Reduction in thermal stresses in monolithic ceramic or ceramic matrix composite shroud

Abstract

A shroud for use in a gas turbine engine has a ring with a plurality of protrusions and a plurality of slots and each of the protrusions having an arc length and parallel sides.

1 . A shroud comprising:
 a ring with a plurality of protrusions and a plurality of slots; and   each of said protrusions having an arc length different from the arc length of each said slot.   
     
     
         2 . The shroud of  claim 1 , wherein said shroud is formed from a monolithic ceramic material or Ceramic Matrix Composite (CMC) material. 
     
     
         3 . The shroud of  claim 21 , wherein each of said slots has parallel sides. 
     
     
         4 . The shroud of  claim 21 , wherein said slots are equally spaced around a circumference of said ring. 
     
     
         5 . The shroud of  claim 21 , wherein said plurality of slots comprises said ring having from 3 to 18 slots. 
     
     
         6 . The shroud of  claim 21 , wherein each said slot has an arc length and said arc length of each slot is greater than the arc length of each said protrusion. 
     
     
         7 . The shroud of  claim 6 , wherein said ring has a minimum thickness and a majority of the ring is dominated by the ring minimum thickness so as to decrease stress concentrations. 
     
     
         8 . The shroud of  claim 6 , wherein each said slot has an arc length in the range of 20 to 60 degrees. 
     
     
         9 . The shroud of  claim 6 , wherein each said slot has an arc length of 3 to 20 degrees. 
     
     
         10 . An engine comprising:
 a rotor;   a ceramic or CMC shroud surrounding said rotor; and   said shroud comprising a ring with a plurality of protrusions and a plurality of slots and each of said protrusions having an arc length and parallel sides.   
     
     
         11 . The engine of  claim 10 , wherein said shroud is located in a hot section of said engine. 
     
     
         12 . The engine of  claim 10 , wherein said shroud is formed from a ceramic material and is monolithic. 
     
     
         13 . The engine of  claim 10 , wherein each of said slots has parallel sides. 
     
     
         14 . The engine of  claim 13 , further comprising a mating ring with mating features that contact the parallel sides of the slots. 
     
     
         15 . The engine of  claim 10 , wherein said slots are equally spaced around a circumference of said ring. 
     
     
         16 . The engine of  claim 10 , wherein said plurality of slots comprises said ring having from 5 to 12 slots. 
     
     
         17 . The engine of  claim 10 , wherein each said slot has an arc length and said arc length of each slot is greater than the arc length of each said protrusion. 
     
     
         18 . The engine of  claim 17 , wherein said ring has a minimum thickness and a majority of the ring is dominated by the ring minimum thickness so as to decrease stress concentrations. 
     
     
         19 . The engine of  claim 17 , wherein each said slot has an arc length in the range of 20 to 60 degrees. 
     
     
         20 . The engine of  claim 17 , wherein each said slot has an arc length in the range of 3 to 20 degrees. 
     
     
         21 . A shroud comprising:
 a ring with a plurality of protrusions and a plurality of slots; and   said shroud being formed from a monolithic ceramic material and being monolithic or Ceramic Matrix Composite (CMC) material.