Shrouded turbine blade with contoured platform and axial dovetail

Abstract

A turbine blade includes an airfoil having a root, a tip, a concave pressure side, and a laterally opposite convex suction side, the pressure and suction sides extending in chord between opposite leading and trailing edges; an outer platform disposed at the tip of the airfoil, the outer platform having spaced-apart lateral edges which each define an interlocking element; an inner platform with two spaced-apart curved lateral edges disposed at the root of the airfoil, the inner platform having a hot side facing the airfoil which is contoured in a non-axisymmetric shape; and a dovetail extending radially inward from the opposite side of the inner platform, wherein the dovetail is axially straight.

What is claimed is: 
     
         1 . A turbine blade comprising:
 an airfoil having a root, a tip, a concave pressure side, and a laterally opposite convex suction side, the pressure and suction sides extending in chord between opposite leading and trailing edges;   an outer platform disposed at the tip of the airfoil, the outer platform having spaced-apart lateral edges, each defining an interlocking element;   an inner platform with two spaced-apart curved lateral edges disposed at the root of the airfoil, the inner platform having a hot side facing the airfoil which is contoured in a non-axisymmetric shape; and   a dovetail extending radially inward from the opposite side of the inner platform, wherein the dovetail is axially straight.   
     
     
         2 . The turbine blade of  claim 1  wherein one of the lateral edges of the outer platform defines a protruding tab, and the other lateral edge defines a recess which a shape complementary to the tab. 
     
     
         3 . The turbine blade of  claim 1  wherein the hot side of the inner platform is contoured in a non-axisymmetric shape including a peak of relatively higher radial height adjoining the pressure side of the airfoil adjacent its leading edge, and a trough of relatively lower radial height disposed parallel to and spaced-away from the suction side of the airfoil aft of its leading edge. 
     
     
         4 . The turbine blade of  claim 1  wherein the hot side of the inner platform includes a trailing edge ridge of relatively higher radial height extending aft of the trailing edge of the airfoil. 
     
     
         5 . A turbine blade according to  claim 1  wherein the peak is centered at the pressure side of the airfoil between the leading edge and a mid-chord position, and decreases in height forward, aft, and laterally therefrom; and the trough is centered at the suction side near the maximum thickness of the airfoil, and decreases in depth forward, aft, and laterally therefrom. 
     
     
         6 . A turbine blade according to  claim 1  wherein one of the lateral edges of the inner platform is convex and the other lateral edge is concave. 
     
     
         7 . A turbine blade assembly comprising:
 A plurality of blades, each blade including:   an airfoil having a root, a tip, a concave pressure side, and a laterally opposite convex suction side, the pressure and suction sides extending in chord between opposite leading and trailing edges;   an outer platform disposed at the tip of the airfoil, the outer platform having spaced-apart lateral edges which are configured with an interlocking element;   an inner platform with two spaced-apart curved lateral edges disposed at the root of the airfoil, the inner platform having a hot side facing the airfoil which is contoured in a non-axisymmetric shape;   the blades disposed in an annular side-by-side array such so as to define a plurality of flow passages each of which is bounded between two of the inner platforms, two of the outer platforms, and adjacent first and second airfoils;   wherein the interlocking elements of adjacent outer platforms are engaged with each other;   wherein the hot sides of the inner platforms in each of the passages are contoured in a non-axisymmetric shape including a peak of relatively higher radial height adjoining the pressure side of the first airfoil adjacent its leading edge, and a trough of relatively lower radial height is disposed parallel to and spaced-away from the suction side of the second airfoil aft of its leading edge; and   wherein the peak and trough define cooperatively define an arcuate channel extending axially along the inner platform between the first and second airfoils.   
     
     
         8 . A turbine blade assembly according to  claim 7  wherein the peak decreases in height around each the leading edge of the first airfoil to join the trough along the suction side of the second airfoil; and the trough extends along the suction sides of the second airfoil to its trailing edge. 
     
     
         9 . A turbine blade assembly according to  claim 1  wherein a line defining the deepest portion of the trough is positioned about 10% of the tangential distance from the suction side of the second airfoil to the pressure side of the first airfoil. 
     
     
         10 . The turbine blade assembly of  claim 7  wherein the hot side of each inner platform includes a trailing edge ridge of relatively higher radial height extending aft of the trailing edge of the airfoil. 
     
     
         11 . A turbine blade assembly according to  claim 1  wherein: the peak is centered at the pressure side of each airfoil between the leading edge and a mid-chord position, and decreases in height forward, aft, and laterally therefrom; and the trough is centered at the suction side near the maximum thickness of the airfoil, and decreases in depth forward, aft, and laterally therefrom. 
     
     
         12 . A turbine blade assembly according to  claim 7  wherein one of the lateral edges of each inner platform is convex and the other lateral edge is concave.