Turbine bucket assembly and turbine system

Abstract

A turbine bucket assembly and turbine system are disclosed. The turbine bucket assembly includes a single-lobe joint having an integral platform, the joint having a first axial length; a non-segmented airfoil having a root section and a tip section integral with the root section, the tip section having a tip end with a second axial length, the second axial length being less than the first axial length; and a turbine wheel having a receptacle with a geometry corresponding to the single-lobe joint and being coupled to the single-lobe joint. The turbine wheel includes a turbine wheel material and the single-lobe joint and the non-segmented airfoil include a turbine bucket material, the turbine bucket material having a higher heat resistance and a lower thermal expansion than the turbine wheel material.

What is claimed is: 
     
         1 . A turbine bucket assembly, comprising:
 a single-lobe joint having an integral platform, the joint having a first axial length;   a non-segmented airfoil extending radially outward from the integral platform and having a root region and a tip region integral with the root region, the tip region having a tip end with a second axial length, the second axial length being less than the first axial length; and   a turbine wheel having a receptacle with a geometry corresponding to the single-lobe joint and being coupled to the single-lobe joint;   wherein the turbine wheel includes a turbine wheel material and the single-lobe joint and the non-segmented airfoil include a turbine bucket material, the turbine bucket material having a higher heat resistance and a lower thermal expansion than the turbine wheel material.   
     
     
         2 . The assembly of  claim 1 , wherein the turbine bucket material is a ceramic matrix composite. 
     
     
         3 . The assembly of  claim 1 , wherein the turbine wheel material is a superalloy. 
     
     
         4 . The assembly of  claim 3 , wherein the turbine wheel material is a nickel-based superalloy, a cobalt-based superalloy, or a steel-based superalloy. 
     
     
         5 . The assembly of  claim 1 , wherein the turbine bucket material is less dense than the turbine wheel material. 
     
     
         6 . The assembly of  claim 1 , wherein the single-lobe joint is removably coupled to the turbine wheel by an axial joint, a circumferential joint, a dovetail joint, a dado joint, a box joint, a tongue-and-groove joint, or a combination thereof. 
     
     
         7 . The assembly of  claim 1 , wherein the geometry of the turbine wheel corresponding to the single-lobe joint defines a rim of the turbine wheel. 
     
     
         8 . The assembly of  claim 1 , wherein the non-segmented airfoil is devoid of a tip shroud. 
     
     
         9 . The assembly of  claim 1 , further comprising an impact strip positioned on a leading edge of the non-segmented airfoil. 
     
     
         10 . The assembly of  claim 1 , further comprising an impact strip positioned on a trailing edge of the non-segmented airfoil. 
     
     
         11 . The assembly of  claim 1 , further comprising an impact strip formed of impact strip material capable of adhering to the turbine bucket material. 
     
     
         12 . A turbine bucket assembly, comprising:
 a single-lobe joint having an integral platform, the joint having a first axial length;   a non-segmented airfoil extending radially outward from the integral platform and having a tip end with a second axial length, the second axial length being less than the first axial length; and   a turbine wheel defining a receptacle with a geometry corresponding to the single-lobe joint and being removably coupled to the single-lobe joint;   wherein the turbine wheel includes a turbine wheel material and the single-lobe joint and the non-segmented airfoil include a turbine bucket material, the turbine wheel material being a superalloy and the turbine bucket material being a ceramic matrix composite.   
     
     
         13 . A gas turbine system, comprising:
 a compressor section;   a combustor section configured to receive air from the compressor section; and   a turbine section in fluid communication with the combustor section, the turbine section comprising a stator and a turbine bucket assembly, the turbine bucket assembly comprising:
 a single-lobe joint having an integral platform, the joint having a first axial length; 
 a non-segmented airfoil extending radially outward from the integral platform and having a tip end with a second axial length, the second axial length being greater than the first axial length; and 
 a turbine wheel defining a receptacle with a geometry corresponding to the single-lobe joint and being coupled to the single-lobe joint; 
 wherein the turbine wheel includes a turbine wheel material, and the single-lobe joint and the non-segmented airfoil include a turbine bucket material, the turbine bucket material having a higher heat resistance and a lower thermal expansion than the turbine wheel material. 
   
     
     
         14 . The gas turbine system of  claim 13 , further comprising a plurality of axially spaced stages of turbine bucket assemblies including a last stage of turbine bucket assemblies. 
     
     
         15 . The gas turbine system of  claim 14 , wherein the airfoil has a leading edge and a trailing edge, and further comprises at least one impact strip attached to at least one of the leading edge and the trailing edge. 
     
     
         16 . The gas turbine system of  claim 15 , wherein impact strips are attached to the leading edges of the plurality of turbine bucket assemblies in one or more of the plurality of turbine stages. 
     
     
         17 . The gas turbine system of  claim 15 , wherein impact strips are attached to the trailing edges of the plurality of turbine bucket assemblies in one or more of the plurality of turbine stages with the exception of the last stage.