Tunable gas turbine engine fan assembly

Abstract

A gas turbine engine fan having blades embedded with a composite material. The size and the stiffness of the composite material control the vibratory characteristics of the blade without affecting the external blade profile. Accordingly, the gas turbine engine fan may use blades having similar external profiles with differing vibratory characteristics. The gas turbine engine fan can then be tuned using the blades with differing vibratory characteristics. Tuning the gas turbine engine fan minimizes the non-integral gas turbine engine fan vibrations.

1 . A rotor for a gas turbine engine, comprising: 
 a rotor mounting a first group of blades;    said rotor also mounting a second group of blades having a shell portion and a core portion; and    wherein said second group of blades has a stiffness different from said first group of blades.    
     
     
         2 . The rotor for a gas turbine engine of  claim 1 , wherein said core portion is embedded in said shell portion.  
     
     
         3 . The rotor for a gas turbine engine of  claim 1 , wherein adjusting the stiffness of said core portion tunes said second group of blades.  
     
     
         4 . The rotor for a gas turbine engine of  claim 1 , wherein adjusting said shell portion size and said core portion size tunes said second group of blades.  
     
     
         5 . The rotor for a gas turbine engine of  claim 1 , further comprising a plurality of core portions, wherein said plurality of core portions has a plurality of stiffnesses.  
     
     
         6 . The rotor for a gas turbine engine of  claim 1 , wherein said blade core portion comprises a composite material.  
     
     
         7 . The rotor for a gas turbine engine of  claim 1 , wherein said composite material is a metal matrix composite.  
     
     
         8 . The rotor for a gas turbine engine of  claim 1 , wherein said second group of blades are disposed between alternating ones of said first group of blades.  
     
     
         9 . The rotor for a gas turbine engine of  claim 1 , wherein said rotor and said blades form part of a fan section for the gas turbine engine.  
     
     
         10 . The rotor for a gas turbine engine of  claim 1 , wherein said first group of blades includes a shell portion and a core portion.  
     
     
         11 . A gas turbine engine, comprising: 
 a fan section;    a compressor;    a combustion section;    a turbine;    at least one of said fan and said turbine including a rotor having a plurality of blades, said plurality of blades comprising a material with a first stiffness and a material with a second stiffness within one or more of said plurality of blades; and    wherein varying said second stiffness tunes said one or more of said plurality of blades.    
     
     
         12 . The gas turbine engine of  claim 11 , wherein said material with a second stiffness is disposed within alternating ones of said plurality of blades.  
     
     
         13 . The gas turbine engine of  claim 11 , wherein profiles of the plurality of blades are generally similar.  
     
     
         14 . The gas turbine engine of  claim 11 , wherein said material with a second stiffness is a metal matrix composite.  
     
     
         15 . The gas turbine engine of  claim 11 , wherein said material with a second stiffness is embedded in said material with a first stiffness.  
     
     
         16 . The gas turbine engine of  claim 11 , wherein said material with a second stiffness comprises a composite material.  
     
     
         17 . The gas turbine engine of  claim 16 , wherein said material with a second stiffness comprises a metal matrix composite.  
     
     
         18 . The gas turbine engine of  claim 11 , wherein said rotor and said blades are part of said fan.  
     
     
         19 . A method of tuning a gas turbine engine fan, comprising the steps of: 
 a) mounting a first fan blade with a first stiffness to a rotor;    b) mounting a second fan blade with a second stiffness to the rotor; and    c) repeating steps a-b selectively mounting the first fan blade and the second fan blade creating a gas turbine engine fan with blades of selected stiffness.    
     
     
         20 . The method of  claim 19 , further comprising the step of varying said first stiffness, wherein varying said first stiffness alters vibratory characteristics of said first fan blade.