including a micro-structurally enlarged inner surface to provide an intimate contact with the fiber-composite core to ensure transfer of forces between the enclosure and the fiber-composite core, and the blade root is located pendularly and frictionally dampened in the recess of the compressor disk within a limited angular range to reduce a bending stress on the fiber-composite core of the blade root.  
   
   
       2 . A compressor blade root connection in accordance with  claim 1 , wherein the fiber-composite core has a high fiber share in relation to a plastic matrix to apply the pressure load predominately to the fibers.  
   
   
       3 . A compressor blade root connection in accordance with  claim 2 , wherein the fiber-composite core comprises fibers compressed in transverse direction to the compressor blade, with the plastic matrix having been infiltrated under compression of the fibers.  
   
   
       4 . A compressor blade root connection in accordance with  claim 3 , wherein the fiber-composite core comprises carbon fibers in a plastic matrix.  
   
   
       5 . A compressor blade root connection in accordance with  claim 1 , wherein the inner surface of the enclosure is micro-structurally enlarged through at least one of glass-bead peening, sand blasting or an attached wire mesh.  
   
   
       6 . A compressor blade root connection in accordance with  claim 1 , wherein the blade root is straight in its longitudinal direction and has a plurality of circularly arched bearing faces in the area of the recess which have different centers to limit a pendular movement of the blade root, with each bearing face moveably locating against a conformally rounded bearing area of the recess.  
   
   
       7 . A compressor blade root connection in accordance with  claim 6 , wherein at least one of the rounded bearing faces and the bearing areas are micro-structured for frictional dampening of the pendular movement of the blade root.  
   
   
       8 . A compressor blade root connection in accordance with  claim 1 , and further comprising a reinforcing wedge extending from a bottom of the blade root and inserted into the fiber-composite core to divide the fiber-composite core into two partial strands in a longitudinal direction of the blade root.  
   
   
       9 . A compressor blade root connection in accordance with  claim 8 , wherein the reinforcing wedge is micro-structured at faces mating to the fiber-composite core.  
   
   
       10 . A compressor blade root connection in accordance with  claim 8 , wherein a large end of the reinforcing wedge is positioned below a fit of the blade root to the compressor disk to avoid delamination forces under centrifugal load.  
   
   
       11 . A compressor blade root connection in accordance with  claim 10 , and further comprising a metal plate attached at a bottom of the reinforcing wedge to reduce clamping forces acting upon the fiber-composite core under load.  
   
   
       12 . A compressor blade root connection in accordance with  claim 3 , wherein the blade root is straight in its longitudinal direction and has a plurality of circularly arched bearing faces in the area of the recess which have different centers to limit a pendular movement of the blade root, with each bearing face moveably locating against a conformally rounded bearing area of the recess.  
   
   
       13 . A compressor blade root connection in accordance with  claim 12 , wherein at least one of the rounded bearing faces and the bearing areas are micro-structured for frictional dampening of the pendular movement of the blade root.  
   
   
       14 . A compressor blade root connection in accordance with  claim 13 , and further comprising a reinforcing wedge extending from a bottom of the blade root and inserted into the fiber-composite core to divide the fiber-composite core into two partial strands in a longitudinal direction of the blade root.  
   
   
       15 . A compressor blade for a gas turbine engine which comprises: 
 a metallic enclosure for engagement with a recess of a compressor disk,    a fiber-composite core, wherein fibers of the fiber-composite core are packed sufficiently densely in the enclosure that compressive loads on the blade act directly upon the fibers, the enclosure including a micro-structurally enlarged inner surface to provide an intimate contact with the fiber-composite core to ensure transfer of forces between the enclosure and the fiber-composite core, the blade root being constructed and arranged to be located pendularly and frictionally dampened in the recess of the compressor disk within a limited angular range to reduce a bending stress on the fiber-composite core of the blade root.    
   
   
       16 . A compressor blade in accordance with  claim 15 , wherein the fiber-composite core has a high fiber share in relation to a plastic matrix to apply the pressure load predominately to the fibers.  
   
   
       17 . A compressor blade in accordance with  claim 16 , wherein the fiber-composite core comprises fibers compressed in transverse direction to the compressor blade, with the plastic matrix having been infiltrated under compression of the fibers.  
   
   
       18 . A compressor blade in accordance with  claim 15 , wherein the inner surface of the enclosure is micro-structurally enlarged through at least one of glass-bead peening, sand blasting or an attached wire mesh.  
   
   
       19 . A compressor blade in accordance with  claim 15 , wherein the blade root is straight in its longitudinal direction and has a plurality of circularly arched bearing faces in the area of the recess which have different centers to limit a pendular movement of the blade root, with each bearing face moveably locatable against a conformally rounded bearing area of the recess.  
   
   
       20 . A compressor blade in accordance with  claim 19 , wherein the rounded bearing faces are micro-structured for frictional dampening of the pendular movement of the blade root.  
   
   
       21 . A compressor blade in accordance with  claim 15 , and further comprising a reinforcing wedge extending from a bottom of the blade root and inserted into the fiber-composite core to divide the fiber-composite core into two partial strands in a longitudinal direction of the blade root.  
   
   
       22 . A compressor blade in accordance with  claim 21 , wherein the reinforcing wedge is micro-structured at faces mating to the fiber-composite core.  
   
   
       23 . A compressor blade in accordance with  claim 22 , wherein a large end of the reinforcing wedge is positioned below a fit of the blade root to the compressor disk to avoid delamination forces under centrifugal load.  
   
   
       24 . A compressor blade in accordance with  claim 23 , and further comprising a metal plate attached at a bottom of the reinforcing wedge to reduce clamping forces acting upon the fiber-composite core under load.  
   
   
       25 . A compressor blade in accordance with  claim 17 , wherein the blade root is straight in its longitudinal direction and has a plurality of circularly arched bearing faces in the area of the recess which have different centers to limit a pendular movement of the blade root, with each bearing face moveably locatable against a conformally rounded bearing area of the recess.  
   
   
       26 . A compressor blade in accordance with  claim 25 , wherein the rounded bearing faces are micro-structured for frictional dampening of the pendular movement of the blade root.  
   
   
       27 . A compressor blade in accordance with  claim 26  and further comprising a reinforcing wedge extending from a bottom of the blade root and inserted into the fiber-composite core to divide the fiber-composite core into two partial strands in a longitudinal direction of the blade root.