High temperature turbine rotor blade
A turbine rotor blade made from the spar and shell construction in which the shell formed from a plurality of shell segments each being a thin wall shell segment made from a high temperature resistant material that is formed by a wire EDM process, and where the shell segments are each secured to the spar separately using a retainer that is poured into retainer occupying spaces formed in the shell segments and the spar, and then hardened to form a rigid retainer to secure each shell segment to the spar individually. The spar includes a number of radial extending projections each with a row of cavities that form the retainer occupying spaces in order to spread the loads around. The retainer can be a bicast material, a transient liquid phase bonding material, or a sintered metal. An old shell can be easily removed and replaced with a new shell by removing parts of the retainer and re-pouring a new retainer with a new shell in place.
1. A turbine rotor blade for a gas turbine engine comprising:
a spar having a radial extending projection with a cavity opening onto a surface of the radial extending projection, the cavity forming a retainer occupying space;
a shell having an airfoil cross sectional shape with a pressure side wall and a suction side wall;
the shell being formed from a plurality of shell segments;
the shell segments each including a retainer occupying space;
a rigid retainer formed within the retainer occupying spaces of the spar and the shell segments to secure the shell segments to the spar; and,
the retainer being poured into place as a non-rigid material and hardened into a rigid material to form the retainer.
2. The turbine rotor blade of claim 1 , and further comprising:
the radial extending projection includes a row of cavities extending along a spanwise direction of the blade;
the shell segments each includes a shell segment retainer securing surface for each spar cavity; and,
the retainer occupies a space formed by the cavities and the shell segment securing surfaces.
3. The turbine rotor blade of claim 2 , and further comprising:
the shell segments each includes a pair of adjacent ribs extending from the pressure side wall to the suction side wall;
the pair of ribs forming a radial extending passage for pouring the retainer material into the spar cavities.
4. The turbine rotor blade of claim 3 , and further comprising:
the pair of adjacent ribs includes openings near the airfoil walls that face inward and form the retainer surfaces for the shell segments.
5. The turbine rotor blade of claim 2 , and further comprising:
the spar includes a plurality of radial extending projections each having a row of cavities extending in the spanwise direction of the blade, and each forming a retainer occupying space to secure the shell segments to the spar.
6. The turbine rotor blade of claim 1 , and further comprising:
the retainer forms a single piece that extends along substantially the entire spanwise length of the shell.
7. The turbine rotor blade of claim 1 , and further comprising:
the spar includes a forward radial extending projection with a row of cavities on a forward side and an aft side of the forward radial extending projection;
the spar includes an aft radial extending projection with a row of cavities on a forward side and an aft side of the aft radial extending projection;
a forward set of shell ribs associated with the cavities on the forward side of the forward projection;
a middle set of shell ribs associated with the cavities on the aft side of the forward projection and the forward side of the aft projection;
an aft set of shell ribs associated with the cavities on the aft side of the aft projection; and,
a forward retainer, a middle retain and an aft retainer each securing the shell to the spar by occupying a space formed by the cavities.
8. The turbine rotor blade of claim 1 , and further comprising:
the retainer a bicast material or a transient liquid phase bonding material, or a sintered metal.
9. The turbine rotor blade of claim 1 , and further comprising:
the retainer is a transient liquid phase bonding material; and,
the spar cavity is coated with a stop-off agent to prevent the retainer from bonding to the spar for ease of removal.
10. The turbine rotor blade of claim 7 , and further comprising:
the retainer a bicast material or a transient liquid phase bonding material, or a sintered metal.
11. The turbine rotor blade of claim 1 , and further comprising:
the retainer is a transient liquid phase bonding material; and,
the spar cavities are coated with a stop-off agent to prevent the retainer from bonding to the spar for ease of removal.
12. The turbine rotor blade of claim 1 , and further comprising:
the shell segments are each formed of Molybdenum or Niobium.
13. The turbine rotor blade of claim 12 , and further comprising:
the shell segments are each a thin walled shell and is formed from a wire EDM process.
14. The turbine rotor blade of claim 1 , and further comprising:
the shell segments each have substantially the same radial height.
15. The turbine rotor blade of claim 1 , and further comprising:
the shell is formed from four shell segments.
16. The turbine rotor blade of claim 1 , and further comprising:
each shell segment includes a leading edge and a trailing edge and a pressure side wall and a suction side wall both extending between the leading edge and the trailing edge.