Turbine bucket assembly and turbine system

Abstract

A turbine bucket assembly and turbine system are disclosed. The assembly includes 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 having a receptacle with a geometry corresponding to the single-lobe joint and being coupled to the single-lobe joint. The joint and the non-segmented airfoil include a turbine bucket material, and the turbine wheel includes a turbine wheel material, the turbine wheel material having a lower heat resistance and a higher thermal expansion than the turbine bucket 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 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 non-segmented airfoil includes a turbine bucket material, and the turbine wheel includes a turbine wheel material, the turbine wheel material having a lower heat resistance and a higher thermal expansion than the turbine bucket material.   
     
     
         2 . The assembly of  claim 1 , wherein the turbine bucket material is a titanium aluminide. 
     
     
         3 . The assembly of  claim 1 , wherein the turbine wheel material is a superalloy. 
     
     
         4 . The assembly of  claim 1 , wherein the turbine bucket material is less dense than the turbine wheel material. 
     
     
         5 . The assembly of  claim 1 , further comprising a tip shroud integrally positioned on the tip end of the non-segmented airfoil. 
     
     
         6 . The assembly of  claim 5 , wherein the tip shroud comprises a sealing rail positioned on an outer surface of the tip shroud distal from the single-lobe joint. 
     
     
         7 . 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. 
     
     
         8 . 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. 
     
     
         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 having a receptacle with a geometry corresponding to the single- lobe joint and being coupled to the single-lobe joint;   wherein the single-lobe joint and the non-segmented airfoil include a turbine bucket material, and the turbine wheel includes a turbine wheel material, the turbine bucket material being a titanium aluminide and the turbine wheel material being a superalloy.   
     
     
         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 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 non-segmented airfoil includes a turbine bucket material and the turbine wheel includes a turbine wheel material, the turbine wheel material having a lower heat resistance and a higher thermal expansion than the turbine bucket 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 edge of the tip regions 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.