Multiple piece turbine rotor blade
A multiple piece turbine rotor blade with a shell having an airfoil shape and secured between a spar and a platform with the spar including a tip end piece. a snap ring fits around the spar and abuts against the spar tip end piece on a top side and abuts against a shell on the bottom side so that the centrifugal loads from the shell is passed through the snap ring and into the spar and not through a tip cap dovetail slot and projection structure.
1. A multiple piece turbine rotor blade comprising:
a spar having a lower end with a fir tree configuration and a top end;
a platform piece with an opening to fit the spar from the bottom side;
the platform having two legs each with a fir tree configuration;
a shell having an airfoil shape;
a snap ring that wraps around the spar; and,
the snap ring has a lower abutment surface for a top end of a shell and a top abutment surface for the spar such that a centrifugal load of the shell is transmitted to the spar through the snap ring.
2. The multiple piece turbine rotor blade of claim 1 , and further comprising:
the shell is a thin walled shell and is made from an exotic high temperature resistant material that cannot be cast or machined like a nickel super-alloy.
3. The multiple piece turbine rotor blade of claim 2 , and further comprising:
the shell is made from Molybdenum or Columbium.
4. The multiple piece turbine rotor blade of claim 1 , and further comprising:
the top end of the spar includes a slot; and,
a tip cap includes a projection on the bottom surface that slides within the slot to secure the tip cap to the spar.
5. The multiple piece turbine rotor blade of claim 4 , and further comprising:
the slot in the spar extends from a forward section of the tip cap on a pressure wall side to an aft section of the tip cap on the pressure wall side.
6. The multiple piece turbine rotor blade of claim 4 , and further comprising:
the slot in the spar is a single slot with a dovetail shape.
7. The multiple piece turbine rotor blade of claim 1 , and further comprising:
the snap ring is formed from two pieces bonded together to form a single piece.
8. The multiple piece turbine rotor blade of claim 7 , and further comprising:
the snap ring includes ship laps on the ends of the two pieces to bond the ends together.
9. A multiple piece turbine rotor blade comprising:
a spar having a lower end and a top end;
a platform piece with an opening to fit the spar from the bottom side;
a shell having an airfoil shape;
a snap ring that wraps around the spar; and,
the snap ring has a lower abutment surface for a top end of a shell and a top abutment surface for the spar such that a centrifugal load of the shell is transmitted to the spar through the snap ring.
10. The multiple piece turbine rotor blade of claim 9 , and further comprising:
the snap ring is formed from two pieces having free-floating ends.
11. The multiple piece turbine rotor blade of claim 9 , and further comprising:
the snap ring is formed from two pieces bonded together to form a single piece.
12. The multiple piece turbine rotor blade of claim 11 , and further comprising:
the snap ring includes ship laps on the ends of the two pieces to bond the ends together.