Steam turbine and blade for steam turbine

Abstract

A steam turbine includes: a turbine rotor shaft; a plurality of blades that are provided on the turbine rotor shaft and are rotated by a steam flow; tip covers that are attached to tip ends of the respective blades and are connected to and in contact with one another; at least one water drip fin that is provided along a circumferential direction at the tip cover, and outwardly extends in a radial direction of each of the blades; and a diaphragm outer ring that is disposed at an outer circumferential side from each of the blades, and has a drain catcher opposed to a tip end portion of the water drip fin, wherein the tip cover is provided with a leading edge that is formed at a downstream side in an axial direction from a leading edge of the blade or at a position in the axial direction corresponding to the leading edge of the blade in the axial direction.

What is claimed is: 
     
         1 . A steam turbine, comprising:
 a turbine rotor shaft;   a plurality of blades that are provided on the turbine rotor shaft and are rotated by a steam flow;   tip covers that are attached to tip ends of the respective blades and are connected to and in contact with one another;   at least one water drip fin that is provided along a circumferential direction at the tip cover, and outwardly extends in a radial direction of each of the blades; and   a diaphragm outer ring that is disposed at an outer circumferential side from each of the blades, and has a drain catcher opposed to a tip end portion of the water drip fin,   wherein the tip cover is provided with a leading edge that is formed at a downstream side in an axial direction from a leading edge of the blade or at a position in the axial direction corresponding to the leading edge of the blade in the axial direction.   
     
     
         2 . The steam turbine according to  claim 1 ,
 wherein the water drip fin is provided along the leading edge of the tip cover.   
     
     
         3 . The steam turbine according to  claim 1 ,
 wherein a tip end position of the water drip fin has an outside diameter smaller than a maximum outside diameter of the tip cover.   
     
     
         4 . The steam turbine according to  claim 1 ,
 wherein a plurality of the water drip fins are provided at the tip cover along the circumferential direction.   
     
     
         5 . The steam turbine according to  claim 1 ,
 wherein each of the blades has a water droplet guide groove that extends in the radial direction of the blade, with one end portion reaching the tip end of the blade, at an upstream side from the leading edge of the tip cover in a side surface at a back side.   
     
     
         6 . The steam turbine according to  claim 1 ,
 wherein the drain catcher has an opening portion with a maximum differential expansion being within a width in the axial direction of an opening even when the maximum differential expansion occurs at a position in the axial direction of the tip end of the water drip fin at a time of a steady state operation.   
     
     
         7 . A blade of a steam turbine, comprising:
 blades rotated by a steam flow;   tip covers that are attached to tip ends of the blades and are connected to and in contact with one another; and   at least one water drip fin that is provided along a circumferential direction at the tip cover, and outwardly extends in a radial direction of each of the blades,   wherein the tip cover is provided with a leading edge that is formed at a downstream side in an axial direction from a leading edge of the blade or at a position in the axial direction corresponding to the leading edge of the blade in the axial direction.