Turbine blade for an aircraft engine and casting mold for its manufacture

Abstract

A hollow-type turbine blade produced by a casting process has a cooling air cavity ( 8 ) and film cooling ducts ( 12 ) originating at this cooling air cavity ( 8 ). Adjacent film cooling ducts with a large length-diameter ratio are connected by cross-ducts ( 13 ) which are offset relative to each other and arranged vertically to the film cooling ducts. The casting mold comprises a core corresponding to a brickwall design of the film cooling ducts and the cross-ducts, with long core pins being intersupported by cross pins. The turbine blade, including all film cooling ducts, can be produced with high quality in a casting process.

1 . A casting mold for the production of a hollow turbine blade having at least one radial cavity flown by cooling air and a multitude of film cooling ducts, radially spaced and arranged one above the other, extending from an inner surface of the cavity to an outer surface, the mold comprising an investment surrounding a core for the production of cavities and ducts which is soluble upon casting, wherein, the core for the formation of film cooling ducts having a large length-diameter ratio comprises a multitude of core pins of an extension corresponding to the duct length which, in a longitudinal direction of the casting mold, are spaced and arranged one above the other and in that adjacent core pins are connected to each other by at least one cross-pin which is arranged generally normal to the core pins and which intersupports the core pins during a core making and a casting process.  
   
   
       2 . A casting mold in accordance with  claim 1 , wherein, in the longitudinal direction of the casting mold, adjacent cross-pins, that lie above one another, are arranged regularly offset to each other.  
   
   
       3 . A casting mold in accordance with  claim 2 , wherein a number of cross-pins arranged between two core pins is variable in dependence of the length of the core pins.  
   
   
       4 . A casting mold in accordance with  claim 3 , wherein the cross-pins are related to the core pins in an area of a portion of the mold forming the trailing edge of the turbine blade.  
   
   
       5 . A casting mold in accordance with  claim 1 , wherein the cross-pins are related to the core pins in an area of a portion of the mold forming the trailing edge of the turbine blade.  
   
   
       6 . A casting mold in accordance with  claim 1 , wherein a number of cross-pins arranged between two core pins is variable in dependence of the length of the core pins.  
   
   
       7 . A cast turbine blade for an aircraft engine having a leading edge, a trailing edge and at least one internal radial cooling air-supplied cavity from which a plurality of cast, radially spaced film cooling ducts extend to an outer surface of the blade to produce a cooling air film, the turbine blade further comprising a plurality of cast cross-ducts, each cross-duct interconnecting two adjacent film cooling ducts, the cross-ducts being positioned generally normal to the film cooling ducts with adjacent cross-ducts connected to a film cooling duct being offset from one another.  
   
   
       8 . A turbine blade in accordance with  claim 7 , wherein a number of the cross-ducts between adjacent film cooling ducts is set in dependence of a length of the film cooling ducts.  
   
   
       9 . A turbine blade in accordance with  claim 8 , wherein adjacent cross-ducts connected to a film cooling duct are offset from one another along a length of the film cooling duct.  
   
   
       10 . A turbine blade in accordance with  claim 9 , wherein the cross-ducts are related to the film cooling ducts in an area of the trailing edge of the turbine blade.  
   
   
       11 . A turbine blade in accordance with  claim 7 , wherein adjacent cross-ducts connected to a film cooling duct are offset from one another along a length of the film cooling duct.  
   
   
       12 . A turbine blade in accordance with  claim 7 , wherein the cross-ducts are related to the film cooling ducts in an area of the trailing edge of the turbine blade.  
   
   
       13 . A method of producing cooling ducts in a turbine blade for an aircraft engine, the turbine blade having a leading edge, a trailing edge and at least one radial cooling air-supplied cavity, the cooling ducts being radially spaced and extending from the air-supplied cavity to an outer surface of the blade to produce a cooling air film, comprising: 
 producing a lost core casting mold for precision casting the turbine blade,    forming a core portion from a material soluble upon casting of the turbine blade, the core portion having a plurality of core pins of an extension corresponding to desired lengths of the cooling ducts which, in a longitudinal direction of the casting mold, are spaced and arranged one above the other, the core pins forming the cooling ducts in the turbine blade when the core material is dissolved during casting of the turbine blade;    forming a plurality of core cross-pins, each of the core cross-pins interconnecting at least two of the core pins to support the connected core pins until dissolved during the casting of the turbine blade, the core cross-pins being formed generally normal to the core pins, the core cross-pins forming cross-ducts between the interconnected cooling ducts when the core is dissolved during the casting of the turbine blade; and    casting the turbine blade to remove the core portion and form the turbine blade.    
   
   
       14 . A method in accordance with  claim 13 , wherein the number of core cross-pins formed between adjacent core pins is varied in dependence of the length of the core pins.  
   
   
       15 . A method in accordance with  claim 14 , wherein adjacent core cross-pins connected to a core pin are offset from one another along a length of the core pin.  
   
   
       16 . A method in accordance with  claim 15 , wherein the cooling ducts are formed in an area of the trailing edge of the turbine blade.  
   
   
       17 . A method in accordance with  claim 13 , wherein adjacent core cross-pins connected to a core pin are offset from one another along a length of the core pin.  
   
   
       18 . A method in accordance with  claim 13 , wherein the cooling ducts are formed in an area of the trailing edge of the turbine blade.