Snubber configurations for turbine rotor blades

Abstract

A rotor blade for use in a turbine of a combustion turbine engine. The rotor blade may include an airfoil having a concave pressure sidewall and a convex suction sidewall extending axially between corresponding leading and trailing edges and radially between the root and an outboard tip. The rotor blade may further include dual snubber shrouds positioned on the airfoil. Each of the dual snubber shrouds may be configured to engage a corresponding snubber shroud on at least one neighboring rotor blade upon installation.

1 . A rotor blade for use in a turbine of a combustion turbine engine, the rotor blade comprising an airfoil that extends from a connection with a root, the airfoil including a concave pressure sidewall and a convex suction sidewall extending axially between corresponding leading and trailing edges and radially between the root and an outboard tip, the rotor blade further comprising:
 dual snubber shrouds positioned on the airfoil;   wherein each of the dual snubber shrouds is configured to engage a corresponding dual snubber shroud on at least one neighboring rotor blade upon installation.   
     
     
         2 . The rotor blade according to  claim 1 , wherein both of the dual snubber shrouds comprises a position at or outboard of a radial mid-region of the airfoil; and
 wherein each of the dual snubber shrouds comprise an axial thickness that is less than half of an axial thickness that the airfoil has at a radial height of each of the snubber shrouds.   
     
     
         3 . The rotor blade according to  claim 2 , wherein the dual snubber shrouds include an inboard snubber shroud and an outboard snubber shroud, the inboard snubber shroud comprising an inboard position relative to the outboard snubber shroud;
 wherein the inboard snubber shroud comprises a circumferentially extending projection from at least one of the pressure sidewall and the suction sidewall of the airfoil;   wherein the outboard snubber shroud comprises a circumferentially extending projection from at least one of the pressure sidewall and the suction sidewall of the airfoil; and   wherein the rotor blade comprises a turbine rotor blade.   
     
     
         4 . The rotor blade according to  claim 3 , wherein:
 the inboard snubber shroud comprises circumferentially extending projections from each of the pressure sidewall and the suction sidewall of the airfoil; and   the outboard snubber shroud comprises circumferentially extending projections from each of the pressure sidewall and the suction sidewall of the airfoil.   
     
     
         5 . The rotor blade according to  claim 4 , wherein:
 each of the inboard snubber shroud and the outboard snubber shroud comprises pressure side contact faces at distal ends of each of the circumferential projections extending from the pressure sidewall of the airfoil; and   each of the inboard snubber shroud and the outboard snubber shroud comprises suction side contact faces at distal ends of each of the circumferential projections extending from the suction sidewall of the airfoil.   
     
     
         6 . The rotor blade according to  claim 5 , wherein the inboard snubber shroud and the outboard snubber shroud are configured such that the pressure side contact faces correspond to the suction side contact faces so to form an interface therebetween when the rotor blade comprises an installed position between neighboring rotor blades having a same design as the rotor blade. 
     
     
         7 . The rotor blade according to  claim 5 , wherein the inboard snubber shroud and the outboard snubber shroud are configured such that the pressure side contact faces engage suction side contact faces of a first neighboring rotor blade if:
 the first neighboring rotor blade comprises a same design as the rotor blade; and   the first neighboring rotor blade and the rotor blade comprise a predetermined installed position relative to each other;   
       wherein the inboard snubber shroud and the outboard snubber shroud are configured such that the suction side contact faces engage pressure side contact faces of a second neighboring rotor blade if:
 the second neighboring rotor blade comprises the same design as the rotor blade; and 
 the second neighboring rotor blade and the rotor blade comprise a predetermined installed position relative to each other. 
 
     
     
         8 . The rotor blade according to  claim 4 , wherein the outboard snubber shroud comprises a position near the outboard tip of the airfoil and the inboard snubber shroud comprises a position near the radial mid-region of the airfoil. 
     
     
         9 . The rotor blade according to  claim 4 , wherein the outboard snubber shroud comprises a shroud positioned just inside of the outboard tip of the airfoil and the inboard snubber shroud comprises a shroud positioned near a radial mid-point of the airfoil. 
     
