Blade segment and fluid flow machine

Abstract

A blade segment ( 1 ) for a fluid flow machine ( 2 ), including: a first blade ( 3 ); a first shroud ( 7 ) attached to the tip of the first blade ( 3 ) and having a contact face ( 11 ); a second blade ( 3 ′); and a second shroud ( 7 ′) attached to the tip of the second blade ( 3 ′) and having a counter-contact face ( 12 ′) for engagement with the contact face ( 11 ) of the first shroud ( 7 ) in the radial direction (R) in such a way that a friction lock (RF) can be created between the contact face ( 11 ) and the counter-contact face ( 12 ′).

1 . A blade segment for a fluid flow machine comprising:
 a first blade;   a first shroud attached to a tip of the first blade and having a contact face;   a second blade; and   a second shroud attached to a second tip of the second blade and having a counter-contact face for engagement with the contact face of the first shroud in a radial direction to permit creation of a friction lock between the contact face and the counter-contact face.   
     
     
         2 . The blade segment as recited in  claim 1  wherein a center of gravity of the first shroud is spaced in a circumferential direction from a centerline of the first blade, and during operation of the blade segment, the first blade bending under action of centrifugal forces to create the friction lock between the contact face and the counter-contact face. 
     
     
         3 . The blade segment as recited in  claim 1  wherein at least one of the contact face of the first shroud and the counter-contact face of the second shroud is configured with an interference dimension in the radial direction for bending the first blade about a root point in a circumferential direction to create the friction lock between the contact face and the counter-contact face. 
     
     
         4 . The blade segment as recited in  claim 1  wherein the friction lock is adapted to produce a reaction torque in a direction about a centerline of at least one of the first and second blades. 
     
     
         5 . The blade segment as recited in  claim 1  wherein at least one of the first and second blades has a basic tilt in an axial direction defined by a basic tilt axis, the contact face and the counter-contact face being arranged obliquely with respect to the basic tilt axis. 
     
     
         6 . The blade segment as recited in  claim 5  wherein the contact face and counter-contact face are arrange at an angle between 45 and 135 degrees to the basic tilt axis. 
     
     
         7 . The blade segment as recited in  claim 1  wherein the contact face and the counter-contact face have an engagement element and a receiving element engaging one another in a circumferential direction. 
     
     
         8 . The blade segment as recited in  claim 1  wherein at least one of the first and second blades is torsionally biased. 
     
     
         9 . The blade segment as recited in  claim 1  wherein the first and second blades are rotor blades. 
     
     
         10 . The blade segment as recited in  claim 1  wherein at least one of the first and second blades is made of a strongly creeping material. 
     
     
         11 . A fluid flow machine comprising the blade segment as recited in  claim 1 . 
     
     
         12 . A turbine comprising the blade segment as recited in  claim 1 .