Conformal liner for gas turbine engine fan section

Abstract

A fan section of a gas turbine engine includes a fan case structure having a first coefficient of thermal expansion. A fan blade is arranged within the fan case structure and has a second coefficient thermal expansion. A continuous ring-shaped liner surrounds the fan blade and includes a third coefficient of thermal expansion that is substantially similar to the second coefficient of thermal expansion and substantially different than the first coefficient of thermal expansion. An elastomeric adhesive operatively connects the liner to the fan case structure. The adhesive is configured to accommodate diametrical change in the liner and maintain a desired radial tip clearance throughout various fan section operating temperatures.

What is claimed is: 
     
         1 . A fan section of a gas turbine engine comprising:
 a fan case structure having a first coefficient of thermal expansion;   a fan blade arranged within the fan case structure and having second coefficient of thermal expansion;   a continuous ring-shaped liner surrounding the fan blade and having a third coefficient of thermal expansion that is substantially similar to the second coefficient of thermal expansion and substantially different than the first coefficient of thermal expansion, and a desired radial tip clearance between the liner and the fan blade; and   an elastomeric adhesive operatively connecting the liner to the fan case structure, the adhesive configured to accommodate diametrical change in the liner and maintain the desired radial tip clearance throughout various fan section operating temperatures.   
     
     
         2 . The fan section according to  claim 1 , wherein the adhesive has a 300% elongation or greater. 
     
     
         3 . The fan section according to  claim 2 , wherein the adhesive is silicone rubber. 
     
     
         4 . The fan section according to  claim 1 , wherein the second coefficient of thermal expansion is greater than the first coefficient of thermal expansion by at least 10×10 −6 /° F. (18×10 −6 /° C.). 
     
     
         5 . The fan section according to  claim 4 , wherein the fan case structure includes a composite fan case. 
     
     
         6 . The fan section according to  claim 5 , wherein the fan case structure includes a honeycomb structure operatively connected radially inward of and to the composite fan case. 
     
     
         7 . The fan section according to  claim 6 , wherein the fan case structure includes a composite septum interconnecting the adhesive and the honeycomb. 
     
     
         8 . The fan section according to  claim 1 , wherein the second and third coefficients of thermal expansion are within 1×10 −6 /° F. (1.8×10 −6 /° C.) of one another. 
     
     
         9 . The fan section according to  claim 8 , wherein the fan blade and the liner are constructed from the same series aluminum alloy. 
     
     
         10 . The fan section according to  claim 8 , wherein the desired radial tip clearance is about 0.030 inch at −65° F. (0.76 m at −54° C.) ambient. 
     
     
         11 . The fan section according to  claim 10 , comprising a rub strip supported on and radially inward of the liner between the liner and the fan blade. 
     
     
         12 . A fan case structure comprising:
 a composite fan case structure having a first coefficient of thermal expansion;   an continuous ring-shaped liner having a second coefficient of thermal expansion that is substantially different than the first coefficient of thermal expansion, wherein the second coefficient of thermal expansion is greater than the first coefficient of thermal expansion by at least 10×10 −6 /° F. (18×10 −6 /° C.) and   an elastomeric adhesive operatively connecting the liner to the fan case structure, wherein the adhesive has a 300% elongation or greater, the adhesive configured to accommodate diametrical change in the liner throughout various operating temperatures.   
     
     
         13 . The fan case structure according to  claim 12 , wherein the composite fan case structure includes a structure constructed from resin and at least one of carbon fibers and fiberglass, and the liner is an aluminum alloy. 
     
     
         14 . The fan case structure according to  claim 13 , wherein the adhesive is silicone rubber. 
     
     
         15 . The fan case structure according to  claim 13 , wherein a rub strip is supported radially inward from and by the liner, and the composite fan case structure includes: a composite septum interconnecting the adhesive to a honeycomb structure that is supported by and radially inward from a composite fan case.