     
         10 . The rotor blade according to  claim 4 , wherein the inboard snubber shroud comprises one disposed within a first range of radial heights defined on the airfoil, wherein the first range includes an inboard boundary at 25% of a radial height of the airfoil and an outboard boundary at 75% of the radial height of the airfoil; and
 wherein the outboard snubber shroud comprises one disposed within a second range of radial heights defined on the airfoil, wherein the second range includes an inboard boundary at 60% of the radial height of the airfoil.   
     
     
         11 . The rotor blade according to  claim 10 , wherein the inboard boundary of the first range comprises 40% of a radial height of the airfoil and the outboard boundary of the first range comprises 60% of the radial height of the airfoil; and
 wherein the inboard boundary of the second range comprises 75% of the radial height of the airfoil and an outboard boundary of the second range comprises 95% of the radial height of the airfoil.   
     
     
         12 . The rotor blade according to  claim 10 , wherein the inboard boundary of the first range comprises 40% of a radial height of the airfoil and the outboard boundary of the first range comprises 60% of the radial height of the airfoil; and
 wherein the inboard boundary of the second range comprises 90% of the radial height of the airfoil.   
     
     
         13 . The rotor blade according to  claim 12 , wherein an outboard tip of the airfoil comprises a winglet. 
     
     
         14 . The rotor blade according to  claim 13 , wherein the outboard snubber shroud is radial spaced apart from the winglet. 
     
     
         15 . The rotor blade according to  claim 14 , wherein the winglet comprises an outboard flaring disposed within a narrow radial section of the airfoil, the narrow radial section having a side contiguous with the outboard tip of the airfoil. 
     
     
         16 . The rotor blade according to  claim 15 , wherein the outboard shroud extends from the winglet. 
     
     
         17 . The rotor blade according to  claim 15 , wherein the winglet includes an inboard edge and an outboard edge, and wherein the outboard flaring includes the winglet having a smaller cross-sectional area at the inboard edge and a larger cross-sectional airfoil area at an outboard edge of winglet;
 wherein the outboard edge of the winglet comprises the outboard tip of the airfoil and the inboard edge of the winglet is spaced a fixed distance from the outboard edge of the winglet about a circumference of the airfoil.   
     
     
         18 . The rotor blade according to  claim 17 , wherein the outboard edge of the winglet comprises a sharp edge defined about the circumference to the airfoil; and
 wherein the outboard flaring of the winglet comprises a concave surface profile.   
     
     
         19 . A gas turbine engine having a turbine that comprises a row of circumferentially spaced rotor blades, wherein each of the rotor blades includes an airfoil extending from a root that connects to a rotor disc, the airfoil including a pressure sidewall and a suction sidewall extending axially between a leading edge and a trailing edges and radially between a platform that forms an outboard boundary of the root and an outboard tip of the airfoil, the airfoil of each of the rotor blades further comprising:
 dual snubber shrouds, an inboard snubber shroud and an outboard snubber shroud;   wherein each of the snubber shrouds comprises a position between the platform and the outboard tip of the airfoil and a configuration that connects each of the rotor blades to neighboring rotor blades positioned to each side; and   wherein the outboard snubber shroud comprises a shroud positioned near the outboard tip of the airfoil and the inboard snubber shroud comprises a shroud positioned near a radial mid-region of the airfoil.   
     
     
         20 . The gas turbine engine according to  claim 19 , wherein the inboard snubber shroud comprises circumferentially extending projections from each of the pressure sidewall and the suction sidewall of the airfoil, and the outboard snubber shroud comprises circumferentially extending projections from each of the pressure sidewall and the suction sidewall of the airfoil; and
 wherein each of the inboard snubber shroud and the outboard snubber shroud comprises pressure side contact faces at distal ends of each of the circumferential projections extending from the pressure sidewall of the airfoil, and each of the inboard snubber shroud and the outboard snubber shroud comprises suction side contact faces at distal ends of each of the circumferential projections extending from the suction sidewall of the airfoil.