Multi-airfoil guide vane unit

Abstract

A multi-airfoil guide vane unit includes a first platform member, a second platform member, and at least two airfoil members, the airfoil members having a longitudinal extent along an airfoil span width and two longitudinal ends, wherein all airfoil members are rigidly affixed to a platform member at a first longitudinal end and at least one airfoil member is rigidly affixed to both platform members at both longitudinal ends. At least one of the airfoil members is floatingly connected to one of the platform members at a second longitudinal end. A longitudinally floating joint arrangement is thus provided between the second longitudinal end of the airfoil member and the platform member, such as to allow displacement of the airfoil member relative to said platform member along the longitudinal extent of said airfoil member.

1 . A multi-airfoil guide vane unit, comprising:
 a first platform member, a second platform member, and at least two airfoil members, the airfoil members having a longitudinal extent along an airfoil span width and two longitudinal ends, wherein all airfoil members are rigidly affixed to a platform member at a first longitudinal end and at least one airfoil member is rigidly affixed to both platform members at both longitudinal ends, wherein at least one of the airfoil members is floatingly connected to one of the platform members at a second longitudinal end and a longitudinally floating joint arrangement is provided between the second longitudinal end of the airfoil member and the platform member, such as to allow displacement of the airfoil member relative to said platform member along the longitudinal extent of said airfoil member.   
     
     
         2 . The multi-airfoil guide vane unit according to  claim 1 , wherein the floating joint arrangement comprises:
 a male joint feature provided at one of the second longitudinal end of the airfoil member and the platform member and a female joint feature provided at the other one of the second longitudinal end of the airfoil member and the platform member, the male feature being received within said female feature.   
     
     
         3 . The multi-airfoil guide vane unit according to  claim 2 , wherein the male joint feature is provided as a peg section at the second longitudinal end of the airfoil member and the female feature is a pocket provided in the platform member. 
     
     
         4 . The multi-airfoil guide vane unit according to  claim 2 , wherein the male joint feature outer surface is a ruled surface spanned by straight parallel lines. 
     
     
         5 . The multi-airfoil guide vane unit according to  claim 3 , wherein the peg section has an airfoil-shaped cross section. 
     
     
         6 . The multi-airfoil guide vane unit according to  claim 2 , wherein the male joint feature and the female joint feature are arranged and configured to form a running fit. 
     
     
         7 . The multi-airfoil guide vane unit according to  claim 6 , wherein the running fit is provided by a fitting member arranged within the female member, wherein the fitting member is in particular provided as one of a bi-cast or an injection molding member. 
     
     
         8 . The multi-airfoil guide vane unit according to  claim 2 , wherein a depth of the female joint feature is larger than a received length of the male joint feature such that a gap is provided between the bottom of the female joint feature and a tip of the male joint feature. 
     
     
         9 . The multi-airfoil guide vane unit according to  claim 1 , the guide vane unit comprising:
 three airfoil members, wherein two outer airfoil members are rigidly affixed to a platform member at both longitudinal ends and a middle airfoil member is rigidly affixed to a first platform member and is floatingly connected to the second platform member.   
     
     
         10 . The multi-airfoil guide vane unit according to  claim 1 , the guide vane unit comprising:
 three airfoils, wherein a middle airfoil is rigidly affixed to a platform member at both longitudinal ends and each of two outer airfoil members is rigidly affixed to a platform member at its first end and is floatingly connected to a platform member at its second end.   
     
     
         11 . The multi-airfoil guide vane unit according to  claim 10 , wherein both outer airfoil members are rigidly affixed to the first platform member and are floatingly connected to the second platform member. 
     
     
         12 . The multi-airfoil guide vane unit according to  claim 10 , wherein a first outer airfoil member is rigidly affixed to the first platform member and is floatingly connected to the second platform member, and a second outer airfoil member is rigidly affixed to the second platform member and is floatingly connected to the first platform member. 
     
     
         13 . An airfoil member for the multi-airfoil guide vane unit according to  claim 1 , wherein a longitudinal end section of the airfoil member is provided with constant cross sections thus forming a generally cylindrical peg section. 
     
     
         14 . A platform member for the multi-airfoil guide vane unit according to  claim 1 , comprising:
 at least one pocket adapted and configured for receiving an airfoil member end section.   
     
     
         15 . The platform member according to  claim 14  wherein at least one concave form-lock feature is provided on the side wall of the pocket and is in particular provided as a circumferential groove.