Turbine blade with micro-turbine nozzle provided in the blade root

Abstract

A turbine blade, in the blade root ( 2 ) of which a curved and converging micro-turbine nozzle is provided, includes a passage duct ( 6 ) with large diameter originating at a cooling-air chamber ( 3 ) in the blade root, with a separately prefabricated micro-turbine nozzle element ( 7 ) with minimized flow cross-section, that is variably adaptable in size to the respective operating conditions, being fitted into said passage duct ( 6 ). Due to the reducible air mass flow that is adaptable to the actual requirements in the space between the turbine rotor wheels, air losses are reduced and efficiency is enhanced.

1 . A turbine blade, comprising:
 an airfoil:   a blade root connected to the airfoil;   a cooling air chamber positioned in the blade root and connected between a cooling air supply and the airfoil;   a passage duct connected between the cooling air chamber and an exterior of the blade to a space between turbine rotor wheels;   a separately prefabricated micro-turbine nozzle element having a portion positioned in the passage duct and attached to the blade root, the micro-turbine nozzle element having a duct for directing cooling air flow from the cooling air chamber to the space between the turbine rotor wheels in a direction opposite to a direction of rotation of the turbine rotor wheels, the duct of the micro-turbine nozzle element having a flow cross-section smaller than a flow cross-section of the passage duct and which is selectable in size depending on respective operating conditions.   
     
     
         2 . The turbine blade of  claim 1 , wherein the prefabricated micro-turbine nozzle element is attached to the blade root by a joining process. 
     
     
         3 . The turbine blade of  claim 2 , wherein the prefabricated micro-turbine nozzle element is attached to the blade root by brazing. 
     
     
         4 . The turbine blade of  claim 1 , wherein the micro-turbine nozzle element is a machined component fabricated from a non-machined but shaped blank. 
     
     
         5 . The turbine blade of  claim 1 , wherein the micro-turbine nozzle element is injection molded. 
     
     
         6 . The turbine blade of  claim 1 , wherein the passage duct is a cast duct. 
     
     
         7 . The turbine blade of  claim 1 , wherein the passage duct is a drilled duct. 
     
     
         8 . The turbine blade of  claim 1 , wherein the micro-turbine nozzle element fits entirely within the passage duct. 
     
     
         9 . A method for producing a turbine blade having an airfoil and a blade root connected to the airfoil, comprising:
 forming a cooling air chamber in the blade root and connected between a cooling air supply and the airfoil;   forming a passage duct connected between the cooling air chamber and an exterior of the blade to a space between turbine rotor wheels;   separately fabricating a micro-turbine nozzle element having a duct for directing cooling air flow from the cooling air chamber to the space between the turbine rotor wheels in a direction opposite to a direction of rotation of the turbine rotor wheels, the duct of the micro-turbine nozzle element having a flow cross-section smaller than a flow cross-section of the passage duct;   varying the flow cross-section of the duct of the micro-turbine nozzle element depending on respective operating conditions;   positioning the micro-turbine nozzle element so that at least a portion thereof is placed in the passage duct;   attaching the micro-turbine nozzle element to the blade root.   
     
     
         10 . The method of  claim 9 , wherein the micro-turbine nozzle element is attached to the blade root by a joining process. 
     
     
         11 . The method of  claim 10 , wherein the micro-turbine nozzle element is attached to the blade root by brazing. 
     
     
         12 . The method of  claim 9 , wherein the micro-turbine nozzle element is fabricated in a cutting shaping process from a blank produced by non-cutting shaping. 
     
     
         13 . The method of  claim 9 , wherein the micro-turbine nozzle element is injection molded. 
     
     
         14 . The method of  claim 9 , wherein the passage duct is integrally cast when casting the turbine blade. 
     
     
         15 . The method of  claim 9 , wherein the passage duct is drilled into the turbine blade. 
     
     
         16 . The method of  claim 9 , wherein the micro-turbine nozzle element is positioned entirely within the passage duct.